Chapter 26. Orofacial Pain

Pain in the oral and facial structures is a common symptom. Although in most cases, the cause can be determined readily, the anatomy of the area is so complex that the diagnosis may be difficult.

Pain originating in the mouth and face is mediated mainly by the fifth (trigeminal) cranial nerve. This nerve has three branches: ophthalmic, maxillary, and mandibular. In addition, the facial (nervus intermedius root), glossopharyngeal, vagus, and cervical nerves also innervate parts of this region. These nerves have a tortuous anatomic course and distribution and do not follow an orderly pattern. All pain fibers from this region (with the exception of those from the cervical nerves) travel to the spinal nucleus of cranial nerve V. From there, they are connected to higher centers.1–4

The emotional significance of pain in this region may be heightened for several reasons. The mouth and face are highly innervated by sensory fibers. This area is represented on the sensory homunculus as much larger than its actual size. The trigeminal nervous system develops early, and reflex suckling activity has been observed in utero. Furthermore, in most western civilizations, the face is one of the few parts of the body exposed to view. It is through the face that humans communicate and express their feelings toward fellow human beings.

It is imperative that a thorough history be obtained before the patient is examined or special tests are ordered. In most cases, the diagnosis may be made with this information alone.

It also is important to obtain the patient’s description of the pain. Primary neuralgias frequently are described as sharp and lancinating, vascular headaches as throbbing, and muscle pain as a continuous, dull ache. The intensity of the pain should be measured against the patient’s own experience of pain, need for medication, and effect on lifestyle, for example, sleep, work, and social activities. The origin of the pain should be ascertained by asking the patient to indicate this with one finger. Its distribution pattern should be traced accurately in terms of the local anatomy. The patient should be urged to remember the events surrounding the original onset of the pain, even though this may have occurred several years previously.

Any other instances of similar pain should be determined, although the patient may not associate these with the current problem. The time relationship of the pain should be clarified in terms of duration, frequency of attacks, and possible remissions. In many instances, aggravating factors (e.g., lying down, chewing, the sight or smell of food, alcohol, or stress) and relieving factors (e.g., heat and cold) are important clues. The effect of past treatment should be elucidated carefully (which medications helped, whether surgery altered the nature of the pain, whether endodontic treatment or extractions affected the pain). Finally, the presence or absence of associated factors, such as swelling, flushing, tearing, and nasal congestion, must be ascertained. The patient may not be able to answer all questions during the first interview. Additional information may be required from relatives and friends to obtain a general picture of the pain and its effect on and perception by the patient. This information usually leads the clinician to a diagnosis.

A complete physical examination and appropriate tests, including blood and urine analyses, radiographs, and, where indicated, referral to other specialists or more sophisticated tests—for example, magnetic resonance imaging (MRI) or computed tomography (CT) scan—will help to confirm the clinical diagnosis and exclude other underlying conditions.

There are various classifications of oral and facial pain, but none5–13 are entirely satisfactory. The International Headache Society classification and diagnostic criteria for headache disorders, cranial neuralgias, and facial pain14 is valuable, and the amplification in the area of orofacial pain and temporomandibular disorders provided by Okeson2 help to improve understanding of these conditions. From a clinical point of view, pain in the mouth or face may be divided into the following groups:

• I. Pain caused by local disease

• • A. Teeth and jaws

  • B. Temporomandibular joint and muscles of mastication

  • C. Salivary glands

  • D. Nose and paranasal sinuses

  • E. Blood vessels

• II. Pain arising from nerve trunks and central pathways

• • A. Group A: no abnormal central nervous system signs (e.g., idiopathic paroxysmal trigeminal and glossopharyngeal neuralgia)

  • B. Group B: abnormal central nervous system signs (e.g., nerve involved by pressure, infiltration, or degenerative disease at an intra- or extracranial location)

• III. Pain arising from outside the face (e.g., ears, eyes, heart, cervical spine)

• IV. Chronic atypical facial and oral pain

Pain Caused by Local Disease

This category includes the greatest number of oral and facial pains encountered in clinical practice. By means of a careful history and appropriate tests, the etiology can be determined.

