glossary of neurology terms

8/2/2019 Glossary of Neurology Terms

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abducens nerve (cranial nerveVI) motor nerve innervating the

lateral rectus muscle,

which abducts the eye; lesions of

the nucleus, which is located in

the dorsal pons, produce a

horizontal gaze palsy; nerve fibers

exit the ventromedial pons &

because of their long course arevulnerable to damage by mass

lesions/increased intracranial

pressure

abduct move away fromthe saggittal plane of the body

absence seizure (petit malseizure) generalized

seizure characterized by abrupt

cessation of ongoing activity with

a blank stare & lost or impaired

consciousness lasting on average10-20 seconds

abulia loss of will, impulse, &decision-making ability


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acalculia "inability to calculate"or difficulty with arithmetic; may

be the result of damage to

the angular gyrusin

the hemisphere dominant for

speech & language

acephalicmigraine migraine variant

consisting of the migraineaura without the headache; also

known as migraine

equivalent accommodation adjust

ment of the focal length of the lens

of the eye in order to keep objects

at varying distances in focus onthe retina

acrocephaly actionpotential see brachycephaly

action potential rapid, transient,all-or-none nerve impulse initiatedat the axon hillock; electrical

signal by which the brain receives,

analyzes, & conveys information


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action tremor tremor that appearsduring movement of the affected

body part

activities of daily living(ADLs) activities a person

performs for self-care (feeding,

grooming, bathing, dressing),

work, homemaking, & leisure;

ability to perform ADLs is oftenused as a measure of

ability/disability

activity limitations difficulties anindividual may have in executing

specific tasks or actions (e.g.,

walking independently).

acute developing over minutes tohours; implies acute metabolic

dysfunction

(e.g., ischemia, seizure )

Acute DisseminatedEncephalomyelitis(ADEM) acute, classically

monophasic demyelinative disease

of theCNS that may follow a viral

syndrome or vaccination or no

identifiable predisposing cause


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adduct move towardsthe saggittal plane of the body

Adies syndrome associationof Adies tonic pupil with absence

of muscle stretch reflexes

Adies tonic pupil irregularlydilated pupil exhibiting minimal or

no reaction to light, slow reaction

to accommodation, &hypersensitivity to pilocarpine;

typically idiopathic & most often

seen in young women

adrenoleukodystrophy typicallyX-linked

recessive demyelinative disease

adrenal dysfunction due to

accumulation of very long chain

fatty acids

afferent sensory pathwayproceeding toward the CNS fromthe peripheral receptor organs

afferent pupillary defect


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(Marcus-Gunn pupil) pupillarydilation in the eye with a pre-

chiasmic optic pathway lesion

(e.g., optic neuritis) in response to

shining a light in the damaged eye

after first shining it in the normal

eye

ageusia impaired sense of taste agnosia inability to recognize &interpret objects, people, sounds,

or smells despite intact primary

sense organs (e.g., inability to

identify a sound despite intact

hearing); typically results from

damage to the occipital or parietal

lobe

agraphia inability tocommunicate ideas in written

language not due to mechanical

dysfunction; typically results fromdamage to the parietal lobe.

akathisia motor restlessness;inability to sit still


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akinesia paucity ofmovement akinetic

mutism disorder of consciousness

characterized by periods of sleep

& periods of wakefulness during

which the patient lies with eyes

open but is unresponsive, mute, &

immobile; often due to frontal lobedamage

alexia inability to read, usuallydue to a lesion of dominant

occipitotemporal cortex

alien hand syndrome syndromecharacterized by the involuntary

movement of a single upper limb

in conjunction with the experience

of estrangement from or

personification of the movements

of the limb; often seenin corticobasal

degeneration allodynia condition

in which an ordinarily painless

stimulus is experienced as being

painful


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alpha motor neurons largemotor neurons that innervate

extrafusal skeletal muscle

fibers alpha-synucleinprotein

expressed predominantly in

the CNS that when aggregated,

can result in neurodegenerative

diseases such as Parkinsondisease, dementia with Lewy

bodies, & multisystems atrophy

Alzheimers disease mostcommon cause of dementia in

older adults; a neurodegenerative

disease characterized by thegradual loss of cognitive ability in

association with the

neuropathological findings of

abnormal protein aggregates

(neuritic plaques & neurofibrillarytangles) & neuron loss in

the cerebral cortex


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amaurosis fugax temporary lossof vision in one eye due to

impairment of blood supply

through the internal carotid

artery or the ophthalmic artery

amblyopia developmentalabnormality in which a child fails

to develop sharp visual acuity amygdala telencephalic gray

matter structure located in the

anterior portion of the medial

temporal lobe involved in

emotion, cognition & the

regulation of autonomic processes;

part of the limbic system

amyotrophic lateralsclerosis (Lou Gehrigs disease)

inexorably progressive & fatal

disease of unknown causecharacterized by slowly

progressive degeneration

of upper & lower motor neurons

analgesia loss of pain sensation


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anencephaly(aprosencephaly) CNS malformat

ion involving failure of closure of

the cephalic end of the neural tube,

resulting in absence of

the forebrain & cerebrum;

rudimentary brainstem may be

present so that reflex actions such

as breathing & responses to soundor touch may occur

aneurysm (brain aneurysm,cerebral aneurysm) a bulging

formation on an artery, usually

caused by hypertension or an

excessive amount of fatty deposits

angular gyrus gyrus locatedimmediately posterior to the

supramarginal gyrus at the

superior edge of the temporal lobe

& involved in recognition ofvisual symbol; lesions can result

in alexia & agraphia

anhidrosis absence of sweating anisocoria pupillary asymmetry


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ankle-foot orthosis (AFO) bracethat is worn on the lower leg &

foot to support the ankle & correct

foot drop

anomia inability to name objectsor to recognize written or spoken

names of objects

anosmia loss of sense of smell anosognosia lack of awareness of

or indifference to ones own

neurological deficit, seen with

nondominant parietal lobe lesions

anterior cerebral artery a branchof the internal carotid artery;

supplies blood to the medial aspect

of thecerebral cortex (leg area

predominant), some areas of the

frontal lobe, corpus

callosum, caudate, & the anterior

limb of the internal capsule


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anterior commissure one of thethree major groups of commissural

fibers that courses through

the basal ganglia & cross the

midline in the anterior forebrain to

interconnect the olfactory

bulbs, amygdala,

&hippocampal areas, among

others anterior communicating

artery branch of the internal

carotid artery that joins together

the paired anterior cerebral arteries

anterior cord syndrome spinalcord injury syndrome associated

with damage to the anterior 2/3 of

the spinal cord, often due to

occlusion of the anterior spinal

artery resulting in

bilateral paralysis, bladderdysfunction, & loss of pain

sensation below the level of the

lesion


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anterior cranial fossa portion ofthe internal base of the skull

housing the frontal lobes

anterior horn (ventralhorn) gray matter in the front of

the spinal cord that

contains motor_neurons

Anton's syndrome formof cortical blindness in which thepatient is unaware of/denies the

visual impairment; due to a lesion

of the occipital lobe extending

from primary visual cortex into

visual association cortex

aphasia syndrome of disorderedexpression or comprehension of

spoken &/or written language

caused by brain injury; see

also non-

fluent, fluent, conduction, global, transcortical motor, & transcortical

sensory aphasia


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aphemia inability to speak wordsdespite being able to make other

sounds

aphonia complete loss of voice apnea test part of the brain

death exam; verifies lack of

responsiveness to carbon dioxide

(paCO2 > 60 mm Hg) in the

presence of respiratory acidosis(pH < 7.3)

apraxia impairedplanning/sequencing of movement

that is not due to weakness,

incoordination, or sensory loss.

Although the movements cannot

be performed for a specific

situation, they may be performed

under other circumstances (e.g.,

inability to lift feet off the floor

when attempting to walk butpreserved ability to perform

bicycling movements of the legs

while lying in bed). Results from

dissociation of parts of

the cerebrum& is often associated

with parietal lobe lesions.


