The striatonigral degenerations. Putaminal pigments and nosology

Three new cases of striato-nigral degeneration (SND) are presented with particular reference to the identification of putaminal pigments. These were studied by histochemical methods, electron microscopy and elemental analysis. Three interrelated parenchymal perikaryal pigments were identified in the putaminal lesions of all 3 patients: a "haematin" pigment, neuromelanin and lipofuscin. The presence of neuromelanin in the putamen may be due to accumulation of dopamine in the synaptic terminals of the nigro-striatal pathway and its polymerization into pigment. This suggests that the putaminal atrophy is the primary lesion in SND which is a true supranigral form of parkinsonism. Clinically this manifests itself in predominance of rigidity over other parkinsonian symptoms and in a poor, or absent, response to treatment with L-dopa and anticholinergic drugs.