Teeth and Jaws

Pain arising from the teeth, supporting structures, and jaws usually is diagnosed accurately by the patient. Hypersensitivity of a tooth as a result of an exposed root surface or a recent deep restoration is described as sharp, usually transient, and well localized. It is aggravated by hot, cold, or sweet foods. A cracked tooth also may cause transient sharp pain on biting. This may be difficult to identify and lead to an erroneous diagnosis. If the pulp is involved in an inflammatory reaction resulting from dental caries, the pain is spontaneous, severe, and less well localized. Heat aggravates and cold relieves the pain; it may persist for minutes or hours. In time, the pain stops, indicating complete necrosis of the pulpal tissue. This may progress to a periapical abscess in which signs of infection are present, and the tooth is tender to bite on and to percussion. Endodontic treatment will save the tooth and eliminate the infection.

The infection, however, may progress to cellulitis and abscess formation. Incision and drainage can usually be accomplished under local anesthesia, but occasionally, a general anesthetic is required. In the most extreme situation, Ludwig’s angina may develop. The infection spreads to the sublingual, submental, submandibular, and pterygomandibular spaces bilaterally and then through the retropharyngeal, pretracheal, and carotid sheath to the mediastinum. In these cases, the airway may be compromised severely. These infections were invariably fatal before antibiotics were discovered. Even today with aggressive antibiotic therapy, surgical drainage, and supportive care, fatalities can occur.

A particularly painful condition occasionally arises after tooth extraction, usually of a mandibular molar. This is termed localized osteitis (frequently called dry socket). The pain is severe and constant, starting 2 to 3 days after the extraction and lasting for 10 to 14 days thereafter. The socket should be irrigated and dressed on a regular basis until granulation occurs. Osteomyelitis of the jaw (usually the mandible) is rare today, but it may present as an intense deep-seated pain, accompanied by appropriate physical and radiographic signs. The chronic sclerotic variety is more insidious and less readily diagnosed. Treatment is surgical debridement with vigorous antibiotic therapy. Osteoradionecrosis is a relentless, extremely painful condition characterized by postirradiation bone necrosis, predominantly of the mandible, with exposure of the bone into the mouth or externally. In most cases, the condition can be controlled only by radical surgical excision of the affected bone. Hyperbaric oxygen may plan an adjunctive role and can markedly reduce the pain.

Referred pain occasionally is encountered. The patient complains of pain in the mandible, but a maxillary tooth is found to be the cause or vice versa. More common is the complaint of earache accompanying an unidentifiable toothache. Referred pain to the ear indicates mandibular tooth disease. The perception of the anatomic site apparently is mistaken within the branches of the trigeminal nerve.

Temporomandibular Joint Disorders and Diseases

Masticatory pain can arise from the muscles of mastication or the temporomandibular joint itself.15–19 Although these sites are a common cause of facial pain, a thorough history and examination must be done to exclude other potentially more serious diagnoses.

Masticatory system disorders have been classified in many different ways. Because of the difficulty encountered in establishing a precise cause, these disorders often are defined on the basis of symptoms and signs. However, broad categories of masticatory problems include masticatory muscle spasm, internal derangement of the temporomandibular joint, chronic hypomobility, trauma, degenerative joint disease, growth disorders, infections, tumors, and congenital abnormalities.

It is imperative to take a detailed history and perform a thorough clinical examination. In addition, the patient’s family, social, and medical history should be ascertained. Clinical examination should include (1) palpation of the muscles of mastication (temporalis, masseter, and medial and lateral pterygoid), (2) observation and measurement of mandibular motion (opening, closing, lateral excursion, and protrusion), (3) palpation or auscultation of joint noises, (4) examination of the dentition and occlusion, and (5) brief neurologic examination of the trigeminal system.

Masticatory muscle spasm (temporomandibular joint or myofascial pain dysfunction) is the most common of all masticatory system disorders. Epidemiologic studies from many countries show that signs and symptoms of such disorders are widespread, and that 28% to 88% of people have detectable clinical signs of dysfunction. Fewer individuals (12%–19%) are aware of symptoms. A smaller group (5% or more) may require treatment.

It is generally agreed that patients with temporomandibular joint dysfunction exhibit one or more of the following signs: (1) decreased range of mandibular motion, (2) impaired function (e.g., deviation, sounds, or sticking), and (3) pain on palpation of the masticatory muscles or joint. One or more of the following symptoms also may occur: (1) temporomandibular joint sounds, (2) fatigue or stiffness of the jaws, (3) pain in the face or jaws, (4) pain on opening the mouth wide, and (5) locking. Radiographic studies of the temporomandibular joint show no evidence of disease.

