aminoff 1-10 neurology

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C. MUSCLE POWER

When muscle power is to be tested, the patient is asked to resist pressure eerted b!

the eaminer. Selected indi"idual muscles are tested in turn, and stren#th on the two

sides is compared so that minor de#rees o$ weakness can be reco#ni%ed. Weakness

can result $rom a disturbance in $unction o$ the upper or the lower motor neurons& thedistribution o$ weakness is o$ paramount importance in distin#uishin# between these

two possibilities. Upper motor neuron lesions 'e.#., stroke( lead to weakness that

characteristicall! in"ol"es the etensors and abductors more than the $leors and

adductors o$ the arms)and the $leors more than the etensors o$ the le#s. Lower

motor neuron lesions produce weakness o$ the muscles supplied b! the a$$ected

neurons& the particular distribution o$ the weakness ma! point to lower motor neuron

in"ol"ement at the spinal cord, ner"e root, pleus, or peripheral ner"e le"el.

On the basis o$ the histor! and other $indin#s, muscles that are particularl! likel! to be

a$$ected are selected $or initial e"aluation, and other muscles are subse*uentl!

eamined to determine the distribution o$ the weakness more $ull! and to shorten the

list o$ dia#nostic possibilities. +or instance, i$ an upper motor neuron 'p!ramidal(lesion is suspected, the etensors and abductors o$ the upper etremit! and the $leors

o$ the lower etremit! are tested in more detail as these muscles will be the most

a$$ected.

Weakness ma! also result $rom a primar! muscle disorder 'm!opath!( or $rom a

disorder o$ neuromuscular transmission. n patients with a motor de$icit in all limbs

that is not due to an upper motor neuron lesion, proimal distribution o$ weakness

su##ests a m!opathic disorder, whereas predominantl! distal in"ol"ement su##ests a

lower motor neuron disturbance. Marked "ariabilit! in the se"erit! and distribution o$

weakness o"er short periods o$ time su##ests m!asthenia #ra"is, a disorder o$

neuromuscular transmission. -pparent weakness that is not or#anic in nature also

shows a characteristic "ariabilit!& it is o$ten more se"ere on $ormal testin# than is

consistent with the patients dail! acti"ities. Moreo"er, palpation o$ anta#onist

muscles commonl! re"eals that the! contract each time the patient is asked to acti"ate

the a#onist.

+or practical and comparati"e purposes, power is best #raded in the manner shown in

/able 012. Monople#ia denotes paral!sis or se"ere weakness o$ the muscles in one

limb, and monoparesis denotes less se"ere weakness in one limb, althou#h the two

words are o$ten used interchan#eabl!. 3emiple#ia or hemiparesis is weakness in both

limbs 'and sometimes the $ace( on one side o$ the bod!& paraple#ia or paraparesis is

weakness o$ both le#s& and *uadriple#ia or *uadriparesis 'also tetraple#ia,

tetraparesis( is weakness o$ all $our limbs.

4. COOR45-/O5

/he coordination o$ motor acti"it! can be impaired b! weakness, sensor!

disturbances, or cerebellar disease and re*uires care$ul e"aluation.

6oluntar! acti"it! is obser"ed with re#ard to its accurac!, "elocit!, ran#e, and

re#ularit!, and the manner in which indi"idual actions are inte#rated to produce a

smooth, comple mo"ement. n the $in#er1nose test, the patient mo"es the inde

$in#er to touch the tip o$

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his or her nose and then the tip o$ the eaminers inde $in#er& the eaminer can mo"e

his or her own $in#er about durin# the test to chan#e the location o$ the tar#et and

should position it so that the patients arm must etend $ull! to reach it. n the heel1

knee1shin test, the recumbent patient li$ts one le# o$$ the bed, $lees it at the knee,

places the heel on the other knee, and runs the heel down the shin as smoothl! aspossible.

Table 5-3. Grading of muscle power according to the system suggested by the

Medical Research Council.

Grade Muscle Power

0 5ormal power

9 -cti"e mo"ement a#ainst resistance and #ra"it!

2 -cti"e mo"ement a#ainst #ra"it! but not resistance

: -cti"e mo"ement possible onl! with #ra"it! eliminated

7 +licker or trace o$ contraction

; 5o contraction

Reproduced, with permission, $romAids to the Investigation of Peripheral Nerve

Injuries.3MSO, 7


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tests, the eaminer looks $or irre#ularities o$ rate, amplitude, and rh!thm and $or

precision o$ mo"ements. With p!ramidal lesions, $ine "oluntar! mo"ements are

per$ormed slowl!. With cerebellar lesions, the rate, rh!thm, and amplitude o$ such

mo"ements are irre#ular.

