Objective: We report clinical and neuropathological findings in 2 cases of sporadic progressive ataxia and palatal tremor (PAPT).

Background: Sporadic PAPT is a rare syndrome characterized by mid- to late adult-onset symptomatic palatal tremor and slowly progressive cerebellar ataxia. To date, there has been only 1 autopsy report, which described a novel 4-repeat tauopathy with hypertrophic olivary degeneration and tau-positive inclusions in olivary neurons and dystrophic neuritic processes termed glomeruloid bodies. We report 2 further autopsy cases.

Methods: We performed thorough clinical and neuropathological evaluation of each patient. Sections from selected paraffin-embedded brain regions were stained with hematoxylin & eosin/Luxol fast blue and processed for immunohistochemistry using antibodies against phosphorylated tau (AT8), 3R-tau, 4R-tau, neurofilament, glial fibrillary acid protein, phosphorylated α-synuclein, phosphorylated TDP-43, beta-amyloid, and p62.

Results: Case 1 is a 77-year-old man who presented with blurred vision and subsequently developed ataxia and gait instability. Dysarthria and palatal tremor appeared later. MRI showed T2 hyperintensity of the pons and bilateral inferior olives. Case 2 is an 89-year-old man who presented with dysarthria and progressed to cerebellar ataxia and palatal tremor. 9 years into his disease course, his palatal tremor spontaneously resolved. Early in his disease course, MRI showed T2 hyperintensity in the bilateral olives. Common pathological findings included bilateral hypertrophic olivary degeneration accompanied by glomeruloid bodies, 3- and 4-repeat tau-positive neuronal inclusions in the olive, and additional tauopathy in the midbrain, pons, and thalamus. Cerebellar cortical degeneration was extensive, but involvement of the dentate was minimal. P62-positive, but tau- and TDP-43-negative, inclusions in the cerebellum of 1 case was also a feature.

Conclusions: While our findings are largely in keeping with the previously published case report, we found a more extensive and mixed 3R/4R tauopathy and additional cerebellar p62 pathology, highlighting our incomplete understanding of the pathogenesis of this disease

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MDS Abstracts - https://www.mdsabstracts.org/abstract/progressive-ataxia-and-palatal-tremor-2-autopsy-cases-of-a-novel-tauopathy/