Carpal tunnel syndrome is a common condition affecting 10% of the population at some time during their life. Prevalence estimates range from 0.1%-0.6% of the population. It preferentially affects people who do manual labor or have hobbies with extensive hand / digit involvement. Carpal tunnel syndrome is caused by median nerve compression within the carpal tunnel (a narrow passageway formed by bones and ligaments on the palmar surface or the hand / wrist), and this may affect sensory, motor, and autonomic neural functions of the median nerve. Patients present with pain and paresthesias affecting the first three digits.

Mild carpal tunnel syndrome is typically not associated with dermatologic findings. When long-standing, autonomic nerve dysfunction occurs, resulting in necrotic carpal tunnel syndrome. Dermatologic manifestations will then include bullae, ulcers, hypohidrosis, vasospasm, and Raynaud phenomenon. Nail changes may also occur and may be a clue to diagnosis of carpal tunnel syndrome.

Nail changes are more common in women, with a median age of 54 years. The right hand is more often involved than the left.

There are case reports of carpal tunnel-associated nail changes in children and young adults; however, it is very rare in children. For late stage carpal tunnel syndrome presenting in children, genetic or metabolic causes should be explored, although there are reports of sporadic cases. These include lysosomal storage diseases (familial thickening of the transverse ligament and diabetes mellitus). Other reported causes are repetitive wrist motion, median nerve fibrolipomas or hemangiomas, hemophilia, automutilation, and trauma.