IENFD assessment has become an important tool for diagnosis of small fiber neuropathy (SFN). Distal leg, distal thigh and proximal thigh are the usual sites of biopsy. At least two-site biopsies are performed to assess for length dependency. Age dependent normative data have been established for distal leg. In some patients with paresthesia, although the distal and proximal biopsies are normal, the distal IENFD is much less compared to proximal density. There is limited literature looking at the significance of the ratio of distal-to-proximal biopsy IENFD.

Total of 56 charts were reviewed. Female to male ratio was 3:1. Mean age was 50±26. Total number of patients with clinical diagnosis of neuropathy (probable and possible) was 46. IENFD was abnormal in 23, normal in 23 with mean distal to proximal ratio of 0.5 and 0.6 respectively. The mean ratio for patients without clinical diagnosis of neuropathy was 0.9. The 23 patients with clinical diagnosis of neuropathy with negative skin biopsy had significant difference in mean ratio compared to patients without clinical diagnosis of neuropathy using T-test (p 0.02).