Nasal CPAP therapy associated with masticatory muscle myalgia

Abstract

This case report describes a rare side effect associated with nasal continuous positive airway pressure (nCPAP), masticatory muscle myalgia. A 69-year-old man was referred to a clinic specializing in orofacial pain and dysfunction with complaints of pain in the area of the masseter muscles. He was diagnosed with severe obstructive sleep apnea (OSA) 9 months earlier, for which he received nCPAP. Six months ago, his pain complaints started. The pain was diagnosed as masticatory muscle myalgia, due to sleep-related tooth clenching and intense tongue thrusting. These activities were likely related to the patient’s attempts to prevent leakage through the oral cavity of the airflow generated by the nCPAP device. The patient did not complain about leaking of the nasal mask itself. Considerable alleviation of the pain complaints as well as reduction of the clenching and thrusting behavior were achieved by substituting the nasal mask with a full face mask. Sleep medicine physicians should be aware of this possible side effect of nCPAP.

Citation:

Lobbezoo F, Li J, Koutris M, et al. Nasal CPAP therapy associated with masticatory muscle myalgia. J Clin Sleep Med. 2020;16(3):455–457.

INTRODUCTION

Dental sleep medicine has recently been defined as “the discipline concerned with the study of the oral and maxillofacial causes and consequences of sleep-related problems.”¹ As such, several categories of dental sleep disorders can be distinguished, namely sleep-disordered breathing (eg, snoring, obstructive sleep apnea), sleep-related orofacial pain, mandibular movement disorders (eg, tooth grinding and clenching), oral moistening disorders (eg, oral dryness), and gastroesophageal reflux disorder.¹ Unfortunately, as argued by Lobbezoo and Aarab,² dental sleep medicine largely remains outside of sleep medicine’s focus, which is not to the benefit of our patients. This report describes a case of a patient seeking relief of his orofacial pain complaints, which turned out to be related to the treatment with nasal continuous positive airway pressure of his comorbid obstructive sleep apnea.

REPORT OF CASE

A 69-year-old man (body mass index 29.5 kg/m²) was referred by his dentist to the Clinic of Orofacial Pain and Dysfunction of the Academic Centre for Dentistry Amsterdam (ACTA) with bilateral pain in the area of the jaw. Prior to the patient’s first consultation at ACTA, he completed a comprehensive e-questionnaire, including, among others, the Axis-II instruments of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD).³ Based on the outcomes of the questionnaire, TMD pain was suspected, along with a suspicion for sleep-related tooth- clenching behavior, somatization, and psychological stress.

During the first consultation, the medical history revealed several health issues, including epilepsy, temporal arteritis, gout, and headache. All conditions were successfully under medical treatment (by means of dedicated pharmacotherapy); only his headache complaints, which were already present for many years, did not respond well to pharmacotherapy thus far. Other than the mentioned conditions, the patient received a diagnosis of severe obstructive sleep apnea (OSA) approximately 9 months earlier, with an apnea-hypopnea index (AHI) of 58 events/h, for which he received a nasal continuous positive airway pressure (nCPAP) device (AirSense 10 Elite, ResMed; mean [range] pressure = 7.5 [4–12] cm H₂O).

The dental history confirmed the self-reported complaints of jaw pain. The patient reported that his headache complaints were unrelated to his jaw pain complaints. The jaw pain was present for at least 6 months, qualified as mild (average intensity of 3 to 4 on a 0 to 10 numeric rating scale), described as nagging, and located in the area of the masseter muscles on both sides. In addition to the pain, sleep-related tooth clenching was reported, along with tongue thrusting while asleep. According to the patient, the latter activity was likely related to his mostly unconscious attempts to prevent leakage through the oral cavity of the airflow generated by the nCPAP device. The patient did not complain about leaking of the nasal mask itself. The psychosocial history showed an elevated level of stress and a considerable effect of the patient’s health issues on his daily life.

Intraoral inspection revealed a healthy, well-maintained dentition, with fixed prosthodontic restorations in the mandibular premolar and molar areas as well as in the upper front. The oral soft tissues showed hyperkeratotic white lines in the cheeks as well as severe tongue scalloping (Figure 1), which is indicative of tooth clenching and tongue-thrusting behavior. Mandibular excursions were within normal limits and did not provoke the jaw pain complaints, whereas dynamic and static orthopedic tests revealed the presence of myalgia in the masseter and anterior temporalis muscles on both sides. This finding was confirmed by manual palpation using the standard operating procedures of the DC/TMD.³

Figure 1. Anterior part of the tongue visible in the oral cavity.

The anterior and lateral sides of the tongue show signs indicative of tongue thrusting (ie, scalloping). Figure shown with patient’s written permission.