The cause of this clinical complex is multifactorial. Among the causes most commonly cited are functional, psychological, and structural factors. It is important to understand that, for a particular patient, a single clear etiologic factor rarely is apparent. More often, several possible factors are identified. Likewise, treatment goals should be formulated that address the several likely causes.

Most patients respond to simple noninvasive treatment plans, and these should always be initiated before invasive therapy is contemplated. These measures should include, but are not necessarily limited to the following.

• 1. Reassurance. It is important that patients realize they are not alone with their symptoms, that the symptoms are essentially self-limiting, and that no disease exists. The role of muscle spasm and its benign nature should be explained carefully.
• 2. Rest. Although it is not prudent to immobilize the mandible, patients should be instructed to have a mechanically soft diet for 2 weeks and avoid yawning and laughing with the mouth open. Such habits as chewing gum, biting fingernails, and posturing the jaws should be discouraged.
• 3. Heat. The application of heat to the sides of the face by heating pad, hot towel, or hot water bottle will be comforting and help to relieve muscle spasms. More vigorous treatment can be achieved with ultrasound or short-wave diathermy heat treatments. These are available in physical therapy departments.
• 4. Medications. Nonsteroidal anti-inflammatory analgesics are valuable in the acute stage. The drugs ibuprofen, naproxen, and indomethocin at a low dose for 2 weeks are used most widely. Anxiolytic agents, such as the benzodiazepines, also are used commonly. Several regimens exist, and doses should be individualized. The usual regimen consists of diazepam, 2.5 to 10 mg, two to four times daily, with an increased bedtime dose as necessary to ensure restful sleep. It is important that this treatment be limited to approximately 2 weeks because there is a potential for dependency. Narcotic analgesics should be avoided.
• Antidepressants have a long history of effectiveness in the treatment of chronic pain. In view of the strong association between temporomandibular joint dysfunction and psychological factors, their use often is justified especially when this disorder is a part of a more global complex of muscle pains and other signs and symptoms of depression are evident. The tricyclic antidepressants are used most widely. A bedtime-only schedule of 25 to 100 mg of amitriptyline or doxopin often can relieve the symptoms in 1 or 2 weeks. Treatment is maintained for 2 to 4 months; then it is tapered to a low maintenance dose or discontinued. The effect of other antidepressants has not been well studied. There are case reports indicating that some of the selective serotonin reuptake inhibitors may, in fact, potentiate bruxism.
• 5. Occlusal therapy. There are many interocclusal appliances, and their multiplicity suggests that the optimal design has not been found. These devices usually are made of processed acrylic and serve the following functions: (1) improving the function of the temporomandibular joint, (2) improving the function of the masticatory motor system and reducing abnormal muscle function, and (3) protecting teeth from attrition and abnormal occlusal loading. In essence, a full-arch occlusal stabilizing appliance (Fig. 26-1) is the type that has been most effective. Partial-coverage appliances tend to produce significant and irreversible changes in the dentition. An appropriate appliance is effective in most patients (70%–90%). They are most successful in reducing masticatory muscle pain and controlling attrition and adverse tooth loading.

• There have been numerous claims that occlusal interferences of various types are the chief cause of masticatory muscle pain and that their elimination by occlusal adjustments will result in improvement. Because masticatory dysfunction is a multifactorial problem, this is unlikely to be true. The negative influence of malocclusion, loss of teeth, and occlusal interferences on masticatory dysfunction is not well supported. On general principles, however, occlusal disharmony (including premature contacts) should be eliminated and missing teeth replaced. The long-term efficacy of repositioning adult nongrowing jaws with occlusal splints or functional appliances has not been proved satisfactorily.
• 6. Behavioral modification. Bearing in mind the psychological effect in this disorder, attempts to lower patient stress are important. Relaxation techniques, conditioning, and biofeedback all have been advantageous. The most important factor is undoubtedly the therapeutic interaction of the practitioner with the patient.
• Internal derangement is another cause of masticatory system disorders. Temporomandibular joint arthrography was developed in the 1940s by Norgaard,20 but it was not until much later that the potential contribution of internal derangement of the meniscus to the spectrum of temporomandibular joint disorders was recognized.21 The meniscus can, either temporarily or permanently, be displaced and cause symptoms of sticking, clicking, locking, and pain.

