Accuracy of the three-window sampling method in morphometric analysis of human sural nerve

Morphometry has an important role in the assessment of sural nerve biopsies as a part of early detection of structural abnormalities in peripheral nerve. Various sampling methods have been used to reduce time and effort needed in the analysis of total nerve fibers but their accuracy remains controversial. We examined the accuracy of three-window sampling method in the morphometric evaluation of human sural nerve biopsies by comparing with the total fiber quantification. Three windows (0.012 mm2 each) were placed in every possible fascicle in the sections and data from all windows were pooled and analyzed for the number of myelinated axons, myelinated fiber diameter, axon diameter, myelin thickness, g ratio as well as myelinated fiber density. Means and ranges of the data from the two techniques were similar and the agreement was further confirmed by intraclass correlation analysis. These findings indicate that the three-window sampling method can be used to evaluate human sural nerve with accuracy.