Carpal tunnel syndrome (CTS)

Carpal tunnel syndrome is caused by compression of median nerve in the carpal tunnel.

History

• pain/pins and needles in thumb, index, middle finger
• unusually the symptoms may 'ascend' proximally
• patient shakes his hand to obtain relief, classically at night

Examination

• weakness of thumb abduction (abductor pollicis brevis)
• wasting of thenar eminence (NOT hypothenar)
• Tinel's sign: tapping causes paraesthesia (T for Tap)
• *Phalen'*s sign: flexion of wrist causes symptoms (P for p(f)lex)

Source: https://www.youtube.com/@osmosis

Causes

• idiopathic
• pregnancy
• oedema e.g. heart failure
• lunate fracture
• rheumatoid arthritis

Electrophysiology

• motor + sensory: prolongation of the action potential