The main categories of internal derangement are, firstly, anterior displacement with reduction. This occurs when the meniscus is displaced in the closed-mouth position and reduces, with a click, to a normal relationship at some time during opening. In these circumstances, the patient complains of the click and a variable amount of pain. On opening, the jaw deviates toward the affected side until the click occurs, and then returns to the midline. Preventing the mouth from closing fully by using a splint, tongue blades, or dental-mirror handle eliminates the click. An MRI study will show a displaced meniscus that is reduced on opening. This clinical situation may include an intermittent locking and may progress to the second category, anterior displacement without reduction (closed lock). Patients again have a variable amount of pain or, if muscle spasm has been relieved adequately, may be pain free. They feel, however, that something in the joint is stopping it from opening. There is usually a history of clicking with intermittent locking. Opening may be limited to 25 to 30 mm, with restriction of motion to the contralateral side. An MRI study shows displacement without reduction (closed lock) and also may demonstrate perforation and degenerative changes. In such cases, the signs and symptoms of degenerative joint disease also may be present.

Initial treatment for internal derangements consists of the noninvasive therapies used for temporomandibular joint disorders (as discussed previously). In patients with anterior displacement with reduction (intermittent locking), these strategies often are successful. In patients with a closed lock, especially those in whom the condition is long standing, these treatments may reduce muscle spasm and pain and restore some motion, but the underlying displacement will remain. When noninvasive treatment has been attempted for several months and the patient remains restricted, arthroscopy or arthrocentesis should be considered.

Chronic hypomobility is a rare but important cause of masticatory system disorders. Ankylosis is the persistent inability to open the jaws. It may result from pathologic involvement of the joint structures (true ankylosis) or limitation produced by extraarticular causes (false ankylosis). Infection and trauma (including previous surgery) are the prime causes of true ankylosis. The findings are severe limitation of opening, possibly with mandibular retrognathism if mandibular growth has been restricted. Radiographs show destruction of the joint surfaces, loss of joint space, and, in extreme cases, ossification across the joint. False ankylosis may be caused by various disorders that can be categorized as myogenic (e.g., masticatory muscle contracture), neurogenic (tetanus), psychogenic (conversion reaction), bone impingement (enlarged coronoid process), fibrous adhesions (occurring after temporomandibular joint surgery, temporal flap, or trauma), and tumors.

Many of these patients require surgery. In those with true ankylosis, even under general anesthesia, it will not be possible to open their mouths. A careful, awake, fiber optic–assisted intubation is required. The key to successful therapy is to identify the cause of the ankylosis and treat it as aggressively as possible. It should be recognized, however, that true ankylosis with fibrosis and calcification can be extremely recalcitrant to treatment.

Trauma is another cause of masticatory system disorders. A blow to the jaw can sprain the temporomandibular joint, cause a joint effusion, or fracture the neck of the mandibular condyle. In an acute sprain, the joint is painful, and there is severe limitation of motion caused by muscle spasm. Heat, rest, and nonsteroidal anti-inflammatory medications resolve the acute symptoms, but other forms of treatment may be required to alleviate residual muscle spasm and pain. In the case of a joint effusion, in addition to pain and limitation, patients are unable to close their teeth together on that side. In a more severe injury, a hemarthrosis may develop, with damage to the meniscus. Active physical therapy is required to restore range of motion and prevent the development of ankylosis. A fracture of the neck of the condyle is a common maxillofacial injury, and, if undisplaced, requires analgesics and a soft diet for a few days. In the unilateral displacement or dislocated variety, the patient has a premature bite on the affected side and deviation to that side on opening. Intermaxillary fixation for 10 days may be required with active physical therapy thereafter to restore function. The patient with bilateral fractures has an anterior open bite and posterior displacement of the mandible, and more aggressive treatment is required to restore the bite and function. Depending on the position of the displaced fragment, it may interfere with mandibular motion.

