[Striatonigral degeneration and sporadic olivopontocerebellar atrophy: a consideration of the clinical entity of multiple system atrophy]

Abstract

Striatonigral degeneration (SND) and sporadic olivopontocerebellar atrophy (sOPCA) are categorized under multiple system atrophy (MSA), since these disorders have common clinical and pathological features. However, it is still uncertain whether these disorders are manifestation of the same disease. In this study, we performed both clinical and neuroradiological studies on patients with SND or sOPCA in whom clinical diagnosis was based on a criteria during eight years in our hospital. A total of forty patients had SND and thirty-one patients had sOPCA. The onset ages of patients with SND (60.7 +/- 8.7, mean +/- SD) were significantly higher than those with sOPCA (55.4 +/- 7.9). In both SND and sOPCA patients, about 20% had clinical symptoms suggesting the involvement of multiple systems: pyramidal, cerebellar, extrapyramidal and autonomic symptoms. In 55% of the SND patients, cerebellar symptoms could be observed, and the same percentage of sOPCA patients had parkinsonism. Although, as defined, cerebellar symptoms were predominant in sOPCA patients and parkinsonism was predominant in SND patients, the SND patient group was particularly homogeneous with respect to clinical characteristics. The initial symptoms of SND were parkinsonian gait or tremors. Almost all patients exhibited asymmetrical appearance of the parkinsonian symptoms, such as rigidity, tremors, and bradykinesia. Tremors at rest were observed in two-thirds of the patients with SND during the course of their illness, but dementia was infrequently observed. There was no detectable limitation in horizontal eye movements in patients with SND. The progression of the disability of patients with SND was rapid; according to the clinical rating scale of parkinsonism, the average level of disability deteriorated to Hoehn-Yahr's stage III after three years from disease onset, and then deteriorated to stage IV after four years. Neuroradiologically, only a small proportion of patients with SND (27%) showed magnetic resonance image (MRI) findings suggesting OPCA pathology, such as volume loss in the brainstem or cerebellum with/without T2-high signaling of transverse fibers of pons or T2-high signaling of the middle cerebellar peduncle. Simultaneously, a small proportion of the patients with sOPCA (20%) showed MRI findings suggesting putaminal pathology, such as T2-low intensity signals of the putamen with linear T2-high intensity signals around the lateral putamen. Our results suggest that SND and sOPCA can be clearly differentiated, at least from clinical or neuroradiological aspects. Since there is still no evidence indicating that each disorder is a clinical variant of a single disease caused by the same etiology, a differentiation might be important for future pathogenetical studies.