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aprosencephaly see anencephaly arachnoid middle layer of

the meninges covering the brain &

spinal cord

arachnoidgranulations (arachnoid villi)

branched tufts of arachnoid thatproject through the dura mater into

the venous sinuses & function to

return CSF to the systemic

circulation

arachnoid villi diverticula ofthe arachnoid mater in

the subarachnoid space that extend

into the veins & venous sinuses of

the dura; a major pathway for the

drainage of cerebrospinal fluid &

transport across the endotheliuminto the blood.

arcuate fasciculus pathwayconnecting Wernickes area in the

posterior left superior

temporal gyrus to Brocas area in


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the left inferior frontal lobe; lesion

results in impaired repetition

area postrema chemoreceptortrigger zone for vomiting that is

located on the dorsal surface of

the medulla

Argyll-Robertson pupil pupilexhibiting light-near

dissociation due to a lesion inthe midbrain periaqueductal

gray matter caused by tertiary

syphilis arousal abrupt change

from sleep to wakefulness, or from

a "deeper" stage of non-REM

sleep to a "lighter" stage

arteriovenous malformation atangled collection of abnormal

arteries & veins

arteritis inflammation of an artery arthrokineticnystagmus nystagmus induced by

passive rotation of the arm of a

stationary subject seated in total

darkness inside a rotating drum


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ascending tract of Deiters directpathway (lying just lateral to

the medial longitudinal fasciculus)

from the vestibular nuclei to

the ipsilateral medial rectus

subnucleus; clinical significance

of this pathway is unclear

aseptic meningitis syndromecharacterized by headache, neckstiffness, low grade fever,

& Cerebro Spinal

Fluid lymphocytic pleocytosis in

the absence of an acute bacterial

pathogen; often usedsynonymously with

viralmeningitis, but also incudes

meningeal inflammation due to

various drugs (e.g., NSAIDs) or

diagnostic procedures (e.g.,angiography); atypical bacterial,

fungal, parasitic,

or parameningeal infection;

neoplastic processes; & various

systemic disorders


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asomatognosia inability torecognize part of ones own body,

seen with nondominant parietal

lobe (or less commonly premotor

cortex) lesions

associated reactions movementsof body parts other than the ones

that are intended to move, oftenincreased with increased effort

association cortex cortical areasinvolved in higher order

processing of sensory information

& integration of multiple sensory

& sensorimotor

modalities astasia inability to

stand because of motor

incoordination

astasia-abasia functional stance &gait characterized by bizarremovements, typically swaying

wildly & nearly falling, but then

recovering at the last minute


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asterixis sudden palmar flappingmovement of the hands at the

wrists; indicative of

metabolic encephalopathy

astrocytes CNS glia that functionto orient neuroblast migration in

the cerebral

& cerebellar hemispheres, providemechanical support, react to

injury, insulate synaptic surfaces,

provide a source & sink for

extracellular potassium, & uptake

neurotransmitters to terminate

their synapticaction astrocytoma most

common central nervous

system tumor derived

from astrocytes astrocytosis reacti

on of astrocytes to neuronal injurycharacterized by an increase in the

number & size of astrocytes

(primary reaction) & cytoplasmic

changes including increased glial

filaments & glassy eosinophilic

cytoplasm followed by formation


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not under conscious control (e.g.,

heartbeat, breathing, sweating)

autonomic nervous system partof the peripheral nervous

system that regulates visceral

function & homeostasis

independent of voluntary control

autoregulation physiologicalprocess by which blood vesselschange caliber to maintain

constant cerebral blood flow over

a wide range of cerebral perfusion

pressures axial transverse plane

producing a cross-section of the

body or head

axon long, slender projection fromthe neruonal cell body that is

specialized for the conduction of

information encoded in the form

of action potentials axonal degeneration neuropathic

process resulting in degeneration

of the axon & its myelin sheath;

preferentially involves the distal

portion of the axon ("dying

back neuropathy")


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axonalspheroid stereotypic axonal respo

nse to injury consisting of marked

swelling due to accumulation of

materials

undergoing axonal transport

measurement of the eyes abilityto distinguish details; typicallyexpressed as a fraction in which

the numerator (20) indicates that

the subject is standing at 20 feet

from a normal test object & the

denominator is the distance fromwhich a normal subject can read

the same normal image . entire

area visible to an eye that is

fixating straight ahead


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Babinski response extension ofthe great toe on stimulation of the

sole of the foot, signifying a lesion

of thecorticospinal tract (a.k.a.,

upgoing toe); see also plantar

response

Balint syndrome syndromecomprising paralysis of visual

fixation, optic ataxia,& impairment of visual fixation

due to bilateral lesions of the

parietal & occipital lobes

basalganglia large subcortical nuclear

masses consisting of

the caudate, putamen, globus

pallidus,subthalamus, & substantia

nigra; part of the motor system

that permits chosen & inhibits

unwanted movement basalpalisading basal layer of small

cells with darkly staining nuclei &

little cytoplasm seen in the

epithelium of craniopharyngiomas


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basilarartery large brainstem artery

located on the ventral surface of

the pons formed by the joining of

the two vertebral arteries &

bifurcating into the posterior

cerebral arteries; supplies blood to

cerebral circulation & ventral pons

basilar migraine formof migraine characterized by avisual aura followed by an often

occipital headache & one or more

of the following

symptoms: dysarthria, vertigo, tinn

itus, decreased hearing, diplopia,blindness,ataxia,

bilateral paresthesia,

bilateral paresis, & impaired

cognition

behavioral symptom complexchanges in personality & behavior


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Bells palsy(idiopathic facial paralysis) crani

al neuritis affecting the facial

nerve thought to be due to

reactivation of the herpes simplex

virus; results in lower motor

neuron facial

weakness, hyperacusis, taste

disturbance, & impairedlacrimation

Bell's phenomenon fluttering ofthe eyes upward when closed

eyelids are opened by the

examiner

BenediktSyndrome ipsilateral oculomotor

palsy

& contralateral hemichoreoathetos

is due to lesion of

theventral midbrain tegmentum affecting the IIII nerve fascicles &

the red nucleus

Berry aneurysm small saccularaneurysm of an intracranial artery


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Binswangers disease(subcortical

leukoencephalopathy) degenerati

ve white matter disease

producingdementia due to

hypertensive microvascular

changes lipohyalinosis of the small

arteries & fibrinoid necrosisof thelarger vessels inside the brain)

blepharospasm excessiveinvoluntary contraction of the

orbicularis oculi sometimes

resulting in functional blindness; a

focal dystonia

blood-brain barrier specializedsystem of capillary endothelial

cells that strictly limits transport

into the brain through both

physical (tight junctions) &metabolic (enzymes) barriers

borderzone infarct see watershedinfarct

brachial relating to the arm


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brachium anatomical structurecomprising a collection

of axons that resemble an arm

brachiumconjunctivum see superior

cerebellar peduncle

brachium pontis see middlecerebellar peduncle

brachycephaly(acrocephaly) premature fusion of

bilateral coronal sutures producing

a foreshortened skull

bradykinesia slowed movementdue to dysfunction of the basal

ganglia & related structures

bradyphrenia slowing of thoughtprocesses that can occur

in Parkinson disease or as a side

effect of antipsychotic medications

brain death see death byneurological criteria

brainstem medulla, pons,& midbrain


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brainstem auditory evoked potentials (BAEP) series of

waves that reflect sequential

activation of neural structures

along the auditory pathways

following a brief click or tone

transmitted via an earphone or

headphone & measured by surface

electrodes placed at the vertex ofthe scalp & ear lobes; provides

information regarding auditory

function & hearing sensitivity &

used to screen for retrocochlear

pathology (e.g., acousticneuroma),

universal newborn hearingscreening, & intraoperative

monitoring

brain death Brocas aphasia see non-fluent

aphasia Brodmann's areas distinct

regions of the cerebral

cortex recognized by variations in

cell size, density, & thickness of

the cortical layers


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Brown Sequard syndrome spinalcord injury syndrome associated

with damage to one lateral half of

the spinal cord (spinal

hemisection) resulting

in ipsilateral weakness & loss of

vibration proprioception &contrala

teral loss of pain sensation

Brudzinskis sign involuntaryflexion of the hips in response topassive flexion of the neck;

