Classification of teased nerve fibers for multicenter clinical trials

Teased nerve fibers are used widely in both clinical and experimental neuro pathology, but anecdotal evidence indicates that even experienced readers f ind little agreement on categories for teased fiber classification. To deve lop a classification scheme that could be used and understood by both exper ienced and naive readers, specific criteria were developed for normal fiber s and those exhibiting Wallerian degeneration, demyelination, hypomyelinati on, remyelination, and abnormal paranodal myelination. Twenty fibers teased from human sural nerve biopsies were selected as examples of one or more o f these categories. Ten readers, including seven having no previous experie nce with teased fibers, were given a set of instructions and asked to score each fiber for all matching categories. These readers averaged high rates of true positive (56-85%) classifications, while average false positive (3- 18%) rates were much lower. Among the three experienced readers, true posit ive agreements averaged between 75 and 100% across the fiber classification s. False positives were correspondingly low, ranging between 0 and 8%. Thes e results suggest that it is possible to design an easily learned, meaningf ul scheme for classifying teased nerve fibers.