$ loss o$ sensation ma! be responsible $or impaired coordination, the maneu"er

should be repeated both with e!es closed and with "isual attention directed to thelimb& with "isual $eedback the apparent weakness or incoordination will impro"e. n

patients with cerebellar disease, the main complaint and ph!sical $indin# are o$ten o$

incoordination, and eamination ma! re"eal little else. +urther discussion o$ the ataia

o$ cerebellar disease and the "arious terms used to describe aspects o$ it will be $ound

in Chapter 2.

E. /E54O5 RE+LE=ES

Chan#es in the tendon re$lees ma! accompan! disturbances in motor 'or sensor!(

$unction and pro"ide a #uide to the cause o$ the motor de$icit. /he tendon is tapped

with a re$le hammer to produce a sudden brisk stretch o$ the muscle and itscontained spindles. /he clinicall! important stretch re$lees and the ner"es, roots, and

spinal se#ments subser"in# them are indicated in /able 019. When the re$lees are

tested, the limbs on each side should be placed in identical positions and the re$lees

elicited in the same manner.

7. -re$leia)-pparent loss o$ the tendon re$lees in a patient ma! merel! re$lect a

lack o$ clinical epertise on the part o$ the eaminer. Per$ormance o$ >endrassik

maneu"er 'an attempt b! the patient to pull apart the $in#ers o$ the two hands when

the! are hooked to#ether( or some similar action 'such as makin# a $ist with the hand

that is not bein# tested( ma! elicit the re$le response when it is otherwise

unobtainable. - re$le ma! be lost or depressed b! an! lesion that interrupts the

structural or $unctional continuit! o$ its re$le arc, as in a root lesion or peripheral

neuropath!. n addition, re$lees are o$ten depressed durin# the acute sta#e o$ an

upper motor neuron lesion, in patients who are deepl! comatose, and in patients with

cerebellar disease.

:. 3!perre$leia)ncreased re$lees occur with upper motor neuron lesions, but the!

ma! also occur with s!mmetric distribution in certain health! sub?ects and in patients

under emotional tension. /he presence o$ re$le as!mmetr! is there$ore o$ particular

clinical si#ni$icance. Clonus consists o$ a series o$ rh!thmic re$le

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contractions o$ a muscle that is suddenl! sub?ected to sustained stretch, with each beatcaused b! renewed stretch o$ the muscle durin# relaation $rom its pre"ious

contracted state. Sustained clonus)more than three or $our beats in response to

sudden sustained stretch)is alwa!s patholo#ic and is associated with an abnormall!

brisk re$le. n h!perre$leic states, there ma! be spread o$ the re#ion $rom which a

particular re$le response can be elicited. +or eample, elicitation o$ the biceps re$le

ma! be accompanied b! re$le $in#er $leion, or elicitin# the $in#er $leion re$le ma!

cause $leion o$ the thumb '3o$$mann si#n(.

Table 5-. Muscle strength refle!es."

Refle! #egmental $er%e


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&nner%ation

'aw Pons Mandibular branch( trigeminal

Aiceps C0, CB Musculocutaneous

Arachioradialis C0, CB Radial

/riceps C8, C@ Radial

+in#er C@,/7 Median

nee L2, L9 +emoral

-nkle S7, S: /ibial

7-t the 5ational nstitutes o$ 3ealth, the re$lees are #raded on the $ollowin# scaleD ;,

absent& 7, reduced, trace response, or present onl! with rein$orcement& : and 2, inlower and upper hal$ o$ normal ran#e, respecti"el!& 9, enhanced, with or without

clonus.

2. Re$le as!mmetr!)-lthou#h the intensit! o$ re$le responses "aries considerabl!

amon# sub?ects, re$lees should be s!mmetric in an! indi"idual. Se"eral #eneral

points can be made re#ardin# re$le as!mmetries.

a. Laterali%ed as!mmetries o$ response, i.e., re$lees that are brisker on one side o$ the

bod! than on the other, usuall! indicate an upper motor neuron disturbance, but

sometimes re$lect a lower motor neuron lesion on the side with the depressed re$lees.

b. +ocal re$le de$icits o$ten relate to root, pleus, or peripheral ner"e lesions. +or

eample, unilateral depression o$ the ankle ?erk commonl! re$lects an S7

radiculopath! resultin# $rom a lumbosacral disk lesion.

c. Loss o$ distal tendon re$lees 'especiall! ankle ?erks(, with preser"ation o$ more

proimal ones, is common in pol!neuropathies.

+. SUPER+C-L RE+LE=ES

7. /he pol!s!naptic super$icial abdominal re$lees, which depend on the inte#rit! o$

the /@1/7: spinal cord se#ments, are elicited b! #entl! strokin# each *uadrant o$ the

abdominal wall with a blunt ob?ect such as a wooden stick. - normal response

consists o$ contraction o$ the muscle in the *uadrant stimulated, with a brie$mo"ement o$ the umbilicus toward the stimulus. -s!mmetric loss o$ the response ma!


