Palatal myoclonus (Palatal tremor)

Palatal myoclonus causes involuntary, rhythmic movements of the soft palate and pharynx.(1-5) The palate may bounce up and down, or twitch rhythmically to one side (Video). Sometimes the larynx, eye muscles, diaphragm, and occasionally other muscles are also involved. The movements persist in sleep. Opening and closing of the Eustachian tube sometimes causes a clicking sound accompanying the movements, audible to the patient and sometimes the examiner. Movements involving the diaphragm or larynx may cause a grunting respiratory noise. Patients with ocular involvement are said to have oculopalatal myoclonus.

Symptomatic palatal myoclonus occurs with a lesion involving the Guillain-Mollaret (myoclonic) triangle that connects the inferior olivary, dentate, and red nuclei, interrupting the central tegmental tract. See Palatal myoclonus due to a brainstem stroke(5) Hypertrophy (pseudohypertrophy) of the inferior olive may occur and can sometimes be seen by MRI. Etiologies of symptomatic palatal myoclonus include cerebrovascular disease, trauma, multiple sclerosis, tumors, neurodegenerative diseases, and other causes.(3) Symptomatic palatal myoclonus differs from essential palatal myoclonus by the presence of neurologic signs other than palatal tremor, absence of ear clicks and olivary hypertrophy. Symptomatic myoclonus causes contractions of the levator veli palatini. Essential palatal myoclonus causes contractions of the tensor veli palatini, patients frequently complain about ear clicks, there is no identifiable etiology, no additional neurologic deficit, and the MRI is unremarkable.(3)

Palatal myoclonus is also referred to as palatal tremor or microtremor but whether palatal myoclonus is best characterized as rhythmic myoclonus or a tremor remains unclear.

Video courtesy of Dr. Jason S. Hawley, Walter Reed National Military Medical Center

References

1. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016. 2. Campbell WW. DeJong's the neurologic examination, 7th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2013. 3. Finke C, Jumah MD, Jöns T, Ploner CJ. Teaching Video NeuroImages: An endoscopic view of symptomatic palatal tremor. Neurology. 2010 Feb 2;74(5):e16. 4. Pearce, JM. Palatal Myoclonus (syn. Palatal Tremor). Eur Neurol. 2008; 60:312-315. 5. Sivakumar S, Rajamani K. Secondary Palatal Myoclonus. N Engl J Med. 2015 Jul 16;373(3):e3