Degenerative joint disease (osteoarthritis, osteoarthrosis) of the temporomandibular joint is a further cause of masticatory system disorders and may result from several different insults to the joint structure that exceed its capacity to remodel and repair. These insults may be traumatic (acute or chronic), chemical, infectious, or metabolic. The patient complains of pain on jaw movement and limitation of movement, with deviation to the affected side. There may be acute tenderness over the joint itself. Joint sounds are described as grating, grinding, or crunching (but not clicking or popping). Initially, radiographs may be normal, but marked degenerative and remodeling changes are seen later, possibly at a time when the symptoms have subsided. The natural course of the disease suggests that the pain and limitation will disappear after several months.

The features of degenerative temporomandibular joint disease are different from those of most other joints in the body. There is a strong predeliction for women to be affected. A significant number of patients are in their third or fourth decades of life. Few have generalized osteoarthritis.

Most patients can be kept comfortable until remission using the noninvasive techniques outlined earlier. Some require injections of corticosteroids into the joint. This treatment generally is reserved for older patients and is limited to two or three injections. In those who are refractory to these techniques, surgery may be indicated to remove loose fragments of bone (so-called joint mice) and to reshape the condyle. Attention should also be directed toward the meniscus because its displacement may be a primary reason for the degenerative changes.

Rheumatoid arthritis also can afflict the temporomandibular joint, and reports of its incidence range widely. In young patients, an association with micrognathia may be found. In advanced cases, ankylosis may be the presenting complaint. Radiographic findings show joint destruction, possibly involving both the condyle and the articular eminence. Other stigmata of the disease are evident, and if medical management is ineffective, alternative treatment of the degenerative joint disease or ankylosis may be necessary.

Postnatal growth abnormalities also can cause masticatory system disorders. Studies of facial growth show the major contribution made by the mandibular condyle to the adaptive growth of the mandible in the functional soft tissue matrix. Several conditions may reduce growth, including hypothyroidism, hypopituitarism, and nutritional deficiency, such as vitamin D deficiency. In gigantism, all skeletal structures are enlarged; in acromegaly, a marked prognathism is produced. Several local conditions, such as trauma, infection, rheumatoid arthritis, exposure to radiation, and scarring from burns or surgery, are other causes of reduced growth.

Temporomandibular joint infections are uncommon today. When seen, the preauricular area is swollen, hot, and tender. Patients have difficulty opening and closing their mouths. Radiographs may show increased joint space, bony destruction, and sclerosis in the chronic stage. Treatment includes drainage, debridement, and appropriate antibiotic therapy.

Temporomandibular joint tumors are rare, but several varieties of primary and metastatic tumors have been reported. The most common are benign cartilaginous or bony tumors. These may cause limitation of motion or malocclusion, but they are not always painful.

Congenital abnormalities constitute the final cause of masticatory system disorders. Complex coordinated growth of the facial structures is necessary to achieve normal form and function. On occasion, the developmental process is altered, and malformations occur. It is beyond the scope of this chapter to review all the possible anomalies encountered in clinical practice, but many abnormalities of the temporomandibular joint occur in conjunction with recognized syndromes, for example, lateral facial dysplasia or Treacher Collins syndrome. A full clinical and radiologic workup is necessary to evaluate the defect fully. Treatment usually is undertaken by a multidisciplinary team.

Salivary Glands

The parotid and submandibular salivary glands occasionally are the site of infection or disease. In the more common condition of submandibular sialolithiasis, Wharton’s duct becomes blocked by a stone or nonopaque “sludge.” Characteristically, the gland swells, and pain is felt by the patient at the sight, smell, or thought of food. The swelling and pain may decrease after the meal, but they recur at the next meal. If the stone is in the duct, a sialolithotomy often can be done to relieve the problem. Surgical excision of the submandibular gland is frequently necessary, because the gland structure is damaged considerably by repeated infections. A gustatory neuralgia has been desribed after trauma or surgery in the parotid region.

Nose and Paranasal Sinuses

Experimental stimulation of various areas in the nose and paranasal sinuses refers pain to well-defined regions of the mouth, face, and cranium. Therefore, in any diagnosis of pain, rhinologic causes should be sought. The most common diagnostic dilemma is differentiating maxillary toothache from maxillary sinusitis, especially because periapical infection from a maxillary premolar or molar occasionally may cause sinusitis.

