PNS Exam

PERIPHERAL NERVOUS SYSTEM

General Inspection

• Arms and shoulder girdles exposed

• Abnormal posture - eg hemiplegia (stroke)
• Muscle wasting - compare one side to the other
• Abnormal movement (tremor)
• Skin - neurofibromatosis, angiomata

The Upper Limbs

The Motor System

GeneralAsk pt to hold out both hands with arms extended, palms upward and eyes closed. Discern drifting (movement 1 or 2 arms from initial position)

Causes of drifting	Cause	Way of drifting
Upper motor neurone lesion	muscle weakness	downwards, starts distally with the fingers and spreads proximally.
Cerebellar disease	hypotonia	usually upwards
Loss of proprioception	loss of joint position sense	any direction.

Tone
"Relax, make your hands nice and heavy and let me move them"

Move patients hand randomly. Resistance felt when a joint is moved passively.
Tone is tested at the wrists and elbows + shoulder.
Flexion and extension of the elbow and wrist joint is performed passively.

• Tone increased - hypertonic, as in an upper motor neurone lesion.
• Tone decreased - hypotonic, as in a lower motor neurone lesion.

Power 
A measure of muscle strength
Age, gender and build should be taken into account

        0 – Complete paralysis
        1 – Flicker of contraction possible
        2 – Movement is possible when gravity is excluded [sideways]
        3 – Movement is possible against gravity but not if any further resistance is added
        4 – Movement is possible against gravity and some resistance
        6 – Normal power

If power is reduced decide if it is symmetrical or asymmetrical and whether it is proximal, distal or general.

1.  Shoulder
"Can you do chicken wing like this"
Abduction - "push up against my hand"
Adduction - "push down against my hand"

2.  Elbow
"Can you do boxing gesture like this"
Flexion - "pull hard against my hand"
Extension - "push hard against my hand"

3.  Wrist
"Hold out your fist please"
Flexion - "Push your fist down against my hand"
Extension - "Push your fist up against my hand"

4. Fingers
Flexion- "can you squeeze my 2 fingers tightly?"

Extension (as wrist extension, but with hands open, not fists) "Keep your hand open, don't let me push then down"
Abduction- "Spread your finger and don't let me push them together"

Adduction- "hold the paper between your two fingers and don't let me pull it out" - (do for each finger)

Coordination

1. Finger-nose test
Ask the patient to touch their nose with the index finger and then to touch the examiner’s outstretched finger at nearly full extension. Ask to repeat but do it faster. Examiner's finger is moved around.

• Intention tremor, which is tremor increasing as the target is approached [cerebellar disease].
• Past-pointing, where the patient’s finger overshoots the target [cerebellar disease].

2. Rapidly alternating movements
Ask the patient to pronate and supinate their hand on the dorsum of the other hand as rapidly as possible. In cerebellar disease this movement is slow and clumsy and is called dysdiadochokinesis

3. Rebound
Ask the patient to lift rapidly the arms from the sides and then stop. Hypotonia from cerebellar disease causes delay in stopping the arms.


Reflexes

1. Biceps  jerk [C5, C6]
Place one forefinger on the biceps tendon and tap this with the tendon hammer. The hammer should be held distally. There is brisk contraction of the biceps muscle with flexion of the forearm.
If the biceps jerk appears to be absent it should be tested again following a reinforcement manoeuvre. Ask the patient to clench their teeth tightly just before you let the hammer fall. Sometimes normal reflexes can only be elicited after reinforcement, but they should be symmetrical.

2. Triceps jerk [C7, C8]
Support the elbow with one hand and tap the triceps tendon. Triceps contraction results in forearm extension.

3. Brachioradialis jerk [C5, C6]
Place your first two fingers over the lower end of the radius just above the wrist. Strike the fingers. Contraction of the brachioradialis causes flexion of the elbow.

        0 Absent reflexes
        + Reduced reflexes
        ++ Normal reflexes
        +++ Exaggerated reflexes
        ++++ Exagerated reflexes and clonus

Sensation

1. Light touch
Some fibres travel in the posterior columns [ipsilaterally] and the rest cross the midline to travel in the anterior spinothalamic tract [contralaterally]
Use cotton wool to test for light touch. Initially touch the anterior chest wall [normal area]; this is to demonstrate to the patient how it feels.
Ask the patient to close their eyes and begin proximally on the upper arm and test in each dermatome [memorise dermatomes] comparing right with left.
Ask patient to tell you when they feel something.

2. Pain
Spinothalamic pathway – fibres enter the spinal cord and cross a few segments higher to the opposite spinothalmic tract.
Using a sharp object touch the patients anterior chest wall [normal area], this is to
demonstrate to the patient that it feels sharp.
Ask the patient to close their eyes and begin proximally on the upper arm and test in each
dermatome comparing right with left.
Ask patient if they can feel object and if it feels sharp or dull.
Map out any area of dullness. Always do this by moving from area of dullness to the area of normal sensation.

