title: The human dorsal spinocerebellar tract: myelinated fiber spectrum and fiber density in controls, autosomal dominant spinocerebellar atrophy, Huntington's chorea, radiation myelopathy, and diseases with peripheral sensory nerve involvement.
abstract: The human dorsal spinocerebellar tract (DSCT) was evaluated morphometrically in 14 control cases of different age and sex using semithin sections of epon-embedded cross sections from the C3, T5, and T10 segments of the spinal cord. A bimodal fiber spectrum was revealed with one peak at 2-3 microns, and a second, broader peak at about 6-8 microns. Fiber density at C3 was 11,188 fibers/mm2 and at T5, 11,156 fibers/mm2. Regression analysis relating fiber density to age disclosed a highly significant loss of myelinated fibers at T5 amounting to about 2.5% per decade. A severe reduction of fiber density and a distinct change in the fiber spectrum with predominant loss of large myelinated fibers were noted in a case of autosomal dominant spinocerebellar atrophy with late onset, and, to a lesser degree, in a case of Huntington's chorea. A subtotal loss of fibers with a persistent normal distribution of fiber sizes was observed rostral to a focus of severe radiation myelopathy, indicating Wallerian degeneration of large numbers of fibers, and a reduction of fiber diameters caudal to the lesion, suggesting retrograde fiber change. By contrast, no primary or transneural changes in the DSCT were detected in six cases of long-term alcoholism, carcinomatous sensory neuropathy, and neurofibromatosis in spite of the involvement of numerous nerve roots.
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000473:pathology; D001284:Atrophy; D002493:Central Nervous System Diseases / Q000235:genetics; D002531:Cerebellum / Q000473:pathology*; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D006816:Huntington Disease / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000473:pathology*; D011832:Radiation Injuries / Q000473:pathology; D013116:Spinal Cord / Q000473:pathology* / Q000528:radiation effects