Clinical-pathological discrepancies in a population based incidence cohort study on parkinsonism in Olmsted County, MN: 1991–2005 (S22.008)

Objective: To identify the frequency of discrepancies between the clinical diagnosis and the pathological findings in a population-based cohort of patients with a parkinsonian disorder. Background: The rate of clinical-pathologic discordance in a population based sample is unclear. Design/Methods: We used a defined population-based incidence cohort of parkinsonism, utilizing the Rochester Epidemiology Project in Olmsted County, MN from 1991 to 2005. We reviewed all the available autopsy reports (n= 62; 11%) of all the cases (n=699) and applied consensus pathologic guidelines for the diagnosis of neurodegenerative diseases. Cases were defined as discrepant when there was a difference between clinical diagnosis and pathological findings. Results: Among 62 patients, 9 (15 but one the clinical diagnosis has been made by a movement disorder specialist %) had a clinical-pathological discrepancy. In all the 9 cases. The median time from diagnosis to death was 5.2 years (range from 2 to 9 years). In four patients with clinical diagnosis of idiopathic Parkinson’s disease (PD), none had Lewy Bodies (LBs) or α-synuclein deposition. The pathologic diagnoses were Progressive Supranuclear Palsy (PSP) in one case and Alzheimer’s disease (AD) in another, whereas in two cases the pathological diagnosis was indeterminate. In the two patients with clinical diagnosis of Dementia with Lewy Bodies (DLB), there was a pathological diagnosis of AD without LBs or α-synuclein. One patient with a clinical diagnosis of PSP had an indeterminate pathological diagnosis and one with unspecified parkinsonism had a pathological diagnosis of AD; neither of them had LBs or α-synuclein deposits. One patient with a clinical diagnosis of essential tremor had diffuse LBs and α-synuclein deposits with a pathological diagnosis of DLB. Conclusions: The diagnosis of subtype of parkinsonism has an overall good concordance with pathological confirmation. However, clinical-pathological discrepancies remain for some patients. Disclosure: Dr. Turcano has nothing to disclose. Dr. Mielke has received personal compensation for activities with Lysosomal Therapeutics, Inc. as a consultant. Dr. Mielke has received research support from Biogen. Dr. Josephs has nothing to disclose. Dr. Graff-Radford has nothing to disclose. Dr. Ahlskog has nothing to disclose. Dr. Bower has nothing to disclose. Dr. Parisi has nothing to disclose. Dr. Savica has nothing to disclose.