Cranial Neuralgias and Facial Pain Disorders
Marianna Shnayderman Yugrakh
Denise E. Chou
INTRODUCTION
Facial pain can originate from various facial structures and includes pain due to disorders of the sinuses, ears, and nose, temporomandibular disorders (TMD), dental and oral pathologies, and various ophthalmologic problems, all of which can activate nociceptive pathways via infection, inflammation, trauma, or malignancy. Primary nervous system disorders causing facial pain span the breadth of the neuraxis and include cranial neuralgias, small fiber neuropathies, primary headache disorders, and central pain disorders involving the spinothalamocortical system. Facial pain may be perceived away from a region of pathology (referred pain) due to the complex sensory innervation of the face (including cranial nerves V, VII, IX, and X, with overlapping innervation of the ear), dural innervation from branches of the trigeminal and vagus nerves, as well as proximity of the spinal trigeminal nucleus to upper cervical afferent pathways. Sensory input convergence in the spinal trigeminal nucleus is one of the mechanisms of referred pain. Table 55.1 highlights etiologies of facial pain including the peripheral nervous system and the tissues innervated. Primary pain syndromes can be recognized and treated only after a workup for secondary etiologies. The general principle for the diagnosis of secondary facial pain disorders, based on the International Classification of Headache Disorders, 3rd edition (ICHD-3), is establishment of a causal relationship between pain and a disorder of facial or cranial structures with respect to chronology, congruous exacerbation, and improvement in symptoms, and signs of the primary pathology evoking pain on physical examination.
FACIAL PAIN DUE TO DISORDERS OF SINUSES, EARS, AND NOSE
RHINOSINUSITIS
Epidemiology and Pathobiology
Rhinitis and sinusitis are not uncommon causes of facial pain and may exacerbate a primary headache disorder. However, the term sinus headache is frequently misused to describe facial and head pain (which in actuality is most often migraine) incorrectly denoting that underlying sinus pathology is the etiology of pain. This attribution of head and facial pain to sinus pathology may have two causes: (1) migraine is a disorder associated with increased parasympathetic outflow with nasal congestion and lacrimation, and (2) the causality between headache and inflammatory changes in the nasal sinuses is difficult to establish, as the latter is highly prevalent and can be asymptomatic. Nasal mucosal changes (particularly in the ethmoid and maxillary sinuses), which may be signs of acute or chronic rhinosinusitis, can be identified in almost 50% of adults who undergo magnetic resonance imaging (MRI) testing for suspected intracranial disease. Although acute rhinosinusitis has long been considered a cause of facial and head pain, only the 3rd edition of the ICHD from 2013 has included chronic rhinosinusitis as a potential etiology. This revision was based on findings from recent studies, such as the American Migraine Prevalence and Prevention (AMPP) study, which reported that patients with chronic rhinitis were one-fourth more likely to be of higher headache frequency categories.
Nasal and sinus mucosa are innervated by the first and second divisions of the trigeminal nerve. The first division innervates the frontal and anterior ethmoid sinuses, whereas the second carries nociceptive signals from the maxillary, sphenoid, and posterior ethmoid sinuses. Infectious or allergic triggers result in release of inflammatory mediators that activate nociceptive neurons in the spinal trigeminal nucleus, signaling local facial pain and additionally may produce referred head pain. More frequent or persistent referred pain may result from peripheral and central sensitization of the trigeminal system.
Clinical Manifestations and Diagnosis
Acute rhinosinusitis symptoms include rhinorrhea and purulence, fever, hyposmia, halitosis, and symptoms akin to an upper respiratory tract infection. Acute sinusitis pain can be localized, described as deep pressure, congestion, or fullness felt in the face and teeth, and is often exacerbated by lying down. Pain may be facial but can also be referred posteriorly. Frontal sinusitis pain is typically behind the eyes and around the center of the forehead, with the frontal region being sensitive to percussion and associated with supraorbital nerve sensitivity. In ethmoid sinusitis, pain is also retroorbital and may radiate to the temples, with eye sensitivity to pressure. Maxillary sinusitis pain is appreciated over the cheeks, but can radiate to the ear or teeth, with sensitivity of teeth to percussion. Isolated sphenoid sinusitis is a relatively rare, serious disorder with the potential complication of cavernous sinus thrombophlebitis. It most commonly presents with refractory nonlocalizing headache, followed by visual complaints and cranial nerve palsies. Because of its deep location, tenderness on exam is not appreciable. Computed tomography (CT), MRI, or endoscopic techniques allow for the diagnosis.
ICHD-3 diagnostic criteria for headache or facial pain attributed to acute rhinosinusitis requires clinical, nasal endoscopic, and/or imaging evidence of acute rhinosinusitis, and two of the following: (1) establishment of a temporal relation of pain to onset of rhinosinusitis, (2) either improvement or worsening of pain symptoms paralleling improvement or worsening of rhinosinusitis symptoms, (3) pain exacerbated by pressure applied over the paranasal sinuses, and (4) pain localized ipsilateral in the case of unilateral rhinosinusitis. Headache or facial pain attributed to chronic rhinosinusitis is diagnosed based on evidence of current or past infection, and evidence of causation as discussed earlier.