indicative ofmeningeal irritation

bruxism grinding one's teethwhile asleep

bulbar pertaining to the lowercranial nerve nuclei


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burst fracture compressionfracture of vertebral body with

expansion in sagittal & coronal

planes due to axial loading;

unstable & often associated with

spinal cord injury measurement of

the eyes ability to distinguish

details; typically expressed as a

fraction in which the numerator(20) indicates that the subject is

standing at 20 feet from a normal

test object & the denominator is

the distance from which a normal

subject can read the same normal

image .entire area visible to an eyethat is fixating straight ahead


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calcarine cortex primaryvisual cortex located in the

occipital lobe (striate area 17)

carotid sinus arterial baroreceptorlocated at the bifurcation of the

external & internal carotid arteries

that regulates arterial pressure &

heart rate in response to changes in

stretch & transmural pressure carphologia see floccillation catamenial referring to menses;

with regard to women

with epilepsy or migraine, a

tendency forseizures/migraines to

occur around the time of menses

cataplexy sudden loss of posturaltone, often triggered by an

emotional stimulus & resulting in

falls to the floor; seen

in narcolepsy


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cauda equina (horses tail)collection of intradural spinal

nerve roots

caudal to the spinal cord thatsupply the lower limbs & pelvis;

since this structure is part of

the peripheral nervous system,

lesions produce lower motor

neuron deficits caudal toward the tail caudate portion of the basal

ganglia that lies in the floor of the

lateral ventricle

cavernoma (cavernousmalformation) vascular

malformations composed

primarily of large venous channels

without a clear-cut arterial

component


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cavernous sinus paired, venousstructures located on either side of

the sella turcica that receive blood

from the superior & inferior

orbital veins & drain into the

superior & inferior petrosal

sinuses; contains thecarotid

artery & its sympathetic plexus,the oculomotor nerves (III, IV,

VI), & the ophthalmic branch of

V; lesions typically result

in ophthalmoplegia, orbital

congestion, & proptosis

centralchromatolysis regenerative

response to axonal injury

consisting of neuronal swelling,

nuclear eccentricity, & loss of

Nissl substance


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central cord syndrome spinalcord injury syndrome associated

with damage to the central portion

of the spinal cord characterized by

bilateral weakness of

distal>proximal muscles in the

arm>leg, bladder dysfunction, & avariable degree of sensory loss

below the level of injury

central herniation downwarddisplacement of the cerebral

hemispheres pushing

the diencephalon &midbrain through the tentorial notch; symptoms

classically follow a rostrocaudal

deterioration

central nervous system(CNS) brain & spinal cord

central pain syndrome intensepain arising from injury to

the central nervous system, most

often in patients who have had

a stroke, multiple sclerosis, or

brain injury.


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central sulcus prominent sulcuson the dorsolateral aspect of

the cerebral hemispheres formed

by the precentral &

postcentral gyri; defines the

boundary between the frontal &

parietal lobes centrum semiovale expansive

region of white matter in the

dorsal core of the frontal &

parietal lobes, named because of

its central position in

the forebrain & its semi-ovalshape

cephalic relating to the head cerebellar peduncle three

major white matter structures

containing #efferent & afferent axons of thecerebellum; named the

inferior, middle, &

superior cerebellar peduncles

cerebellar tonsil lateral portionsof the uvula located in the

posterior lobe of the cerebellum


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cerebellopontine angle spacelocated at the junction of

the cerebellum, pons,

& medulla containing cranial

nerves V-XI, blood vessels,

the flocculus of the cerebellum, &choroid plexus

cerebellum brain structurein posterior fossa that coordinates

the many muscles active in any

given movement; receives input

from spinal cord & cerebralcortex & projects to postural &

voluntary motor control systems

& red nucleus

cerebral amyloid angiopathy(congophilicangiopathy) vascular disorder in

which beta amyloid protein is

deposited within the media &

adventitia of small- to medium-

sized meningeal & cortical blood

vessels, causing them to become


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brittle & break; important cause of

predominantly lobar intracerebral

hemorrhage in the elderly

cerebral aqueduct portion of theventricular system that lies in the

dorsal midbrain & connects the

third & fourth ventricles

cerebralarteriosclerosis thickening &hardening of the arteries within the

brain

cerebral atherosclerosis build-upof fatty deposits in the inner wall

of cerebral arteries; form

of cerebral arteriosclerosis

cerebral atrophy the shrinking ofthe brain or brain cells.

cerebral autosomal dominantarteriopathy

with subcortical infarcts &leukoencephalopathy

(CADASIL) familial arterial

disease of the brain caused by

mutations in the Notch3 gene &

consisting of

recurrent subcortical strokes starti


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ng in midadult life, dementia,

depression, & migraine

cerebral cortex highly convolutedlayer of gray matter that

constitutes the outermost layer of

the cerebrum& is responsible for

integrating sensory impulses & for

higher intellectual functions

cerebral hemisphere symmetricalhalf of the cerebrum as separatedby the sagittal sulcus & containing

thecerebral cortex, basal

ganglia, hippocampus,

& amygdala

cerebral peduncle (cruscerebri) white matter tracts

(corticospinal & corticobulbar) on

the ventral surface of

the midbrain containing

the efferent axons of cerebralcortex that project to brainstem &

spinal cord

cerebral perfusion pressure(CPP) mean arterial pressure

(MAP) intracranial pressure

(ICP)


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cerebral salt wasting centrally-mediated hypovolemic

hyponatremia associated with

negative sodium balance that

occurs in approximately 30-50%

of patients with subarachnoidhemorrhage despite their being

given maintenance volumes of

fluids; excessive sodium loss is

thought to be due to impaired

sodium reabsorption in the

proximal tubule & may be causedby disruption of sympathetic input

to the kidneys, production of a

circulating natriuretic factor, or

both

cerebritis inflammation of thebrain


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cerebrospinal fluid (CSF) clear,colorless fluid bathing the entire

surface of the CNS, most of which

is secreted by the choroid

plexus & the remainder by brain

capillaries; flows through theventricles & out into

thesubarachnoid space via the

foramen of Magendie in the

midline & the two foramina of

Luschka at the lateral margins of

the roof of the 4th ventricle, thenis absorbed through the arachnoid

villi in the walls of dural sinuses &

returned to the systemic

circulation

cerebrum anteriorportion of thebrain consisting of the

two cerebral hemispheres that each

contain four lobes

Charcot-Bouchardaneurysm aneurysmal dilation of

small intraparenchymal vessels


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commonly seen in the brains of

patients with hypertensive

hemorrhage

Charcot joint progressivedestruction & deformity of bone &

soft tissue at weight bearing joints

due to severe sensory orautonomic neuropathy cheiro relat

ing to the hand

Chiarimalformation CNS disorder

characterized

by cerebellar elongation &protrusion through the foramen

magnum into the cervical spinal

cord. Type I consists

of caudal displacement of

the medulla & inferior pole ofthe cerebellar hemispheres through

the foramen magnum. Type

II=type I + hydrocephalus &

lumbosacralspina bifida. Type III

involves herniation of the

entire cerebellum through the


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foramen magnum with a

cervicalspina bifida cystica. Type

IV involves cerebellar hypoplasia

chorea involuntary, irregular,rapid, jerking movements

choroid plexus intraventricularstructure thatsecretes cerebrospinal fluid

choroid plexuspapilloma histologically benign

intracranial tumor of

neuroectodermal origin that is

most commonly located in

a ventricle (lateral>fourth>third),

where it often presents with non-

communicating hydrocephalus due

to overproduction of CSF; may

also be seen inthe cerebellopontine angle

chronic daily headache headachedisorder consisting of frequent

headache occurring 15 or more

days per month & including


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headache associated with

medication overuse

chronic paroxysmalhemicrania indomethacin-

responsive headache disordercharacterized by the occurrence of

multiple daily attacks lasting 5 to

30 minutes of severe unilateral

head pain often associated

withautonomic phenomenon (eye

tearing, eye redness, eyelid edema,nasal congestion, runny nose); also

known as atypical cluster

headache

chronic-progressive developingover months to years; impliesgradual deterioration as occurs

with degenerative diseases

like Alzheimer

disease, Huntington disease, etc.

