Visuospatial functions in atypical parkinsonian syndromes.
OBJECTIVE
Visuospatial deficits have been occasionally reported but never systematically studied in atypical parkinsonian syndromes. The interpretation of existing studies is complicated by the possible influence of motor and frontal executive deficits. Moreover, no attempt has been made to distinguish visuoperceptual from visuospatial tasks. The aim of the present study was to assess visuoperceptual and visuospatial abilities in three atypical parkinsonian syndromes while minimising the influence of confounding variables.


METHODS
Twenty patients with multiple system atrophy (MSA), 43 with progressive supranuclear palsy (PSP), and 25 with corticobasal degeneration (CBD) as well as 30 healthy age matched controls were examined with the Visual Object and Space Perception Battery (VOSP).


RESULTS
Visuospatial functions were intact in MSA patients. PSP patients showed mild deficits related to general cognitive decline and the severity of oculomotor symptoms. The CBD group showed the most pronounced deficits, with spatial tasks more impaired than object based tasks. Performance on object based, but not spatial, tasks was related to general cognitive status. The extent of the visuospatial impairment could not be predicted from disease duration or severity.


CONCLUSIONS
Visuospatial functions are not consistently impaired in atypical parkinsonian syndromes. The degree and pattern of impairment varies across the diseases, suggesting that the observed deficits could have a different neural basis in each condition. The distinction between the object based ("ventral stream") and the space oriented ("dorsal stream") processing might be useful in the interpretation of visuospatial deficits in parkinsonian syndromes, especially in CBD.
Bak
T H
TH
MRC Cognition and Brain Sciences Unit, Cambridge CB2 2EF, UK.
Caine
D
D
Hearn
V C
VC
Hodges
J R
JR
D000368:Aged; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology; D004185:Disability Evaluation; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000453:epidemiology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000209:etiology*; D013028:Space Perception / Q000502:physiology*; D013132:Spinocerebellar Degenerations / Q000453:epidemiology; D013494:Supranuclear Palsy, Progressive / Q000453:epidemiology; D014796:Visual Perception / Q000502:physiology*