Sporadic Progressive Ataxia and Palatal Tremor: An Autopsy Case without Tau Pathology
Antonio Costa, Vasco Abreu, Diogo Costa, Margarida Calejo, Miguel Pinto, Luís Botelho, Jorge Oliveira, Alexandre Mendes, Ricardo TaipaAbstract
Background
Sporadic Progressive Ataxia with Palatal Tremor (PAPT) is an extremely rare movement disorder syndrome with only three autopsy reports published in the literature to date. Previously described cases showed hypertrophic olivary degeneration with tau‐positive neuronal inclusions, although differences were noted in tau isoforms and the presence of additional neurodegenerative pathology. We report an additional autopsy case with morphological similarities in pathology but without tau inclusions.
Objectives
To describe clinically, radiologically and neuropathologically a case of PAPT.
Methods
Retrospective clinical data collection from electronic records, authorized video material and postmortem neuropathology study.
Results
A 74‐year‐old women presented with a gait ataxia and parkinsonism at the age 67, followed three years later by rhythmic chin and palatal tremor. Probable REM sleep behavior disorder was reported approximately ten years before symptom onset. MRI demonstrated bilateral T2/T2‐FLAIR hyperintensity and enlargement of the inferior olivary nuclei. The clinical progression was dominated by the ataxia, and the tremor remained throughout the disease course. Neuropathological findings showed hypertrophic olivary degeneration with glomeruloid bodies, without tau pathology and occasional neuronal and dendritic p62 immunoreactivity. Focal neuronal loss and gliosis were observed in cerebellar dentate nucleus. There was substantia nigra neuronal loss with Lewy pathology in neocortical stage (Braak stage 5), but without involvement of inferior olivary nucleus or cerebellum.
Conclusions
Our findings confirmed hypertrophic olivary degeneration as the pathologic substrate of PAPT. The absence of tau pathology distinguishes it from previously reported cases, indicating heterogeneity in the underlying pathophysiological disease mechanisms. Concomitant Lewy body pathology may have contributed to parkinsonism and REM sleep behavior disorder.