Myoclonus is a frequently observed hyperkinetic movement disorder, which is often classified according to its anatomical origin. [1] Palatal myoclonus is characterized by involuntary palatal contractions, causing clicking tinnitus due to the action of soft palate muscles on the membranous Eustachian tube. [2]
Proposed Mechanism
The palatal myoclonus might be secondary to a CNS lesion, however, most of the time will be a disorder of unknown etiology involving involuntary movement of the uvula and soft palate, with movement of the tensor veli palatine. [3]
Treatment
In case of an essential palatal myoclonus, without evidence of CNS involvement, the management includes relaxation techniques, voluntary mechanisms (such as Valsalva maneuver), and dental devices. Medications such as anticonvulsants, benzodiazepines, anticholinergic agents and BoNT-A have been reported with mixed results. [4]
(1) There are maneuvers or sensory tricks that seems to reduce the movements of the palate by altering the position and tone of the muscle involved in altering the pressure in the ear canal. Some examples are pushing the palate with the thumb, wide mouth opening and Valsalva maneuver. [5] The use of dental devices, such as an acrylic plates, might be useful to improve phonetics and oral motor function. [6]
(2) The use of benzodiazepines (like clonazepam) produces a gamma amino butyric acid (GABA) agonistic property which might be responsible for the reduction of dysfunctional movements. Other medications that have been used are sodium valproate [7] and piracetam. [8]
(3) The use of BoNT-A to reduce the contractions of tensor veli palatine muscle opens the Eustachian tube and reduces the movement of the palate. [9] [10]
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References
[1] Zutt, R., Elting, J., Van Zijl, J., Van der Hoeven, J., Roosendaal, C., Gelauff, J., Tijssen, M. (2018). Electrophysiologic testing aids diagnosis and subtyping of myoclonus. Neurology., Neurology , 2018;90:1-11.
[2] Persaud, R., Garas, G., Silva, S., Stamatoglou, C., Chatrath, P., & Patel, K. (2013). An evidence-based review of botulinum toxin (Botox) applications in non-cosmetic head and neck conditions. JRSM Short Reports, 4(2), 10.
[3] Kitamura, T., Sato, T., Hayashi, N., Fukushima, Y., & Yoda, T. (2015). Essential Palatal Tremor Managed by Cognitive Behavioral Therapy. Case Reports in Dentistry., 2015, 414620.
[4] Pandurangi, A., Nayak, R., Bhogale, G., Patil, N., Chate, S., & Chattopadhaya, S. (2012). Clonazepam in the treatment of essential palatal tremors. Indian Journal of Pharmacology.,44(4), 528-530.
[5] Zadikoff, C., Lang, A., & Klein. (2006). The ‘essentials’ of essential palatal tremor: A reappraisal of the nosology. Brain : A Journal of Neurology., 129(Pt 4), 832-840.
[6] Carlstedt, K., Henningsson, G., & Dahllöf, G. (2003). A four-year longitudinal study of palatal plate therapy in children with Down syndrome: Effects on oral motor function, articulation and communication preferences. Acta Odontologica Scandinavica, 61(1), 39-46.
[7] Borggreve, F., & Hageman, G. (1991). A case of idiopathic palatal myoclonus: Treatment with sodium valproate. European Neurology, 31(6), 403-404.
[8] Campistol-Plana, J., Majumdar, A., & Fernández-Alvarez, E. (2006). Palatal tremor in childhood: Clinical and therapeutic considerations. Developmental Medicine and Child Neurology.,48(12), 982-984.
[9] Cho, J., Chu, K., & Jeon, B. (2001). Case of essential palatal tremor: Atypical features and remarkable benefit from botulinum toxin injection. Movement Disorders : Official Journal of the Movement Disorder Society., 16(4), 779-782.
[10] Carman, K., Ozkan, S., Yarar, C., & Yakut, A. (2013). Essential palatal tremor treated with botulinum toxin. Pediatric Neurology., 48(5), 415-417