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be o$ dia#nostic si#ni$icance. /he response ma! be depressed or lost on one side in

patients with an upper motor neuron disturbance a$$ectin# that side. Se#mental loss o$

the response ma! relate to local disease o$ the abdominal wall or its inner"ation, as in

a radiculopath!. Ailaterall! absent responses are usuall! o$ no si#ni$icance, occurrin#

in the elderl!, the obese, multiparous women, and patients who ha"e had abdominal

sur#er!.:. /he cremasteric re$le, mediated throu#h the L7 and L: re$le arcs, consists o$

retraction o$ the ipsilateral testis when the inner aspect o$ the thi#h is li#htl! stroked&

it is lost in patients with a lesion in"ol"in# these ner"e roots. t is also lost in patients

with contralateral upper motor neuron disturbances.

2. Stimulation o$ the lateral border o$ the $oot in a normal adult leads to plantar

$leion o$ the toes and dorsi$leion o$ the ankle. /he Aabinski response consists o$

dorsi$leion o$ the bi# toe and $annin# o$ the other toes in response to strokin# the

lateral border o$ the $oot, which is part o$ the S7 dermatome& $leion at the hip and

knee ma! also occur. Such an etensor plantar response indicates an upper motor

neuron lesion in"ol"in# the contralateral motor corte or the corticospinal tract. t can

also be $ound in anestheti%ed or comatose sub?ects, in patients who ha"e had asei%ure, and in normal in$ants. -n etensor plantar response can also be elicited,

thou#h less reliabl!, b! such maneu"ers as prickin# the dorsal sur$ace o$ the bi# toe

with a pin 'Ain# si#n(, $irml! strokin# down the anterior border o$ the tibia $rom knee

to ankle 'Oppenheim maneu"er(, s*uee%in# the cal$ muscle 'ordon maneu"er( or

-chilles tendon 'Scha$er maneu"er(, $lickin# the little toe 'onda maneu"er(, or

strokin# the back o$ the $oot ?ust below the lateral malleolus 'Chaddock maneu"er(. n

interpretin# responses, attention must be $ocused onl! on the direction in which the

bi# toe $irst mo"es.

. -/

n e"aluatin# #ait, the eaminer $irst obser"es the patient walkin# at a com$ortable

pace. -ttention is directed at the stance and posture& the $acilit! with which the patient

starts and stops walkin# and turns to either side& the len#th o$ the stride& the rh!thm o$

walkin#& the presence o$ normall! associated mo"ements, such as swin#in# o$ the

arms& and an! in"oluntar! mo"ements. Subtle #ait disorders become apparent onl!

when the patient is asked to run, walk on the balls o$ the $eet or the heels, hop on

either $oot, or walk heel1to1toe alon# a strai#ht line. ait disorders occur in man!

neurolo#ic disturbances and in other contets that are be!ond the scope o$ this

chapter. - motor or sensor! disturbance ma! lead to an abnormal #ait whose nature

depends upon the site o$ patholo#ic in"ol"ement. -ccordin#l!, the causes and clinical

t!pes o$ #ait disturbance are best considered to#ether.7. -praic #ait)-praic #ait occurs in some patients with disturbances, usuall!

bilateral, o$ $rontal lobe $unction, such as ma! occur in h!drocephalus or pro#ressi"e

dementin# disorders. /here is no weakness or incoordination o$ the limbs, but the

patient is unable to stand unsupported or to walk properl!)the $eet seem #lued to the

#round. $ walkin# is possible at all, the #ait is unstead!, uncertain, and short1stepped,

with marked hesitation 'F$ree%in#G(, and the le#s are mo"ed in a direction

inappropriate to the center o$ #ra"it!.

:. Corticospinal lesions)- corticospinal lesion, irrespecti"e o$ its cause, can lead to a

#ait disturbance that "aries in character dependin# on whether there is unilateral or

bilateral in"ol"ement. n patients with hemiparesis, the selecti"e weakness and

spasticit! lead to a #ait in which the a$$ected le# must be circumducted to beP.70


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ad"anced. /he patient tilts at the waist toward the normal side and swin#s the a$$ected

le# outward as well as $orward, thus compensatin# $or an! tendenc! to dra# or catch

the $oot on the #round because o$ weakness in the hip and knee $leors or the ankle

dorsi$leors. /he arm on the a$$ected side is usuall! held $leed and adducted. n mild

cases, there ma! be no more than a tendenc! to dra# the a$$ected le#, so that the soleo$ that shoe tends to be ecessi"el! worn.

aminoff 1-10 neurology

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