Blood Vessels

The many names ascribed to facial migrainous neuralgias have confused clinicians, as shown by the considerable length of time between onset of symptoms and appropriate diagnosis and treatment of this condition. The Subcommittee on Taxonomy of the International Association for the Study of Pain has provided a provisional summary description for pain of vascular origin.22

Cluster headache (see Chap. 25) usually is unilateral in the ocular, frontal, and temporal areas, but it also may be situated in the infraorbital region and maxilla. The condition afflicts men predominantly and usually starts between 18 and 40 years of age. Attacks are grouped in bouts of several weeks to months, with pain-free intervals of several months’ duration. Bouts often last from 4 to 8 weeks, with one to three attacks every 24-hour period and a maximum of eight attacks daily. The pain is excruciating. It is described as constant, stabbing, burning, and throbbing. Associated features include ipsilateral ptosis and miosis, tearing, rhinorrhea, and blocked nose. Treatment includes ergot preparations, prednisone, and methysergide. Chronic cluster headache is similar to cluster headache, but it is rarer. The diagnosis requires at least two or more attacks per week over a period of more than a year. Treatment is the same as that for cluster headache, but lithium carbonate tends to work better in patients with chronic cluster headache.

Chronic paroxysmal hemicrania (see Chap. 25) involves the ocular, frontal, and temporal areas and, occasionally, the occipital, infraorbital, aural, mastoid, and nuchal areas (invariably on the same side). It occurs predominantly in women. Patients have attacks every day, usually for 15 to 30 minutes in a 24-hour period. Characteristically, the attacks fluctuate in frequency and severity. Attacks may last 5 to 45 minutes at their maximum, and are excruciating. Ipsilateral conjunctival injection, lacrimation, nasal stuffiness, and rhinorrhea occur in most patients. Attacks occur at regular intervals through the day and night, and patients may be awakened by a nocturnal attack. Indomethacin provides immediate and absolute relief. Although these vascular pains usually are situated in the cranium, they can occur in the infraorbital region of the maxilla and lead to confusion with sinus or dental disease. Such patients frequently undergo extensive dental treatment before the correct diagnosis is made.

Temporal giant cell arteritis (see Chap. 25) afflicts patients older than 60 years of age. There is a dull persistent pain in the temple after chewing. The temporal artery is nonpulsatile, tortuous, and tender. Referral to an ophthalmologist is essential to exclude ophthalmic artery involvement and the possibility of permanent blindness. Corticosteroids ameliorate this condition.

Pain Arising from Nerve Trunks and Central Pathways

Group A: No Abnormal Central Nervous System Signs

Facial neuralgias include the primary idiopathic neuralgias. These have been recognized for many centuries and are among the most severe pains felt by humans. The features of trigeminal neuralgia are well described.23 Characteristically, there is a trigger zone in the area of the nasolabial fold or upper or lower lip. When stimulated by washing, shaving, talking, or any slight movement, pain occurs that is severe, lancinating, and lasts only a few seconds. There is no objective sensory loss. An untreated patient initially may present in an unkempt state, drooling from the mouth, and unwilling to move or touch the trigger area. Injection of a local anesthetic into the area abolishes the trigger for the duration of the anesthesia. Remission for months or years commonly occurs.

Although this description is classic and usually well recognized, patients who have undergone various treatments in the past may give different descriptions that may confuse the diagnosis. Furthermore, several less typical features may be reported, such as continuous or long-lasting aching or burning between paroxysms and spontaneous changes in sensation.

Although no cause has been found, some patients describe a previous traumatic event. Pathologic examination of resected nerve tissue has shown evidence of hypomyelination or demyelination in the region of the trigeminal ganglion. Some neurosurgeons believe that impingement of blood vessels on the nerve in the region of the ganglion is the cause of this disease. It is important to recognize that, in some patients, especially those younger than 40 years of age, symptoms of trigeminal neuralgia may indicate an underlying disease, such as multiple sclerosis or a space-occupying lesion at the cerebellopontine angle.24

A similar condition, glossopharyngeal neuralgia, has the same characteristics except that the trigger zones are in the tonsil, lateral pharyngeal wall, or base of the tongue. This condition should not be confused with Eagle’s syndrome,25 in which an elongated styloid process may impinge on the soft tissue of the throat during neck movement or swallowing, or Trotter’s syndrome,26 in which a tumor of the nasopharynx may cause pain in the lower jaw, tongue, and side of the head. In these cases, however, other signs such as deafness (from occlusion of the eustachian tube) and asymmetry in mobility of the soft palate (from tumor invasion of the levator palati muscle) should be sought.

