To Identify Small Fiber Neuropathy (SFN) as Cause of Autonomic Dysfunction and/or Pain/Sensory Dysfunction in Children

Small fiber neuropathy remains under-recognized in children and underdiagnosed. Etiology remains unknown in most patients for the same reasons. Genetic and autoimmune etiology is suspected to be the most common cause and only recently some genes and antibodies respectively have been identified in adults.

Children suspected to have SFN based on symptoms underwent skin biopsy at the Child Neurology clinic, Arnold Palmer Hospital. It was processed at pathology laboratory, Therapath. All 10 children were found to have small fiber neuropathy. ENFD (Epidermal Nerve fiber density) and SGNFD (Sweat Gland Nerve fiber density) were used to diagnose SFN based on normative values available in literature. Clinical information was  extracted from the charts.

The age range at time of diagnosis was 4-17 years. Most common symptoms of autonomic dysfunction was gastric dysmotility disorders presenting as feeding intolerance, stooling difficulty ,chronic nausea and slowed intestinal transit times and POTS (Postural orthostatic tachycardia syndrome) in 9/10 patients. Pain or numbness/tingling was present in 7/10 children which did not follow any nerve or root distribution pattern of neuropathy. The symptoms started early on, usually 1-4 years before the diagnosis could be made.  One child each had NF-1, autism, epilepsy and sickle cell disease. Etiology of SFN remains unknown in most of these children despite extensive testing including WES (Whole exome sequencing).

Small fiber neuropathy remains under-recognized cause of pain syndromes and autonomic dysfunction in children. Symptoms start much earlier in life and are usually subacute or chronic in onset. Recognizing the constellation of symptoms and signs is the key to managing these children appropriately. Early recognition provides a window to possibly finding a cure since some of these children might have an autoimmune etiology responsive to immunomodulation.