Spinocerebellar tracts

The pathological hallmark of PCD with Yo antibodies is degeneration and loss of Purkinje cells and often of granule cells as well. CD8+ cells are found in the cerebellum and sometimes in the cerebral cortex, and there is diffuse microglial activation [72]. In some cases, there are changes in the corticospinal and spinocerebellar tracts and dorsal columns [42]. 

VPPn ventral peduncular pontine nucleus 51 VRe ventral reuniens thalamic nucleus 24-33, 80, 98-101 vsc ventral spinocerebellar tract 53-77, 83-85, 96-103 VTA ventral tegmental area 40-47, 80-82, 95-98 VTg ventral tegmental nucleus 53-55, 80, 99-100 vtgx ventral tegmental decussation 40-45, 79-81, 96, 98 VTM ventral tuberomammillary nucleus 35-38, 82, 90 VTRZ visual tegmental relay zone 40-42, 80, 98 VTT ventral tenia tecta 6-8, 80-81, 98-101... 

Fig. 198. Diagram of the restiform body and middle cerebellar peduncle and their contributions to the cerebellar commissure. The dorsal spinocerebellar tract (DST) is part of the restiform body the ventral spinocerebellar tract (VST) enters the cerebellum after passing rostral to the trigeminal nerve. Voogd (1967).

Anatomical classifications of the spinocerebellar tracts are based on their level and nuclei of origin, their decussation within the spinal cord, their position in the lateral funiculus, their entrance route into the cerebellum and their lobular and zonal distribution. These different criteria are not necessarily correlated. Oscarsson (1973) in his comprehensive review of the functional organization of spinocerebellar paths, distinguished the classical dorsal and ventral spinocerebellar tracts and added a third tract, the rostral spinocerebellar tract (Oscarsson and Uddenberg 1964), that originates from the cervical cord. Moreover, Oscarsson (1973) included the cuneocerebellar tract as one of the direct spinocerebellar pathways. 

The dorsal spinocerebellar tract takes its origin from Clarke s column and from a group of neurons in Rexed s (1954) dorsal laminae IV-VI (see Yaginuma and Matsushita, 1987 Matsushita and Hosoya, 1979 Matsushita et al., 1979 and Grant and Xu, 1988, and Xu and Grant, 1994, for complete references on rat and cat). It terminates, mainly ipsilaterally, in nine strips in the vermis, the pars intermedia and the extreme lateral part of the lobules III-V of the anterior lobe (Fig. 206C), bilaterally in lobule Vlll of the caudal vermis and in parts of the paramedian lobule. 

The rostral spinocerebellar tract takes its origin from cell groups in Rexed s (1954) laminae VI, VII and VIII of the intermediate zone and a cell group in lamina V of the dorsal horn. The fibers from lamina VIII cross within the cord, the others ascend in the ipsilateral lateral funiculus (Petras, 1977 Petras and Cummings, 1977 Snyder et al., 1978 Matsushita et al., 1978, 1979 Wiksten and Grant, 980, 1986). The rostral spinoeerebellar tract terminates more dorsally than the dorsal and ventral spinocerebellar traet, in the lobules IV, V of the anterior lobe and in the lobules VI, VIII and the paramedian lobule. Their distribution is bilateral, but mainly ipsilateral. Spinocerebellar fibers from lower cervical segments terminate mainly in the vermis of the simple lobule (Matsushita et al., 1985 Matsushita and Ikeda, 1987). 

Hirai N, Hongo T, Sasaki S (1978) Cerebellar projection and input organizations of the spinocerebellar tract arising from the central cervical nucleus in the cat. Brain Res., 157, 341-345. 

Hirai N, Hongo T. Sasaki S (1984) A physiological study of identification, axonal course and cerebellar projection of spinocerebellar tract cells in the central cervical nucleus of the cat. Exp. Brain Re. s., 55, 272-284. 

Matsushita M, Hosoya Y (1979) Cells of origin of the spinocerebellar tract in the rat, studied with the method of retrograde transport of horseradish peroxidase. Brain Res., 173, 185-200. 

Matsushita M, Ikeda M, Tanami T (1985) The vermal projection of spinocerebellar tracts arising from lower cervical segments in the cat An anterograde WGA-HRP study. Brain Res., 360, 389-393. 

Oscarsson O, Uddenerg N (1965) Properties of afferent connections to the rostral spinocerebellar tract in the cat. Acta Physiol. Scand., 64, 143-153. 

Watson CRR, Broomhead A, Holst M-C (1976) Spinocerebellar tracts in the brush-tailed opossum, Tri-chosurus vulpecula. Brain Behav. EvoL, 13, 142-153. 

Lateral involves dorsal spinocerebellar tracts (arm and leg dys-taxia) and corticospinal tracts (spastic paralysis). 

In most cases, hepatic myelopathy will develop after several episodes of HE. For unknown reasons, most patients described are men. Imaging of the spinal cord by MRI or myelography reveals normal results, as does the examination of CSF. The main pathological finding in HM is demyelination of the cortico-spinal tracts predominantly in the lower part of the cervical and the thoracic spinal cord. Occasionally demyelination has also been found in the ventral pyramidal tracts and in the posterior columns and spinocerebellar tracts (Campellone et al., 1996, Weissenbom et al., 2003). 

---