🖐️ Carpal tunnel syndrome (CTS) is the most common mononeuropathy, caused by compression of the median nerve within the carpal tunnel. It typically presents with nocturnal paraesthesia, hand pain, and sometimes thenar muscle weakness or wasting.

📌 About

Most common entrapment neuropathy
Median nerve compressed beneath the flexor retinaculum at the wrist
Classically affects dominant hand, but can be bilateral

🧬 Aetiology

Median nerve runs with 9 flexor tendons in the carpal tunnel → space-occupying or thickening processes lead to compression
Can cause thenar wasting and impaired thumb opposition/abduction
Weakness of abductor pollicis brevis and intrinsic hand muscles supplied by the median nerve

Carpal tunnel diagram

⚠️ Causes / Risk Factors

Rheumatoid arthritis, pregnancy, acromegaly
Colles’ fracture, minor trauma, idiopathic
Amyloidosis (β2-microglobulin in dialysis patients)
Myxoedema (hypothyroidism), obesity, diabetes

🩺 Clinical Features

Paraesthesia and pain in radial 3½ fingers (thumb, index, middle, radial half of ring finger); palm sparing due to palmar cutaneous branch
Nocturnal symptoms common; may radiate to forearm/shoulder
Motor: thenar weakness, difficulty opposing thumb, thenar wasting late
Provocative tests:
- 🔔 Tinel’s sign: percussion over flexor retinaculum → tingling
- 📐 Phalen’s test: forced wrist flexion 60 sec → symptoms reproduced

Clinical signs in CTS

🔬 Investigations

Bloods: FBC/U&E usually normal; TFT (hypothyroidism), B12 (neuropathy screen), ESR/protein studies if myeloma suspected
Nerve conduction studies → delayed conduction across wrist (gold standard for diagnosis & severity grading)
Needle EMG can show denervation if severe

🔎 Differentials

Cervical radiculopathy (C6–C7): often with neck pain and dermatomal distribution
Peripheral neuropathy (e.g. diabetic, B12 deficiency)

💊 Management

🔹 Treat underlying cause (e.g. hypothyroidism, inflammatory arthritis)
🔹 Splinting: neutral wrist splints, especially nocturnal
🔹 Analgesia ± corticosteroid injection into carpal tunnel (may cause transient worsening)
🔹 Surgery: carpal tunnel decompression (division of flexor retinaculum) if intractable symptoms, weakness, or NCS-confirmed severe disease

Cases — Carpal Tunnel Syndrome (CTS)

Case 1 — Classic presentation ✋: A 48-year-old secretary reports tingling and numbness in the thumb, index, and middle fingers, worse at night and relieved by shaking her hand (“flick sign”). Exam: positive Tinel’s and Phalen’s tests. Diagnosis: idiopathic CTS. Managed with wrist splints and steroid injection if persistent.
Case 2 — Secondary cause 🩺: A 36-year-old pregnant woman (third trimester) develops hand paraesthesia and nocturnal wrist pain. Exam confirms median nerve distribution sensory loss. Diagnosis: CTS secondary to fluid retention in pregnancy. Managed conservatively (splints, reassurance) as symptoms usually resolve postpartum.
Case 3 — Severe disease 🔪: A 62-year-old man with type 2 diabetes presents with progressive numbness, thenar muscle wasting, and reduced grip strength. Nerve conduction studies: delayed median nerve conduction. Diagnosis: advanced CTS. Managed with surgical decompression (carpal tunnel release).

Teaching Point 🩺: CTS is due to median nerve compression in the carpal tunnel. Risk factors include diabetes, pregnancy, hypothyroidism, obesity, and repetitive wrist use. Early disease is often nocturnal and sensory; late disease causes motor weakness and thenar wasting. Nerve conduction studies confirm severity.

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Carpal tunnel syndrome