cingulategyrus cortical component of


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the limbic system located on the

medial aspect of the hemisphere

superior to the corpus callosum;

involved in emotional & cognitive

processing

cingulate herniation horizontaldisplacement of a cerebralhemisphere due to an expanding

lesion that forces the cingulate

gyrus under the falx

cerebri, compressing the internal

cerebral vein &

the contralateralhemisphere circadian rhythm innate daily

fluctuation of physiological or

behavioral functions, including

sleep-wake states generally tied to

the 24-hour daily dark-light cycle Circle of Willis the main arterial

anastomatic trunk located at the

base of the brain; place where the

twointernal carotid arteries &

the basilar artery come together,

allowing blood to be redistributed


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to the anterior,middle,

& posterior cerebral arteries

classic migraine see migrainewith aura

ClaudeSyndrome ipsilateral oculomotor

palsy & contralateral ataxia &hemichoreoathetosis due to

adorsal midbrain tegmental lesion

affecting the III

nerve fascicles, superior cerebellar

peduncle, & red nucleus

claustrum thin plate of graymatter lying in the white

matter between the insula &

the basal ganglia that

modulates cortical activity

clay shovelers fracture typicallystable fracture through a spinousprocess due to hyperextension

injury

clonic seizure generalizedseizure characterized by jerking


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movements on both sides of the

body

clonus rhythmic contractionrelaxation tremor due to cyclic

alternations of the spindle stretch

reflex & theGolgi tendon

organ reflex; indicative of

exaggerated stretch reflexes cluster headache primary

headache syndrome characterized

by intense, unilateral orbital,

supraorbital, &/or temporal pain

lasting 15-180 minutes &occurring in "clusters" up to

several times per day for a period

of one or more months before

going into "remission" for months

or years; diagnosis requires one or

more of the


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following autonomic abnormalities

ipsilateral to the headache:

conjunctival injection,

lacrimation, ptosis, miosis, eyelid

edema, nasal congestion,

rhinorrhea, or facial sweating

CNS central nervous system CNS metastasis metastatic tumors

typically spread by a

hematogenous route & found at

the junction between gray

matter & white matter where they

are trapped by the acute anglebranching of the microvasculature

cogwheeling ratchety movementdue to superimposition

of tremor on rigidity

coital headache indomethacin-responsive headache disordercharacterized by sudden, severe,

throbbing, occipital headache that

occurs just before or during

orgasm


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cold calorics see oculovestibularresponse

coma state of unarousableunresponsiveness with closed

eyes, no speech, & no purposeful

movements

common carotid artery arterythat arises from thebrachiocephalic artery on the right

& from the aortic arch on the left,

ascending in the neck & dividing

at the upper border of the thyroid

cartilage into the external

&internal carotid arteries to supply

the head & neck

common migraine see migrainewithout aura communicating

hydrocephalus blockageof CSF flow outside the

ventricular system, either at the

level of the arachnoid

granulations or because of

overproduction of CSF (e.g., from


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a choroid plexus papilloma) that

exceeds the rate of absorption

complex partial seizure partialseizure in which consciousness or

awareness is impaired; epileptic

discharge either originates

in limbic structures (hippocampus)

or spreads to them from neocortex,

especially from the frontal lobe complex tic distinct, coordinated

patterns of successive movements

involving several muscle groups;

complex vocal tics include

meaningful syllables, words, or

phrases; complex motor tics arecoordinated or sequential patterns

of movement such as twirling a

pencil or touching other people

concussion traumatic closed headinjury that results in temporaryimpairment of neurological

function, e.g., transient loss of

consciousness

conduction aphasia selectiveimpairment of the ability to repeat

due to a lesion of the arcuate


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fasciculus, which connects

Wernickes area to Brocas area

conduction block failure ofimpulse conduction along an

anatomically intact axon;

characteristic

ofdemyelinating neuropathy

contracoup opposite to the site ofimpact

contracture permanent shorteningof the muscles & tendons adjacent

to a joint, which can result from

severe spasticity & interferes with

normal movement around the

affected joint

contralateral located on theopposite side of the body (brain)

contusion edematous brain lesioncontainingpunctuate parenchymal hemorrhag

es on the surface of the brain that

may extend bidirectionally into

the white matter &

the subdural & subarachnoid


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spaces; occur at the site of impact

(coup contusion) with direct

trauma & at a site opposite to the

site of impact

(contracoupcontusion) with

acceleration/deceleration injury

conus medullaris caudal-mostpart of the spinal cord located

between the first & second lumbar

vertebrae. Since this structure is

part of the spinal cord but is in

close proximity to spinal nerveroots, lesions often produce

both upper motor neuron & lower

motor neuron deficits

convergence coordinated inwardmovement of the eyes in order tofixate on a near

object convergence-retraction

nystagmus form

of nystagmus consisting of jerking

eye movements inward &


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backward; associated with

dorsal midbrain lesion

coprolalia uncontrolled, oftenobsessive use of obscene language

occasionally seen in Tourette

syndrome

coronal vertical plane from headto foot & parallel to the

shoulders corona radiata fan-like

arrangement of fibers projecting

from all aspects of the cerebral

cortex & converging towardthe thalamus where they will form

the internal capsule

corpus callosum large fiberstructure that makes connections

between homotopic regions ofthe cerebral hemispheres; bend at

its anterior limit is called the genu;

bend at its caudal end is called

the splenium; portion between the

two is called the body.

corpus striatum see striatum


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cortical referring to the cerebralcortex, the outermost layer of

the cerebrum

cortical blindness apparent lackof visual functioning in spite of

anatomically & structurally intact

eyes due to bilateral lesions of the

primary visual cortex

corticobasaldegeneration progressiveneurological disorder

characterized by nerve cell loss in

the cerebral cortex & basal

ganglia &

producing parkinsonism, dementia

, visual-spatial impairment, alien

hand syndrome, apraxia,

& myoclonus

corticobulbartract axons originating in theposterior frontal lobe & projecting

to lower motor neurons in

the brainstem

corticospinal tract (pyramidaltract) motor pathway responsible

for voluntary movement that arises


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from primary motor cortex, area 6,

& somatosensory cortex &

descends through the corona

radiata, internal capsule, cerebral

peduncle,

medullary pyramid (where it

decussates), & spinal cord to alpha

motor neurons in spinal cord gray

matter cough headache indomethacin-

responsive headache disorder

characterized by transient, severe,

explosive head pain upon

coughing, sneezing, weight lifting,

bending, or stooping coup lesion at the site of

impact Cowdry A inclusion

bodies eosinophilic nuclear

inclusions surrounded by a clear

halo in neurons or glial cellsoccurring in herpes

simplex encephalitis Cowdry B

inclusion bodies large glassy

eosinophilic nuclear inclusions

occurring in herpes

simplex encephalitis


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craft palsy dystonia occurring inthe setting of a highly learned

skilled task, e.g., writers cramp,

yips in golfers

craniectomy surgical removal of asection of bone (bone flap) fromthe skull for the purpose of

operating on the underlying tissues

or relieving intracranial pressure,

in which the bone flap is not

replaced at the end of theprocedure

craniopharyngioma suprasellarWHO grade I tumor of

children/young adults that causes

significant morbidity & mortality;characterized histologically by

basal palisading, wet keratin, &

infiltrative fingers of tumor that

make it difficult to

cure cranioplasty surgical repair

of a defect or deformity of the


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skull; replacement of a bone

flap craniorachischisis

totalis fatal neural tube defect

consisting of total failure

of neurulation; a neural plate-like

structure is entirely exposed

without overlying bony or dermal

covering

craniosynostosis prematureclosure at birth of one or more

cranial sutures, which limits head

growth perpendicular to

the suture(s); seealso brachycephaly, oxycephaly, p

lagiocephaly, scaphocephaly,trigo

nocephaly

craniotomy surgical removal of asection of bone (bone flap) fromthe skull for the purpose of

