Abstract
To describe three patients with recurrent severe paroxysmal headache precipitated by yawning. Pain elicited by yawning is a well-recognized clinical phenomenon in patients with cranial neuralgia, temporomandibular joint dysfunction syndrome and Eagle syndrome. Clinical history, neurological and oral examinations, brain magnetic resonance imaging (MRI), cranial nerve electrophysiological testing and skull X-rays are reported. In all the patients pain was induced by yawning; in the third patient pain was also triggered by eructation. None had history of migraine. Facial gestures and forceful opening of the mouth did not reproduce the pain. The first patient had retroauricular pain, simvastatin-induced myopathy and subclinical axonal peripheral neuropathy; the second patient had a post-viral benign sensory neuropathy; and the third had retroauricular and facial pain and no underlying neurological illness. Cranial nerve testing and MRI of the brain were normal except for a coincidentally found pituitary adenoma on the first patient. Headache or cranial pain with yawning may occur in patients with no apparent cause (primary yawning headache). It is a chronic, benign condition that requires no specific treatment but needs to be distinguished from secondary yawning headache, of greater clinical relevance.
Introduction
Yawning is a normal phenomenon in mammals that signifies drowsiness, fatigue, hunger or boredom (1). Yawning in male rodents is associated with penile erection, representing sexual arousal or pre-coital behaviour that is mediated by nitric oxide, oxytocin and dopamine, and can be precipitated by cortical spreading depression (1–4). Yawning is a sign of dopaminergic hyper-responsiveness in migraineurs and may be tested readily in this population by administering sublingual apomorphine, a dopamine agonist agent (5). Yawning also constitutes an unusual migraine premonitory symptom that may occur in isolation without associated drowsiness (6, 7). Conversely, yawning may trigger cephalic, pharyngeal or upper cervical pain in patients with trigeminal, glossopharyngeal and geniculate neuralgia. Yawning will cause pain in patients with temporomandibular joint (TMJ) dysfunction syndrome and Eagle syndrome (ES) (8). Three patients with no apparent cause for their yawning-induced headache (primary yawning headache) are reported. None had intracranial lesions that could explain their symptoms, nor evidence of styloid ligament calcification or significant elongation.
Case reports
Case one
A 71-year-old female was sent to the neurologist because of generalized muscle pain and mild elevation of her blood creatinine kinase (CK) with a normal sedimentation rate, 6 weeks after initiating treatment with simvastatin, prescribed for hypercholesterolaemia. She described episodes of severe paroxysmal left retroauricular pain, precipitated by yawning, especially during the evening hours, lasting for approximately 1½ min. Yawning lasted from 5 to 8 s on average. Pain was intense, stabbing-like, followed immediately the onset of yawning and was not precipitated by simulating yawning or by facial gestures. She had a history of hiatal hernia, peptic ulcer, sinusitis, osteoarthritis, osteoporosis and compressed fractures of the thoracic spine. She had chronic back pain. Her sister had Alzheimer's dementia. Her general physical examination was normal. Neurological examination was normal but formal visual field testing showed bitemporal hemianopsia. Electromyogram of the legs detected complex motor unit potentials indicative of chronic reinnervation; her left peroneal and tibial motor responses were of low amplitude diagnostic of axonal loss. Her muscle biopsy showed neurogenic atrophy with no evidence of myositis. Her brain magnetic resonance imaging (MRI) disclosed a coincidental pituitary adenoma causing chiasmal compression, that was subsequently and successfully removed with no sequela. Her oral examination, Panorex skull views and cranial nerve testing were normal. Her muscle pain improved when simvastatin was discontinued. Retrospectively it was concluded that she had an underlying peripheral neuropathy and pituitary adenoma unrelated to her muscle pains and to her yawning retroauricular pain. At follow-up no new symptoms have developed.
Case two
A 30-year-old male developed muscle pains and numbness of the hands and left leg following the flu. He complained of intense, recurrent, left submandibular pain with yawning of recent onset. The pain was of short duration and followed the onset of yawning. His past medical history was unremarkable. His mother had migraine. General physical examination was normal except for flat feet. Neurological examination was normal. Wide opening of the mouth or making facial gestures did not result in pain. Nerve conduction velocities (NCV), cranial nerve testing, MRI of the brain, Panorex X-rays of the skull and oral examination were normal. His muscle pain and hand numbness improved after several weeks. In retrospect, he was diagnosed with a benign post-viral neuropathy and primary yawning pain.
