PNS PESA

General Sensory Screening

Describe how you would assess general sensation in the upper and lower extremities.

How to test:

Why must sensation always be compared side-to-side?

General Sensory Screening

Sensation is assessed using light touch over multiple areas of the upper and lower extremities, comparing side-to-side and covering both dermatomal and peripheral nerve distributions.

Side-to-side comparison is essential to detect asymmetry, which is more clinically meaningful than absolute sensation alone.

Dermatomes vs Peripheral Nerves

If you find an area of decreased sensation, what two patterns are you trying to distinguish?

What does each pattern suggest about lesion location?

Dermatomes vs Peripheral Nerves

The two patterns being assessed are:

Dermatomal pattern

Peripheral nerve pattern

Dermatomal sensory loss suggests nerve root (radiculopathy) pathology.

Peripheral nerve sensory loss suggests mononeuropathy or plexopathy or something affecting the peripheral nerve somewhere after the root.

Pattern recognition is critical for accurate localization and will come with further study, time and experience.

PART II - DEEP TENDON REFLEXES

Complete the table below.

Reflex

How to Test

Nerve Root(s) / Nerve

What an Abnormal Result Suggests

Biceps

Brachioradialis

Triceps

Patellar

Achilles

Reflex

How to Test

Nerve Root(s) / Peripheral Nerve

(these are to remind you, not tested in PESA)

What an Abnormal Result Suggests

Biceps

Arm partially flexed; examiner places thumb over biceps tendon and strikes thumb

C5-C6 (musculocutaneous nerve)

Decreased reflex suggests LMN or peripheral nerve pathology at C5-C6; hyperreflexia suggests UMN lesion above this level

Brachioradialis

Arm resting; strike tendon ~1-2 inches proximal to radial styloid (alternative to tapping over muscle is acceptable)

C5-C6 (radial nerve)

Asymmetry suggests nerve root or peripheral nerve dysfunction

Triceps

Arm relaxed and flexed; strike tendon just above olecranon

C7-C8 (radial nerve)

Reduced reflex suggests LMN lesion at C7; hyperreflexia suggests UMN pathology

Patellar

Legs dangling; strike patellar tendon

L3-L4 (femoral nerve)

Decreased reflex suggests peripheral neuropathy or radiculopathy; increased reflex suggests UMN lesion

Achilles

Slight dorsiflexion of foot; strike Achilles tendon

S1 (tibial nerve)

Early loss common in peripheral neuropathy; hyperreflexia suggests UMN lesion above S1

Reflex Interpretation

What does hyperreflexia suggest?

What does hyporeflexia or absence suggest?

How are reflexes graded?

Hyperreflexia → upper motor neuron involvement

Hyporeflexia or absence → lower motor neuron, peripheral nerve, or muscle pathology

· Reflexes are graded on a 0-4+ scale:

o 0 - Absent No visible or palpable response, even with reinforcement → Suggests lower motor neuron, peripheral nerve, or severe neuropathy

o 1 - Diminished / Hyporeflexive Less than expected, but present → Can be normal in some individuals; may suggest peripheral nerve or LMN pathology if asymmetric or new

o 2 - Normal Expected response for that reflex → Symmetric and appropriate amplitude

o 3 - Brisk More active than normal, but no clonus → May be normal, especially if symmetric; consider UMN if focal or asymmetric

o 4 - Hyperactive with clonus Very brisk response with repetitive oscillations → Strongly suggests upper motor neuron pathology

Asymmetry is more important than absolute reflex grading

Muscle Group

How You Test

What Weakness Suggests

Biceps / Triceps

Forearm flexors / extensors

Hand grip / finger abduction

Hip flexors / extensors

Quadriceps / Hamstrings

Ankle dorsiflexors / plantarflexors

Muscle Group

How You Test

What Weakness Suggests

Biceps / Triceps

Elbow flexion and extension against resistance

Cervical radiculopathy, peripheral nerve lesion, or myopathy

Forearm Flexors / Extensors

Wrist flexion and extension against resistance

Median or radial nerve pathology

Hand Grip / Finger Abduction

Squeeze examiner's fingers; abduct fingers against resistance

Distal weakness suggests peripheral neuropathy or ulnar nerve involvement

Hip Flexors / Extensors

Patient lifts thigh or pushes thigh backward against resistance

Proximal weakness suggests radiculopathy, myopathy, or central pathology

Quadriceps / Hamstrings

Knee extension and flexion against resistance

Femoral or sciatic nerve involvement

Ankle Dorsiflexors / Plantarflexors

Patient dorsiflexes or plantarflexes foot against resistance

Foot drop suggests L5 or peroneal nerve pathology; plantarflexion weakness suggests S1 involvement

How do you document normal strength?