operating on the underlying

tissues, in which the bone flap is

replaced at the end of the

procedure creatine kinase enzyme

that catalyzes the conversion of


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creatine to phosphocreatine & is

released into the blood by

tissuesparticularly musclethat

consume adenosine triphosphate

(ATP) rapidly; elevated levels are

seen in myopathy

cremasteric reflex superficial(cutaneous) reflex elicited by

stroking the superior & medial

part of the thigh in a downward

direction; normal response is

contraction of the cremastericmuscle that pulls up the scrotum &

testis on the side stroked;

dependent on nerve roots L1 & L2

Creutzfeldt-Jakobdisease fatal prion diseasecharacterized by spongiform

changes in the brain,

progressivedementia, psychiatric

changes, & myoclonus; form

of spongiform encephalopathy


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crossed adductor reflex reflexcontraction of the adductor

magnus caused by tapping the

opposite knee; indication of

hyperreflexia on the side of the

adductor contraction; commonly

thought to be due to stimulation of

the adductor muscle on the

hyperreflexive side through slightjarring of the pelvis

crural relating to the leg cruscerebri see cerebral peduncle

cryptogenic occurring withoutknown cause; in the context

of epilepsy, indicates cases in

which a lesion & distinct

pathogenesis are presumed

cyclotorsion (a.k.a. torsion):rotation of the eye around an

anterior-posterior axis;see excyclotorsion,incyclotorsion

corticobasaldegeneration measurement of the

eyes ability to distinguish details;

typically expressed as a fraction in

which the numerator (20) indicates


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that the subject is standing at 20

feet from a normal test object &

the denominator is the distance

from which a normal subject can

read the same normal image

. entire area visible to an eye that

is fixating straight ahead


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Dawsonsfingers ovoid demyelinating lesio

ns with their long axis

perpendicular to the ventricular

surface seen in multiple sclerosis

death by neurologicalcriteria irreversible loss of all

brain function

decerebrate rigidity stereotypedposture consisting of extension ofall four limbs occurring with

transaction between the superior

collicui & inferior colliculi in

the midbrain; often used

synonymously with extensor

posturing

decorticate rigidity stereotypedposture consisting of flexion of the

forelimbs & extension of the

hindlimbs occurring withtransaction between

the diencephalon & midbrain;

often used synonymously

with flexor posturing


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decussate to cross deja vu feeling as if one has lived

through or experienced this

moment before; may occur in

people without any medical

problems or as a seizure aura_

delayed sleep phasesyndrome circadian

rhythm disorder in which in thedaily sleep/wake cycle is delayed

with respect to clock time such

that sleep occurs well after the

conventional bedtime; common in

young adults

delirium abnormal mental statecharacterized by disorientation,

inattention, confusion, fear,

irritability, perceptual disturbance,

& fluctuating level of

consciousness; common with toxic& metabolic disorders & acute

febrile systemic infections


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dementia acquired & sustainedloss of memory & other

intellectual functions that is of

sufficient severity to interfere with

daily functioning dementia

pugilistica chronic

traumatic encephalopathy caused

by cumulative & repetitive head

trauma & manifestingas dementia & parkinsonism

demyelination destruction or lossof the myelin sheath

surrounding axons; results in

impaired nerve impulse

conduction

dendrite receiving portion ofthe neuron

denervation loss of nerve supply dermatome distribution of

sensory innervation on the skin ofthe body & the limbs


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diabetes insipidus inability toconcentrate urine resulting from

decreased secretion of antidiuretic

hormone; reflects a lesion of

the hypothalamic osmoreceptors,

supraoptic or

paraventricular nuclei, or the

supraopticohypophyseal tract &may occur in transtentorial

herniation due to downward

traction on

thehypothalamic median eminence

diaphragmasellae thin dural membraneoverlying the sella turcica that is

fenestrated to allow passage of the

infundibulum

diaschisis depression ofmetabolism at sites distant from,but connected with, a site of

cerebral injury (e.g.,infarction) due

to interruption

of afferent or efferent fiber

pathways


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diastematomyelia longitudinaldivision of the spinal cord by a

septum of bone

diencephalon thalamus, hypothalamus, subthalamic nucleus,

& pineal

diffuse axonal injury widespreaddamage to white matter due to

rotational shearing forces withhead trauma

diffuse Lewy body disease (Lewybody dementia) form

of dementia associated with

fluctuating alertness, recurrent

visual hallucinations,

& parkinsonism & defined

pathologically by cortical (as well

as nigral) Lewy bodies

diplegia see paraplegia diplopia double vision dissociated sensory


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deficit impairment ofpain/temperature sensation with

preservation of

vibration/proprioception or vice

versa; implies lesion

of brainstem or spinal cord

involving 1 sensory tract but

sparing the other dolichocephaly see scaphocephaly dolls

phenomenon see oculocephalic

response

dorsal posterior dorsal

columns ascending axonal tract

running in the dorsal funiculus of

the spinal cord that carries tactile

&proprioceptive information to

the brain; fibers cross in theventromedial medulla to become

the medial lemniscus dorsal

horn see posterior horn


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dorsal motor nucleus of thevagus parasympathetic nucleus

that stimulates secretion from

glands of the pharynx & thoracic

& abdominal viscera

dorsal rhizotomy surgicalprocedure involving sectioning of

the dorsal spinal nerve roots

performed to reducespasticity dorsal root ganglion collection of

cell bodies located in the

intervertebral foramina that

transduce sensory information into

neural signals & transmit these

signals to the CNS

dose failure phenomenon inwhich an individual dose of

medication has no effect; occurs

in Parkinson diseasepossibly in

association with a tablet gettingstuck in the throat or delayed

gastric emptying


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double simultaneous stimulation(DSS) ability to detect two stimuli

applied simultaneously to opposite

sides of the body; for tactile DSS,

if a patient is able to identify

which side is being touched when

each side is touched individually,

but extinguishes or neglects one of

the sides when both sides aretouched simultaneously; indicates

dysfunction of the contralateral

posterior parietal lobe

drop metastases tumor masses inthe lumbosacral spinal cord due

to CSF spread of neoplastic cells(e.g.,medulloblastoma)

duction movement of one eye dura mater outermost layer of

the meninges covering the brain &

spinal cord; consists of a thickfibrous tissue that is adherent to

the inner table of the skull &

forms a protective sheath in the

vertebral canal


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dural tail sign tailof dural enhancement seen on CT

or MRI in association with

meningeal neoplasms such

asmeningioma Duret

hemorrhages secondary

hemorrhages occurring in

the diencephalon, midbrain,

& ponsas downward movement ofthe brainstem relative to the

immobile blood vessels on the

surface of the brainstem results in

injury to small penetrating blood

vessels; sequelae of cerebral

herniation dysarthria inability to pronounce

or articulate words due to

disorders of the vocal apparatus

(e.g., lips, tongue, larynx)

dysdiadochokinesia impairedability to perform rapid alternatingmovements (e.g.,

pronation/supination of hands);

indicates cerebellar dysfunction


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dysesthesia pain or discomfort inresponse to a stimulus (e.g., touch)

that would not be expected to

cause pain

dysgeusia distorted tasteperception

dysgraphia a writing disabilitythat results in incorrectly spelled

or written words dyskinesia blanket term for

movement disorders characterized

by increased motor activity

dyslexia disorder that limits theability to read

dysmetria difficulty judging &controlling the speed, distance, or

power of motor actions; tendency

to over- or underestimate the

extent of motion needed

dysphagia difficulty inswallowing

dysphonia voice disorder, oftenrelated to weakness of laryngeal

muscles, in which sound

production is impaired


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dysraphism defective closure ofa raphe, particularly the neural

tube

dyssomnia disorder in which themain complaint is about

inadequate or unrefreshing sleep

dystonia involuntary musclespasms that produce peculiar

postures of different body parts downward displacement of the

cerebral hemispheres pushing

the diencephalon & midbrainthr

ough the tentorial notch;

