Carpal tunnel syndrome
Exam Tips
- Classic OSCE clue: nocturnal median-nerve paraesthesia relieved by shaking the hand ('flick sign').
- Median sensory territory in CTS usually spares the thenar skin (palmar cutaneous branch arises proximal to tunnel).
- Differentiate from ulnar neuropathy: little finger symptoms suggest ulnar involvement, not isolated CTS.
- Look for red flags for urgent referral: thenar wasting, constant numbness, rapidly progressive weakness, or severe pain/swelling suggesting alternative pathology.
- Provocation tests support diagnosis but are not definitive alone; combine with distribution of symptoms and neurological exam.
- In viva, mention anatomy explicitly: median nerve + flexor tendons under flexor retinaculum at the wrist.
Definition
Carpal tunnel syndrome is a compressive mononeuropathy of the median nerve at the wrist, where the nerve passes through the fibro-osseous carpal tunnel beneath the transverse carpal ligament. It typically causes nocturnal paraesthesia, numbness, and pain in the median-innervated digits, and in more advanced cases leads to thenar weakness, impaired dexterity, and persistent sensory loss.
Pathophysiology
The carpal tunnel is bounded dorsally/laterally by carpal bones and volarly by the transverse carpal ligament, containing the median nerve and flexor tendons. Any process that reduces tunnel volume (for example synovial swelling, altered wrist mechanics, mass lesions) or increases content volume raises intracarpal pressure, especially with prolonged flexion/extension. Repeated or sustained pressure impairs intraneural blood flow, causes focal demyelination and eventually axonal injury, producing sensory symptoms first (intermittent paraesthesia/pain) and later motor deficits (thenar weakness/wasting). For anatomy revision, correlate with a cross-sectional wrist diagram showing median nerve position deep to the flexor retinaculum.
Risk Factors
- Female sex and increasing age (UK primary care incidence higher in women; common around mid-life)
- Obesity
- Pregnancy (fluid retention-related, often improves postpartum)
- Diabetes mellitus
- Hypothyroidism
- Inflammatory arthritis (especially rheumatoid synovitis at the wrist)
- Repetitive forceful hand/wrist work and use of vibrating tools
- Local structural causes: ganglion cyst, tumour, scar tissue, thumb base/MCP osteoarthritic change
Clinical Features
Symptoms
- Intermittent numbness, tingling, burning pain in thumb, index, middle, and radial half of ring finger
- Nocturnal worsening; waking from sleep and relief by shaking/flicking the hand
- Pain may radiate to wrist/forearm (occasionally to shoulder)
- Reduced grip, clumsiness, dropping objects, difficulty with buttons/jars
- In severe disease: constant numbness or persistent pain
Signs
- Positive Phalen test (wrist flexion reproduces median-distribution symptoms)
- Positive Tinel sign at volar wrist
- Positive Durkan carpal compression test
- Reduced light touch/pinprick in median distribution
- Weak thumb abduction/opposition, reduced pinch or grip strength
- Thenar eminence wasting in advanced compression
Investigations
Management
Lifestyle Modifications
- Explain condition and modify aggravating activities (repetitive forceful grip, prolonged extreme wrist flexion/extension, vibrating tools)
- Night wrist splint in neutral position as first-line for mild to moderate symptoms (typically trial for at least 6 weeks)
- Address reversible contributors: weight reduction where appropriate, optimize diabetes and thyroid disease, manage inflammatory arthritis
- Advise urgent review if progressive weakness, constant numbness, or thenar wasting develops
Pharmacological Treatment
Simple analgesia (symptom support, not disease-modifying)
- Paracetamol 1 g orally every 4-6 hours (max 4 g/day)
Use short term for pain if needed; does not relieve nerve compression.
NSAID analgesia (if inflammatory pain and no contraindication)
- Ibuprofen 200-400 mg orally up to three times daily with food (max 1.2 g/day OTC; higher doses by prescription)
Avoid/caution in peptic ulcer disease, CKD, heart failure, uncontrolled hypertension, anticoagulant use, and late pregnancy.
Local corticosteroid injection into carpal tunnel
- Methylprednisolone acetate 20-40 mg single local injection
- Triamcinolone acetonide 10-20 mg single local injection
- Hydrocortisone acetate 25 mg single local injection
Provides short-term symptom relief and may delay surgery. Use strict aseptic technique; avoid injection if local/systemic infection. Counsel on transient pain flare, skin depigmentation/subcutaneous atrophy, rare tendon or nerve injury, and temporary hyperglycaemia in diabetes. Repeated injections should be limited and persistent/recurrent symptoms should prompt surgical referral.
Surgical / Interventional
- Carpal tunnel decompression (division of transverse carpal ligament), open or endoscopic
- Indications: severe/progressive neurological deficit (thenar wasting, persistent sensory loss), failure of conservative management, or recurrent disabling symptoms
- Post-op counselling: scar tenderness/pillar pain can occur; monitor for incomplete symptom resolution if longstanding denervation
Complications
- Sleep disturbance and reduced quality of life from nocturnal pain/paraesthesia
- Functional impairment: poor dexterity, weak grip/pinch, difficulty with fine motor tasks
- Persistent median sensory deficit with prolonged compression
- Thenar weakness/wasting with possible irreversible motor loss if late presentation
Prognosis
The course is variable: a substantial proportion improve spontaneously, especially younger patients, those with shorter symptom duration, and pregnancy-related CTS. Poorer outcomes are associated with bilateral disease, longer-standing symptoms, and objective neurological deficit. Untreated cases may remain stable, improve, or worsen; severe compression risks permanent sensory or motor impairment.
Sources & References
🏥BMJ Best Practice(4)
✅NICE Guidelines(1)
- Carpal tunnel syndrome[overview]
📖Textbook References(20)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1121)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 953, 954)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1004, 1005)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 949)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1112)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1005)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1004, 1005)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1133, 1134)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 847, 848)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1132)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 926)[context]
- Netter F. Netter Atlas of Human Anatomy. Classic Regional Approach 8ed 2022.pdf(pp. 665)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 447)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 446, 447)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 561)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 321, 322)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 572)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 560, 561)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 520)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 483)[context]