A quantitative method for the assessment of intraepidermal nerve fibers in small-fiber neuropathy

The purpose of this paper is to present an easy-to-use and reproducible morphometrical method of determining the density of intraepidermal nerve fibers (IENF) per epidermal area with the corresponding reference range of the IENF-counts.

Thirty patients and 22 controls were included in this study. The patients were divided into three groups: small-fiber (SFN), diabetic and demyelinating neuropathy. All subjects underwent punch skin biopsy. Specimens were fixed routinely in formalin and thereafter embedded in paraffin. Nerve fibers were revealed using immunoperoxidase staining with panaxonal antibody PGP 9.5. Using light microscopy, immunopositive nerves were counted morphometrically per epidermal area (NPEA) and, for comparison, per epidermal length (NPEL).

Both the NPEA and NPEL estimates of SFN and diabetic neuropathy group differed significantly from those of control specimen (p < 0.001 and p < 0.001, Mann-Whitney test). Our method of counting, NPEA, shows a good correlation to NPEL (r = 0.945).

IENF-counting by a new morphometric modification is reproducible and diagnostically sensitive and can easily be adopted in any laboratory familiar with the basic immunohistochemical methodology. The method is less dependent on costly technical support systems and seems to be less time consuming when compared with conventional methods for IENF-counting.