symptoms classically follow

a rostrocaudal deterioration

measurement of the eyes abilityto distinguish details; typically

expressed as a fraction in which


the subject is standing at 20 feetfrom a normal test object & the

denominator is the distance from

which a normal subject can read





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echolalia imitation of soundswithout comprehension of their

meaning

echopraxia imitative repetition ofthe movements, gestures, or

posture of another person

occasionally seen inTourette

syndrome

Edinger-Westphalnucleus accessory nucleus of eachoculomotor nerve that supplies

preganglionic parasympathetic

fibers for pupillary constriction &

lens accommodation; located in

the midline between the

extraocular oculomotor nerve

nuclei

efferent motor pathwayproceeding from the CNS toward

the peripheral end organs electromyography graphical

representation of the electrical

activity in a muscle

eidetic memory (photographicmemory) ability to vividly recall

visual images, sounds, or objects


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in memory with extraordinary

detail

electroencephalogram(EEG) system for recording the

electrical potentials of the brain

derived from electrodes attached

to the scalp eloquent

cortex regions of the cerebral

cortex responsible for motor,sensory, language or other

cognitive processing that if

removed, will result in a

neurological deficit; identification

of eloquent cortex through brain

mapping is a vital part of theplanning for epilepsy surgery &

resection of brain tumors &

vascular malformations in order to

minimize adverse outcomes from

surgery


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empty sella downwarddisplacement & compression of

the pituitary

gland by cerebrospinal fluid filling

thesella turcica; primary empty

sella syndrome occurs when asmall defect in the diaphragma

sellae increases pressure in the

sella & compresses the pituitary;

secondary empty sella syndrome

occurs when the sella is empty

because the pituitary has shrunkenfollowing injury, surgery, or

radiation

encephalitis inflammation ofbrain tissue

encephalocele failure of bonefusion in the posterior midline ofthe skull resulting in a bony cleft

through which meninges &/or

brain parenchyma protrude

encephalomalacia focal softening

of the brain in areas of tissue death


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following cerebral infarction,

infection, trauma, etc.

encephalopathy literally, "brainsuffering"; diffuse brain

dysfunction that may be caused by

toxins, infection, metabolic or

mitochondrial disease, tumor orincreased intracranial pressure,

trauma, or lack of blood flow or

oxygen to the brain; the hallmark

is impaired level of consciousness

endomysium innermost layer ofconnective tissue that forms aninterstitial layer around each

individual muscle fiber

endoneurium (epilemma)innermost layer of connective

tissue of a peripheral nerve thatforms an interstitial layer around

each individual axon / Schwann

cell unit

enophthalmos recession of theeyeball within the orbit


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eosinophilic neuronalnecrosis neuronal response

to ischemia & hypoxia characteriz

ed by brightly eosinophilic (red)

cytoplasm & nuclear shrinkage

ependyma epithelial lining of theventricles of the brain & the canal

of the spinal cord

ependymal cells typeof glia consisting of cuboidal cellslining the adult ventricles & spinal

canalependymal true rosette halo

of cells surrounding an empty

lumen; fairly specific for, though

infrequently seen

in, ependymomas

ependymoma WHO grade IIprimary CNS tumor of children

(involving the 4th ventricle) &

young adults (involving the spinalcord); characterized histologically

by perivascular pseudorosettes,

ependymal true rosettes, sharp

demarcation, & enhancement on

CT/MRI


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esotropia an eyewith strabismus that deviates

inward

essential tremor medium or highfrequency (4-9 Hz) tremor that

occurs with action or holding a

sustained posture that typically

affects the arms, the head/neck, or

the voice evoked potentials recordings of

the nervous systems electrical

response to the stimulation of

specific sensory pathways; see

also somatosensory evoked

potentials, brainstem auditory

evoked potentials, & visual

evoked potentials

excessive daytime sleepiness(hypersomnolence) subjective

difficulty in staying awake &easily falling asleep when

sedentary

excyclotorsion (a.k.a.extorsion): cyclotorsion of an eye

such that the superior pole rotates

outward


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executive functions higherintellectual functions such as

judgment, insight, reasoning,

abstraction

exophthalmos see proptosis exotropia an eye

with strabismus that deviates

outward

Expanded Disability StatusScale (EDSS) 20-point scale,

ranging from 0 (normal

examination) to 10 (death) by half-

points, that

measures impairment (gait is

heavily emphasized); used in

clinical trials of multiple sclerosis

extensor plantarresponse extension of the greattoe (upgoing toe) with fanning

of the other toes in response to

application of a stimulus to the

skin of the foot or leg; signifies a

lesion of the corticospinal tract

extensor posturing


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suppression of more rostral motor

areas that have been damaged

extensor spasm manifestationof spasticity in which the legs

involuntarily straighten into an

extended position where they

remain for several minutes

extinction see doublesimultaneous stimulation

extra-axial within the skull orvertebral column but outside of the

brain or spinal cord

extrapyramidal movementdisorder not involving

the corticospinal tracts; typically

refers to basal

ganglia orcerebellar disorders

extrasylvian outside of the areasurrounding the Sylvian fissure;

often used synonymously with"transcortical," as in transcortical

motor aphasia & transcortical

sensory aphasia




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F-wave long latency muscle actionpotential seen after supramaximal

stimulation to a nerve

facial masking(hypomimia) decreased facial

expression due to rigidity of facial

muscles

facial nerve (cranial nerveVII) predominantly motor nervesupplying muscles of facial

expression; also carries sensation

(external ear, taste from anterior

2/3 of tongue) via the nervus

intermedius &

preganglionicparasympathetic fibe

rs to the lacrimal, palatal, & nasal

glands

fainting falx cerebri fold of dura mater in

the sagittal sulcus between thetwo cerebral hemispheres

fascicle bundle of axons (nervefascicle) or muscle fibers (muscle

fascicle) surrounded by a layer of

contractile cells (perineurium for

nerves or perimusium for muscles)


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fasciculation spontaneous firingof an axon resulting in a visible

twitch of all the muscle fibers it

contacts; indicative of denervation

festination an involuntarytendency to take short accelerating

steps in walking that can occur

in Parkinson disease

fibrillation spontaneous firing of asingle muscle fiber not visible tothe naked eye, indicative of

denervation or irritable myopathy;

seen electrographically as a brief

action potential with initial

positive (down) wave followed by

negative (up) wave filum

terminale delicate fibrous tissue

structure surrounded by a few

nerve fibers that extends

downward from the conusmedullaris to the first segment of

the coccyx

finger agnosia typeof agnosia characterized by

inability to identify the fingers; a


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component of Gerstmann

syndrome

Fisher scale scale for grading CTappearance in patients with

nontraumatic subarachnoid

hemorrhage; higher scores

predictive of developing

symptomatic cerebral vasospasm

DescriptionGroup Nosubarachnoid blood detected 1Diffuse subarachnoid blood or

vertical layers of blood < 1 mm

thick 2 Localized clots &/or

vertical layers of blood < 1 mm

thick 3 Intracerebral orintraventricular clots with diffuse

or no subarachnoid blood 4

febrile seizure typicallybenign seizure associated with

high fever in children aged 3months to 5 years


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fibrinoid necrosis brightlyeosinophilic lesions in the small

vessels of the brain postulated to

occur because of disordered

cerebral autoregulation in

association with aging &

hypertension; contributes to thedevelopment of lacunar

infarction & hypertensive

hemorrhage

flaccidity severe form of


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flexor plantar response flexion(curling down) of all toes

