Small fiber neuropathy

Small fiber neuropathy affects the smallest peripheral nerve fibers, the ones that carry pain and temperature sensation and help run automatic functions. It has many causes, most commonly diabetes, and up to about a third of cases remain idiopathic with no clear cause identified. A share of cases appear to be immune-related or occur alongside autoimmune conditions such as Sjogren's syndrome, and researchers are also identifying genetic contributors, including mutations in a sodium channel gene that make nerve fibers more excitable.

Research estimates a prevalence around 53 cases per 100,000 people, though this figure likely undercounts milder or undiagnosed cases. Diagnosis typically relies on measuring nerve fiber density in a small skin biopsy, since standard nerve conduction studies often appear normal.

Common signs

Burning, stabbing, or electric pain and tingling, often starting in the feet and sometimes the hands, along with numbness and, when autonomic fibers are involved, lightheadedness, dry eyes and mouth, or gut and bladder changes.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.