Parkinson's disease without expected neuropathologic abnormality

A case is reported of an initially 78-year-old man whose presentation and course, closely followed over 10 years by an academic neurologist, were consistent with classic idiopathic Parkinson's disease (PD), including unilateral onset, obvious cogwheeling, and a very good prolonged response to levodopa/carbidopa (LD/CD). Yet at autopsy, there was no neuronal loss in the substantia nigra nor were there any Lewy bodies or immunochemical evidence of alpha synuclein in the multiple brain structures studied. This case does not support the hypothesis that the use of LD/CD is toxic to the substantia nigra in people. This patient had been on traditional doses of LD/CD for approximately 10 years, yet the number of cells in the substantia nigra was well within the normal range at autopsy. These findings are not unique, but point out the need to explain the occurrence of typical PD symptoms and course in the absence of any PD-related neuropathologic changes.