Evidence of small‐fiber neuropathy in neurofibromatosis type 1

Introduction Large‐fiber neuropathy is rare in neurofibromatosis type 1, but small‐fiber neuropathy has not been studied. Methods Patients with neurofibromatosis type 1 underwent nerve conduction studies for large‐fiber assessment. Small‐fiber tests included quantitative thermal thresholds, laser Doppler flare imaging, intraepidermal nerve fiber density, and corneal nerve fiber length. Results Of the 52 patients enrolled, 31 (60%) were female and the mean age was 33.0 ± 12.3 years. Four (8%) patients had abnormal nerve conduction studies. Small‐fiber tests were frequently abnormal: thermal thresholds in 7 (13%); laser Doppler flare imaging in 10 (19%); intraepidermal nerve fiber density in 11 (22%); and corneal nerve fiber length in 27 (52%). The mean corneal nerve fiber length was below normative level (10.1 ± 2.7 mm/mm3). Discussion Small‐fiber neuropathy may be common in neurofibromatosis type 1, and should be investigated in symptomatic patients.