Progressive ataxia and palatal tremor: Two autopsy cases of a novel tauopathy.

BACKGROUND

Sporadic progressive ataxia and palatal tremor 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 one 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 on 2 additional autopsy cases.

METHODS

Sections from selected paraffin-embedded brain regions were stained with hematoxylin and eosin/Luxol fast blue and processed for phosphorylated tau, 3-repeat tau, 4-repeat tau, neurofilament, glial fibrillary acid protein, phosphorylated α-synuclein, phosphorylated TAR DNA-binding protein 43, beta-amyloid, and p62 immunohistochemistry.

RESULTS

Two male patients were aged 74 and 64 years at onset. Both had clinical findings consistent with progressive ataxia and palatal tremor and T2 hyperintensity in the bilateral olives on MRI. Pathological findings included bilateral hypertrophic olivary degeneration accompanied by glomeruloid bodies, 3-repeat 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 TAR DNA-binding protein 43-negative, inclusions in the cerebellum of 1 case was also a feature.

CONCLUSIONS

Whereas our findings are largely in keeping with the previously published case report, we found a more extensive and mixed 3/4-repeat tauopathy and additional cerebellar p62 pathology, highlighting our incomplete understanding of the pathogenesis of this disease. © 2017 International Parkinson and Movement Disorder Society.