Autonomic Component of Carpal Tunnel Syndrome

Abstract

Carpal tunnel syndrome (CTS) is the most common compression neuropathy. The median nerve contains sensory, motor, and sympathetic fibers. Involvement of the different fibers of the median nerve in CTS may vary; hence, one of the sensory, motor, or autonomic dysfunctions may be dominant. Autonomic fibers of the median nerve consist of postganglionic sympathetic vasomotor and sudomotor fibers. An incomplete interruption of the axoplasmic flow may provoke a reflex that increases the sympathetic activity, leading to sweating, Raynaud phenomenon, and paleness of fingers. A complete sympathetic axoplasmic flow disruption blocks the sympathetic activity that leads to vasodilation, and the affected area in the hand is believed to be swollen, warmer, pinker, and dryer than the rest of the limb. In advanced and severe autonomic dysfunction, the fingertips may ulcerate, and nail growth changes may occur. Carpal tunnel syndrome diagnosis is a constellation of symptoms and signs; however, there has been limited attention to the autonomic component of CTS. Regeneration and reinnervation capacity of thin unmyelinated sympathetic fibers after compression and axonal degeneration is poor. Ignoring the important role of the autonomic component of CTS may lead to persistent symptoms and unsuccessful CTS surgery. Early carpal tunnel release in patients with autonomic findings is indicated and may provide improved outcomes.