Dr Lee Kim En

Dr Lee Kim En

Neurology Revision Tutorial 2

Peripheral nervous system

Approach to lower limb exam

Stem : This patient has difficulty walking, examine the lower limbs

Optimal position for peripheral nervous system examination : Patient lying on 1 pillow, bed flat

Inspection :

Inspect for early wasting at tibialis anterior (will show up as concavity), extensor digitorum brevis bulk when asking patient to extend big toe. Quadriceps are affected rather late.

Look for scars indicative of a nerve biopsy, for sural nerve (2/3s down of the calf towards the foot). Muscle biopsy will be over major muscle mass, at the quadriceps.

Look for fasciculations, definition of fasciculations is spontaneous twitching of the muscles, but can tap gently to try to elicit

Look for any deformities, flexion, extension, unusual posture

Tone :

Explain to patient what you’re going to do

When examining tone, only interested in whether it is normal, or increased

If increased, is it spastic or rigid.

Push patella down to see whether it is brisk, as a sign of increased tone

Normally, just lift up with hands behind knee, make sure hamstrings relaxed. Must be a sudden movement, as spasticity is best elicited that way. Can try distracting patient with conversation to make her more relaxed.

When doing ankle clonus, must provide traction and counter-traction. Hold patient’s leg in slight hip flexion and knee flexion, with one hand underneath the knee and the other eliciting clonus. Can hold the leg straight, or slightly bent

Key in clonus is to look for asymmetry, but most people’s normal limit should be at about 3 beats

Reflexes :

Correct use of a tendon tapper is to swing and let it drop freely. Do not use it as a hammer and hit. Tap it perpendicularly to the tendon.

Grading of reflexes :

0 Absent

1+ Diminished

2+ Normal

3+ Brisk

4+ Brisk + ankle clonus

Don’t hyperextend ankle for ankle jerk, makes it harder to elicit, just a slight degree of extension is sufficient.

Babinski song :

This is a wooden stick, it is blunt not sharp. I am about to use it to scratch the sole of your foot, it is going to be uncomfortable, but please bear with me. If it hurts, let me know and I will stop immediately.

Do NOT use a pen to do Babinski, absolutely not allowed, even as a doctor

Draw a path up the lateral side of the foot, then curve inwards at the ball of the foot

First 2/3s of the path is to check stimulus, if too strong, patient will already react and withdraw. So alter strength of stimulus, and look carefully at final 1/3 (ie when you start to curve in)

For modesty, not allowed to abduct both legs at once.

If patient is ticklish, there are other ways to elicit a plantar response :

Draw a path from posterior to anterior on lateral side of dorsum, below the lateral malleolus going straight forward. Chaddock sign

Pull 4th toe down and then let go briskly. Gonder sign

Abdominal reflex : divide into quadrants, draw from out to in, draw from middle to down, and from middle to up, forming a diamond

Cremasteric reflex : Will not be asked to do in exam, but good to know how to examine

Thus when you test reflexes, test the deep tendon reflexes, Babinski, and offer the other 2 superficial reflexes above.

How to report plantar response :

→  Big toe is either downgoing or upgoing

→  Plantar response is either flexor or extensor

→  Babinski positive or negative : involves extension of the big toe and fanning out of the other digits

→  Avoid other combinations such as “The big toe is negative”

Power:

Test using one hand to maintain concordance of results.

For hip flexion: use constant pressure if keeping leg straight, do not press down intermittently

Can also test with hip and knee in 90 degrees of flexion, and ask the patient to further flex with your arm supporting his calf, and the hand resisting hip flexion.

Hip extension: test with your hand underneath the tendo-achilles/heel

Knee flexion and extension: make sure heel is off the bed when testing, can use the hitchhiker sign to indicate direction

Ankle dorsiflexion : must invert as you press down. One of the strongest muscles, so if it can be overcome even slightly, there is weakness

Hypertonia is only UMN if there is

1. Spasticity

2. Babinski sign positive

3. Presence of UMN pattern of weakness (Lower limb extension stronger than flexion, UL flexion stronger than extension)

Flaccidity must have either fasciculations or wasting to show that it’s LMN.