(downgoing toe) in response to

application of a stimulus to the

skin of the foot or leg; normal

response flexorposturing stereotyped posture

occurring incoma in response to

stimulation in which the upper

extremity flexes & the lower

extremity extends; reflects release

of primitive responses from thesuppression of more rostral motor

areas that have been damaged & is

reminiscent of the decorticate state

demonstrated in animals with

transaction of corticospinal fibersabove the midbrain


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flexor response in thearm stereotyped posture occurring

in coma in response to stimulation

in which the upper extremity

flexes & the lower extremity

extends; reflects release of

primitive responses from thesuppression of more rostral motor

areas that have been damaged & is

reminiscent of the decorticate state

demonstrated in animals with

transaction of corticospinal fibers

above the midbrain flexor spasm often painful

manifestation of spasticity in

which the legs involuntarily pull

upward into a clenched position

for a period of a few seconds floccillation purposeless picking

at clothing or bedding seen

in delirium

flocculus small lobe of theposterior cerebellum; comprises


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the lateral portion of the

vestibulocerebellum

fluent aphasia (Wernickes orreceptive aphasia) impairment of

language comprehension including

impaired repetition due to lesion

of the posterior left superior

temporal gyrus (Brodmann

area 22) fontanel soft membranous gap

between the incompletely formed

cranial bones of a fetus or an

infant; the anterior fontanel (where

the metopic, the two coronal, &

the sagittal sutures come together),fuses at 7-19 months; the posterior

fontanel (where the lambdoid

& sagittal sutures come together)

is often fused at birth

foramen magnum large openingat the base of the skull throughwhich the spinal cord & vertebral

arteriespass from the vertebral

cavity into the cranial cavity

foramen of Magendie midline exitof CSF from the


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fourth ventricle into

the subarachnoid space

foramen of Monro permitscommunication of the

third ventricle with each of the

lateral ventricles on anterolateral

aspect of the third ventricle

foramina of Luschka lateral exitsof CSF from either side of thefourth ventricles into

the subarachnoid space

forebrain portion of the centralnervous system derived

from prosencephalon; commonly

used to denotecerebral

hemispheres & diencephalon

fornix white matter structurecontaining axons that connect

the hippocampus to

the hypothalamus & septalnuclei fortification spectrum

(teichopsia) complex

visual migraine aura consisting of

zig-zag lines or an arc of

scintillating lights forming into a

herringbone pattern & expanding


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to encompass an increasing

portion of a visual hemifield

Foster-Kennedysyndrome ipsilateral anosmia,

ipsilateral optic atrophy,

& contralateral papilledema due to

frontal lobe or olfactory groove

mass lesion

fovea center most part ofthe macula responsible for detailedcentral vision

Fovillesyndrome ipsilateral lateral gaze

palsy, ipsilateral peripheral facial

palsy,

& contralateral hemiplegiadue to

a dorsal pontine tegmentum lesion

affecting the paramedian pontine

reticular formation, facial

nervenucleus or fascicle,& corticospinal tract

fracture-dislocation fracturethrough the articular processes &

disc with or without associated

fracture through a vertebral body

due to flexion/extension with axial


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loading; unstable & often

associated with spinal cord injury

freezing sudden, brief cessation ofmovement; common in Parkinson

disease

Fresnel prisms clear, flexiblepolyvinyl chloride plastic sheets

composed of a series of small

prisms that are used to assess &correct diplopia

fried egg artifact perinuclear haloaround oligodendrocytes caused

by formalin fixation artifact

Friedreichs ataxia autosomal

recessive neurodegenerative

disease caused by GAA triplet

repeat mutation in the gene that

encodes for frataxin, a protein that

regulates mitochondrial

functioning; characterized byweakness, ataxia, sensory loss,

scoliosis, & cardiomyopathy


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frontal eye fields (FEF) regionwithin the frontal lobes from

which voluntary lateral eye

movements originate; with

stimulation (as in seizure), the

eyes move conjugately to the

opposite side; with destruction (as

in a stroke), the eyes look towardsthe lesioned side (loss of

controversion), implying

unopposed stimulation from the

undamaged side

frontotemporal dementia groupof dementing illnesses in whichdisordered behavior (e.g.,

disinhibition) or language

(e.g., aphasia) are

disproportionately impaired in

relation to memory;includes Picks

disease &corticobasal

degeneration


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functional not due to organicdisease


expressed as a fraction in whichthe numerator (20) indicates that





the same normal image . entirearea visible to an eye that is



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gadolinium-enhancinglesion abnormality on MRI that

becomes bright after injection of

the chemical compound

gadolinium; implies breakdown in

the blood-brain barrier

gamma motorneurons neurons that contract the

ends of the muscle spindle so thatspindle sensitivity to passive

stretch is kept constant throughout

muscle shortening

ganglia aggregations of nerve cellbodies gegenhalten see paratonia

gemistocyte reactive astrocyte having increased glial filaments &

glassy eosinophilic cytoplasm

generalized seizure seizure thataffects both cerebral

hemispheres simultaneously &causes unconsciousness at the

outset


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geniculateganglion sensory ganglion of

the facial nerve that innervates

taste buds on the anterior 2/3 of

the tongue

genu kneelike bend in the anteriorpart of the corpus

callosum or internal capsule

germinal matrix a highlyvascular, metabolically active areaof the brain located just beneath

the ependymallining of the

ventricular walls, which is the

source of neurons & glial cells that

will later migrate to cerebral

cortex. It involutes in the second

trimester. Germinal matrix vessels

are fragile & are believed to have

impaired autoregulation, making

them prone to rupture in prematureinfants, resulting in

intraventricular hemorrhage.


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Gerstmann syndrome aneurological disorder that includes

a writing disability

(agraphia or dysgraphia), a lack of

understanding of the rules for

calculation or arithmetic

(acalculia or dyscalculia), an

inability to distinguish right from

left, & an inability to identify

fingers (finger agnosia) that is due

to a lesion of the angular gyrus of

the dominant parietal lobe

Glasgow Coma Scale (GCS) mostwidely used scoring system to

quantify level of consciousness

following traumatic brain injury;

scores range from 3 to 15, basedon the sum of the best eye opening

response, the best verbal response,

& the best motor response

Eye Opening(E)

Verbal Response(V)

MotorResponse


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glia supporting cells of thenervous system that provide

structural & metabolic support for

the neurons;includes astrocytes, oligodendrocy

tes, ependymal cells, & microglia

(M)

4=Spontaneous 5=Normal 6=Normal 3=To voice 4=Disoriented 5=Localizesto pain 2=To pain 3=Inappropriate 4=Withdrawto pain 1=None 2=Incomprehensible 3=Flexes topain 1=None 2=Extends topain 1=None

Total = E+V+M


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glioblastoma multiforme WHOgrade IV astrocytoma

characterized by hemorrhagic

necrosis, endothelial proliferation,

crossing of the corpus

callosum, ring-enhancement on

imaging, & poor survival

gliosis scar or dense fibrousnetwork of glial processes in anarea of CNS injury

global aphasia impairment oflanguage production,

comprehension, & repetition due

to lesion of entire perisylvian

region; usually associated with

right hemiparesis

globus pallidus most medialcomponent of the basal ganglia &

generator of most basal ganglionic

output


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glossopharyngeal nerve (cranialnerve IX) nerve containing motor,

sensory, & parasympathetic fibers;

motor fibers originate in

the nucleus ambiguus & innervate

the stylopharyngeus to elevate the

palate; sensory fibers originate in

the superior & petrosal ganglion &

supply taste to the posterior thirdof the tongue & tactile sensation to

the posterior tongue, pharynx,

middle & external ear, & eustacian

tube; parasympathetic fibers

originate in the inferior salivatory

nucleus & carry secretory &vasodilatory fibers to the parotid

gland


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gray matter part ofthe CNS consisting

of neuronal cell bodies

& dendrites

Guillain-Barre syndrome (acuteinflammatory demyelinating pol

yneuropathy) acute, ascending, &

progressive neuropathy believed to

result from an autoimmuneresponse triggered by an

antecedent illness or various

medical conditions &

characterized by

weakness, paresthesias,

hyporeflexia, &labile autonomicdysfunction; most

patients exhibit absent or

profoundly delayed conduction in

nerve fibers resulting

fromdemyelination, but in a subsetof patients, there is a direct

cellular immune attack on

the axon itselfgustatoryrelating to

the sense of taste


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gyrus convoluted ridge on theouter surface of the brain caused

by infolding of the cerebral

cortex & bound by sulci



the numerator (20) indicates thatthe subject is standing at 20 feet





area visible to an eye that isfixating straight ahead


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habenula diencephalic structurelocated on the dorsomedial surface

