medical neurology · 1-fundamental clinical skills of history –taking & physical examination....
TRANSCRIPT
Medical Neurology
Dr Sadik AL-Ghazzawi
MRCP, FRCP UK
Lecture 1
217-Oct-19
Neurology
Principles of clinical neurology
Anatomy and physiology
317-Oct-19
Nerve cells
Types of nerve cells
1-Neuron (variety of neuron)
2-Glial cells
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a-Astrocyte:
it is the framework which has the following
functions :
*supporting the neuron
*biochemical control of neuron environment
*blood brain barrier by Astrocyte foot
processes.
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b- Oligodendrocyte:
The function of these cells is the formation
and maintenance of the myelin sheath which
is value for transmission of action potential .
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Neuron
(Nerve cell )is the basic unit of the nerve system
,characterized by:
1-limitless connection.
2-Adaptability and variability of functions.
3-Has several projection.
4-The axon transmits the impulses which are
generated in the neuron.
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Anatomical organization of the nervous
system
ONE
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1-Central nervous system (C.N.S.)
A-The brain :- which consist of :
* Cerebral context (CC) :-which consist of:
- Frontal lobe
-Occipital lobe
- Parietal lobe
-Temporal lobe
*Brain stem (mid brain, pones)
*Cerebellum
B- Spinal cord
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2-Peripherals nervous system (P.N.S.)
❖Cranial nerves(12 pairs
❖Spinal nerves ( 31 pairs) divided into :
▪ Cervical spinal nerves (8 pairs)
▪ Thoracic S N (12 pairs)
▪ Lumbar SN (5 pairs)
▪ Sacral SN (5 pairs)
▪ Coccygeal SN ( 1 Pair)
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3-Autonomic nervous system (A.N.S.)It is divide into :
A-Parasympathetic autonomic nervous system
(crainio-sacral) ,this is because it run with cranial
nerves (3rd ,7th, 9th & 10th cranial nerves) and the
sacral spinal nerves ( 2nd ,3rd & 4th).
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B-Sympathetic autonomic nervous
system
( Thoraco-Lumbar), this is because it
runs with thoracic spinal nerves & lumbar spinal
nerves (T1-L3) and also it run with the sympathetic
trunk with its ganglia.
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Functional organization of the
nervous system
TWO
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Functional organization of the
nervous system
The nervous system is divided into the
following parts according to the function of
that part :
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1-Cerebral hemispheres:
at that level the highest nervous system
functions are carried
A-Anterior half
of the cerebral hemisphere
deals with executive functions of the
human brain
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B-Posterior half of the cerebral
hemispheres deals with the
perception of the environment .
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The nervous system is divided physiologically
into:
1-The motor system:
which is responsible for different movement of
different parts of the body.
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Movement definition:
is a contraction or controlled relaxation of a group
of muscles and never a single muscle
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To perform a voluntary movement we need the
participation of the following:
A-The Motor Area
(Precentral area of the frontal lobe:
in this area the first spark for starting the action of
movement
,i.e. cells of motor cortex = movement.
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B-The cerebellum :
which complements the function of the motor area by
adding :
a-coordination
b- timing of contraction and relaxation of the muscle fibers
.
3- Extrapyramidal motor system,
complement the function of the motor area by giving the
movement its smooth and nice shape
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i.e.Cerebellum control the coordination of movement and
Extrapyramidal motor system control the shape and
smoothness of the movement ,while the motor area ignite
the spark of the voluntary movement .
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4- Anterior horn cells of the spinal cord and motor cranial
nuclei .-----------
5- The muscle fiber
SO,
A group of anterior horn cells = muscle
Cells of the motor cortex = movement
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Anatomy of the motor system
1-The motor system starts within the PCJ(1) of the cerebral
cortex of the frontal lobe .
2- motor signals passes within the corticospinal tract(2)
through the internal capsule(3) ,brain stem(4) were motor
fibers
coming from the motor cranial nuclei to join the CST to
decent down to
3-the spinal cord (anterior horn of the spinal cord).
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*PCJ initiates movements of different parts of the opposite
side of the body.
The representations of the movement of different parts of
the body are represented from below-upward (upside
down) in the precentral jyris cells ( the foot ,legs ,thigh
,arm ,hand ,face and tongue )are represented upside
down were the cells of the movement of the foot are
uppermost and the cell of the movement of the tongue are
the lower most.
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NOTE,
This wide representation of the body in the
precentral
jyrus leads to a limited loss of function when part of
the PCJ is affected ,example: monoplegia
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Upper motor neuron
Which include the motor system from the cerebral cortex
down to the anterior horn cell of the spinal cord passing
through the corticospinal tract which decussates below the
brain stem (lateral corticospinal tract).
