Acquired and progressive myelinated nerve fibers.

Follow-up data are presented on a previously described child in whom myelinated nerve fibers presumably developed 5 1/2 months after an optic nerve decompression. During the subsequent five years, the myelinated nerve fibers have progressively enlarged. Five years after surgery, myelinated nerve fibers appeared in the patient's fellow eye. An additional two cases of documented acquired myelinated nerve fibers without any predisposing factors are reported. Myelinated nerve fibers can appear and progress after infancy.