Prevalence of denervation in the intrinsic foot muscles in patients with distal predominantly small fiber neuropathy

Abstract

We aimed to evaluate the significance of electromyographic findings in the intrinsic foot muscles (IFMs) of patients with skin biopsy proven small fiber neuropathy (SFN). This was a single-center retrospective analysis of patients who underwent skin biopsy for intra-epidermal nerve fiber density (IENFD) measurement and electrodiagnostic (EDX) study for evaluation of polyneuropathy. A total of 1416 patents with normal lower extremity EDX studies proximal to the foot were included. Active denervation was seen in 16.1% of IFMs in patients with skin biopsy proven SFN and 4.1% of patients without SFN (P < .0001). Reinnervation changes without active denervation were observed in 30.4% of SFN patients and 23.8% of patients without SFN (P = .01). IENFD was lower in SFN patients with active denervation in IFMs than without (P < .0001). Evaluation of active denervation in the IFMs can reveal large fiber dysfunction in SFN patients with otherwise normal routine EDX findings.