3. Vibration and proprioception
These fibres enter and ascend ipsilaterally in the posterior columns of the spinal cord to the nucleus gracilis and nucleus cuneatus in the medulla, where they decussate.

Vibration
The base of a vibrating tuning fork is placed on the anterior chest wall. It should be explained to the patient that it is the sensation of vibration and not cold or touch which is being detected.
The base of the vibrating tuning fork is then placed on one of the distal interphalangeal joints. The patient is asked can they feel it vibrate and to indicate when vibration stops. They are then asked to repeat this with their eyes closed. Stop the tuning fork vibrating by touching it and the patient should be able to say exactly when this occurs. Compare one side with the other.
Should vibration sense be lost or impaired distally then the tuning fork should be moved proximally in order to establish the level at which it is normally appreciated. [Ulnar head at wrist, olecranon at elbow and then the shoulders]

Proprioception
Grasp the distal phalanx from the sides on the patient’s index finger and move it up and down to demonstrate these positions. Then ask the patient to close the eyes while these manoeuvres are repeated. Normally movement through even a few degrees is detectable, and should be reported correctly.
If there is an abnormality, proceed to test the wrists and elbows similarly.

	UMNL	LMNL
Tone	Increased (hypertonic)+/-clonus Spasticity	Decreased (hypotonic) Flaccidity
Power	Weak abductors/extensors in upper limb	Distal muscles weakened more than proximal
Reflexes	Increased(hyperreflexia)	Decreased
Other	Muscle wasting rare	Muscle wasting Fasciculation

The Lower Limbs

The Motor System
Gait
Make sure the patient’s legs are clearly visible. Ask pt to

• Walk normally for a few metres and then to turn around quickly and walk back.
• Walk heel-to-toe [midline cerebellar lesion].
• Walk on the toes [S1 lesion will make this impossible].
• Walk on the heels [L4/L5 lesion causing footdrop will make this impossible].
• Squat and then stand up [proximal myopathy].
• Stand erect with the feet together and the eyes open. Once the patient is stable ask them to close the eyes. Compare steadiness shown with eyes open then closed. Marked unsteadiness with the eyes closed is seen with cerebellar or vestibular dysfunction.

The Romberg test: a tendency to sway or fall while standing upright with the feet to-gether, the arms outstretched and the eyes closed. A positive Romberg’s sign suggests loss of proprioceptive sensation.

Inspection
Inspect the legs with the patient lying in the bed and the legs and thighs entirely exposed.
Urinary catheter -? spinal cord lesion.
Abnormal posture, muscle wasting, fasciculations(irregular contractions of small areas of muscle which have no rhythmical pattern) If present with weakness and wasting, fasciculation indicates degeneration of the lower motor neurone e.g. motor neurone disease.


Tone
Resistance felt when a joint is moved passively.
Patient must be relaxed lying on the bed.
Place your hands on the right leg below the knee and rock the leg gently from side to side. The passive movements of the ankle are observed. Repeat on left side.
Place your hand under the knee and flex and extend the knee joint. Feel for resistance to muscle stretch. When the patient is relaxed this should occur without resistance.
Compare sides.
Tone may be increased [hypertonia] or decreased [hypotonia].

Ankle clonus
This is sustained rhythmical contraction of the muscles when put under sudden stretch. It is due to hypertonia from an upper motor neuron lesion.
Hold the leg with the knee bent and sharply dorsiflex the foot. When ankle clonus is present, recurrent ankle plantar flexion movement occurs. This may persist for as long as the examiner sustains dorsiflexion of the ankle.

Patellar clonus
To test for patellar clonus place your hands on the lower part of the quadriceps with the knee extended and move the patella down sharply. Sustained rhythmical contraction of the quadriceps occurs as long as the downward stretch is maintained.


Power 
A measure of muscle strength
Age, gender and build should be taken into account

        0 – Complete paralysis
        1 – Flicker of contraction possible
        2 – Movement is possible when gravity is excluded [sideways]
        3 – Movement is possible against gravity but not if any further resistance is added
        4 – Movement is possible against gravity and some resistance
        6 – Normal power

If power is reduced decide if it is symmetrical or asymmetrical and whether it is proximal, distal or general.

1.  Hip
Flexion -Ask patient to lift up their straight leg. Place your hand on the leg above the knee and attempt to push the leg down saying to the patient ‘do not let me push down your leg’.
Extension - Ask the patient to keep the leg down and not to let you pull it up.
Abduction - Ask the patient to abduct the leg and not to let you push it in.
Adduction - Ask the patient to keep the leg adducted and not to let you push it out.

2. Knee
Flexion - Ask the patient to bend the knee and not to let you straighten it.
Extension - With the knee bent ask the patient to straighten the knee and not to let you bend it.

