Abstract
Abnormalities of the upper airway anatomy are an underrecognized cause of obstructive sleep apnea. We present a unique case of a 51-year-old man with episodic sleep-maintenance insomnia and oromandibular dystonia requiring botulinum toxin injections of the temporalis and masseter muscles. He underwent multiple sleep studies and was found to have obstructive sleep apnea temporally associated with the severity of dystonia symptoms and dosing of botulinum toxin.
Citation:
Hsu N, Hsieh C, Thomas A, Chang M. Obstructive sleep apnea due to oromandibular dystonia and treated with botulinum toxin. J Clin Sleep Med. 2020;16(7):1209–1212.
Keywords: obstructive sleep apnea, botulinum toxin, dystonic disorders, insomnia
INTRODUCTION
Obstructive sleep apnea (OSA) is a chronic disorder characterized by recurrent episodes of partial or complete upper airway closure, resulting in intermittent hypoxia and sleep fragmentation.1 In adults, obesity and aging are well-known risk factors for the development of OSA.2–4 However, abnormalities in the upper airway anatomy, such as retrognathia, macroglossia, adenotonsillar hypertrophy, or dystonia, may also play a role.5 Oromandibular dystonia (OMD) is a movement disorder characterized by abnormal and involuntary contractions of the masticatory, facial, pharyngeal, or laryngeal muscles, which can lead to pain in addition to dysarthria, dysphagia, or impaired mastication.6 We describe a patient whose OSA had an inverse temporal association with the dosing of botulinum toxin and consequent severity of his OMD.
REPORT OF CASE
A 51-year-old man was referred for fatigue, difficulty falling asleep, snoring, and frequent nocturnal awakenings. His medical history included hypertension, sarcoidosis (involving the lung, liver, and kidney) with consistently normal pulmonary function testing, traumatic brain injury, post-traumatic stress disorder, migraine headaches, prior facial trauma requiring multiple jaw surgeries with sequential titanium prostheses causing overbite and overjet (Figure 1), and chronic oromandibular (jaw-closing) dystonia requiring as-needed botulinum toxin injections of the temporalis and masseter muscles for relief of trismus. These muscles were selected based on a dental examination under general anesthesia performed at an outside hospital. His medications included prednisone, azathioprine, hydroxychloroquine, duloxetine, prazosin, valproic acid, baclofen, and gabapentin. At the time of the initial consultation, his Epworth Sleepiness Scale was 24/24 and Insomnia Severity Index was 26/28.
Figure 1. Computed tomography scout film showing titanium jaw prostheses with an overbite and overjet.
On physical examination, his vital signs were within the normal range and his body mass index was 29 kg/m2. He had tenderness to palpation of the frontalis, temporalis, and masseter muscles with an inability to open his jaw past 1 finger breath. His modified Mallampati class was 4. The remainder of his physical examination was unremarkable.
A home sleep test was performed 43 days following a botulinum toxin injection, and it showed a respiratory event index of 6.5 events/h. He was initiated on positive airway pressure (PAP) therapy for mild OSA but, due to poor tolerance, he was referred for split-night diagnostic polysomnography, which occurred within 2 weeks of botulinum toxin administration (Figure 2). Sleep latency was 93 minutes, sleep efficiency was 75%, apnea-hypopnea index was 0 events/h, and periodic limb movement index was 0 events/h (Table 1). PAP therapy was discontinued given the absence of OSA. However, the patient subsequently experienced worsening insomnia and fatigue, which he felt paralleled the waning effect of botulinum toxin and recurrence of his dystonia.
Figure 2. Representative 10-minute window from the patient’s baseline polysomnogram performed 13 days after botulinum toxin administration.
Table 1.
