Carpal Tunnel Syndrome

Compressive neuropathy of the median nerve at the wrist. The most common peripheral nerve entrapment.

Mechanism and risk

Any cause of raised carpal tunnel pressure impairs median nerve microcirculation and conduction: tenosynovial swelling, repetitive wrist flexion-extension, vibration, bony deformity, or a space-occupying lesion (ganglion, tumour, accessory muscle).

Category	Factors
Non-modifiable	Female sex (about 3:1), age over 40, genetics, congenital narrowing
Modifiable	Obesity, diabetes, smoking, alcohol, inactivity
Medical	Pregnancy, hypothyroidism, rheumatoid arthritis, acromegaly, amyloidosis, renal failure
Occupational	Forceful repetitive gripping, vibrating tools, prolonged wrist flexion

The occupational link is real but modest. CTS is multifactorial, so always exclude medical causes.

Presentation

Numbness and tingling in the thumb, index, middle and radial half of the ring finger. The little finger is spared.
Nocturnal symptoms wake the patient, who shakes the hand for relief (flick sign)
Pain may radiate to the forearm or shoulder
Weakness and clumsiness are late. Thenar wasting indicates significant axonal loss.

Test	Method
Tinel’s	Tap over the tunnel
Phalen’s	Wrist flexion for 60 seconds
Durkan’s	Direct compression over the tunnel

These tests have moderate sensitivity and low specificity. History dominates.

Differential

C6 to C7 radiculopathy, ulnar neuropathy, thoracic outlet syndrome, proximal median neuropathy, polyneuropathy.

Investigations

Nerve conduction studies and EMG: reference standard. They confirm and grade severity, exclude other neuropathies and predict surgical outcome, but false negatives occur. Treat a typical picture even if the study is borderline.
Ultrasound: enlarged median nerve cross-sectional area. Useful when NCS is equivocal.
MRI for atypical cases or suspected mass. Bloods (TSH, HbA1c, RF) if a systemic cause is suspected.

Management

Night splint in neutral: first-line for mild to moderate disease.
Activity modification. Treat systemic causes. Pregnancy-related CTS often resolves postpartum.
Corticosteroid injection: effective short to medium term, and a bridge to surgery.
Nerve gliding, physiotherapy, therapeutic ultrasound: modest evidence.
Surgical release (open or endoscopic): moderate to severe disease, thenar wasting, or failure of 3 to 6 months of conservative care. A well-established operation with low complication rates.

References

Carpal tunnel syndrome, Nat Rev Dis Primers 2024, doi:10.1038/s41572-024-00521-1
Front Public Health 2024, doi:10.3389/fpubh.2024.1407302
Arch Phys Med Rehabil 2018, doi:10.1016/j.apmr.2017.08.482

Medical disclaimer: this article is general information, not personal medical advice. Always consult a qualified doctor about your own situation.