A case report of palatal tremor in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a sporadic, adult-onset neurodegenerative disease and the second most common form of neurodegenerative parkinsonism after idiopathic Parkinson's disease. Palatal tremor (PT), characterized by brief, involuntary, rhythmic contractions of the soft palate, is a rare movement disorder and an even more exceptional finding in PSP.

We present an 85-year-old, Filipino male who manifested with progressive gait imbalance, postural instability leading to multiple falls, ocular motor dysfunction, axial rigidity, bradykinesia, and cognitive impairment. Supporting features were poor levodopa response and midbrain atrophy on brain imaging, particularly the "hummingbird" and "morning glory" signs. The clinic-radiographic findings were consistent with the diagnosis of probable PSP, particularly the Richardson's syndrome (PSP-RS). During the last consult, there was surprising new-onset palatal tremor in the soft palate and uvula, consisting of rhythmic, oscillatory involuntary movements with a rate of 2-3 Hz per second. Palatal tremor has only been recorded among three PSP cases in the literature (1991, 1997, 2015) as of this writing. Notably, his brain MRI did not show the classic hypertrophy of the inferior olivary nuclei, which is the usual feature of symptomatic PT. But instead, T2 hyperintensity of both inferior olivary nuclei was found.

Reporting the presence of this rare movement disorder may raise awareness of the clinical diversity of PSP. Physicians must be diligent in habitually checking the mouth to uncover hidden abnormal movements of the tongue, soft palate and other structures.