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Table of Contents   
CASE REPORT  
Year : 2020  |  Volume : 31  |  Issue : 2  |  Page : 315-317
Primary orthostatic tremor in mandible: A rare case report


1 Department of Dentistry, University of Pernambuco, Recife, Brazil
2 Department of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
3 Department of Dentistry, University of Pernambuco, Recife; Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil

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Date of Submission23-Dec-2018
Date of Decision13-Jun-2019
Date of Acceptance25-Nov-2019
Date of Web Publication19-May-2020
 

   Abstract 


Primary orthostatic tremor (POT) is a rare movement disorder of unknown pathophysiology, characterized by fast tremor affecting a specific part of the body. The present paper reports a case of POT in mandible, discussing the approach and management. A 37-year-old male patient complained of involuntary mandibular movements, with onset 6 years ago, with no history of precipitating event. Usually, tremors were not present during patient's mastication or phonation. The oscillations presented rhythmically and symmetrically, with high frequency and low range of motion. Surface electromyography revealed an electromyographic discharge pattern bilaterally in the masseters, presenting a mean frequency of 13 Hz, and a predominance of postural type. Based on the history and clinical characteristics and electromyography, a diagnosis of POT was made. Several treatments have been employed over the years. Currently, the patient is being treated with buspirone hydrochloride 10 mg/day with a significant reduction of tremors. It can be concluded that knowledge of the characteristics of this condition is essential for the elaboration of a correct diagnosis and the better management of POT patients.

Keywords: Jaw, orthostatic tremor, tremor

How to cite this article:
Kosminsky M, Grossmann E, Poluha RL. Primary orthostatic tremor in mandible: A rare case report. Indian J Dent Res 2020;31:315-7

How to cite this URL:
Kosminsky M, Grossmann E, Poluha RL. Primary orthostatic tremor in mandible: A rare case report. Indian J Dent Res [serial online] 2020 [cited 2020 Jul 16];31:315-7. Available from: http://www.ijdr.in/text.asp?2020/31/2/315/284592



   Introduction Top


Tremor is defined as rhythmic and involuntary oscillations of a body part involving alternating contraction of agonistic and antagonistic muscle groups.[1],[2] There are no population data available;[1],[2] however, the literature reports a higher number of cases in women at the end of the fifth decade.[3],[4] Tremors may be primary or associated with other neurological conditions.[5] Primary orthostatic tremor (POT) is a rare movement disorder of unknown pathophysiology and may be associated with oscillations in neural networks related to the cerebellum.[5],[6] The unique electrophysiological characteristics of TOP are tremors of 13 to 18 Hz induced by orthostatism usually in the lower limbs and trunk, defined in the consensus of the Society of Movement Disorders.[7]

Patients with POT have a markedly reduced quality of life, with serious commitment in the personal relationship and at work.[6] There is no absolute consensus on treatment.[4] In the current literature, there is only one reported case presenting clinical characteristics and electromyography compatible with POT involving the mandible.[8] The present paper aims to report a case of POT in mandible, discussing the approach and management.


   Case Report Top


A 37-year-old male patient complained of involuntary mandibular movements, with onset 6 years ago, with no history of precipitating event. In the previous phase, there was description of a sensation compatible with mandibular instability, followed by fasciculation in the bilateral masseter. The tremors appeared later and presented slow progression, being exacerbated by the cold environment, stress and anxiety; and attenuated by closing the mandible in protrusion, at maximum mouth opening, with the use of a massager directly on the masseter muscles or alcohol ingestion.

Usually, tremors were not present during mastication or phonation; however, in very cold environment, they might arise even during phonation. The duration of a tremor was approximately 3 to 4 s, with successive episodes. In very cold environment or under stress, the time of each episode was increased. The refractory period lasted from 1 to 2 s. The oscillations presented rhythmically, symmetrically, with a high frequency and low range of motion, approximately 2 mm, measured with the interincisal distance. Surface electromyography (EMG) revealed a pattern of electromyographic rhythmic discharge, bilaterally present in masseters, presenting a mean frequency of 13 Hz, and a predominance of postural type (Video in the supplementary file).



There were no tremors in other body segments. The patient did not report any systemic pathology or continued use of any medication or substance. No abnormalities were recorded in nuclear magnetic resonance imaging (MRI) of the brain and concomitant in computed tomography of the maxilla and mandible, as well as in complete blood biochemistry. No psychological or neurological condition was found. Based on the history and clinical characteristics and electromyography, a diagnosis of POT was made.

The tremors had an important impact on social interaction, especially in the work environment. Several treatments had been employed over the years. The synthesis of the evolution of complaints, treatments and results are shown in [Table 1]. Currently, the patient is being treated only with buspirone hydrochloride 10 mg/day, with a significant reduction in tremors. The reduction of the tremors promoted by each treatment was measured in percentage (%) with a visual analogue scale (0–10), where the patient was asked to mark the improvement perceived.
Table 1: Complaints, treatments and results

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   Discussion Top


POT is a rare disease, with little knowledge available about the demographic characteristics, natural history of the disease, associated factors and treatment responses.[9] Unlike the prevalence reported in the literature,[3],[4] the present patient was male in the third decade of life. In addition, to the best of our knowledge, this is the second case of POT reported in the mandible. Schrag et al., in 1999, reported 24-year-old woman with an unusual tremor of the jaw, with a frequency of 16 Hz. During the following 6 years, she experienced bouts of jaw tremor lasting for seconds to many months. Carbamazepine, clonazepam and acetazolamide had no significant effect on the patient's jaw tremor. For a few months while on 120 mg propranolol per day, the tremor remitted but then returned. Primidone at a dose of 200 mg per day abolished the episodes of jaw tremor almost completely, although the patient continued to have an inward subjective feeling of tremor.[8]

