Clinical and imaging characterization of a patient with idiopathic progressive ataxia and palatal tremor

Palatal Tremor - Pathophysiology, Clinical Features, Investigations, Management and Future Challenges

Background:

Palatal tremor is involuntary, rhythmic and oscillatory movement of the soft palate. Palatal tremor can be classified into three subtypes; essential, symptomatic and palatal tremor associated with progressive ataxia.

Methods:

A thorough Pubmed search was conducted to look for the original articles, reviews, letters to editor, case reports, and teaching neuroimages, with the keywords “essential”, “symptomatic palatal tremor”, “myoclonus”, “ataxia”, “hypertrophic”, “olivary” and “degeneration”.

Results:

Essential palatal tremor is due to contraction of the tensor veli palatini muscle, supplied by the 5^th cranial nerve. Symptomatic palatal tremor occurs due to the contraction of the levator veli palatini muscle, supplied by the 9%^th and 10%^th cranial nerves. Essential palatal tremor is idiopathic, while symptomatic palatal tremor occurs due to infarction, bleed or tumor within the Guillain-Mollaret triangle. Progressive ataxia and palatal tremor can be familial or idiopathic. Symptomatic palatal tremor and sporadic progressive ataxia with palatal tremor show signal changes in inferior olive of medulla in magnetic resonance imaging. The treatment options available for essential palatal tremor are clonazepam, lamotrigine, sodium valproate, flunarizine and botulinum toxin. The treatment of symptomatic palatal tremor involves the treatment of the underlying cause.

Discussion:

Further studies are required to understand the cause and pathophysiology of Essential palatal tremor and progressive ataxia and palatal tremor. Similarly, the link between tauopathy and palatal tremor associated progressive ataxia needs to be explored further. Oscillopsia and progressive ataxia are more debilitating than palatal tremor and needs new treatment approaches.

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.

Hypermetabolism of Olivary Nuclei in a Patient with Progressive Ataxia and Palatal Tremor

Background

The pathophysiology of the movement disorder progressive ataxia with palatal tremor (PAPT) is unclear.

Case report

A 77-year-old male presented with dysarthria, ataxia, and 1–2 Hz palatal tremor. A diagnosis of probable sporadic PAPT was established. Brain magnetic resonance imaging was normal at the presymptomatic phase but later showed olivary hypertrophy. Brain [¹⁸F]-fludeoxyglucose (FDG) positron emission tomography (PET) showed bilateral hypermetabolism in the olivary nuclei.

Discussion

This second reported patient with PAPT and FDG-PET shows that olivary hypertrophy is paralleled with hypermetabolism. The olivary nuclei pathology also appears to be temporally associated with symptom onset.

[A case of progressive ataxia and palatal tremor (PAPT) with ear clicks]

A 71-year-old man noted clicking sounds in the ear. At the age of 75, he developed progressive unsteadiness of gait and became unable to walk without assistance at the age of 76. There was no family history of neurologic illness. Neurological examination revealed truncal ataxia and 1-2 Hz rhythmic palatal tremor, which persisted during sleep. Consistently, brain magnetic resonance imaging showed mild cerebellar atrophy and increased signal intensity of bilateral inferior olivary nuclei on T2-weighted image. progressive ataxia and palatal tremor (PAPT) has recently been described as a rare sporadic neurodegenerative disease and the features of our case consistent with those of PAPT. However, for correct diagnosis of PAPT, multiple system atrophy, spinocerebellar ataxia, progressive supranuclear palsy or adult-onset Alexander's disease should be carefully ruled out.

Perrault Syndrome with progressive nervous system involvement

A 21-year-old woman with a Perrault Syndrome (PS) presented with progressive ataxia. PS comprises gonadal dysgenesis and sensorineural deafness in females. More recent studies have asked whether the neurologic signs in some of the patients are a coincidental finding or part of the syndrome. Magnetic resonance imaging in PS patients shows high intensity signals in the periventricular and the subcortical white substance, as well as in the centrum ovale, suggestive for cerebral leucodystrophy, which is one of a wide spectrum of neurologic symptoms found in PS. The fluorodeoxyglucose positron emission tomography (PET) of our patient brought results indicating a progressive heredoataxia. PET is helpful in the early detection of the progressive central nervous involvement of PS.

Cerebral glucose metabolism in oculopalatal tremor

No study adopted the statistical parametric mapping (SPM) analyses of (18)F-fluorodeoxy glucose (FDG) PET in a large number of patients with oculopalatal tremor (OPT). To determine regional cerebral glucose metabolism in patients with OPT, nine patients with OPT underwent FDG-PET of the brain. Their glucose metabolism was compared with that of 50 normal controls (NC) by using SPM analyses. Three patients had bilateral and six showed unilateral pseudohypertrophic degeneration of the inferior olivary nucleus (ION) on MRI. Compared with NC, OPT patients did not show any metabolic derangement in the anterolateral medulla where the pseudohypertrophic ION locates. Instead, six patients with unilateral ION changes had hypometabolism in ipsilesional pontine tegmentum and hypermetabolism in contralesional thalamus. Their metabolic changes did not depend on the lateralization of ION changes. Our study failed to present any metabolic evidence for the role of ION in the generation of OPT. In part, the failure might originate from the different pathomechanism between OPT and pure palatal tremor or sensitivity/specificity issues of PET and SPM analyses. But, our results suggest that impaired cell groups of the paramedian tract and thalamic tremor cells may contribute to the generation of OPT.