Surgical management of facial pain, including migraines

Introduction

Facial pain encompasses a broad range of pain confined to the head and neck region, including the oral cavity. Though accurate data are lacking on the prevalence, it has been estimated that facial pain affects 1.9% of the world’s population, with twice as many women affected compared to men. There is no single etiology as various anatomic structures and disease processes can result in facial pain. As such, it is not uncommon for multiple medical and surgical specialties (neurologists, dentists, otolaryngologists, plastic surgeons, neurosurgeons, pain management, physical medicine specialists, psychiatrists, etc.) to be involved in the treatment of facial pain. Paralleling the multidisciplinary nature of caring for patients with facial pain, there is an equal, if not greater, number of classification systems of facial pain. These include the most widely used International Classification of Headache Disorders (ICHD) as well as the classification systems from the American Academy of Orofacial Pain, Orofacial Pain Special Interest group of the International Association for the Study of Pain, International Headache Society, etc. Because of its complex nature, a team-based approach is preferred in the diagnosis and treatment of facial pain.

The third edition ICHD system (ICHD-3) classifies headaches based on symptoms rather than etiology. The most common type of recurrent headache is classified as episodic migraine with or without aura. Episodic migraines, in particular those associated with aura, are thought to originate from the central nervous system at the neuronal level of the brain. Criteria for episodic and chronic migraine headache are well defined based on headache quality and number of headache days per month ( Table 16.1 ). Chronic migraine is estimated to affect 0.9%–1.3% of the overall population. Chronic tension-type headache is distinct from chronic migraine in that these headaches are bilateral and not associated with phonophobia or photophobia. Though chronic tension-type headaches are more common than chronic migraine, affecting an estimated 2.2% of the total population, less is known about the pathophysiology of this entity.

The economic effects of migraine headaches include direct and indirect costs. Direct costs include the medical costs to treat the condition while indirect costs include productivity loss and lost wages. As of 2018, total costs for migraine patients has been estimated at $2649 per year for each patient with episodic migraine, and $8243 per year for each patient with chronic migraines; 60% of these costs are estimated to be direct medical costs. A recent review of inpatient hospitalization data from 1997 to 2012 found that costs per hospitalization have been rising from $5939 per admission in 1997 to $21,576 in 2012, accounting for $1.2 billion in inpatient hospital expenditures in 2012. Headaches are among the top three most commonly reported pain conditions resulting in lost productivity at work, resulting in an average of 3.5 hours of lost productivity per week and an additional cost of $2600 to the employer in short-term disability and workers’ compensation claims.

Types of facial pain

Overview of migraine headache surgery

Migraine surgery, a form of peripheral nerve decompression surgery, began serendipitously after several patients reported unexpected elimination of their migraine headaches after forehead rejuvenation surgery. This observation was investigated with a retrospective study of forehead rejuvenation patients in which 79.5% of migraineurs reported significant improvement or complete elimination of their migraine symptoms. The contemporaneous introduction of BTX-A for the treatment of chronic migraine provided a physiologic mechanism by which migraine surgery affected headache symptoms – namely, chemical paralysis vs. surgical resection of muscle causing compression of peripheral nerves. This theory of anatomic muscle compression of peripheral nerves was investigated through multiple anatomic and translational studies. For instance, in the frontal region, the anatomic relationship of the corrugator supercilii, depressor supercilii, and procerus vis-à-vis the supraorbital and supratrochlear nerves was investigated. In the temporal region, the anatomic relationship between the zygomaticotemporal branch of the trigeminal nerve and surrounding muscular structures was measured and recorded. In the occipital region, anatomical studies found that the greater occipital nerve (GON) passed through the semispinalis capitis muscle to innervate the scalp. These findings provided an anatomic basis both to chemodenervate these muscles as a diagnostic test (or even provide non-surgical treatment in some patients) as well as to surgically decompress peripheral head and neck nerves by selective partial muscle resection.

This muscle compression theory was first tested by injecting migraine patients with BTX-A in the corrugator supercilii muscles; patients who had improvement in migraine symptoms subsequently underwent migraine surgery with resection of the corrugator supercilii muscles alone or with ablation of the zygomaticotemporal branch of the trigeminal nerve. Of these surgical patients, 45% of patients had significant improvement in headache symptoms while 50% reported complete elimination. Guyuron subsequently reported the first GON decompression procedure that involves partial resection of the semispinalis capitis muscle followed by transposition of an inferiorly based three-sided local adipose flap – essentially a subcutaneous nerve transposition. The results of these novel surgical procedures prompted the investigation of additional trigger sites including the frontal, temporal, occipital, and rhinogenic sites. Guyuron et al . performed a intervention–sham surgery comparison study investigating these trigger sites (except rhinogenic trigger sites) and reported statistically significant improvement in headache symptoms in the patients who underwent peripheral nerve decompression. The study found an 83.7% reduction in migraine headache symptoms in the intervention surgery group compared to 57.7% reduction in migraine headache symptoms in the sham surgery group (P<0.05). Additionally, 49.0% of patients in the intervention surgery group reported complete elimination of migraine headache symptoms as compared to 3.8% in the sham surgery group (P<0.001).

As anatomic understanding of peripheral nerve trigger sites grew, so did the realization that muscle compression was not the only culprit in nerve compression. Janis et al . published their findings that arteries play a compressive role in peripheral nerve compression migraine headaches. The first of these studies reported that the occipital artery is a compressive force in GON-mediated migraine headaches. Later studies demonstrated that arteries were implicated in nummular headaches since ablation of the offending vessel eliminated headaches in the affected region. Further studies also investigated the role that bony foramina and fascial bands can play in the peripheral nerve compression migraine headache trigger sites. Fallucco et al . classified the four most common bony foramen morphologies of the supraorbital nerve and foramen. More recent studies have found evidence linking the extracranial nerves to the trigeminal nucleus of the brainstem via bony canals, cranial sutures, and foramina of the skull. This provides an explanation for how extracranial peripheral nerve compression can trigger an intracranial migraine-like phenomenon. Each anatomic trigger point will be discussed in further detail in the following sections.