Case three
A 73-year-old female had right retroauricular and upper facial pain for 6 months triggered by yawning and belching, and occasionally by turning her head to the right. The pain was severe, steady and of approximately 60–90 s duration. It was not reproduced with every spontaneous yawning; however, volitional gestures, forceful opening of the mouth or deep inspirations did not reproduce the pain. She had history of hypertension, coronary artery disease and hypercholesterolaemia. Her daughter had migraine. Physical examination was unremarkable and on neurological examination some tenderness was found upon palpation of the right lateral neck, submaxillary and retroauricular regions, that did not induce her typical pain. There was no pain on percussion of the cervical spinous processes. She had complete range of motion of her neck in all directions. Her computerized tomography (CT) and MRI of the neck showed bilateral, small benign lymphoadenopathies. MRI of the cervical spine showed mild C6 disc bulging and osteoarthritis with bilateral neuroforaminal narrowing at various levels, expected for her age. Carotid ultrasound, MRI of the brain, cranial nerve testing, Panorex views of the skull, TMJ X-rays and tonsillar fossa palpation were within normal limits. At follow-up, she denies having new symptoms.
Discussion
Secondary yawning pain in patients with cranial neuralgia is recognized because of the presence of spontaneous pain in the specific areas of anatomic distribution of the affected nerve, i.e. facial in trigeminal neuralgia, the ear in geniculate neuralgia and the pharynx in glossopharyngeal neuralgia. In TMJ dysfunction syndrome there is pain around the temporomandibular joints, worse with every attempt to open the mouth widely. The patients will have tenderness on palpation of the pre-auricular area, masseters and temporalis muscles (9). In contrast, in greater auricular neuralgia, the pain is spontaneous and periauricular pain in location (10). Cases one and three of this series have retroauricular pain but only during yawning; case three also had facial pain.
Eagle syndrome (ES) is perhaps less recognized by neurologists as a cause of cranial pain induced by yawning. ES, first described by Eagle in 1937, is characterized by neuralgic or steady pharyngeal pain radiating to the ear, worsened by swallowing and yawning (8). It may produce a foreign body sensation in the throat, dysphagia and, rarely, dysphonia and clicking of the jaw (11, 12). ES is caused by elongation or calcification of the stylohyoid ligament. It can manifest as typical glossopharyngeal neuralgia or carotidynia, in which case symptoms dissipate with surgical resection of the elongated styloid process. ES is diagnosed by digital palpation of the styloid process in the tonsillar fossa and by anteroposterior and lateral (Panorex) skull films. An excellent discussion on the pathogenesis of ES may be found in the article by Montalbetti et al. (8).
None of the patients herein described had clinical or radiographic evidence of significant elongation of the styloid or of a calcified stylohyoid ligament. Less frequent cases of yawning pain are bursitis of the hamular process or tenosynovitis of the tensor veli palatini muscle, ‘silent’ fractures of the styloid (sometimes caused by yawning!) and auditory tubal dysfunction following upper respiratory tract infections (13–15). Although headaches have been reported in patients with pituitary adenoma (i.e. case two) the location of the pain in those cases is not retroauricular and is not caused by yawning (16).
The pathogenesis of primary yawning headache is unclear. It may be speculated that a reflex arch is formed by capsular temporomandibular joint and cranial muscle stretch receptors in the afferent limb, and by trigeminal nerve fibres, including those travelling through the facial, vagus and upper cervical nerves in the efferent limb. The yawning pain experienced by these patients was perceived in different anatomic regions and in the absence of identifiable local pathology. A facilitatory role by the cerebral hemispheres in primary yawning pain is essential, since the pain reported by these patients occurs only during yawning and not simply when they open their mouth forcefully or stretch their facial muscles while gesturing, suggesting the probable presence of an elaborate central psychophysiological mechanism. It is of interest that pain was also brought on by belching in the third patient, implicating the participation of the diaphragm, innervated by the phrenic nerve and the C3, C4 and C5 spinal cord segments. Although two of the patients had family history of migraine, they did not have migraines themselves, making it difficult to suggest the presence of underlying dopaminergic dysfunction without first performing an apomorphine challenge test (5).