Define the motor deficits as a monoparesis, hemiparesis, paraparesis, quadriparesis, or tetraparesis depending on the diagnosis in your mind.

Sensation :

Vibration: put over sternum first, make sure patient understands it is vibration he is supposed to feel, not presence of the tuning fork. Then extinguish and confirm with pt that it is no longer present

Do over bony prominences, can do over first MTP joint, medial malleoli, ASIS etc. As long as it is intact distally, no point testing proximally

For temperature, can use tuning fork. Put on pt’s neck to show her it is cold, then can test over medial aspect of calves, more sensitive to temperature. (in contrast to say, the dorsum of the foot, which is relatively insensitive)

When testing proprioception, separate rest of the toes from the big toe, demonstrate to patient what is up and what is down with the patient able to see the toe. Do with fingers on lateral sides of toe, not superior and inferior aspects to prevent patient from feeling the pressure on the skin.

Don’t use a very wide movement when testing, as it can stretch the skin and confuse issues. Do subtle movements to challenge patient’s sense of proprioceptioin.

When doing 4th toe, separate rest of the toes from the 4th toe. More sensitive as it has the smallest cortical representation in the brain.

When testing pain, toothpicks are NOT sharp enough. If you really want to test pain, try to use a round topped, metal pin. Round top is so that when you demonstrate over the sternum, there is a contrast between sharp and not sharp.

If suspect peripheral neuropathy, can do from distal to proximal, to look for area of demarcation. Then confirm with proximal to distal.

If suspecting transverse myelopathy or other cord lesions, test sensory levels, go by dermatomes.

Basically at this stage, the examination should be guided, not random. Should already know what you’re testing for.

For light touch, use cotton wool. Not as good because there is overlap between the two tracts, does not distinguish as well.

If spastic paraparesis, don’t do lumbosacral spine x-ray! Has to be at thoracic spine or higher.

Modesty and decorum very important in exam hall. If has to expose abdomen, roll up sleeves or pants in female patient, please ask chaperone or pt to do it for them. If discussing patient, or stopped by examiner for any reason, cover up patient, then discuss with examiner.

Approach to examination of the UL

Inspection same as LL. Muscle biopsy will be over deltoids, or triceps. Scar should be about 1-2 inches long

Best position for examination is to ask patient to rest hands on abdomen

Inspection :

Look for muscle wasting, in 1st dorsal interosseus, and look for guttering of the small intrinsic muscles of the hand

Look for abnormal movements : choreoathetoid movements, tics

Look for fasciculations, tap to elicit

Then ask patient to lift hands up, look for pronator drift

Tone :

Bring arm to 90 degrees of elbow flexion, then do quick supination. Look for a slight give. Can also do sudden wrist extension to test for a catch, or clonus

Interlock fingers with patient, then slow wrist flexion and extension to test for cog-wheeling

Hoffmann’s sign: Flick fingers at DIP, with the other hand stabilizing the MCP and PIPs. Look for ingoing of the thumb. Sign of hypertonia. Can be present in normal people also.

Reflexes :

For biceps, rest hands on abdomen and elbows on couch, then do. Practise doing the left arm, as it is a common place for students to stumble.

For supinator, rest hands on abdomen, look for brachioradialis contraction, as well as finger flexion.

Inverted supinator reflex implies a C5-C6 CORD lesion, resulting in absent biceps reflex, diminished or reduced brachioradialis, prominent finger flexors, and brisk triceps.

Power :

Test shoulder abduction, elbow flexion and extension

Test finger extension by placing edge of hand close to MCPs, do not place distally on tips of fingers, everybody will be weak

Test finger flexion by interlocking fingers with patient, and trying to pry open. This muscle should not be overcomable.

When testing finger abduction, place index finger of each hand at the PIP joints on either side, and press inwards, do not place at DIP or MCP

For testing thumb abduction, ask patient to lay the hand palm up, press the thumb in with your hand, then ask patient to bring thumb towards nose. This isolates the movement so that only the abductor pollicis brevis is tested

Report power as Grade X, not as X over 5.

