CLINICAL evaluation of small fiber neuropathy (SFN) remains inconsistent across neurology subspecialties, with survey data revealing wide variation in diagnostic practices, even when faced with common patient scenarios.
The findings suggest that while most neurologists rely on a core group of diagnostic tests, practices differ substantially across specialties and scenarios.
In this national survey of 800 randomly selected AAN members, including 400 neuromuscular specialists, clinicians were asked about their diagnostic approaches to distal symmetric SFN. Of the 234 respondents (29.3% response rate), nearly half identified neuromuscular medicine as a primary or secondary specialty.
When presented with a typical initial evaluation scenario for SFN, respondents ordered an average of 12 tests, ranging from none to 26. The most commonly ordered labs included complete blood count (87%), vitamin B12 (86%), basic metabolic panel (84%), thyroid-stimulating hormone (78%), and hemoglobin A1c (77%), tests broadly aligned with those used in evaluating distal symmetric polyneuropathy.
However, practice patterns diverged in more complex clinical decisions. For example, 65% of neuromuscular specialists reported they would order a skin biopsy to assess intraepidermal nerve fiber density, compared to just 38% of non-neuromuscular specialists. Conversely, 52% of non-neuromuscular specialists said they would include a paraneoplastic panel in a secondary workup, compared to 35% of their neuromuscular counterparts.
Despite the existence of a 2009 AAN Practice Parameter for distal symmetric polyneuropathy, no such guideline exists specifically for SFN, an absence that may contribute to the inconsistent approaches revealed in this study. Notably, even tests with high diagnostic yield were not universally used, suggesting potential gaps in adherence to best practices or uncertainty about what constitutes an optimal diagnostic pathway.
These findings indicate a pressing need for updated, specialty-inclusive AAN guidelines to standardize the evaluation of SFN, enhance diagnostic accuracy, and improve patient care across neurology subspecialties.
Reference:
Thawani S et al. How Well do We Evaluate Small Fiber Neuropathy?: A Survey of American Academy of Neurology Members. J Clin Neuromuscul Dis. 2025;26(4):184-195.
