Rare neuropathy explains widespread body pain

A newly identified neuropathic disease appears to cause disabling, widespread body pain in children, according to research from Massachusetts General Hospital.  

Juvenile-onset small-fiber polyneuropathy has been rarely diagnosed in children, although the disease has been shown to cause widespread chronic pain and multisystem complaints in older adults. It causes damage to the nerve fibers that carry pain signals and that control heart rate, blood pressure, and sweating. Pain often begins in the lower legs and feet, accompanied by gastrointestinal problems, dizziness or fainting when standing, rapid heart rate, and changes in the skin.

The researchers identified 41 patients who had been evaluated for unexplained widespread pain beginning before they were aged 21 years and analyzed their medical records for diagnostic testing for small-fiber polyneuropathy (neurodiagnostic skin biopsy, nerve biopsy, and autonomic function), histories, symptoms, and other tests and treatments. Participants were matched with healthy controls who underwent the same diagnostic tests.

Analysis showed that 24 of the 41 patients had at least 1 test result that was positive for the disease. Sixteen of the 17 remaining patients were shown to possibly or probably have the disease based on test results. Sweat production, the most sensitive of the autonomic function tests, was reduced in 82% of patients compared with controls. One   patient’s tests were entirely normal.  

Most patients were moderately or severely ill and more than two-thirds had been hospitalized or had required medical leaves from school or work. No other pathogenic diagnoses explained their widespread pain. Sixty-one percent reported becoming ill after infection and 31% reported a traumatic injury as a trigger; both infection and injury can precipitate autoimmune neuropathy.

The findings suggest that small-fiber polyneuropathy can develop even in preschool-aged children and persist into adulthood, so identifying the tests that confirm a pediatric presentation will eliminate other ineffective, costly, and potentially harmful testing and guide timely and definitive treatment of symptoms.