Peripheral Neuropathy

INTRODUCTION

This can be a mononeuropathy (e.g. CTS), mononeuropathy multiplex or a polyneuropathy.

Features of a polyneuropathy

• Lower motor neurone disorder

• Distal sensory loss in limbs—tingling, burning or numbness

• Symmetrical glove and stocking loss (all modalities) ± distal motor loss in limbs

• Reduction or loss of reflexes

The many causes include metabolic (e.g. diabetes, renal failure); acute porphyria; toxins and vitamin deficiency states (e.g. alcohol, folate deficiency); various drugs (e.g. amiodarone, phenytoin); connective tissues disorders (e.g. rheumatoid arthritis, SLE); malignant disease and infections (e.g. HIV).

It is important to accurately diagnose early the acquired idiopathic (inflammatory) polyneuropathies, namely the acute (Guillain–Barré syndrome) and chronic (slower and more protracted) types. The acute type is potentially fatal with respiratory paralysis.

GUILLAIN–BARRÉ SYNDROME

Acute development of:

• ascending weakness in limbs—usually symmetrical

• both proximal and distal muscles affected

• facial paralysis (50%)

• extraocular or bulbar paresis (rare)

• reflexes depressed or absent

• paraesthesiae or pain in the limbs

Sensory loss is minimal or absent.

Diagnosis:

• CSF examination (elevated protein, normal cells)

• abnormal motor nerve conduction studies

Refer for inpatient care: plasmapheresis or IV immunoglobulin used for more severe cases.

Prognosis: 80% recover completely; up to 10% die; 10% residual disability; 5% relapse