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Lesion of UMN above the decussating results in :
❖Loss of some voluntary movement on the opposite side of
the body .
❖Preservation of the reflex activity (difference between UMN
and LMN ).
❖Heightened (increase the reflex activity because of the loss
of the inhibitory action of the UMN on the LMN .
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Upper motor neuron lesion results in :
A-Positive phenomenon (increase reflex activity )
b- Negative phenomenon (loss of voluntary movement).
Signs of UMN dysfunction
➢ Muscle paralysis on the opposite side of the body for the
voluntary movement
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Hypertonia:
increase in the muscle tone ,which is of clasp knife type or
spastic type , which has pyramidal distribution i.e: involve
the flexor muscles of the upper limb and the extensor
muscles of the lower limb.
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➢ Hyperreflexia.
➢ Extensor planter
➢ All on the opposite side.
➢ Loss of abdominal reflexes
➢ No muscle atrophy but long term disuse atrophy.
➢ Normal electrical activity in the muscle fibers.
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Anatomy of lower motor neuron
Include,
1-Anterior horn cells
2- Anterior nerve roots
3- Peripheral motor nerves
4- Muscles
i.e .Motor unit=AHC +Axon +Group of muscle fibers
Note: the nutrition of the muscles depend on the LMN
integrity.
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Signs of LMN dysfunction
1-Paralysis of all movements (voluntary and involuntary),
the difference between UMN and LMN.
2- Hypotonia (flaccidity): loss of muscle tone.
3-Hporeflexia or areflexia.
4-Preservation of the abdominal reflexes
5-Flexor planter reflex
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6- Wasting of the muscles supplied by the LMN in 2-3 weeks
time, this is because the nutrition of the muscles depends
on the integrity of the LMN.
7- Fibrillation (spontaneous single fiber contraction), which
is invisible and it is electromyographic feature.
8- Fasciculation: Spontaneous contraction of a group of a
muscle fibers (visible).
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2-Basal ganglia----- (EPS)
which are collection of ganglions in the depth of the
cerebral hemisphere to complement the function of
the motor system(PS) for optimum motor control.
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3-Thalamus,
This part of the brain deals with the
appreciation and attention to the sensory
perception .
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4-Limbic system ,
deals with the emotions and memory .
5-Hypothalam the part of the brain which
deals with the internal body
functions (internal environment).
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6-Brain stem,
That part of the central nervous system which
has the following functions:
A-harboring the sensory and the motor
pathways entering and leaving the cerebral
hemisphere .
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B-Housing nuclei of the cranial nerves (3rd &4th)
which control the conjugate eye movements
( internuclear mechanism of the conjugate eye
movements) .
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C-containing the central nuclei for the cardio-
respiratory control.
D-Maintenance of the arousal of the human brain .
(RAS)
E-Complement the cerebellum for the balance
control .
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7-Spinal cord,
it has the following functions:
A-Containing the afferent and efferent fibers to the
central nervous system.
B-It contains and control the lower order motor
reflexes.
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C-Primary processing of the sensory information
coming through the sensory system, including the
pain sensation analysis.
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8-Peripheral nervous system
which compose of:
A-Afferent and efferent connection.
B-Sensory cells in the dorsal root ganglia .
C-Motor cells in the anterior horn of the spinal
cord .
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These 3 divisions of the peripheral nervous
system compose the essential parts of the (lower
motor neuron unit) .
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.
9-The autonomic nervous system,
( sympathetic
and parasympathetic )
has the following function:
A-Unconscious neural control of the body
physiology.
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B-Cardiovascular and respiratory system control.
C-Control Smooth muscles and the glands of
gastrointestinal
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Note:-
The ANS is controlled centrally by diffuse
modulatory system in the brain stem , limbic
system and frontal lobe
(the arousal(1) and
Background(2) behavioral responses to threat.
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Clinical skills in Solving Neurological Problem
ONE
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1-fundamental clinical skills of history –taking & physical
examination.
Neurological diagnosis . divided, to,
1-Functional diagnosis.
2-Etiological diagnosis
3-anatomical diagnosis,(what is the site of the lesion in
the N.S.)
4-pathological diagnosis,(what disease process has
occurred at the site).
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The history.
Rule ONE
important in determining both the anatomical &
pathological diagnosis.
Rule TOW-
many neurological patients have no abnormal
signs, or simply have physical features that
confirm clinical suspicions base on the history.
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Rule THREE
In complex problems, the history can only yield a , short
list, of potential site of the lesion(s) & final localization
must wait the formal examination.
Rule FOUR -
this is because disease at one site in the N.S may produce
symptoms mimicking a lesion at another site.
