The occurrence of homolateral involvement of the pyramidal tract in infratentorial tumors is not rare. Thus Gould,1 in an analysis of 50 cases of tumors of the posterior fossa, reported homolateral increase in tendon reflexes in 27, 16 of which were lateral recess growths and 11 intracerebellar tumors. This author did not find any discoverable relation between the size and location of the growth and the occurrence of changes in tendon reflexes; nor was there any parallelism between the degree of ventricular distention or papilledema and involvement of the cranial nerves on the one hand, and disturbances of the pyramidal tracts on the other. Gould explained the occurrence of homolateral involvement of the pyramidal tract by "contrecoup" pressure of tumors exerted on the contralateral pyramid which fits snugly against the basioccipital bone.
The occurrence of homolateral signs of the pyramidal tract in supratentorial tumors is not so common, and
YASKIN JC. HOMOLATERAL INVOLVEMENT OF THE PYRAMIDAL TRACT IN CEREBRAL TUMORSREPORT OF A CASE. Arch NeurPsych. 1929;22(5):1024–1028. doi:10.1001/archneurpsyc.1929.02220050162009