[Secondary degeneration of substantia nigra following massive basal ganglia infarction]

Two autopsied cases of massive unilateral cerebral infarction due to occlusion of the middle cerebral artery (MCA) were reported with special reference to presence of the secondary degeneration of the substantia nigra. Case 1 was a 70-year-old male who suddenly suffered from left hemiplegia 3 years and 2 months prior to death. CT scan showed massive infarction involving basal ganglia and fronto-parietal white matter on the right side. Some parkinsonian features such as oily face and rigidity of limbs were noted during the course. At autopsy, the proximal portion of rt MCA was found occluded and the right substantia nigra was found depigmented. Case 2 was a 71 year-old male who suddenly became hemiplegic 4 years prior to death. CT scan revealed a low density area in the corona radiata of the right cerebral hemisphere. On carotid antiography, complete obstruction of the horizontal portion of right MCA at its distal end was observed, which was confirmed at autopsy. Histologically, the right substant a nigra in case 1 showed marked neuronal loss with gliosis as well as presence of many extracellular melanin pigments. These changes were more prominent in its medial portion where chromatolytic neurons were occasionally seen. The adjacent fronto-pontine tract and pyramidal tract showed secondary degeneration. The left substantia nigra appeared normal. In case 2, the substantia nigra on both sides appeared normal. The whole right cerebral peduncle, on the other hand, showed diffuse myelin pallor.(ABSTRACT TRUNCATED AT 250 WORDS)