Nerve Injuries: Seddon Classification, Wrist Drop, Claw Hand & Rehab

Peripheral Nerve Injuries

Peripheral nerve injuries cause loss of motor function, sensation, and autonomic control. Recovery depends on the severity of the lesion.

1. Seddon's Classification

• Neuropraxia: Conduction block (compression). No structural damage. Full recovery in days/weeks.
• Axonotmesis: Axon damaged, sheath intact. Wallerian degeneration occurs. Recovers at 1mm/day.
• Neurotmesis: Complete transection of nerve. Requires surgery. Poor prognosis.

2. Specific Nerve Lesions

Radial Nerve: "Wrist Drop". (Loss of extensors). Saturday Night Palsy.
Ulnar Nerve: "Claw Hand" (Hyperextension of MCP, Flexion of IP). Froment's Sign.
Median Nerve: "Ape Hand" (Thenar wasting), "Pointing Index" (Benediction Hand).

3. Signs of Regeneration

• Tinel's Sign: Tapping the nerve end causes tingling distally. The point of tingling advances as the nerve grows (1mm/day).
• Sweating test: Skin becomes dry (anhydrosis) in denervation. Return of sweating = Recovery.

25 Practice MCQs

Q1. Which Seddon classification has the best prognosis?

Answer: A). Temporary physiological block.

Q2. Wrist Drop is caused by injury to the:

Answer: A). Paralysis of wrist extensors.

Q3. Claw Hand involves hyperextension of MCP and flexion of IP joints due to:

Answer: A). Lumbricals are paralyzed; EDC (extensor) unopposed at MCP.

Q4. Wallerian Degeneration occurs:

Answer: A). The disconnected part dies.

Q5. Rate of nerve regeneration is approx:

Answer: A). Important for prognosis.

Q6. Ape Hand deformity (Thenar wasting) is due to:

Answer: A). Loss of thumb opposition.

Q7. Tinel's Sign monitors:

Answer: A). Advancing Tinel's is a good sign.

Q8. Foot Drop involves which nerve?

Answer: A). Dorsiflexors paralyzed.

Q9. Froment's Sign ("Book Test") checks for:

Answer: A). Patient flexes thumb IP joint (FPL - Median) to compensate for weak adductor.

Q10. Saturday Night Palsy is compression of:

Answer: A). Sleeping with arm over chair/head. Neuropraxia.

Q11. Pointing Index (Hand of Benediction) occurs when attempting to make a fist in:

Answer: A). Cannot flex index/middle fingers (FDS/FDP paralysis).

Q12. The "Ulnar Paradox" states:

Answer: A). Clawing requires intact FDP to flex the IP joints.

Q13. Winging of Scapula is due to:

Answer: A). Medial border wings out.

Q14. Neurotmesis requires:

Answer: A). Nerve is cut; won't heal alone.

Q15. Cock-up splint is used for:

Answer: A). Maintains functional position.

Q16. Knuckle Bender splint is for:

Answer: A). Allows IP extension if MCP is blocked in flexion.

Q17. Axillary Nerve injury results in:

Answer: A). Common in shoulder dislocation.

Q18. Sural nerve is often used for:

Answer: A). Sensory nerve, minimal donor deficit.

Q19. Anhydrosis (dry skin) in a nerve distribution indicates:

Answer: A). Used in starch-iodine test.

Q20. Tendon transfers are performed:

Answer: A). Replaces lost function.

Q21. Anterior Interosseous Nerve (AIN) palsy causes:

Answer: A). Pure motor branch of Median nerve.

Q22. Tarsal Tunnel Syndrome compresses:

Answer: A). Medial ankle pain.

Q23. Crutch Palsy involves:

Answer: A). Incorrect crutch use.

Q24. Guyon's Canal Syndrome affects:

Answer: A). Cyclist's palsy.

Q25. Neuroma-in-continuity means:

Answer: A). Confusing intra-operative finding.