Sleep study parameter comparison between the baseline and repeat studies.
| Variable | Baseline HST | Initial PSG | Repeat PSG |
|---|---|---|---|
| Time since last botulinum toxin treatment, days | 43 | 13 | 83 |
| Total recording time, minutes | 314 | 425 | 504 |
| Total sleep time, minutes | — | 320 | 303 |
| Sleep efficiency, % | — | 75 | 60 |
| Sleep latency, minutes | — | 93 | 130 |
| Arousal index, n/hour | — | 3 | 48 |
| Stage N1, minutes (%) | — | 15 (5) | 40 (13) |
| Stage N2, minutes (%) | — | 305 (95) | 196 (65) |
| Stage N3, minutes (%) | — | 0 (0) | 8 (3) |
| Stage REM, minutes (%) | — | 0 (0) | 58 (19) |
| Apnea-hypopnea index, events/h | 6.5 | 0 | 84 |
| AHI, supine, events/h | — | 0 | 120 |
| AHI, REM, events/h | — | — | 60 |
| Saturation nadir, % | — | 90 | 67 |
| Periodic Limb Movements of Sleep index, n/hour | — | 0 | 9 |
AHI = apnea-hypopnea index, HST = home sleep test, PSG = polysomnography, REM = rapid eye movement.
A repeat polysomnography (Figure 3) performed when the patient felt the effects of the botulinum toxin to be at a nadir (83 days since the last dose) demonstrated an apnea-hypopnea index increase from 0 to 84 events/h. Auto-titrating PAP therapy was resumed given the severity of his OSA, and the patient was referred back to his pain specialist for consideration of more frequent botulinum toxin treatments.
Figure 3. Representative 10-minute window from the patient’s repeat polysomnogram performed 83 days after botulinum toxin administration.
DISCUSSION
In the present case, OMD was presumed to be the underlying anatomic etiology of OSA. The temporal association between the botulinum toxin injections and the recrudescence of OSA was mediated by worsening dystonia. Laryngeal dystonia has been implicated in sleep-disordered breathing, but to our knowledge, this is the first published report of OSA due to chronic dystonia of the facial muscles.
The masticatory muscles are composed of the temporalis, masseter, and pterygoid (lateral and medial) muscles. The temporalis elevates and retracts the mandible; the masseter elevates and protrudes the mandible; the pterygoids lie deeper within the jaw and contribute to jaw protrusion and horizontal movement.7 While reducing hypertonicity of the temporalis may allow protrusion, laxity of the masseter would be expected to cause mandibular retrusion. In this patient, we suspect that reduced tone of the temporalis and masseter muscles via botulinum toxin injection with preserved tone of the pterygoids allowed sufficient jaw protrusion to effectively increase airway patency and improve sleep apnea.
Botulinum toxin is a neurotoxin produced by Clostridium botulinum that blocks synaptic cholinergic activity and impedes muscle contractions.8 In jaw-closing dystonia, the target sites for injection are the masseters, temporalis, and medial pterygoids.8 Botulinum toxin is variably dosed based on symptom severity, and it has demonstrated benefit in the treatment of OMD with efficacy potentially persisting for years, although generally lasting 3 to 6 months.6 However, it has not been well studied in the setting of sleep-disordered breathing. In a case report describing an otherwise healthy man with OSA due to laryngeal dystonia who was intolerant of PAP therapy, botulinum toxin injection of the vocal folds improved his apnea-hypopnea index from 43 to 9 events/h.9 In a separate cohort of 8 patients without symptomatic OSA, botulinum toxin injections of the soft palate improved snoring.10
The American Academy of Sleep Medicine recommends nocturnal PAP therapy as the first-line treatment for OSA, with potential alternative therapies depending on the patient’s anatomy, risk factors, and preferences.1 In a patient who is intolerant of PAP therapy with structural or functional abnormalities of the upper airway, treatment of the underlying anatomical defect can be effective. OSA should be considered in patients who have OMD and insomnia, and treatment of the underlying dystonia may improve or cure sleep-disordered breathing. In our patient, botulinum toxin injection was indicated as a treatment of OMD, and its beneficial effects on sleep-disordered breathing resulted from the patient’s unique anatomy due to prior facial trauma and extensive surgeries. Therefore, botulinum toxin is not a treatment for OSA per se but can be considered on a case-by-case basis for individuals with OMD and OSA. Video polysomnography can elucidate the effect of jaw posturing on obstructive respiratory events, and although not performed in this case, drug-induced sleep endoscopy can provide more comprehensive information regarding airway patency during sleep.
DISCLOSURE STATEMENT
All authors have seen and approved the manuscript. Work for this study was performed at VA Greater Los Angeles Healthcare, Los Angeles, CA. The authors report no conflicts of interest.
ABBREVIATIONS
- OMD
oromandibular dystonia
- OSA
obstructive sleep apnea
- PAP
positive airway pressure
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