o Features: numbness/tingling in radial 3½ fingers, worse at night.
o Thenar wasting, weak thumb opposition.
o Tinel’s (tapping) and Phalen’s (flexion) tests positive.
o Risk factors: diabetes, hypothyroidism, pregnancy, repetitive wrist use.
o Lesion at elbow (cubital tunnel) or wrist (Guyon’s canal).
o Features: weakness of finger abduction/adduction, hypothenar wasting, sensory loss in ulnar 1½ fingers.
o Compression in spiral groove (e.g., sleeping on arm).
o Features: wrist drop, finger drop, sensory loss over dorsum of hand.
o Compression at fibular head (crossed legs, prolonged squatting).
o Features: foot drop, weak dorsiflexion and eversion, sensory loss over lateral shin and dorsum of foot.
• Typical features:
o Symmetrical distal sensory > motor symptoms ("glove and stocking").
o Loss of vibration, proprioception early if large-fibre involvement; pain and temperature if small-fibre.
• Common causes:
o Diabetes mellitus: most common in UK; sensory predominant ± autonomic features.
o Alcoholism: nutritional deficiency (B1, B12), direct neurotoxicity.
o Vitamin deficiencies: B12 (subacute combined degeneration), B6, B1.
o Drugs/toxins: chemotherapy (vincristine, cisplatin), isoniazid, amiodarone.
o Paraproteinaemias (e.g., myeloma, amyloidosis).
o Hypothyroidism, CKD (uraemic neuropathy), HIV.
• Investigations:
o Bloods: glucose, HbA1c, B12/folate, TFTs, renal and liver function, paraprotein screen.
o Nerve conduction studies (NCS): demyelinating vs axonal.
• Features:
o Rapidly progressive ascending weakness, often starting in legs.
o Areflexia (universal finding), possible sensory symptoms (paresthesia).
o Cranial nerve involvement (e.g., bilateral facial weakness).
o Autonomic dysfunction: arrhythmias, BP swings, urinary retention.
• Preceding infections:
o Campylobacter jejuni most common (diarrhoea history).
o CMV, EBV, Mycoplasma.
• Investigations:
o LP: albuminocytologic dissociation (↑ protein, normal or few cells).
o NCS: demyelination (↓ conduction velocity, conduction block).
• Management:
o IV immunoglobulin or plasma exchange.
o Monitor vital capacity (risk of respiratory failure).
o Supportive: DVT prophylaxis, autonomic monitoring.
Extra Revision Pearls
• Claw hand → ulnar nerve; wrist drop → radial nerve; ape thumb → median nerve.
• B12 deficiency → subacute combined degeneration (posterior columns + corticospinal tracts).
• GBS → always check forced vital capacity regularly (consider intubation if <15 mL/kg).
• Diabetes → can cause distal symmetric neuropathy, mononeuropathy (CN III palsy sparing pupil), or radiculoplexopathy.
• Small-fibre neuropathy → pain and autonomic symptoms, normal NCS (needs skin biopsy or thermal threshold testing).
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