Treatment of the primary neuralgias initially is medical.27 Carbamazepine, baclofen, or neurontin are effective in many cases. Some patients, however, are allergic to these medications or develop bone marrow depression as an adverse effect. Traditionally, peripheral neurectomy of the maxillary or mandibular division of cranial nerve V or phenol or alcohol blocks have been used to denervate the area permanently. With the introduction of the radiofrequency lesion, the pain fibers specifically supplying the trigger zone may be destroyed selectively without necessarily interfering with sensory function. This is a relatively benign procedure with excellent long-term results. Other neurosurgeons prefer intracranial surgery, in which vascular structures are dissected off the trigeminal ganglion; good results can be obtained despite the greater risks of this major surgical intervention.28,29 Glycerol injection and other surgical procedures also have been used successfully (see Chap. 35). Gamma knife treatment has recently been suggested as an alternative approach.

Another group A disorder is postherpetic neuralgia30,31 (see Chap. 40). A significant number of patients (approximately 25%) develop chronic pain after acute herpes zoster, and its incidence increases with age. Although the mechanism is poorly understood, it appears that the initial acute inflammation results in fibrosis of the nerve sheath and dorsal root ganglion, with loss of large myelinated axons.

Herpes zoster also may occur in the distribution of the trigeminal nerve. The first division, especially, is affected, and the possibility of corneal ulceration and scarring should be remembered. The pain is described as a constant burning sensation, with a stabbing component. Hyper- or hypesthesia may be present.

Treatment is not entirely satisfactory. Various medications may reduce the pain of acute herpes zoster, such as topical idoxuridine, oral amantadine, intramuscular interferon, intravenous acyclovir, and intravenous vidarabine. Steroids also have been advocated, and sympathetic block can be useful.

In chronic postherpetic neuralgia, few approaches provide significant relief. Anticonvulsants, antidepressants, and antipsychotic agents all have been used. Occasionally, neurosurgical procedures are indicated.

Group B: Abnormal Central Nervous System Signs

The cause in these syndromes may be extracranial or intracranial. This includes trauma, osteomyelitis, Paget disease, primary or metastatic tumors32 or space-occupying lesions at the cerebellopontine angle24 and the middle cranial fossa, disseminated sclerosis, cerebrovascular disease, syphilis, and syringobulbia.

Pain Arising from Outside the Face

Pain perceived in the face may be a result of irritation of pain receptors in tissues that are related embryologically to the segmental innervation of the face. This pain may originate in the eyes, ears, heart, or cervical spine. Common ocular causes of pain33 include refractive error, convergence insufficiency, extraocular muscle imbalance, trauma (e.g., abrasion, contact lens damage, or foreign body), otitis, angle-closure glaucoma, and so-called dry eye syndrome. Common causes of ear pain are outlined in Table 26-1.

Coronary artery disease classically is described as left substernal pain referred to the arm and side of the neck that is brought on by physical exertion, emotional upset, or ingestion of food. It is relieved rapidly by rest or sublingual nitroglycerine. On occasion, the pain sweeps up the neck and into the angle of the jaw. If the pain occurs in the jaw without other related symptoms, the diagnosis may be missed. The dorsal root of cervical nerve III supplies the skin overlying the angle of the mandible. A cervical strain injury, cervical osteoarthritis, or spondylitis may irritate these nerves and cause pain in their distribution. Pressure on the occipital nerve (cervical nerve II) can cause occipital neuralgia with a sharp lancinating quality that shoots forward over the head. Local anesthetic and steroid injections may be necessary.

Chronic Atypical Facial and Oral Pain34–37

Many patients have intractable facial pain that may be termed atypical facial pain. In these patients, the pain is a multifactorial problem characterized by equivocal physical findings, diffuse descriptions, and ill-defined psychiatric symptoms. In addition, malingerers, drug abusers, and patients with Munchausen syndrome may be encountered.

