Carpal Tunnel Syndrome

KEY FEATURES

Essentials of Diagnosis

• Pain, burning, and tingling in the distribution of the median nerve

• Initially, most bothersome during sleep

• Late weakness or atrophy, especially of the thenar eminence

• Can be caused by repetitive activities using the wrist

• Commonly seen during pregnancy, diabetes mellitus, or rheumatoid arthritis

General Considerations

• Caused by compression of the median nerve between the carpal ligament and other structures within the carpal tunnel

• May occur due to fluid retention of pregnancy, in individuals with a history of repetitive use of the hands, or following injuries of the wrists

• The contents of the tunnel can be compressed by

  • Synovitis of the tendon sheaths or carpal joints

  • Recent or malhealed fractures

  • Tumors

  • Tissue infiltration

  • Congenital syndromes (eg, mucopolysaccharidoses)

• Patients with diabetes can get mononeuropathies, possibly related to high glucose levels

• Can be a feature of hyperparathyroidism, rheumatic diseases, or infiltrate disorders, such as

  • Rheumatoid arthritis

  • Inflammatory tenosynovitis

  • Myxedema

  • Amyloidosis

  • Sarcoidosis

  • Leukemia

  • Acromegaly

• There is a familial type in which no etiologic factor can be identified

CLINICAL FINDINGS

Symptoms and Signs

• Initial symptoms

  • Pain, burning, and tingling in the distribution of the median nerve

  • Most bothersome at night

• Aching pain may radiate proximally into the forearm and occasionally to the shoulder, neck, and chest

• Pain exacerbated by manual activity, particularly extreme volar flexion or dorsiflexion of the wrist

• Impairment of sensation in the median nerve distribution may or may not be demonstrable

• Subtle disparity between affected and opposite sides shown by testing two-point discrimination or texture identification between thumb and index finger

• A Tinel or Phalen sign may be positive (eTable 43–2)

  • A Tinel sign is tingling or shock-like pain on volar wrist percussion

  • The Phalen sign is pain or paresthesia in the distribution of the median nerve when the patient flexes both wrists to 90 degrees for 60 seconds

• The carpal compression test, in which numbness and tingling are induced by the direct application of pressure over the carpal tunnel, may be more sensitive and specific than the Tinel and Phalen tests (eTable 43–2)

• Muscle weakness or atrophy, especially of the thenar eminence, can appear later than sensory disturbances as compression of the nerve worsens