Jama 2000;283;3110; 2002;288:1245

Cause: Local swelling and entrapment of median nerve at wrist

Pathophys: Swelling within the carpal tunnel formed by the transverse carpal ligament impairs blood flow to median nerve

Similar entrapment syndromes can occur elsewhere but are very rare, eg, very similar TARSAL TUNNEL SYNDROME in lateral foot; in the pronator teres (Nejm 1970;282:858); or of the ulnar nerve at the wrist, usually sx there only after sx’s in median nerve distribution first

Associated with occupational repetitive hand movements (but not computer keyboard use?—Jama 2003;289:2963) in 2/3, also pregnancy, myxedema, amyloidosis, tumor, rheumatoid arthritis, tenosynovitis, acromegaly, diabetes, wrist fracture, gout, myeloma, ganglia, renal failure with chronic dialysis

Female/male = 2:1 usually but in an occupational setting ratio is equal (Am J Publ Hlth 1991;81:741). Prevalence = 125-500/100 000 adults; but up to 15/100 in high-risk occupations; perhaps as high as 2+% (Jama 1999;282:153, 186)

Figure 18.2 Suggested algorithm for the diagnostic evaluation of patients with low-back pain

Reproduced with permission from Jarvik JG, et al. Diagnosis evaluation of low back pain with emphasis on imaging. Ann Int Med. 2002;137:586

Sx: Numbness in median nerve distribution of the hand; worse at night (77%), shaking and/or hanging improves; pain and paresthesias often radiate proximally to elbow and shoulder; later, weakness of pincer grip, eg, holding a cup

Si: No pain, position or touch loss objectively, but often hypesthesia in median nerve distribution. Thenar wasting (15%) from loss of all but short thumb flexor

Tinel’s sign (60% sens, 67% specif) = paresthesias when tap over median nerve at wrist; or Phalen’s sign (75% sens, 47% specif) = paresthesias with forced wrist flexion for 60s; or median nerve paresthesias with 1 min of BP cuff pumped up above systolic pressure

Slowly progressive, or may wax and wane

Permanent loss of thenar median nerve function, weakness and/or numbness

r/o other causes of similar sx including Raynaud’s, cervical arthritis w radiculopathy, bursitis of shoulder, thoracic outlet syndrome, and ulnar neuropathy from elbow entrapment, which is less easily helped by local measures (Nejm 1993;329:2016)

Lab:

Noninv: EMG nerve conduction velocities markedly decreased (90% sens, ?% specif)

Rx: NSAIDs; steroids (BMJ 1999;319:884) 4 mg of methylprednisolone or 25 mg hydrocortisone locally injected proximally improves 80% at 1 mo, 50% at 1 yr; diuretics; splinting; change jobs; yoga program × 8 wk helps more than splint (Jama 1998;280:1601)

Surgical, esp if thenar wasting present, or if patient plans to continue heavy work, or when conservative rx has failed