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Medicine 3# Peripheral Nerve Injury
1. Which pathological feature best explains the reversibility of neurapraxia?
Axonal disruption with intact epineurium
Focal demyelination without Wallerian degeneration
Complete nerve division with intact myelin
Endoneurial disruption with axonal continuity
Explanation:
Neurapraxia is characterized by focal demyelination causing conduction block without axonal injury or Wallerian degeneration, allowing rapid and complete recovery.
2. Wallerian degeneration is expected in which Seddon classification?
Neurapraxia only
Neurotmesis only
Axonotmesis and neurotmesis
All nerve injuries
Explanation:
Wallerian degeneration occurs when the axon is disrupted, as in axonotmesis and neurotmesis, but not in neurapraxia.
3. A patient presents with wrist drop after sleeping intoxicated with his arm over a chair. The most likely pathology is:
Neurapraxia of the radial nerve
Axonotmesis of the posterior interosseous nerve
Neurotmesis at the spiral groove
Median nerve entrapment
Explanation:
Saturday night palsy is due to transient compression of the radial nerve causing neurapraxia and wrist drop.
4. Failure of recovery after a closed nerve injury within the expected time frame indicates:
Immediate epineural repair
Continued observation only
Direct muscular neurotization
Delayed repair with resection of neuroma and distal glioma
Explanation:
In closed injuries, failure of recovery warrants delayed surgical repair with excision of proximal neuroma and distal glioma.
5. Which factor most strongly favors nerve recovery?
Neurapraxia injury pattern
Proximal nerve injury
Mixed motor and sensory loss
Delayed surgical repair
Explanation:
Neurapraxia has the best prognosis among nerve injuries due to preserved axonal continuity.
6. Tingling progressing distally during nerve recovery represents:
Hoffmann sign
Positive Tinel’s sign
Phalen’s phenomenon
Double-crush syndrome
Explanation:
Tinel’s sign indicates regenerating axons and progresses distally as recovery continues.
7. Which structure forms the roof of the carpal tunnel?
Proximal carpal row
Scaphoid and trapezium
Transverse carpal ligament
Hook of hamate
Explanation:
The transverse carpal ligament forms the palmar roof of the carpal tunnel.
8. The most sensitive clinical test for carpal tunnel syndrome is:
Tinel’s test
Phalen’s test
Tourniquet test
Durkan’s test
Explanation:
Durkan’s test involves direct compression of the carpal tunnel and is the most sensitive.
9. Loss of hip abduction with a positive Trendelenburg sign indicates injury to:
Inferior gluteal nerve
Superior gluteal nerve
Femoral nerve
Obturator nerve
Explanation:
The superior gluteal nerve supplies gluteus medius and minimus, essential for hip abduction.
10. Foot drop following fibular neck fracture is due to injury of:
Common peroneal nerve
Tibial nerve
Sciatic nerve (tibial division)
Femoral nerve
Explanation:
The common peroneal nerve is superficial at the fibular neck and commonly injured, causing foot drop.
11. Earliest symptom of entrapment neuropathy is:
Muscle atrophy
Complete numbness
Tingling and neuropathic pain
Loss of reflexes
Explanation:
Sensory irritation (tingling, neuropathic pain) precedes sensory loss and motor weakness.
12. Double-crush syndrome implies:
Single severe compression site
Proximal compression increases susceptibility to distal compression
Purely sensory nerve involvement
Irreversible axonal loss
Explanation:
Impaired axonal transport at one site makes the nerve more vulnerable at another site.
13. Which injury has no chance of spontaneous recovery?
Neurapraxia
Axonotmesis
Compression neuropathy
Neurotmesis
Explanation:
Neurotmesis involves complete nerve division and requires surgical repair.
14. Loss of sensation over the sole of the foot predisposes most to:
Trophic ulcers
Foot drop
Claw toes
Gait ataxia
Explanation:
Tibial nerve injury causes loss of sole sensation, leading to pressure-related trophic ulcers.
15. Difficulty extending fingers with preserved wrist extension suggests injury to:
Radial nerve at spiral groove
Superficial radial nerve
Posterior interosseous nerve
Median nerve
Explanation:
PIN syndrome causes finger extension weakness without sensory loss or wrist drop.
16. Which deformity is associated with anterior interosseous nerve injury?
Claw hand
No OK sign
Ape thumb
Wrist drop
Explanation:
AIN injury prevents flexion of DIP of index finger and thumb IP joint, abolishing the OK sign.
17. Median nerve compression at the elbow is termed:
Carpal tunnel syndrome
Guyon’s canal syndrome
Cubital tunnel syndrome
Pronator syndrome
Explanation:
Pronator syndrome is compression of the median nerve by the pronator teres near the elbow.
18. Most sciatic nerve injuries involve which division?
Common peroneal division
Tibial division
Posterior femoral cutaneous nerve
Inferior gluteal nerve
Explanation:
The common peroneal division is more superficial and injured in ~90% of sciatic nerve lesions.
19. Which nerve injury causes winging of the scapula?
Spinal accessory nerve
Dorsal scapular nerve
Long thoracic nerve
Suprascapular nerve
Explanation:
Injury to the long thoracic nerve paralyzes serratus anterior, causing scapular winging.
20. Which surgical technique has not shown superior outcomes over epineural repair?
Primary epineural repair
Fascicular repair
Early exploration in open injury
Tension-free nerve alignment
Explanation:
Fascicular repair is technically demanding but has not demonstrated better outcomes than epineural repair.