muscle power and tone examination

Examination of the

Motor SystemIn association with

Dr David Smith

Consultant Neurologist

Walton Centre for Neurology

and Neurosurgery

10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 110/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK

10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK

Note

This study guide is designed with

right-handed examiners in mind.

please substitute appropriately if left-

handed

Arrows on photographs depict the

direction of movement of the limb

10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 3

CONTENTS

Tone and Clonus

Limb Power

Reflexes


The motor system

Messages travel from the motor cortex via subcortical

nuclei and brainstem to spinal cord, thence to

nerve roots, peripheral nerves and finally to

muscles

Upper Motor Neurone (UMN)

From the motor cortex to anterior horn cell of

the spinal cord

Lower Motor Neurone (LMN)

from anterior horn cell to neuromuscular

junction


Testing muscle

tone and

clonus


Tone

NORMAL

passive movement of the limbs should be neither floppy

nor stiff

INCREASED due to -

lesions of pyramidal tract (UMN) – SPASTICITY

or lesions of the extrapyramidal tract – RIGIDITY

REDUCED

caused by LMN lesions, is called FLACCIDITY

Abnormal tone will be accompanied by other signs

which help to localise the lesion

10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 6


Testing for spasticity in the arms 1

Support the elbow with your left

hand

Hold patient’s hand as if shaking

hands

Rapidly supinate and pronate the

arm

Use the same technique on each

arm

Always use the same hand to

assess movement for the patients

right and left


Testing for spasticity in the arms 2

While still supporting

the elbow passively

flex and extend the

elbow

Use same technique

on both arms

If tone is normal there

will be no resistance to

these movements


Testing for spasticity in the legs 1

With the patient relaxed, place your hands on the

thigh and roll the whole leg

Observe the movement of the foot

If tone is normal the range of movement of the foot

is similar to the rotation of the leg

Alternatively

Flex and extend the knee

If tone is normal there should be no resistance to

this movement


Lower Limb Tone 2


Testing for spasticity in the legs 2

(Clonus)

Position the patient with the

knee flexed and the hip

externally rotated

Sharply dorsiflex the foot

In most people with normal

tone the foot will not move

But 2-3 beats of clonus

(plantar flexion followed by

dorsiflexion of the foot)

can be within normal limits

Sustained clonus is a

sign of an upper motor

neurone problem


Pyramidal tract (UMN) lesion;

SPASTICITY

There is initial resistance to movement which

gives way as the movement continues

Arm; SUPINATOR CATCH

Leg; CLASP KNIFE phenomenon

There is usually SUSTAINED CLONUS

(>3-4 beats)



Testing Power


The grading of muscle power (MRC)

Grade Meaning

0 Complete paralysis

1 Flicker of contraction possible

2 Movement possible if gravity eliminated

3 Movement against gravity but not resistance

4 Movement possible against some resistance

5 Power normal (it is not normally possible to

overcome a normal adult’s power)6


Patterns of weakness 1

Help to localise the problem within the

nervous system

A limited examination allows you to

differentiate between UMN and LMN lesions

Different patterns of LMN weakness may

require more detailed examination



Motor power

Ask the patient to make the required

movement

Attempt to overcome the movement

remembering that this is not a test of relative

strength

Avoid mechanical advantage to the examiner



Summary of motor supply to the upper limb

Extension

C7/8

Flexion

C5/6

Extension

C7/8

Flexion

C6/7

Extension

C7/8

Flexion

C7/8

Abduction

C5/6 Adduction

C6/7/8

Adduction

C8/T1


Shoulder abduction (C5/6) and adduction

(C6/7/8)

Position patient with shoulders

abducted to 90°

Ask patient to maintain position

whilst you attempt to overcome by

pressing down on upper arm

Position patient with arms at approx

30° of abduction, with elbows

flexed

Ask patient to bring elbows

towards side against resistance

“Stop me

pushing your

arms down”

