Essential Tremor Associated With Focal Nonnigral Lewy Bodies

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Abstract
Background Essential tremor is one of the most common neurological diseases. Its links with Parkinson disease (PD) are often debated. There have been few published postmortem studies. Objective To study our first case of essential tremor through the recently established Essential Tremor Centralized Brain Repository. Design Report of a case of a patient with a diagnosis of severe essential tremor for 46 years who exhibited no signs of parkinsonism. Results On postmortem examination, gross brain sections showed no abnormalities. Results of microscopic examination of hematoxylin-eosin–stained sections revealed that the locus coeruleus contained multiple Lewy bodies (LBs), although none were found in the substantia nigra, dorsal vagal nuclei, thalamus, substantia innominata, inferior olivary nucleus, or cerebellum. Immunochemical staining using antibodies directed against α-synuclein confirmed the presence of many LBs in the locus ceruleus and showed rare LBs in the substantia innominata and dorsal vagal nuclei. There were no LBs in the substantia nigra. Conclusions Our patient had a very focal presence of LBs in the locus ceruleus, an anatomically restricted form of LB disease. This study provides support for the link between essential tremor and LB disease and raises the question as to what proportion of patients with essential tremor might have unusual forms of LB disease.