Background
- Entrapment compression median nerve beteeen carpal bones and flexor retinaculum
- M:F = 1:3. Bilateral in 60%
- Genetic component
- Assoc. pregnancy, overuse, trauma, ↓T4, CRF, DM, arthropathies, obesity
Clinical
- Intermittant pain/altered sensation in radial 3½ digits
- Sometimes assoc. forearm/arm/shoulder pain
- Worse at night or with overuse
- ↓grip strengt and ↓sensation med. N distribution
- Eased with "flicking" the wrist
- ↓LOAF muscle power (↓thumb abduction)
- Thenar wasting late
- Hand elevation above head x2 min = thumb anaesthesia (most specific test)
- Tinel's sign = tingling with percussion over carpal tunnel
- Phalen's test = tingling with wrists flexed to 90° x 1 min
- Prayer sign = Paraestesia (Med. N.) wrist flexed x1 min.
- Durkan's test = Tingling with 3 finger pressure on carpal tunnel x30 sec
Differential Dx
ASSUMING NO RECENT TRAUMA (local haematoma etc):
- Polyneuropathy - particularly diabetic (check BM in all)
- Cubital (elbow) tunnel synd.: Ulnar nerve so thumb is spared
- Early arthropathy / mono-arthritis (consider RhF or autoantibodies)
- Cervical (C6/7) radiculopathy (neck movement)
- Hypothyroid (TFTs ?)
- Vibration white hand syndrome (Hx should be a giveaway!)
- De Quervain's (pain rather than Δ sensation)
- Motor neuron disease does not have sensory component
Investigations
- GP to arrange EMG studies
- HbA1c with GP
- GP to refer to hand / ortho surgeon
Management
- Treat reversible causes
- Wrist splint (in 0° flexion) particularly at night
- Consider steroid injection into tunnel (NOT the nerve!) - transient relief
- Transient relief with PO steroids
- GP to refer for surgery