foot drop / mononeuropathies

Question 1

What is the pathophysiology of footdrop ?

Answer 1

common peroneal nerve palsy
or
prolapsed disc at L4/5

causing demyelination or axonal damage

Question 2

What are the differentials for a patient presenting with suspected footdrop ?

Answer 2

• common peroneal nerve palsy
• lumber nerve root lesion (radicilopathy)

disc prolapse is u likely because there would be significant back pain and absent ankle reflex on same side

Question 3

What are the signs and symptoms of a common peroneal palsy?

Answer 3

• foot drop on affected side
• weakness in foot (dorsiflexion and eversion)
• present ankle reflex
• pinprick sensation loss over outer shin and top of foot
• painless

Question 4

What causes a common peroneal nerve palsy ?

Answer 4

often a period of unusual (for the patient) activity involving prolonged kneeling/knee flexion

Question 5

What is the commonest cause of a nerve root lesion that causes foot drop ?

Answer 5

L4/5 prolapsed disc

Question 6

What is one way of differentiating between the two main causes of foot drop ?

Answer 6

Prolapsed disc gives weakness to all ankle movements and an absent ankle reflex

1. common peroneal nerve palsy = weakness on
   - dorsiflexion
   - eversion
   - present ankle reflex
2. prolapsed disc at L4/5 = weakness on
   - dorsiflexion
   - eversion
   - inversion
   - loss of ankle reflex

Question 7

What is recovery time from foot drop ?

Answer 7

if a demyelination lesion = weeks/month for full recovery

if compressive axonal loss = months for potentially incomplete recovery

Question 8

What type of neuropathy is
a) common peroneal nerve palsy ?
b) disc prolapse at L4/5 ?

Answer 8

CPN palsy = mononeuropathy

Disc prolapse = radiculopathy

Question 9

Describe the pattern of sensory innervation supplied by the median nerve ?

Answer 9

median nerve = thumb, index, middle and 1/2 ring finger

(palmar surface)

Question 10

Describe the pattern of sensory innervation supplied by the ulnar nerve ?

Answer 10

ulnar nerve = pinky and 1/2 ring finger

(palmar surface)

Question 11

Describe the pattern of sensory innervation supplied by the radial nerve ?

Answer 11

radial nerve = snuffbox area between index and thumb

(dorsal surface)

Question 12

What actions of the hand would be weak in the instance of a median nerve neuropathy ?

Answer 12

median nerve
- thumb abduction
- thumb opposition
- distal thumb flexion

Question 13

What actions of the hand would be weak in the instance of an ulnar nerve neuropathy ?

Answer 13

ulnar nerve
- finger abduction
- finger adduction

Question 14

What actions of the hand would be weak in the instance of a radial nerve neuropathy ?

Answer 14

radial nerve
- finger extension
- wrist extension

Question 15

Which is the most common upper limb mononeuropathy ?

Answer 15

median nerve neuropathy due to carpal tunnel syndrome

Question 16

Does carpal tunnel syndrome have a
a) sensory aspect ?
b) motor aspect ?

Answer 16

both !

so if there is just motor aspects then it’s unlikely to be carpal tunnel syndrome

Question 17

Does carpal tunnel syndrome have a
a) sensory aspect ?
b) motor aspect ?

Answer 17

both !

so if there is just motor aspects then it’s unlikely to be carpal tunnel syndrome