0 No movement

1 Slight flicker of movement

2. Able to move, but not against gravity

3 Able to sustain movement against gravity, but not resistance

4 Able to sustain movement against resistance, but not full power

5 Full power

Cerebellar examination :

10 steps in this system! 2 in head, 2 in UL, 2 in LL, sit, pendular knee jerk, stand, and walk

2 in the head :

Look for horizontal nystagmus, at extremes of abduction.

Test for speech “British constitution” or ‘Baby hippotamus” or “West register street”

Patient might try to slow down and speak softly to try to mask, ask patient to speak clearly and loudly. If positive, phrase will vary in volume and speed

For non-english speakers : 1-10 in Chinese, “la la la” fast and clear

2 in UL :

Dysmetria : Get patient to abduct shoulders, place your finger at suitable distance ( not too far or near), try not to move for first few times, move finger only when patient’s finger is going back to her nose, not when it is moving towards your finger. Don’t move your finger to touch the patient’s finger

Dysdiadokinesia : Demonstrate to patient, make sure it is an alternate smacking action, and not only pronation and supination

2 in LL :

Heel shin test : Demonstrate to patient what are the 4 steps, and ask her to do the steps only when you say the number.

1 : Bring the heel of the foot directly over the contralateral knee

2: Bring the heel down to touch the knee

3 : Slide the heel down the shin of the test
4 : Return the leg to the bed

Make sure she doesn’t do it all at once first, bring her through it step by step, until you are sure it is intact, then all in sequence

Toe finger test :

Make sure target is realistic

Sitting :

Ask patient to sit up and observe for any difficulty

Pendular knee jerk:

Look for asymmetry in number of swings, but can be influenced by hyperreflexia

Standing :

Look at stance of patient. Anything wider than the shoulder is considered broad based

Don’t ask for Rhomberg’s test, as it is traditionally associated with proprioception testing.

(Prof loong however, says the division is artificial and makes no logical sense, as rhomberg’s can also be used to test stability of patient while standing, due to it being the next logical step after asking patient to stand with feet together. But for exams’ sake, don’t offer to do)

When walking patient, before starting, make sure patient is stable, pants are secure, and no other joint pains. Best done without shoes.

Get patient to walk in a straight line, stop, start, stop and turn, start, stop.

If gait normal, ask patient to stand on toes, and to stand on heels, which might unmask a mild foot drop.

Cerebellar gait: broad-based gait, turning by numbers

Waddling gait: hands at back, torso swaying from side to side

Spastic hemiplegic gait: UL flexed, “in-toe”, circumducting gait.

High-stepping gait: Exaggerated action of hip flexors

Parkinsonian gait : Stooped posture, mask like facies, lack of arm swing, short shallow shuffling steps, chasing their own center of gravity, difficulty stopping (might have tendency to fall).

Ataxic gait : Initiation failure

Spastic diplegic gait : In-toeing gait, knees bent.

LL in exam :

Always look at stem first, what is the hint

“ This patient has weakness in the legs, examine his lower limbs”

For cerebellar “This patient has unsteadiness, examine his coordination”

Is it a one leg problem or two leg problem? Mono vs paraparesis

Is it a UMN or LMN problem?

If you see a patient with flaccid paraparesis or quadriparesis, no reflexes, it’s most likely due to peripheral neuropathy secondary to DM. Make sure to ask to examine ULs also to differentiate para from quadri

If examiner tells you that pt has only had this for a few days, cause is probably AIDP, aka Guillain Barre

Can also be due to neurotoxins, or snake bites

Spastic paraparesis : Reasonable to ask to examine the UL, or sensory level examination, to try to localize it more accurately. Thoracic or cervical involvement? Thoracic = para, Cervical = quadri

Look at patient’s age also : if young, transverse myelitis, multiple sclerosis (examine cerebellar system also, and eyes for optic neuritis). Look out for urinary bag

Elderly : Most likely is a cervical myelopathy, which almost never involves bladder or bowels