13. Carpal tunnel syndrome – methods of diagnosis and treatment

Definition

• Compression of N. medianus which runs from the forearm through the carpal tunnel into the hand at the base of the palm
• Innervates most of the muscles of forearm and hand and provides sensory innervation to palm except fifth and ulnar part of fourth finger

Etiology

• Forceful use of the hand
• Repetitive motion
• Awkward position of the hand
• Vibration
• Crush injuries

Pathogenesis

• Thickening of irritated tendon or swelling of paratendon → narrows tunnel → nerve is trapped usually between ligaments and bone surface
• Repetitive trauma and compression of nerve with friction, sliding over sharp, stretched ridges results in microvascular ischemic changes, perineural microinsults, edema, axonal alteration → in severe chronic cases: incomplete nerve recovery (permanent changes)

Clinical manifestations

• Wrist pain that increases over time
• Numbness
• Pricloing
• Decreased sensory perception
• Muscle weakness
• Motor disorders of hand:
• Ape hand
• Hand of Benediction

Diagnosis

• History
• Physical exam:
• Weakness in opposing the thumb against resistance
• Paresthesia and pain when palpated
• EMG
• US