Anatomy Msk · Year 1 · from Anatomy Msk
Case 2: Carpal Tunnel Syndrome
Clinical Image
Source: Wikimedia Commons - Carpal Tunnel - CC BY-SA 4.0
Case Presentation
A 52-year-old woman presents with a 6-month history of numbness and tingling in her right hand that wakes her from sleep several times per week. She reports the symptoms are worst in her thumb, index, and middle fingers, and improve when she shakes her hand (flick sign). She works as a data entry clerk and notes worsening symptoms with prolonged computer use. Over the past month, she has noticed weakness when opening jars and occasionally drops objects. Physical examination reveals decreased two-point discrimination in the median nerve distribution (thumb, index, middle finger, and radial half of ring finger). There is thenar muscle atrophy with weakness of thumb abduction and opposition. Tinel sign is positive at the wrist (tapping over the carpal tunnel reproduces paresthesias). Phalen test is positive (sustained wrist flexion for 60 seconds reproduces symptoms). Nerve conduction studies confirm severe median neuropathy at the wrist with prolonged distal motor and sensory latencies. Given the moderate to severe findings with thenar atrophy, she undergoes carpal tunnel release surgery with complete resolution of nighttime symptoms at 6-week follow-up.
Key Learning Points
- The carpal tunnel is bounded by carpal bones dorsally and the flexor retinaculum (transverse carpal ligament) volarly
- Nine flexor tendons (FDS x4, FDP x4, FPL) and the median nerve pass through the carpal tunnel
- Compression of the median nerve causes sensory symptoms in the thumb, index, middle, and radial ring finger
- Motor findings include weakness of thumb abduction (APB) and opposition (opponens pollicis), with thenar atrophy
- The palmar cutaneous branch of median nerve is superficial to the retinaculum and is typically spared