3. Ankle
Plantar flexion - Ask the patient to push the foot down and not to let you push it up.
Dorsiflexion - Ask the patient to bring the foot up and not to let you push it down.
Eversion -With the foot in complete plantar flexion ask the patient to evert the foot against resistance.
Inversion - Ask the patient to invert the foot against resistance

4. Toes
Plantar flexion - Ask the patient to plantar flex the big toe and not to let you push it up.
Dorsiflexion - Ask the patient to bring the big toe up and not to let you push it down.


Coordination
The cerebellum plays an integral role in coordinating voluntary movement. A number of tests are used to test coordination.

1.  Toe-finger test
Ask the patient to raise the foot with the knee bent and touch the examiners finger with the big toe. Look for intention tremor.

2.  Heel-shin test
Ask the patient to place one heel on the opposite knee and to slide the heel accurately down the front of the shin to the ankle and back again at a moderate pace.

3.  Foot-tapping test
Ask the patient to tap the sole of the foot quickly on the examiners hand; this movement is slow and clumsy in cerebellar disease.


Reflexes
Knee jerk [L3, L4]
Slide the left arm under the knees so they are slightly bent and supported.
The tendon hammer is allowed to fall on to the infrapatellar tendon.
Contraction of the quadriceps causes extension of the knee.
If the knee jerk appears to be absent it should be tested again following a reinforcement manoeuvre. Ask the patient to interlock the fingers and then to pull    apart hard at the moment before the hammer strikes the tendon [Jendrassik manoeuvre].

Ankle jerk [S1, S2]
Have the foot in the mid-position at the ankle with the knee bent and thigh externally rotated. The hammer is allowed to fall on the Achilles tendon. The normal response is plantar flexion of the foot with contraction of the gastrocnemius muscle.

Plantar reflex [L5, S1, S2] 
Use a blunt object such as a key. This is drawn slowly along the lateral border of the foot from the heel towards the little toe until a response is elicited.
The normal response is flexion of the big toe at the metatarsophalangeal joint. The extensor response is abnormal [Babinski response] and indicates an upper motor neurone lesion.

The reflexes can be recorded as follows:

        0 Absent reflexes
        + Reduced reflexes
        ++ Normal reflexes
        +++ Exaggerated reflexes
        ++++ Exagerated reflexes and clonus


Sensation
1.  Light touch
Some fibres travel in the posterior columns [ipsilaterally] and the rest cross the midline to travel in the anterior spinothalamic tract [contralaterally]
Use cotton wool to test for light touch. Initially touch the anterior chest wall [normal area]; this is to demonstrate to the patient how it feels.
Ask the patient to close their eyes and begin proximally on the upper leg and test in each  dermatome [memorise dermatomes] comparing right with left. Ask patient to tell you when they feel something.

2.  Pain
Spinothalamic pathway – fibres enter the spinal cord and cross a few segments higher to the opposite spinothalmic tract.
Using a sharp object touch the patients anterior chest wall [normal area], this is to demonstrate to the patient how it feels sharp.
Ask the patient to close their eyes and begin proximally on the upper leg and test in each dermatome comparing right with left. Ask patient if they can feel object and if it feels sharp or dull.
Map out any area of dullness. Always do this by moving from area of dullness to the area of normal sensation.

3.  Vibration and proprioception
These fibres enter and ascend ipsilaterally in the posterior columns of the spinal cord to the nucleus gracilis and nucleus cuneatus in the medulla, where they decussate.

Vibration
The base of a vibrating tuning fork is placed on the anterior chest wall. It should be explained to the patient that it is the sensation of vibration and not cold or touch which is being detected.
The base of the vibrating tuning fork is then placed on the dorsum of the terminal phalanx. The patient is asked can they feel it vibrate and to indicate when vibration stops.
They are then asked to repeat this with their eyes closed. Stop the tuning fork vibrating by touching it and the patient should be able to say exactly when this occurs.
Compare one side with the other.
Should vibration sense be lost or impaired distally then the tuning fork should be moved proximally in order to establish the level at which it is normally appreciated.
    [Lateral malleolus, upper part of tibia, iliac crest, costal margin]

Proprioception
Grasp the distal phalanx from the sides and move it up and down to demonstrate these positions. Then ask the patient to close the eyes while these manoeuvres are repeated. Normally movement through even a few degrees is detectable, and should be reported correctly.
If there is an abnormality, proceed to test the ankles and knees similarly.


Sensory level
If there is peripheral sensory loss attempt to map out the upper level.
This may involve testing over the abdominal or even the chest dermatomes.
Establishing a sensory level on the trunk indicates the spinal cord level that is affected.
An area of hyperaesthesia often occurs above the sensory level and it is the upper level of this that should be determined as it usually indicates the highest affected spinal segment.

The abdominal reflexes
Test these by lightly stroking the abdominal wall diagonally towards the umbilicus in each of the four quadrants of the abdomen. Reflex contractions of the abdominal wall are absent in upper motor neurone lesions above the segmental level.
They are also absent in patients who have had surgical operations interrupting the nerves.