Essential palatal tremor

Essential palatal tremor, also known as essential palatal myoclonus or isolated palatal tremor, describes a rare movement disorder characterised by continuous and rhythmic palatal movement caused by contraction of the tensor veli palatini muscle, without an obvious structural cause.

Epidemiology

Essential palatal tremor is considered a rare disorder ^1-3, although the exact incidence is unknown. It is notably less common than causes of symptomatic palatal tremor ¹. There is no known gender predilection ^2,3.

Clinical presentation

• rhythmic movements of the soft palate ^1-3

  • the frequency is often 0.5-5 Hz, but there can be significant variability

  • may stop during sleep in ~50% of patients ^2,3

  • may demonstrate entrainment if there is a functional (psychogenic) aetiology ^2,3

• audible ear clicking ^1-3

  • can be unilateral (more common on the left) or bilateral ^2,3

• no other neurological signs or symptoms ^1-3

  • in patients with a functional (psychogenic) aetiology, other features of a functional neurological disorder may be present ¹

Pathology

The aetiopathogenesis of essential palatal tremor is yet to be fully elucidated. Many theories have been proposed, including central mechanisms, peripheral mechanisms, and functional (psychogenic) mechanisms ^2,3. Additionally, in some patients, palatal tremor can be induced voluntarily ^2,3.

Radiographic features

Neuroimaging, such as CT or MRI brain, are normal in essential palatal tremor ^1,2. However, these should be performed to exclude causes of symptomatic palatal tremor (e.g. hypertrophic olivary degeneration), which can present similar clinically ^1,2.

Treatment and prognosis

Potential pharmacological management can include clonazepam, sodium valproate (and other antiseizure medications), flunarizine, sumatriptan, or botulinum toxin A injections to the tensor veli palatini muscle ^2,3. Cognitive behavioural therapy can also be a useful management strategy, likely more effective in functional (psychogenic) cases ².

History and etymology

Palatal tremor was first described by Adam Politzer (1835-1920), Austrian physician, in 1862 ⁴.

Differential diagnosis

• symptomatic palatal tremor due to hypertrophic olivary degeneration

• progressive ataxia and palatal tremor