“Stop me

pushing your

arms up”


Elbow flexion 2

(C5/6) and extension (C7/8)

Position patient with elbow

flexed

Ask them to resist your attempt

to straighten arm

Position patient with elbow

extended beyond 90 °

Ask them to resist your attempt

to flex the elbow (‘push me

away’)

“Pull me towards you”

“Push me away”


Finger extension (C7, C8)

Position patient with fingers extended

While supporting wrist ask them to resist your attempt to flex fingers

“Stop me trying to

bend your fingers

down”


Finger flexion

Ask patient to curl fingers towards palm

And to keep fingers flexed while you attempt to straighten them

Alternatively

ask them to squeeze two of

your fingers placed in

either of the patient’s palms


“Stop me

pulling

your

fingers

straight”

“Squeeze

my fingers”


Summary of lower limb motor supply

Abduction

L4/5/S1Adduction

L2/3/4

Inversion

L5/S1

Eversion

L5/S1

Extension

L3/4

Flexion

L2/3Extension

L5/S1/2

Dorsiflexion

L4

Plantar flexion

S1/S2

Flexion

L5/S1


Hip flexion (L2/3) and extension (L5/S1/2)

Position the patient with the leg

elevated to approx 30°

Attempt to overcome by

pressing down on thigh

Position patient with leg flat on

couch

Place your hand underneath

thigh and attempt to elevate

leg while patient presses

down

“Stop me

trying to raise

your leg up”

“Stop me

pushing your

leg down”


Knee flexion (L5/S1)

Position patient seated with knee flexed

Place your left hand on patient’s thigh

Place your right hand behind heel/ankle/calf

Ask patient to bring heel towards buttocks against

resistance10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 24

“Stop me trying to straighten your leg”


Knee extension (L3/4)

Position patient seated

with knee flexed

Place your left hand on

patient’s thigh

Place your right hand

over patient’s shin

Ask patient to

straighten leg against

resistance


“Stop me trying to bend your

knee”


Dorsiflexion (L4) and plantar flexion (S1/2) of the foot

Dorsiflexion: Ask patient

to bring foot upwards


pressing down on foot

Plantar flexion: Ask

patient to push foot down


pressing upwards on sole

“Stop me pushing your

foot down”“Stop me pushing your

foot up”


Patterns of weakness 2

UMN lesion

there is weakness of the;

extensors in the arms

flexors in the legs

The unopposed action of unaffected muscles produces the

characteristic posture seen in patients with stroke

LMN lesion

involvement of nerve endings (peripheral

neuropathy) produces a predominantly distal

pattern of weakness



Testing the

reflexes


Reflexes

Normal reflex arc requires :-

Stimulus to stretch receptors

Intact sensory afferent pathway

Link with a motor unit

Intact motor neurone

Contractile element

The order in which you test reflexes should be logical

and may vary from one examiner to another

The patient must be relaxed


Documenting reflexes

Absent -

Present with reinforcement +/-

Normal + or ++

Brisk +++


Reflexes can be recorded as follows:


The reflexes

Biceps (C5/6)Triceps (C7/8)

Supinator

(C5/6)

Finger (C8)

Ankle (S1/2)

Plantar (L5/S1/2)

Knee (L3/4)

Abdominal


Testing for reflexes

Position the limb correctly

Hold the tendon hammer like a hammer

Place your finger over the tendon and strike it,

for some reflexes you will strike the tendon itself (see

slides below)

(except the ankle – see slide 38)

Observe the relevant muscle for contraction

(not the limb movement)

Be aware of the range of normality.

Abnormal reflexes rarely seen without other relevant

signs10/13/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 32


Reinforcement

Where a reflex appears difficult

to elicit, reinforcement might

be tried.

