Palatal Myoclonus

Question

Answer

Palatal myoclonus can cause an objective form of tinnitus. According to the classification system used by Jastreboff, palatal myoclonus is an extra-cochlear muscular somatosound. Hazell classified it as a non-pulsatile somatosound. Pulsatile tinnitus is normally associated vascular somatosounds (e.g. venus hums, carotid bruits). In this sense, palatal myoclonus is not pulsatile tinnitus as it is not correlated to pulse. This type of tinnitus is also referred to as muscular tinnitus. The patient typically hears a clicking or snapping sound caused by the opening of Eustachian tube due to myclonic contractions in the tensor or levator palati.

Palatal myoclonus must be differentiated from tensor tympani myclonus. The main difference is that tensor tympani myoclonus is not objective and can be observed during immittance recordings, as first proposed by Klockhoff. Generally, tensor activity is described as a flutter. If the myoclonic immittance changes are not observed on regular dynamic immittance recordings, one can use acoustic reflex decay measures at best operating pressure without a reflex activator signal. Some adjustment of pressure may be necessary. Some patients also have myoclonic stapedius activity.

The three types forms of muscular tinnitus might be differentiated by observation. Palatal myoclonus generates objective tinnitus that can be auscultated and can be observed in contractions of the soft palate and sometimes suprahyoid muscles in the neck. Tensor tympani myoclonus is not objective (i.e. it can only be heard by the patient), but can be observed as changes in tympanic membrane position (by otoscopy or immittance). Stapedious myoclonus cannot be observed in either palatal or tympanic membrane movement.

Kyle C. Dennis, Ph.D.
Deputy Director
Audiology and Speech Pathology Service
(117A) VA Central Office
50 Irving Street NW
Washington DC 20422