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presenting complain;
1-allow the patient sufficient uninterrupted time to
speak. age. occupation. handedness. hemisphere
dominance.
History
1-probe the history in specific areas.
2-timing of symptoms.
onset, progression, duration, recovery, frequency.
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Discriminate questions ;is
To differentiate between tow pathology which
could produce similar clinical picture .e.g. ,
Glove & stocking sensory loss in peripheral
neuropathy & C. spinal cord disease.
(neck pain , injury, sphincter dysfunction)
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Examination .
Initial impression,
Gait, facial expression, hand shake, speech,
cognitive function.
(Screen) examination,
1-level of consciousness.
2-cognitive function.
3-speech.
4-cranial nerves.
5-neck & trunk
6-limbs-motor & sensory examination.
7-gait.
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1-Neurological disease may produce systemic
signs and systemic disease may affect the
nervous system
2-a complete general examination must
therefore accompany that of the
central nervous system.
3-in particular , note the following:
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Temperature Evidence of weight loss
Septic source, teeth ,ears
Blood pressure Breast lumps
Skin marks, e.g. reshes
Neck stiffness lymph adenopathy
café-au-lait spots
Pulse irregularity hepatic & splenic
angiomata
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Carotid bruit enlargement
Anterior fontanelle baby
Cardiac murmurs Prostatic irregularity
Head circumference
Cyanosis /respiratory
insufficiency
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CNS examination is described systematically
from the head downward
and include:
1-Conscious level and higher cerebral function
2-Cognitive skills –Memory –Reasoning -
Emotional states
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2-Cranial nerves(1-12)
--------------------------------------------------------------------
-------------------------------------
3-Upper limbs
-Motor system –wasting
- tone
-power
-Sensory system- pain
-touch
-temp
-proprioception
-stereognosis
-Reflexes
-Coordination -
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4-Trunk
-sensation
-reflexes
----------------------------------------------------------------------
---------------------------------
5-Sphincters
----------------------------------------------------------------------
---------------------------------
6-Lower limbs
-motor system
- -wasting
-tone
-power
-sensory system
- -pain
-touch
-tempt
-proprioception
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-reflexes
coordination-gait,- stance
----------------------------------------------------------------------
--------------------------------
*Alternatively the examiner may prefer to work
through individual systems for the whole
body,e.g.motor system, sensory system
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Symptomology in Nervous System
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Central Nervous System
(Upper Motor Neuron)
1-Brain
2-Spinal Cord
UMN Lesion
1-Cognitive disorders
2-Spastisity
3-Hyperreflexia
4-Sensory alteration
5-Pathological reflexes
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1-Cerebral Hemispheres
1-White Matter Tracts
2-Cerebellum
3-Basal Ganglia
4-Brain Stem
Ii-Spinal Cord
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A-Cortical (gray matter) lesions
Defect in Higher cortical functions
1-Dementia.
2-Aphasia.
3-Seizures.
B-Subcortical (white matter) lesions
1-Hemiparesis
2-Hemisensory defects.
C-mixed cerebral lesions
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Peripheral Nervous System(PNS)
Lower motor neurons
A-Weakness
B-Flaccidity.
C-Sensory alterations.
D-loss of deep tendon reflexes.
E-absence of pathological reflexes
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-Cranial nerves iii—xii
Spinal nerves & nerve roots—
Cauda equina
Lmn
(anterior horn cell, neve root , plexus
,peripheral nerves,
Neuromuscular junction,skeletal muscles).
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Higher cortical functions
TWO
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Higher cortical functions
1-Frontal lobe functions
a- Executive functions
b- Behavioral function
c- Motor area
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The functional area of the frontal lobe are :
1-Primary motor cortex (pre central jyrus)
2-Brocas area (speech center)
3-Frontal eye field center (Broadman 8)
4-Higher order motor control
5-Micturation center
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Frontal lobe syndromes:
1-Personality changes: with diffuse frontal lobe
damage.
2-Behavioral disturbances
3-Antisocial behavior
4-Expressive dysphasia
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5-Incontinence
6-Anosmia
7-Contralateral hemiparesis
8-Return of primitive reflexes i.e. sucking reflex ,grip
reflex.
9-Focal motor seizure
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Parietal lobe function:
❖Integration of sensory perception.
Dominant parietal lobe dysfunctions:
▪Language disorder
▪Calculations disorders
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▪Apraxia :
▪
is the inability to perform complex organized function in
▪
the presence of a normal basic motor ,sensory and
▪
cerebellar system (planning and ideation disorder) .
▪
It is resulted from sensory inattention and spatial
perception disorder .
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Temporal lobe
It contains the following:
1- Primary auditory cortex
2- Primary vestibular cortex
3- Memory function
Occipital lobe
It contains the visual and image processing.