Objective: To report the clinical presentation and neuroimaging findings of sporadic PAPT.

Background: Progressive ataxia and palatal tremor (PAPT) manifests as mid to late-adult onset slowly progressive cerebellar ataxia and palatal tremor. It’s a subtype of symptomatic palatal tremor (SPT). Unlike most cases of SPT, with lesions located within the dentato-rubro-olivary pathway (Guillain-Mollaret triangle), the exact location of the lesion in sporadic PAPT is uncertain, making it a poorly understood neurodegenerative disorder. Misdiagnosis as other degenerative cerebellar ataxia (ex: MSA-C or spinocerebellar ataxia) is common.

Method: A 70-year-old male with underlying diabetes mellitus and hyperlipidemia, presented with dizziness, progressive unsteady gait, limbs incoordination, and articulation problem during the past 2 years. The dizziness was not induced by posture change. At first, he had gait difficulty especially when going up and down stairs, but recently he needs a single cane for walking aid. He was initially diagnosed with multiple system atrophy-cerebellar type (MSA-C) in another hospital. There was no contributory family history, no history of alcohol, neurotropic drug or toxin exposure. Neurological examination showed gaze-evoked nystagmus, dysmetric saccade, mild degree limbs ataxia and impaired tandem gait. A 2-Hz palatal tremor was also noted.

Results: Clinical laboratory tests including thyroid function, autoimmune profiles, and tumor markers were within normal limits. The TRODAT-1 SPECT showed nearly normal result. Brain SPECT showed hypoperfusion in bilateral frontotemporal, right parietal lobes and right basal ganglia, and relatively hyperperfusion in the cerebellum. Autonomic testing including SSR, RRIV, and head-up tilting table test were normal. Cognitive tests were normal. Brain MRI showed bilateral inferior olivary nuclei hypertrophy, anterior-superior cerebellar and frontotemporal cortical atrophy. No old structural lesion can be found within dentato-rubro-olivary pathway. His clinical presentation and neuroimaging were consistent with the diagnosis of sporadic PAPT syndrome.

Conclusion: To date, there have been 3 autopsy cases of PAPT, showing evidence of a characteristic tauopathy most severely involving the inferior olivary nucleus and cerebellum. Further studies including newer imaging techniques (ex: tau PET), biomarkers and neuropathological assessments are needed to get a closer insight of the pathogenesis of PAPT.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sporadic-progressive-ataxia-and-palatal-tremor-a-case-report/