An unusual case of hypnic headache ameliorated utilizing a mandibular advancement oral appliance

Abstract

AbbreviationsHH Hypnic headacheTMJ Temporomandibular jointBMI Body mass indexMAD Mandibular advancement applianceCH Cluster headacheOSA Obstructive sleep apneaCPAP Continuous positive airway pressureSCN Suprachiasmatic nucleusPAG Periaqueductal graySRBDs Sleep-related breathing disordersIntroductionHypnic headache (HH), first reported by Raskin [1], is arare and recurrent benign headache disorder that occursexclusively during sleep and usually presents after the ageof 60. Generally described as a primary headache of theelderly [2], the attacks are usually of short duration(30 min) and awaken the patient at a constant time eachnight. According to the International Classification ofHeadache Disorders, second edition (ICHD-2) [3], HHmust fulfill the following criteria:1. A dull headache fulfilling criteria 2–4:2. Develops only during sleep and awakens the patient3. At least two of the following characteristics:(a) Occurs >15 times per month(b) Lasts ≥15 min after waking(c) First occurs after the age of 50 years4. No autonomic symptoms and no more than one ofnausea, photophobia or phonophobia5. Not attributed to another disorderIn a case series, HH has been reported to account for0.07% of all headache patients [4]. The pathophysiology ofhypnic headache is yet to be fully elucidated, but due to itscircadian nature as well as its reported responsiveness tolithium [1], a disturbance of chronobiologic rhythmsappears to be putative. Previous reports of utilizing positiveairway pressure in hypnic headache patients have proven tobe inconclusive [5–8].The relationship between headache and sleep haspreviously been reported in the literature [9]. As hypnicheadaches will only occur during sleep, it potentiallyprovides us with the most robust insight into the commonetiologic mechanisms of these two entities. Additionalprimary headaches that occur during nocturnal sleep aremigraine, cluster headache, and chronic paroxysmal hemi-crania [10]. Other disorders that should be considered withheadaches that awaken us are obstructive sleep apnea(OSA) or sleep hypoxia/hypercapnia, restless leg syndromeor periodic limb movements during sleep, psychophysio-logic insomnia, chronic pain syndrome or fibromyalgia, ordepression/anxiety [10]. All should be considered in thedifferential until proven otherwise. A comprehensivehistory is necessary to accurately diagnose these headachedisorders. Headaches associated with OSA or sleep hypox-ia/hypercapnia are classified as secondary headaches orheadaches attributed to a disorder of homeostasis [11].Morning headaches will occur at a rate of 18–74% ofpatients with OSA [12]. About 40% of patients withinsomnia have headaches in the morning [13]. It has beenreported that 65% of sleep bruxism (SB) patients reportedfrequent headaches [14, 15]. However, laboratory studieshave demonstrated that most morning headaches are notdirectly correlated with SB [16, 17].