Substantia nigra degeneration in motor neurone disease: a quantitative study.

There is increasing evidence of degeneration of nerve cells other than motor neurones in sporadic motor neurone disease (MND). Sporadic MND is occasionally associated with Parkinsonism. The aim of this study was to determine whether neuronal loss occurs in the substantia nigra of MND patients. Case records and pathological material from 14 patients with MND were reviewed. No patient had Parkinsonism documented. Sections of substantia nigra from the patients and 14 age/sex matched controls were analysed by neuronal and macrophage quantitation. The mean number of pigmented neurones at one standard level of substantia nigra was 863 in cases and 1094 in controls (p < 0.02); on average 21% (95% CI, 7-35%) fewer in the cases. The mean number of macrophages containing neuromelanin in cases was 106 and in controls 45 (p < 0.02). The results indicate that patients with MND have degeneration of the substantia nigra. Thus MND should be considered as a type of multiple system atrophy in which the motor neurone bears the brunt of the disease. The implication of this to the relationship between classical MND and MND with Parkinsonism-Dementia of the Western Pacific is discussed.