Normal strength is documented as 5/5

· Strength is graded on a 0-5 scale:

o 0/5 - No contraction No visible or palpable muscle contraction → Severe lower motor neuron, muscle, or tendon pathology

o 1/5 - Trace contraction Visible or palpable contraction, but no movement → Profound weakness; often acute nerve injury

o 2/5 - Movement with gravity eliminated Full range of motion only when gravity is removed → Significant weakness; cannot overcome gravity

o 3/5 - Movement against gravity only Full range of motion against gravity, but no resistance → Key functional cutoff; patient can lift limb but not resist examiner

o 4/5 - Movement against gravity and some resistance Reduced strength compared to examiner or contralateral side → Mild to moderate weakness

o 5/5 - Normal strength Full strength against resistance → Symmetric and appropriate for patient

What does 3/5 strength represent?

3/5 strength indicates movement against gravity only, without resistance

Bilateral testing allows detection of subtle asymmetry

How is vibration sense tested and what does loss of vibration suggest?

Vibration is tested using a tuning fork on bony prominences (e.g. DIP great toe, malleolus, tibial tuberosity, DIP finger joint, ulnar styloid, olecranon); start distally, move proximally if abnormal; early loss suggests peripheral neuropathy or dorsal column dysfunction.

How do you test proprioception, and what does abnormal proprioception indicate?

Proprioception is tested by moving a digit up or down with eyes closed; abnormal results indicate posterior column or peripheral nerve dysfunction.

How would you distinguish a dermatomal sensory deficit from a peripheral nerve deficit on exam?

Dermatomal deficits follow nerve root distributions; peripheral nerve deficits follow named nerve territories. If you found a difference in sensation when testing from side-to-side, you would then use dermatome maps and the maps of peripheral cutaneous nerve distributions to map out the specific area of sensory problem as well as using other special tests to determine what types of sensation were diminished.

How is Tinel's sign performed and what does a positive result suggest?

Tinel's sign: tapping over a nerve reproduces tingling; suggests nerve compression.

How is Phalen's test performed and what pathology is it associated with?

Phalen's test: wrist flexion reproduces median nerve symptoms; suggests carpal tunnel syndrome.

How is the Jendrassik maneuver performed and why is it used?

Jendrassik maneuver: voluntary contraction elsewhere enhances reflex response.

Describe one test used to evaluate thoracic outlet syndrome.

Thoracic outlet testing includes Roo's and Adson's and evaluates neurovascular compression with arm positioning. (These test similar but potentially different pathological causes)

A patient has decreased ankle reflexes, distal sensory loss, and weakness in foot dorsiflexion. This pattern most suggests:

A. Upper motor neuron lesion

B. Peripheral neuropathy

C. Cerebellar disease

D. Cortical stroke

Correct answer: B - Peripheral neuropathy

Rationale: This is a classic length-dependent, distal pattern:

· Early loss of Achilles reflex

· Distal sensory loss (stocking distribution)

· Foot dorsiflexion weakness (common peroneal involvement)

Together, these findings strongly suggest peripheral neuropathy rather than central nervous system pathology.

Which finding best supports a lower motor neuron lesion?

A. Hyperreflexia B. Spasticity C. Fasciculations and atrophy D. Positive Babinski

Correct answer: C - Fasciculations and atrophy

Rationale: Lower motor neuron (LMN) lesions directly affect the motor unit, leading to:

· Muscle atrophy

· Fasciculations

· Decreased tone

· Hyporeflexia or areflexia

These findings reflect loss of innervation to the muscle.

A patient has numbness isolated to the thumb and index finger, with normal sensation elsewhere. Is this more consistent with a dermatomal or peripheral nerve pattern?

Peripheral nerve pattern (median nerve).

*** Important note - you do not need to memorize the dermatomal and peripheral nerve charts for the practical exam. Just know why we do this and how you would look up these things in charts to determine if it was peripheral or dermatomal.

Reflexes are difficult to elicit in an anxious patient despite proper technique. What maneuver could improve your exam?

Jendrassik maneuver or reinforcement techniques.

Loss of vibration sense is an early finding in peripheral neuropathy. (T/F)

true

Reinforcement maneuvers change the underlying neurologic pathology. (T/F)

false

Match the test with the best description.

a. Tinel's sign

b. Phalen's test

c. Jendrassik maneuver

d. Vibration testing

e. Proprioception testing

Helps elicit deep tendon reflexes

Detects posterior column dysfunction

Nerve irritation causing paresthesia

Median nerve compression

Joint position sense

a → 3 b → 4 c → 1 d → 2 e → 5