Treatment and Outcome
Infectious rhinosinusitis may be treated with antibiotics, depending on patient risk profile for bacterial infection. Facial pressure and pain caused by inferior and middle nasal turbinate congestion can
be relieved with a nasal corticosteroid spray, such as mometasone furoate, or systemic decongestants. Allergic rhinitis treatment involves identifying the allergens and desensitization, or antihistamine use during seasonal episodes, and topical steroids. If aggressive medical therapy fails, surgical approaches targeting nasal anatomic abnormalities predisposing recurrent infection may be considered.
be relieved with a nasal corticosteroid spray, such as mometasone furoate, or systemic decongestants. Allergic rhinitis treatment involves identifying the allergens and desensitization, or antihistamine use during seasonal episodes, and topical steroids. If aggressive medical therapy fails, surgical approaches targeting nasal anatomic abnormalities predisposing recurrent infection may be considered.
TABLE 55.1 Etiologies of Facial Pain Including the Peripheral Nervous System and Tissues Innervated | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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FACIAL PAIN ATTRIBUTED TO DISORDERS OF THE NOSE AND MUCOSAL CONTACT POINTS
Other conditions that may cause facial pain and headache include nasal passage abnormalities due to septal deflections, hypertrophic turbinates, and nasal septal spurs. Mucosal contact points are defined as two structures in the nasal cavity that remain in contact after decongestion therapy, and have been cited as an etiology of facial pain; several surgical outcomes series indicate that patients obtain relief from headache and facial pain after endoscopic endonasal surgery. On the other hand, a large cohort study of consecutive patients in a rhinology clinic identified equal prevalence of nasal mucosal contact points in patients with and without facial pain, and yet another study found presence of contact points on CT imaging in 55% of patients without correlation to facial or head pain, both suggesting that their coexistence is coincidental. The causality of mucosal contact points and facial pain requires further investigation.
OTALGIA ATTRIBUTED TO DISORDER OF EARS AND REFERRED PAIN
Otalgia is diagnosed based on the identification of a primary ear disorder and evidence of causation. Ear pain can be dull, aching, or stabbing; may radiate to the temples; and may be associated with ear fullness, tenderness, burning, or itching. Primary disorders of the ear by compartment are listed in Table 55.1. About half of all earaches are due to structural lesions of the external or middle ear; the rest are due to referred pain from remote structures. This is due to overlapping sensory innervation in this small region: branches of the mandibular division of V and branches of C2 and C3 to the pinna; mandibular division branches of V as well as VII, IX, and X branches to the external auditory canal and the tympanic membrane; and branches of VII to the middle ear. Etiologies of referred otalgia are also summarized in Table 55.1.
FACIAL PAIN DUE TO TEMPOROMANDIBULAR DISORDERS AND DISORDERS OF THE TEETH OR MOUTH
Dental pain, frequently poorly localized, has several major causes as summarized in Table 55.1. Nondental intraoral pain can be secondary to oral mucosa malignancies, inflammatory and infectious disorders, or blockage of a major salivary gland duct with pain that is predominantly preprandial. Periodontal disorders involve bone and periodontal ligament; these are associated with clearly localized pain and are typically managed with conventional dental treatments. Atypical odontalgia, or posttraumatic trigeminal neuropathic pain that is localized to an area where a tooth has previously been extracted, is a subtype of persistent idiopathic facial pain discussed later in the chapter.
TEMPOROMANDIBULAR JOINT DISORDERS (TMD)
Epidemiology and Pathobiology
TMDs encompass pathologies related to the joint and/or to the muscles and constitute one of the most common causes of orofacial pain, affecting 10% to 15% of the population. The temporomandibular joint (TMJ) is composed of an upper and lower compartment separated by a fibrocartilaginous disk allowing rotary and translational movement of the mandible. Dysfunction may be secondary to trauma, changes in occlusion, and behavioral influences including clenching and grinding of the teeth. Other risk factors include asymmetry in joints, poor posture causing muscle strain, and female gender. Joint disorders associated with pain include arthritis, degenerative disk disease, and joint dysfunction such as disk-condyle incoordination or articular disk displacement. Pain is mediated via the pain-sensitive joint capsule and posterior disk attachment, with nociceptive signals transmitted via the mandibular branch of the trigeminal nerve. The pathophysiology of primary muscle pain, including myalgia and myofascial pain with referral is poorly understood.
Pressure on tender trigger points, or nodular bands under the skin in muscles, tendons, or fascia, can cause pain locally or in other parts of the body via referral patterns. Initial muscle aggravation may be associated with oral habits or postural abnormalities.
Pressure on tender trigger points, or nodular bands under the skin in muscles, tendons, or fascia, can cause pain locally or in other parts of the body via referral patterns. Initial muscle aggravation may be associated with oral habits or postural abnormalities.
Clinical Manifestations and Diagnosis
Common symptoms of TMD, in addition to jaw pain, include discomfort with biting or chewing, clicking or popping sounds when opening or closing the mouth, markedly limited mouth opening (<40 mm) if a disk becomes permanently displaced relative to the joint, and crepitus with mandibular movements in degenerative joint disease. MRI is the gold standard for imaging soft tissues and disk position, whereas CT can identify degenerative changes. The evidence-based diagnostic protocol and classification system for TMD, updated in 2014, combines clinical and radiologic findings. Pain originating in the TMJ may be aching, throbbing, sharp, or a tightening sensation, present at rest or provoked with movement in the ramus of the mandible, temporal area, and preand postauricular areas. Myofascial pain is described as dull or achy, associated with the presence of trigger points which may involve the masseters or temporalis muscles directly or refer pain to the preauricular area, temporal region, ear, or head. Facial pain or headache secondary to TMD is diagnosed based on evidence of causation including temporal relationship of pain to the disorder, exacerbation of pain by movement or pressure on the joint or muscles, and same laterality.
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