Ask the patient to close their

eyes:

lower limb

ask the patient to grasp the

fingers of each hand and to

pull apart on instruction just as

the reflex is tested

upper limb

the teeth may be clenched

Reinforcement for a lower limb

reflex – with patient’s eyes

closed


The upper limbReflex Testing


Supinator (brachioradialis) reflex (C5/6)

Position patient sitting relaxed, with elbows flexed and hands resting on thigh/groin

Place your left index/middle finger(s) over supinator tendon

Strike finger(s) with falling head of hammer

Observe slight elbow flexion or contraction of belly of brachioradialis

Observe for contraction of brachioradialis here

You may notice momentary elbow flexion


Biceps reflex (C5/6)

In same position clasp

patient’s elbow so that

biceps tendon can be felt

under your thumb or finger

Strike your thumb or finger

Observe elbow flexion

there may be little movement

but you should feel the

contraction


Triceps reflex (C7/8)

Position patient with their arm across the abdomen with elbow flexed to 90°

Strike the triceps tendon direct

Observe for elbow extension

or contraction of the muscle bellyYou may feel muscle contract

with free hand


The finger jerk (C8)

Ask patient to rest their

fingers on index and middle

fingers of your left hand and

curl their fingers slightly

Strike your fingers

Patient’s fingers may flex

This can be normal


The lower limbReflex Testing


Knee reflex (L3/4)

Support one or both

knees, so they are

slightly bent

Strike the patellar

tendon direct

Observe

quadriceps contraction

with or without knee

extension

Infrapatellar ligament

Patella


Ankle reflex S1/2

Patient is seated

Place your left hand on

ball of patient's foot

Passively dorsiflex the

ankle

Strike your fingers

Observe/feel for

plantarflexion


Plantar reflex (L5/S1/2)

Patient seated with leg flat on couch

Drag thumbnail or blunt object along the lateral border of the foot and across the sole towards other side

The normal response is flexion of the big toe may be absent if feet

are cold


Patterns of reflex change

UMN lesion

Reflexes brisk below the level of the lesion

plantar response is usually extensor

A pathologically brisk finger flexion jerk is the

upper limb equivalent of an extensor plantar

response

LMN lesion (peripheral neuropathy)

reflexes are absent

distal reflexes are first to be lost10/13/2011 43


Summary

Parameter UMN lesion LMN lesion (peripheral

neuropathy)*

Posture Flexed UL, Extended LL May be wasting,

fasciculation

Tone Increased (spasticity) Reduced (flaccidity)

Power Weakness of UL

extensors and LL flexors

Distal weakness

Reflexes Brisk Absent

Plantar response Extensor Flexor or absent


There are other patterns of lower motor neurone

lesions (nerve root, individual peripheral nerve).*


Reminder

What you have learned so far will allow you

to distinguish between UMN and LMN

lesions

In future you will learn additional skills

needed to localise lesions according to

particular presentations

E.g. examination of the intrinsic hand muscles

in someone with weakness or tingling in the

hand/fingers.



Finger abduction

Support patient’s wrist with your

left hand

Ask patient to spread fingers

wide

Ask patient to maintain this

position while you try to push

little finger inwards

Ask patient to maintain this

position while you try to push

index finger inwards

10/13/2011 46

“Stop me pushing your

fingers”


Thumb abduction (T1, median)

Support patient’s wrist

with your left hand

Ask patient to lift

thumb upwards

Ask them to maintain

that position against

resistance


“Stop me pushing your thumb

down to your palm”

Thumb abduction is 90° to finger abduction


Thumb opposition (T1,Median)


with left hand

Ask patient to place tip

of thumb onto tip of

index finger

And to hold this

position while you try to

separate the thumb

and index finger

48

“Stop me pulling your fingers

apart”


Thumb adduction (T1, Ulnar)


with your left hand

Ask patient to trap your

index and middle

fingers between the

base of their thumb

and their index finger

Ask them to maintain

that position while you

try to lift their thumb

10/13/2011 49

“Stop me trying to lift your

thumb up”

muscle power and tone examination

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