Olfactory function in atypical parkinsonian syndromes

• Published in: Acta neurologica Scandinavica Vol. 91; no. 4; p. 247
• Main Authors: Wenning, G K, Shephard, B, Hawkes, C, Petruckevitch, A, Lees, A, Quinn, N
• Format: Journal Article
• Language: English
• Published: Denmark 01.04.1995
• Subjects: Adult; Aged; Basal Ganglia - physiopathology; Basal Ganglia Diseases - diagnosis; Basal Ganglia Diseases - physiopathology; Cerebral Cortex - physiopathology; Diagnosis, Differential; Female; Humans; Male; Middle Aged; Nerve Degeneration - physiology; Olfaction Disorders - diagnosis; Olfaction Disorders - physiopathology; Olfactory Bulb - physiopathology; Olfactory Pathways - physiopathology; Olivopontocerebellar Atrophies - diagnosis; Olivopontocerebellar Atrophies - physiopathology; Parkinson Disease, Secondary - diagnosis; Parkinson Disease, Secondary - physiopathology; Sensory Thresholds - physiology; Supranuclear Palsy, Progressive - diagnosis; Supranuclear Palsy, Progressive - physiopathology
• ISSN: 0001-6314
• DOI: 10.1111/j.1600-0404.1995.tb06998.x

Olfaction is markedly impaired in patients with idiopathic Parkinson's disease (IPD). This deficit contrasts with reports of preserved or only mildly reduced olfaction in patients with atypical parkinsonism. However, the sensitivity and specificity of olfactory function testing in the differential diagnosis of parkinsonian syndromes has not been studied. In addition, olfactory function in patients with corticobasal degeneration (CBD) is unknown. Using the University of Pennsylvania Smell Identification Test (UPSIT) with a test score ranging from 0 to 40 we studied olfactory function in patients with IPD as well as other parkinsonian syndromes including CBD and progressive supranuclear palsy (PSP). UPSIT scores in 118 patients with IPD, 29 with MSA, 15 with PSP, and 7 patients with CBD, as well as in 123 healthy control subjects revealed a marked impairment in the IPD group in contrast to mild impairment in MSA patients and normal olfaction in PSP and CBD patients. An UPSIT score of 25/40 was associated with a sensitivity of 77% and a specificity of 85% in differentiating IPD from atypical parkinsonism. These results indicate that olfactory function is differentially impaired or preserved in distinct parkinsonian syndromes and that it might also have some value as a diagnostic pointer. Thus, preserved or mildly impaired olfactory function in a parkinsonian patient is more likely to be related to atypical parkinsonism such as MSA, PSP or CBD, whereas markedly reduced olfaction is more suggestive of IPD.