Palato-Pharyngo-Laryngeal Myoclonus with Facial Involvement After an Ischemic Stroke.

Abstract

Palatal myoclonus, also described as palatal tremor, is characterized by rhythmic continuous 0.5 to 5 Hz movements of the soft palate and pharynx.1 There are two categories described: symptomatic palatal tremor, because of a brainstem or cerebellar lesion, and essential palatal tremor, with no associated structural lesion.2, 3 Palatal myoclonus can rarely be associated with synchronous myoclonus of other branchial arch muscles, the diaphragm, facial muscles, or even the extremities.2 One specific variant is termed palato-pharyngo-laryngeal myoclonus, which can result in dysphagia, dysphonia, and dysarthria.4 A 56-year-old woman awoke from sleep with new right-sided weakness and dizziness. Magnetic resonance imaging (MRI) of the brain showed restricted diffusion in the right superomedial cerebellum consistent with an acute infarct (Fig. 1). The etiology of stroke was atheroembolism from an aortic arch plaque atheroma, for which she was started on aspirin. The follow-up MRI of the brain 4 months later showed a new fluid-attenuated inversion recovery (FLAIR) signal abnormality in the left medulla involving the left inferior olivary nucleus, reflecting hypertrophic olivary degeneration related to the chronic cerebellar infarct in the proximity of the contralateral dentate nucleus (Fig. 2). Ten months after the stroke, the patient reported a subjective, rhythmic, non-suppressible “whooshing” sound in her right ear that did not correspond to her heart rate and persisted during sleep. A computed tomography (CT) angiogram of the head and neck ruled out any vascular abnormalities. Nasopharyngolaryngoscopy showed spasm of the hypopharyngeal musculature and larynx. The patient returned to clinic to report new involuntary twitching of the right lower face. On examination, she had ~2 Hz rhythmic myoclonus of the right lip, chin, and throat (Video 1) as well as the palate (Video 2). There was no evidence of facial weakness, ocular motility problems, dysarthria, or dysphagia. She was prescribed a trial of carbamazepine 200 mg twice daily for palatal tremor followed by baclofen 5 mg twice daily with mild relief. She declined to try clonazepam or botulinum toxin injections. Palato-pharyngo-laryngeal myoclonus is a rare condition that can be idiopathic or lesional. Symptoms of palatal tremor are usually delayed 6 to 9 months after the initial injury, but can be delayed up to 30 months.1 The etiology of palatal tremor is disruption of the dento-rubro-olivary pathway, known as the Guillain Mollaret triangle. A lesion in this pathway causes denervation of olivary neurons from inhibitory cerebellar inputs, leading to hypertrophy and sustained synchronized oscillations causing tremor.2, 3 We present a unique case of palato-pharyngo-laryngeal and facial myoclonus caused by an ischemic stroke of the cerebellum. The patient also had pulsatile tinnitus, which correlated with direct visualization of spasms of the palate, hypopharyngeal musculature, and larynx via nasopharyngolaryngoscopy. Pulsatile tinnitus is most common in essential palatal tremor because of contraction of the tensor veli palatini on the eustachian tube. Although symptomatic palatal tremor affects the levator veli palatini, it can also rarely cause subjective auditory phenomena, likely because of some fibers inserting on the eustachian tube.1, 5 The patient's mild improvement in symptoms with the combination of baclofen and carbamazepine suggest a potential therapeutic option that warrants further investigation. (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. C.L.N.: 1B, 1C, 3A S.Q.: 1B, 1C, 3A M.S.: 1A, 3B Per the University of Pennsylvania Institutional Review Board, “a single retrospective case report is a medical/educational activity and does not meet the Federal Policy for the Protection of Human Subjects definition of research which is a systematic investigation, including research development, testing and evaluation, designed to develop or contribute to generalizable knowledge. Therefore, the activity does not require review by the IRB. Under HIPAA, a single case report is an activity to develop information to be shared for medical/educational purposes. Therefore, the use of protected health information to prepare a paper for publication of a single case report does not require IRB review for HIPAA purposes.” The patient provided verbal consent while at a clinic visit. The patient also provided signed/written consent which was mailed to the Neurology office. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work. M.S. has received clinical trial support from AbbVie, Abbott, United States (US) World Meds, and Sanofi. C.L.N. and S.Q. have no other financial disclosures to report.