In an effort to diagnose and treat patients with chronic joint pain, a chronic facial pain group (consisting of an oral and maxillofacial surgeon, psychopharmacologist, neurologist, and neurosurgeon), which interviewed and examined patients at the same time. The pain was classified using the McGill-Melzack scale,38 the International Association for the Study of Pain axes, the Diagnostic and Statistical Manual, Third Edition, Revised psychiatric classification, and the International Classification of Disease. In a study39 of 107 patients, 88 were women, and 19, men (mean age, 44.6 years; range, 17–87 years). These patients had experienced pain for a mean of 7.8 years (range, 0.5–46 years) and had consulted a mean of 5.8 physicians. They typically described their pain as continuous and fluctuating in intensity. All patients had used some medications (mean, 5.7); 58% had used narcotic analgesics, and 34% had used antidepressant medications.

Fifty-one percent of these patients had undergone some previous surgical intervention, and 14% had undergone temporomandibular joint surgery (15 patients and 23 operations). Forty percent of the patients had been treated with physical therapy, and 33% of the patients had used occlusal splints of one type or another. In addition to the facial pain (42% bilateral, 30% left, and 28% right), 58% of the patients had cranial pain, 36% had neck pain, and 46% had pain in other areas.

Most of these patients had more than one diagnosis. According to the classification systems, 65% of the patients had definable psychiatric problems, chiefly depression (38%); 36% had symptoms attributable to the masticatory system (temporomandibular joint and muscles); 29% had neuralgias of the trigeminal nerve; and 15% had pain of vascular origin. The rest were classified as atypical facial pain of unknown or mixed cause.

A variant of atypical facial pain is phantom-tooth pain or atypical odontalgia40 in which pain is reported in a tooth or its supporting structures. Fillings, endodontic treatment, extractions, and bone currettage often are performed without relief. The same sequence is followed in a neighboring tooth until a whole region of the mouth is rendered edentulous.

Burning mouth and burning tongue (glossodynia) is a troublesome condition with several different causes.41 On first presentation, a complete oral examination should be performed and a comprehensive history taken. Laboratory tests are necessary to exclude diabetes mellitus, pernicious anemia, and vitamin B12 and folate deficiency. Other causes include xerostomia, geographic tongue, median rhomboid glossitis, trauma, candidiasis, and psychogenic factors. In all cases of atypical pain, a thorough physical and radiographic examination is necessary, and a psychiatric workup is indicated. Evidence now exists that burning mouth syndrome may be a neuropathy of thermal sensitivity.

As indicated, depression frequently is associated with chronic pain, either as a premorbid or reactive condition. In either instance, the patient will benefit greatly from treatment. Antidepressant medications have a long history of effectiveness and safety. They can reduce anxiety, reverse both mood and vegetative signs and symptoms of depression, and improve sleep patterns. The tricyclic antidepressants (amitriptyline and doxepin) are used most widely, and a bedtime-only schedule of 25 to 100 mg often achieves improvement in 1 to 2 weeks.42 The treatment can be continued for several months and then tapered to a low maintenance dose. Monoamine oxidase inhibitors and lithium salts also may be prescibed on occasion.

Anxiety sometimes is associated with chronic facial pain, and it may or may not be associated with a specific major life change, for example, illness, death, or acute stress. A careful history usually uncovers many symptoms, including tachycardia, dizzy spells, headaches, unsteadiness, paresthesias, breathing difficulties, trembling, excessive perspiration, a choking sensation, or hyperventilation. Relaxation techniques (such as meditation, hypnotherapy, behavior therapy, and biofeedback) are useful, and the minor tranquilizers (chlordiazepoxide and diazepam) are prescried widely.43

Other psychiatric conditions also may present with pain; for example, hysteria, schizophrenia, and hypochondriasis. Even when these diagnoses have been excluded, there remain many patients with various emotional problems that may contribute to or cause pain. Hackett44 developed the Madison scale to describe the characteristics that correlate with the psychogenicity of pain and are helpful in evaluating such patients.

Treatment for patients with chronic facial pain depends on its cause and may consist of multiple concurrent approaches.45,46 A multidisciplinary approach has been found to be helpful in the diagnosis and treatment of these patients, but it is evident that, despite the best efforts of physicians and the use of sophisticated imaging techniques and tests, the needs of many of these patients are not met. They continue to seek medical consultations and undergo surgical intervention with no relief of their pain. A pain management program may ultimately be helpful for these individuals.