[Hemiplegia in posterior cerebral artery infarctions: analysis of various responsible mechanisms]

When cerebral infarction determines hemiplegia or hemiparesia which accompany a hemilateral sensitive deficit and hemianopsia and even neuropsychologic symptoms (aphasic alterations in the case of injury to the left hemisphere, heminegligence and anosognosy in the case of injury to the right hemisphere) the involvement of a sylvian artery syndrome is usually considered. Nonetheless, recent contributions have reported that such symptoms may appear in infarctions of the territory of the posterior cerebral artery. Two clinical-radiologic observations in this line are presented. Nuclear magnetic resonance demonstrated injury to the posterior arm of the internal capsule in one case and in the other the lesion developed over three times, in the latter of which injury to the cerebral peduncle was produced causing hemiparesia. The authors emphasize that hemiplegia or hemiparesia in some infarctions of the posterior cerebral artery may be due to 1) mesencephalic infarction in the posterior plane of the retromamillar Foix and Hillemand pediculum (or G. Lazorthes interpedunculum), 2) infarction or "ischemic penumbra" in the internal capsule by involvement of any of the perforating branches of the posterior cerebrum irrigating the thalamus, except for the medial posterior choroid artery or even of the Foix and Hillemand thalamus-tuberian pediculum (or Lazorthes inferior and anterior) which principally initiates at the posterior communicating branch with a fragment of the posterior branch of the internal capsule perhaps not always being under its control. In this case, the thrombus occupying the posterior cerebrum may extend to the cited communicating branch or a hemodynamic deficit may be produced in the territory of the same.(ABSTRACT TRUNCATED AT 250 WORDS)