MULTIPLE SYSTEM ATROPHY - NATURAL-HISTORY, MRI MORPHOLOGY, AND DOPAMINE-RECEPTOR IMAGING WITH (123)IBZM-SPECT

Sixteen patients with a clinical diagnosis of probable multiple system atrophy (MSA) were examined clinically by MRI and by I-123-iodobenzam ide single photon emission computed tomography (IBZM-SPECT). The clini cal records of another 16 patients were also analysed retrospectively. On the basis of their clinical presentation, patients were subdivided into those with prominent parkinsonism (MSA-P, n = 11) and those with prominent cerebellar ataxia (MSA-C, n = 21). Autonomic symptoms were present in all patients and preceded the onset of motor symptoms in 63 % of patients. Calculated median lifetime and the median time to becom e wheelchair bound after onset of disease were significantly shorter f or MSA-P than for MSA-C (lifetime: 4.0 v 9.1 years; wheelchair: 3.1 v 5.0 years) suggesting a better prognosis for cerebellar patients. A si gnificant loss of striatal dopamine receptors (below 2 SD threshold) w as detected by IBZM-SPECT in 63% of the patients (56% below 2.5 SD thr eshold). There was no difference between patients with MSA-C and those with MSA-P in the proportion with significant receptor loss and the e xtent of dopamine receptor loss. Planimetric MRI evaluation showed cer ebellar and brainstem atrophy in both groups. Atrophy was more pronoun ced in patients with MSA-C than in those with MSA-P. Pontocerebellar h yperintensities and putaminal hypointensities on T2 weighted MRI were found in both groups. Pontocerebellar signal abnormalities were more p ronounced in MSA-C than in MSA-P, whereas the rating scores for area b ut not for intensity of putaminal abnormalities were higher in MSA-P. MRI and IBZM-SPECT provide in vivo evidence for combined basal ganglia and pontocerebellar involvement in almost all patients in this series .