Usually, the diagnosis of POT is reached after years of follow-up, mainly because in the initial phase of the disease the patient does not report tremor as a descriptor of symptoms.[4] In addition, since tremors may not be present during the consultation, diagnosis can be a major challenge. Sometimes the tremors may not be visible, even when referred by the patient; however, they can be noticed by palpation. Upon hearing of these tremors, a helicopter-like sound may occur.[7] POT diagnosis is based on the association of clinical examination and EMG.[1],[2] The main clinical characteristics include tremors of reduced amplitude, with rhythmic character, present in muscular rest and absent during function.[1],[2] In most cases, POT is idiopathic, and MRI images of the brain structures are normal or nonspecific,[4],[9] as well as the laboratory data.[5] Thus, electromyography can be an important tool for differential diagnosis of POT, Parkinson's tremor and essential tremor. The POT usually presents a high frequency, varying between 13 Hz and 18 Hz in the limbs[7] and in the mandible.[8] Even with tremor progression, electromyographic data remain stable.[3],[10]

Regarding the natural course of the disease, in a prospective study with an average of 6 years (range of 5 to 25 years) of follow-up, there was an increase of tremors in approximately 80% of POT cases.[9] In the present case, aggravation of the intensity of tremors was accompanied by the increasing impact on the patient's social life. In addition, the presence of tremors during phonation in an extremely cold environment, reported by the patient, can be explained both by the possible reduction of body temperature and by the progression of the disease, which in the advanced stage cause tremors even during movement.[3]

In general, POT response to treatment is unsatisfactory, but patients are often relieved to know the diagnosis.[1],[2] Pharmacological control has been employed empirically.[5] There are isolated cases of success with the use of propranolol, clonazepam, gabapentin, pregabalin or topiramate.[1],[2],[3] Because this patient requires a high degree of cognition in his professional activity, buspirone hydrochloride was prescribed because it does not present great sedative effects, and the patient presents with a significant reduction of tremors and in follow-up. Buspirone is a member of the azapirone class of drugs. It has anxiolytic activity, but the mechanism of action has yet to be fully explained. Evidence to date suggests that its activity is based on its effects on serotonin (5-HT) receptors. It acts as an agonist of presynaptic and partial agonist of postsynaptic 5-HT1A subtype receptors.[10] Since this is a rare disorder, there are no studies with adequate design to define the appropriate management. Thus, each treatment should be used with caution, under professional supervision, while present satisfactory results, without risk to the patient.

It can be concluded that knowledge of the characteristics of this condition is essential for the elaboration of a correct diagnosis and the better management of POT patients.

Declaration of patient consent

The written patient consent has been obtained to publish clinical video.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Kumar H, Jog M. A patient with tremor, part 1: Making the diagnosis. CMAJ 2011;183:1507-10.  Back to cited text no. 1
    
2.
Kumar H, Jog M. A patient with tremor, part 2: From diagnosis to treatment. CMAJ 2011;183:1612-6.  Back to cited text no. 2
    
3.
Yaltho TC, Ondo WG. Orthostatic tremor: A review of 45 cases. Parkinsonism Relat Disord 2014;20:723-5.  Back to cited text no. 3
    
4.
Hassan A, Ahlskog JE, Matsumoto JY, Milber JM, Bower JH, Wilkinson JR. Orthostatic tremor: Clinical, electrophysiologic, and treatment findings in 184 patients. Neurology 2016;86:458-64.  Back to cited text no. 4
    
5.
Benito-León J, Domingo-Santos Á. Orthostatic tremor: An update on a rare entity. Tremor Other Hyperkinet Mov (N Y) 2016;6:411.  Back to cited text no. 5
    
6.
Lenka A, Pal PK, Bhatti DE, Louis ED. Pathogenesis of primary orthostatic tremor: Current concepts and controversies. Tremor Other Hyperkinet Mov (N Y) 2017;7:513.  Back to cited text no. 6
    
7.
Bhatia KP, Bain P, Bajaj N, Elble RJ, Hallett M, Louis ED, et al. Tremor task force of the International parkinson and movement disorder society. Consensus statement on the classification of tremors. from the task force on tremor of the International parkinson and movement disorder society. Mov Disord 2018;33:75-87.  Back to cited text no. 7
    
8.
Schrag A, Bhatia K, Brown P, Marsden CD. An unusual jaw tremor with characteristics of primary orthostatic tremor. Mov Disord 1999;14:528-30.  Back to cited text no. 8
    
9.
Ganos C, Maugest L, Apartis E, Gasca-Salas C, Cáceres-Redondo MT, Erro R, et al. The long-term outcome of orthostatic tremor. J Neurol Neurosurg Psychiatry 2016;87:167-72.  Back to cited text no. 9
    
10.
Skolnick P, Paul SM, Weissman BA. Preclinical pharmacology of buspirone hydrochloride. Pharmacotherapy 1984;4:308-14.  Back to cited text no. 10
    

Top
Correspondence Address:
Dr. Rodrigo Lorenzi Poluha
Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Al. Octávio Pinheiro Brisola, 9-75, 17012-901 Bauru, SP
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_933_18

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