Progressive ataxia and palatal tremor

Progressive ataxia and palatal tremor (PAPT) is a rare sporadic or familial syndrome characterized by symptomatic palatal tremor/myoclonus and progressive cerebellar ataxia, usually in the setting of bilateral hypertrophic olivary degeneration without an identifiable causative lesion to the triangle of Guillain and Mollaret (dentatorubro-olivary pathway).

Epidemiology

Progressive ataxia and palatal tremor is considered very rare ^1,2, but the exact incidence is unknown. Most patients with sporadic disease present as middle-aged adults ².

Clinical presentation

The cardinal clinical features in all cases of progressive ataxia and palatal tremor include ^1-3:

• symptomatic palatal tremor/myoclonus

  • rhythmic 1-3 Hz involuntary movement of the soft palate and uvula

  • often persists during sleep

  • no associated audible clicking

• progressive cerebellar ataxia

  • saccadic pursuit

  • oscillopsia

  • limb/truncal/gait ataxia

In the sporadic form, patients may additionally have ¹:

• dysarthria

• dysphagia

In rare familial forms, patients may have a broader phenotype depending on the underlying cause, including ^1,2:

• upper motor neuron signs (e.g. spasticity, weakness)

• movement disorders (e.g. parkinsonism, dystonia, chorea)

• cognitive impairment

• seizures/epilepsy

• ophthalmoplegia

• optic atrophy

Pathology

Progressive ataxia and palatal tremor may be sporadic or familial ^1-3. The aetiopathogenesis of sporadic progressive ataxia and palatal tremor has not been fully elucidated, but there is typically no lesion to the triangle of Guillain and Mollaret (dentatorubro-olivary pathway) ^1-3. It has been postulated that there may be a neurodegenerative basis, and multiple studies have identified pathological evidence of tau deposition in the inferior olives in affected patients post-mortem ¹.

Familial progressive ataxia and palatal tremor is often seen in the context of other broader syndromes with genetic basis, such as Alexander disease, certain spinocerebellar ataxias, celiac disease, and POLG-related disorders ^1-3.

Radiographic features

MRI is the imaging modality of choice to evaluate progressive ataxia and palatal tremor.

MRI

Sporadic progressive ataxia and palatal tremor typically shows features of bilateral hypertrophic olivary degeneration (see article for detailed discussion) ^1-5. In contrast, familial progressive ataxia and palatal tremor often do not demonstrate hypertrophic olivary degeneration, but may instead have a diverse range of potential radiological manifestations depending on the specific underlying cause ^1,2. Within this potentially diverse range, in familial forms, the most common anomalies present include brainstem and cervical cord atrophy ^1,2.

Treatment and prognosis

Management is supportive and there is no disease-modifying therapy available for the sporadic form ^1-3. In familial forms, management should be directed towards the underlying broader syndrome (e.g. gluten-free diet in celiac disease) ¹.

Differential diagnosis

• other causes of hypertrophic olivary degeneration and symptomatic palatal tremor/myoclonus

• essential palatal tremor