|Year : 2016 | Volume
| Issue : 2 | Page : 91-93
Essential palatal myoclonus: A rare cause of objective tinnitus
Thuruthiath Nisha, Arayamparambil Rajagopalan Vinayakumar
Department of ENT, Amala Institute of Medical Sciences, Thrissur, Kerala, India
|Date of Web Publication||19-Dec-2016|
Arayamparambil Rajagopalan Vinayakumar
Department of ENT, Amala Institute of Medical Sciences, Thrissur - 680 555, Kerala
Source of Support: None, Conflict of Interest: None
Palatal myoclonus is one of the rare causes of tinnitus characterized by rhythmic involuntary contraction of muscles of soft palate as well as pharynx. Among the two types, the essential palatal myoclonus, which is idiopathic as no cause can be identified in children, is rarely reported in literature. In this case report, we present a 12-year-old girl who complained of hearing abnormal sound in her ears, which could be perceived by the examiner also. She had myoclonus of soft palate and uvula for which no obvious cause could be identified. Hence, it was diagnosed as essential palatal myoclonus and was successfully treated with clonazepam.
Keywords: Palatal myoclonus, soft palate, tinnitus, uvula
|How to cite this article:|
Nisha T, Vinayakumar AR. Essential palatal myoclonus: A rare cause of objective tinnitus. Int J Adv Med Health Res 2016;3:91-3
| Introduction|| |
Myoclonus of the larynx and pharynx was first described by Spencer. Palatal myoclonus is one of the rare causes of tinnitus. It is a condition characterized by rhythmic involuntary contraction of muscles of soft palate as well as pharynx. Palatal myoclonus is of two types, essential and symptomatic palatal myoclonus. Essential palatal myoclonus is idiopathic. There are no characteristic radiologic signs whereas symptomatic palatal myoclonus is caused by a lesion in the brainstem, more specifically in the Guillain Mollaret triangle (dentate nucleus, red nucleus, inferior olivary nucleus, and central tegmental tract). We report a rare case of essential palatal myoclonus which presented as objective tinnitus in a 12-year-old girl.
| Case Report|| |
A 12-year-old girl presented to ENT Department with a complaint of hearing unusual sound in her ears for 2 weeks following an episode of upper respiratory tract infection. She was given antibiotics and was also treated for Eustachian tube dysfunction. The patient remained symptomatic and her parents complained that they could also hear a clicking sound near the girl's head which was absent in sleep. The tinnitus was audible in both ears with the same quality, not synchronous with her pulse and there were no other auditory or visual symptoms. The girl was anxious about the clicking sound from her head, and she was not able to stop it or alter the sound on her own. History revealed no regular medications, or any other illness. Clinical examination of ears and nose was normal. The rhythmic clicking sound was audible up to 50 cm from the ear. Examination of oral cavity and oropharynx revealed myoclonus of the soft palate producing the characteristic sound. It was involuntary and regular, and was absent during swallowing. Central nervous system examination was normal, and there was no carotid bruit. Routine blood investigations and throat swab were unremarkable. Pure tone audiometry revealed normal hearing on both sides, and tinnitus matching showed that it was of high pitch. Electroencephalogram (EEG) and magnetic resonance imaging (MRI) of brain were normal. The cerebrum, cerebellum, and brainstem were normal and magnetic resonance angiography showed no abnormal vascular loop. Thus, a diagnosis of essential palatal myoclonus was made. She was treated with oral clonazepam 0.5 mg once daily for 3 weeks. The patient responded within 1 week and got relieved of her symptoms after 3 weeks. There was no recurrence of the symptom even after 1 year.
| Discussion|| |
There is no identifiable cause for essential palatal myoclonus. Diagnosis is by exclusion. In essential palatal myoclonus, the imaging studies are unremarkable. Objective tinnitus perceived by patient and examiner is due to the contraction of peritubal muscle which produces the clicking noise. The exact mechanism of objective tinnitus is unclear. Levator veli palatini muscle contractions can induce pressure changes into the Eustachian tube and this, in turn, can produce tympanic oscillations and tinnitus. The high-pitched clicking quality of tinnitus in this case, confirmed by tinnitus matching in physical therapy assistant, is due to its muscular origin and it is not seen in tinnitus of vascular origin. Essential palatal myoclonus is a sort of tremor rather than true myoclonus as it varies in its frequency from one person to another as well as from time to time in an individual. It persists during sleep in 50% of patients. Patients can voluntarily stop the tremor in the early stages.
Symptomatic palatal myoclonus is usually associated with hypertrophic degeneration of inferior olivary nucleus. Inferior olivary nucleus receives gamma amino butyric acid–ergic neuronal inputs. When this is abolished, it leads to oscillations of the neurons producing myoclonus. It can also occur following infarct in the brainstem or cerebellum. In that case, it is attributed to denervation hypersensitivity due to lesions involving Dentato-Rubro-Olivary system. Symptomatic palatal myoclonus/tremor are found to be present even during sleep and this differentiates it from essential palatal myoclonus. Although physiological myoclonus can occur in sleep, it can also occur as a consequence of hepatic encephalopathy, Creutzfeldt–Jakob disease, and toxins such as bismuth and bromide.
Sinclair et al. described that 40% patients presented with myoclonus following a viral upper respiratory infection. Medical management with anticonvulsants was ineffective and botulinum toxin was found to be effective. Botulinum toxin was injected transorally (2.5 U) into the tensor veli palatini to control tinnitus and on either side of uvula to control myoclonus.
Diagnosis of palatal myoclonus in a case of objective tinnitus is primarily by clinical examination of oropharynx. To differentiate it as essential or symptomatic palatal myoclonus, MRI brain is needed. Electrophysiological tests such as electromyography of neck muscles and EEG are useful in identifying the type of myoclonus, whether its cortical, subcortical, or spinal or psychogenic.
As no cause for the sudden onset palatal tremor apart from an upper respiratory tract infection could be found in our patient, it could be considered as essential. It has been described in literature that beta-hemolytic streptococci infection can cause reversible myoclonus. Management of palatal myoclonus includes anticonvulsants and botulinum toxin injection. We found improvement with oral clonazepam 0.5 mg once daily for 3 weeks and symptoms subsided within 1st week of initiation of treatment and was asymptomatic on follow-up.
| Conclusion|| |
There are no radiologic signs described for essential palatal myoclonus. Diagnosis of palatal myoclonus in a case of objective tinnitus is primarily by clinical examination of oropharynx. It could be treated effectively using oral clonazepam.
We acknowledge the valuable help of Dr. Ajith TA, Professor, Department of Biochemistry, Amala Institute of Medical Sciences, Thrissur, Kerala, India, during the preparation of this manuscript.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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