FFinalistSouthampton · 2027
Neurology
AKT · Neurology/Cord & peripherallow yield

Peripheral nerve palsies

Focal single-nerve injury/entrapment (mononeuropathy)

Overview

Injury or entrapment of a single peripheral nerve (mononeuropathy), producing a focal motor/sensory deficit in that nerve’s territory. The exam tests recognising the classic deficits: carpal tunnel (median), wrist drop (radial), claw hand/Froment (ulnar), and foot drop (common peroneal).

Recognise

  • Carpal tunnel (median): paraesthesiae of the thumb/index/middle finger, worse at night, thenar wasting; Phalen/Tinel positive
  • Radial nerve palsy: WRIST DROP (e.g. "Saturday night palsy")
  • Ulnar nerve palsy: claw hand, weak finger abduction, positive Froment sign
  • Common peroneal (fibular) nerve: FOOT DROP, weak ankle dorsiflexion/eversion (e.g. after fibular-neck compression)

Red flags

  • Multiple separate nerves (mononeuritis multiplex) → think vasculitis/diabetes; rapidly progressive; functional loss

Differentials & how to tell them apart

Radiculopathydermatomal/myotomal (root), not a single peripheral-nerve territory
Mononeuritis multiplex≥2 named nerves separately → vasculitis/diabetes
Peripheral neuropathysymmetrical glove-and-stocking
StrokeUMN pattern, central signs

Investigations

Clinical localisation; nerve conduction studies confirm the site; identify cause (entrapment, trauma, diabetes, vasculitis).

Management

Conservative (splint/activity modification) ± decompression for entrapment (e.g. carpal tunnel)

  1. 1Localise the nerve clinically; conservative measures (splinting, remove the compressive cause); carpal tunnel → night wrist splint ± corticosteroid injection.Gate: Several separate named-nerve palsies (mononeuritis multiplex) is NOT simple entrapment — investigate for vasculitis or diabetes
  2. 2Refractory entrapment/significant deficit → nerve conduction studies and surgical decompression (e.g. carpal tunnel release).
Treat cause / conservative — splinting, activity modification; carpal tunnel: night splint ± steroid injection

Key points

Match the deficit to the nerve: median = carpal tunnel, radial = wrist drop, ulnar = claw hand/Froment, common peroneal = foot drop. Multiple nerves separately = mononeuritis multiplex (vasculitis/diabetes).

Monitor & prognosis

Recovery, function, cause-specific control.

Good for entrapments after decompression; depends on the cause for others.

Source: NICE CKS (carpal tunnel); neurology