of the caudal thalamus that

receivesafferents from the

septal nuclei & hypothalamus via

the stria medullaris & projects

to midbrain nuclei; involved

in autonomic processing

hangmans fracture fracturethrough bilateral pedicles of C2via various mechanisms; typically

unstable

hemianesthesia loss ofsomatosensation on one half of the

body

hemianopia loss of vision in onehalf of the visual field, indicating a

pathological process posterior to

the optic chiasm

hemiballismus involuntary violentflinging or jerking of a limb (orlimbs) in an uncoordinated manner

caused by a lesion of

the contralateral subthalamus


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hemicraniacontinua indomethacin-responsive

headache disorder characterized

by steady, moderately intense

unilateral head pain on which are

superimposed episodes of more

intense pain

with autonomicsymptoms (eye

tearing, eye redness, eyelid edema,nasal congestion, runny nose)

occurring several times a day

hemifacialspasm segmental myoclonus of

muscles innervated by the facial

nerve; may be due to vascularcompression of the facial nerve or

facial nerve injury or tumor, or it

may have no apparent

cause hemifield one-half of the

binocular visual field hemiparesis weakness on one side

of the body

hemiplegia paralysis on one sideof the body


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hemiplegic migraine familialform of migraine characterized by

temporary (usually < 1 hour but

occasionally lasting up to a

week) hemiparesis hemisensory

symptoms often associated with

visual aura & headache; in about

50% of affected families, a defect

may be found on chromosome 19or on chromosome 1 & involves

abnormal calcium channels

heterotopia tissue occurring in anabnormal anatomical

position hindbrain medulla, pons

& cerebellum

hippocampalformation cortical structure in the

medial temporal lobe comprising

the dentate gyrus,hippocampus,

& subiculum; involved in short-term declarative memory


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hippocampus convolutedstructure at the medial margin of

the cortical mantle of the cerebral

hemisphere, bordering the choroid

fissure of the lateral ventricle, &

forming part of the limbic system,

which is concerned with memory

& emotion

Hoffmans sign contraction offingers & thumb when a stimulusis applied to a distal phalanx in

that hand; indication of

hyperreflexia in the upper

extremity

holoprosencephaly failure ofcleavage at the rostral end of the

notochord resulting in midline

fusion of the frontal lobes, midline

facial abnormalities, &

often hydrocephalus & heterotopias Homer-Wright rosettehalo of

cells surrounding a central lumen

containing neuropil; found

in medulloblastomas & PNETs


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Horner'ssyndrome ptosis, miosis,

& anhidrosis ipsilateral to

damaged sympathetic nerve fibers

H-reflex electrical equivalent ofthe monosynaptic stretch reflex

elicited by selectively stimulating

the Ia fibers of the posterior tibial

or median nerve


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Hunt & Hess scale scale forgrading clinical status in patients

with nontraumatic subarachnoid

hemorrhagethat correlates well

with clinical outcome

Description Grade Asymptomatic,

mild headache,slight nuchal

rigidity 1 Moderate to

severe headache,

nuchal rigidity ,no neurologic

deficit other than

cranial nerve

palsy 2 Drowsiness /

confusion, mild

focal neurologic

deficit 3 Stupor, moderate-

severe

hemiparesis 4


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coma, decerebrateposturing 5

Huntington disease fatalautosomal dominant

neurodegenerative disorder

characterized by chorea &

progressive dementia; due to a

trinucleotide CAG-repeat mutation

on chromosome 4 hydranencephaly birth defect in

which the majority of the cerebral

hemispheres & striatum are absent

& replaced by sacs filled

with cerebrospinal fluid;

considered to be an extreme formof porencephaly

hydrocephalus literally "water onthe brain;" increase in size of

ventricles & amount

of cerebrospinal fluid in the brain


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hyperacusis abnormally increasedsensitivity to sound

hyperpathia exaggerated responseto painful stimuli

hypersomnolence see excessivedaytime sleepiness

hypertensivehemorrhage intraparenchymal

hemorrhage with a predilection to

occur deep in the cerebral

hemispheres, especially in

the putamen, thalamus, &

deep white matter, as well as

the pons & cerebellum. These sites

are all supplied by small

penetrating arteries that are subject

to high sheer stress & have no

collaterals, making themvulnerable to the effects of

increased blood pressure

hypertonicity increase in passivemuscle resistance, such

as spasticity or rigidity


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hypertropia an eyewith strabismus that deviates up

hypnagogic hallucination vividdreamlike hallucination that

occurs as one is falling asleep; oneof the symptoms of narcolepsy,

but also experienced by some non-

narcoleptic individuals

hypnic headache indomethacin-responsive headache disorder

characterized by diffuse, throbbing

headache arising exclusively

during sleep, typically between

1:00 & 3:00 AM

hypnic jerk sensation of falling, &then "jerking" awake just as onedrifts to sleep

hypnopompic hallucination vividdreamlike hallucination that

occurs as one is waking up; one of

the symptoms of narcolepsy, but


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also experienced by some non-

narcoleptic individuals

hypoglossal nerve (cranial nerveXII) motor nerve that innervates

all tongue muscles except thepalatoglossus; lesions result in

deviation of the protruded tongue

towards the paralyzed side &

deviation of the tongue at rest

away from the paralyzed

side; nucleus is located inthe medulla

hypomimia see facial masking hypophysis see pituitary gland hypothalamus basal part of

the diencephalon that controlshunger, thirst, body temperature,

& various metabolic processes,

including the maintaining of water

balance

hypotonicity reduction in passivemuscle resistance


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hypotropia an eyewith strabismus that deviates down

hypoxia reduction in the supply ofoxygen to the brain or other vital

organ

hypsarhythmia abnormal EEG pattern of excessive slow activity &multiple areas

of epileptiform activity; associated

with infantile spasms







which a normal subject can readthe same normal image . entire




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ice cream headache nicknamegiven to headaches that are cold

induced; common in migraine

ice-pick headache indomethacin-responsive headache disorder

characterized by momentary,

sharp, &/or jabbing pain that

occurs either once or several times

a day at irregular intervals ictus sudden attack, stroke,

or seizure

idiopathic occurring withoutknown cause; in the context

of epilepsy, indicates cases in

which no lesion is found & a

genetic cause is presumed

impairment problem in bodyfunction or structure such as a

significant deviation or loss (e.g.,

weakness = impairment in themuscles' capability to produce

force)

incisura fissure that separatesthe uncus from the apex of the

temporal lobe


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incyclotorsion (a.k.a.intorsion): cyclotorsion of an eye

such that the superior pole rotates

inward

indomethacin-responsiveheadache class of primary

headache disorders characterized

by a prompt & often complete

response to indomethacin to theexclusion of other nonsteroidal

anti-inflammatory drugs &

medications usually effective in

treating other primary headache

disorders; includes ice-pick

headache, chronic paroxysmalhemicrania, hemicrania

continua, cough headache,

& hypnic headache, among others

infantile spasms formof cryptogenic generalized epilepsy characterized by sudden,

forceful forward flexion of the

trunk & extension of the arms


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infarction permanent tissuedamage & death of all cellular

elements (neurons, glia, vessels)

due to prolonged or

severe ischemia

inferior cerebellar peduncle(restiform body) paired bundle of

fibers traveling to & from

the cerebellum;afferent fibers fromthe dorsal spinocerebellar

tract carry proprioceptive informat

ion from the upper

body;efferent fibers travel to the

vestibular nuclei in

the dorsal brainstem

inferior colliculus pairedstructures on the dorsal surface of

the caudal midbrain overlying

the cerebral aqueduct that process

& relay auditory signalsfrom brainstem centers to

the medial geniculate nucleus of

thethalamus; with the superior

collicui, make up the tectum &

the quadrigeminal bodies


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inferior olivarynucleus prominent nucleus in the

ventral medulla located just lateral

& dorsal to the

medullary pyramids; source of

climbing fibers that provide a

critical input to

the cerebellum involved in

Purkinje cell plasticity & motorlearning

infratentorial belowthe tentorium cerebelli,

i.e., brainstem & cerebellum

infundibulum connectionbetween the hypothalamus &

the pituitary gland (also called the

"pituitary

glossary of neurology terms

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