Increased number of Purkinje cell dendritic swellings in essential tremor

Background and Purpose: Essential Tremor (ET) is among the most prevalent neurologic disorders. Growing clinical and neuro-imaging evidence implicates cerebellar dysfunction in the pathogenesis of ET and emerging postmortem studies have identified structural changes in the cerebellum, particularly in Purkinje cells. In this study we systematically quantified focal Purkinje cell dendritic swellings (DS) in 20 ET vs. 19 control brains. Methods: In each brain, a standard parasagittal neocerebellar tissue block was harvested. DS were quantified in one 7-mu m thick section stained with Luxol Fast Blue/Hematoxylin and Eosin (LH&E) and one section stained with Bielschowsky method. Results: The number of DS were higher in cases than controls by LH&E (1.50 +/- 1.79 vs. 0.05 +/- 0.23, P = 0.002) and Bielschowsky methods (2.70 +/- 3.10 vs. 0.37 +/- 0.50, P = 0.002). The number of DS was correlated with the number of torpedoes and marginally inversely correlated with the number of Purkinje cells. Conclusion: The current study documents and quantifies an additional structural abnormality in the ET cerebellum, adding to the growing list of such changes in this disease. The mechanisms that underlie this and other structural changes observed in ET are currently unknown, and they deserve additional exploration.