Based on the aforementioned findings, the dentist made the diagnosis of myalgia of the jaw-closing muscles on both sides, with sleep-related tooth clenching in combination with intense tongue thrusting as the most likely etiologic factors. After multidisciplinary team discussion, it was decided to suggest changing the nCPAP mask to a full face mask, under the assumption that this would prevent the intense tongue thrusting and the concomitantly occurring tooth clenching behavior. The patient organized the change of mask immediately. The same pressure settings were used for both masks, and according to the patient neither of them was leaking. The AHI values with the full face mask (mean ± standard deviation over the 4 months following the change of mask = 2.81 ± 0.10 events/h) were only slightly higher as compared to the ones achieved with the nasal mask (mean ± standard deviation over the 4 months preceding the change of mask = 1.68 ± 0.39 events/h).

One week after the change of mask, the dentist contacted the patient by telephone for a first follow-up report. The patient indicated that he already experienced a small improvement of his jaw-muscle pain complaints and a reduction of his tongue thrusting behavior. Another 2 weeks later, during a clinical consultation session, the jaw-muscle pain was reportedly reduced more than 50%, whereas the headache complaints remained unchanged. In addition, the patient reported a considerable alleviation of the sleep-related tooth clenching and tongue thrusting activities.

Written informed consent was obtained from the patient to use his history data, clinical data, and images for this publication.

DISCUSSION

In this case report, it has been described that a nasal mask can be associated with TMD pain through a causal chain with the tongue forcefully sealing off the oral cavity and a concomitant increased jaw-muscle activity, that is, tooth clenching behavior. The substitution of the nasal mask with a full face mask prevented air leakage through the mouth and thus reversed the tongue thrusting and clenching activities. This resulted in a considerable and fast reduction of the associated myalgia.

CPAP is considered the gold-standard treatment strategy for severe OSA.⁴ Unfortunately, the use of CPAP masks is associated with several commonly occurring adverse effects, such as dry mouth, increased number of awakenings, blocked-up nose, pressure intolerance, and air leakage,⁵ which could be detrimental for compliance.⁶ Dental side effects, which are common for oral appliance therapy,⁷ are much less frequently reported by adult CPAP users. Tsuda et al⁶ describe dental changes due to pressure of the nasal mask on the lip, thus causing a retrusion of the upper incisors. Interestingly, a recent case report by Pliska and Almeida⁸ describes the labial outward tipping of the upper and lower anterior teeth as a side effect of nCPAP. The authors reason that the tipping was likely due to an increased anteriorly oriented force of the tongue that was pushed forward by the inflow of air. To the best of our knowledge, no other studies have reported on dental side effect associated with nCPAP.

The patient described in the current case report also reported nCPAP-related dental side effect, albeit not related to tooth position changes but to jaw-muscle overuse. The air pressure of on average 7.5 cm H₂O forced him to seal off the oral cavity with his tongue to prevent leakage of the airflow via the mouth. The resultant tongue thrusting occurred with simultaneous tooth clenching; the latter behavior was one of the main etiologic factors of TMD pain.⁹ This was reported as such by the patient, but is also comprehensible from a physiologic point of view: Valdés et al¹⁰ demonstrated that anterior positioning of the tongue is associated with increased levels of masseter and temporalis muscle activity as compared to the condition with the tongue in the floor of the mouth. It should be noted that the average air pressure of 7.5 cm H₂O is not very high. Apparently, the patient’s musculoskeletal load-bearing capacity must have been reduced due to, for example, his self-reported elevated levels of somatization and psychological stress, which is in line with the current insights into the multifactorial etiology of TMD pain (eg, psychosocial factors, oral behaviors, genetics, etc.).⁹

This report stresses the importance that CPAP-prescribing and monitoring physicians be aware of the possibility that nCPAP can yield dental positional changes due to the pressure of the mask on the maxillary structures and induce musculoskeletal pain in the masticatory system due to clenching in relation to tongue thrusting in individuals with a reduced load-bearing capacity. Hence, patients need to receive counseling on this aspect prior to treatment onset. The fact that TMD pain negatively affects oral health-related quality of life⁹ and has detrimental consequences for the patients’ adherence with nCPAP or CPAP therapy, underlines the notion that a high-quality professional collaboration between sleep medicine physicians and dentists specializing in dental sleep medicine is important.²

ABBREVIATIONS

ACTA

Academic Centre for Dentistry Amsterdam

AHI

apnea-hypopnea index

DC/TMD

Diagnostic Criteria for Temporomandibular Disorders

nCPAP

nasal continuous positive airway pressure

OSA

obstructive sleep apnea

TMD

temporomandibular disorders

DISCLOSURE STATEMENT

All authors have seen and approved the manuscript. Work for this study was performed at the department of Orofacial Pain and Dysfunction of Academic Centre for Dentistry Amsterdam (ACTA). The Department of Orofacial Pain and Dysfunction of Academic Centre for Dentistry Amsterdam (ACTA) receives research support from: Airway Management, SomnoMed-Goedegebuure, and Sunstar Suisse S.A. This support is unrelated to the current work. The authors report no conflicts of interest.