This article includes discussion of ulnar neuropathies, Guyon canal neuropathy, ulnar neuropathy at the wrist, and flexor carpi ulnaris exit compression.
Jun. 07, 2021
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The relationship between headache and oromandibular disorders, such as temporomandibular joint dysfunction, is confusing to many physicians. This article explores this complex relationship and specifically describes overlapping disorders, such as atypical odontalgia, chronic orofacial pain (COFP), contact point headache, and “lower-half migraine,” which create diagnostic difficulties. This article also includes guidance for diagnosis and management, including updated treatment options such as onabotulinum toxin A and pulsed sphenopalatine (pterygopalatine) ganglion treatment for oromandibular disorders and referred facial pain.
• Temporomandibular joint disorders are common and are comorbid with headache disorders such as migraine.
• Evidence suggests central sensitization is a very common problem in temporomandibular joint disorders, atypical odontalgia, and primary headache disorder.
• It is unclear whether successful treatment of temporomandibular joint disorders will improve coexisting headache.
• In many common primary headache disorders, such as migraine, cluster headache, and trigeminal neuralgia, pain is referred to dental structures.
• It is important to know that dental pain can be referred from primary headache disorders to avoid unnecessary antibiotics and surgical interventions.
Head pain and pain in the oromandibular structures (eg, teeth, gums, jaw, tongue) may be related in 2 ways: (1) headache arising in the oromandibular structures and referred to the head and (2) head pain perceived in the oromandibular structures. The ala-tragus line, running from the lateral surface of the external nose to the inferior boarder of the tragus (92) is an artificial division of the head: neurologists treat problems that arise from structures above the line and dentists treat problems that arise from structures below the line. Because of this division, there has not been as much exploration of the relationship between oromandibular structures and head pain compared to investigation regarding one or the other (70). This article reviews the relationship between head pain and oromandibular structures and the importance of considering both cranial and oromandibular pathologies in the differential diagnosis of oromandibular or head pain.
As several disorders of oromandibular pain do not have an identifiable structural cause, understanding that pain can occur even without external nociceptive stimuli (55) is important to the diagnosis and management of these disorders.
(I) Pain arising in oromandibular structures and referred to the head
(a) Dental disease
(II) Pain arising intracranially or peripherally referred to oromandibular structures
(b) Trigeminal autonomic cephalalgias
1. Cluster headache
2. Paroxysmal hemicrania
(c) Cranial neuralgias and facial pain syndromes
1. Trigeminal neuralgia, trigeminal neuropathy
2. Burning mouth syndrome
(d) Contact point headache
Dental disease. Dental disease may be pulpal or periodontal. Pulpal pain may be divided as follows (1) irreversible pulpitis, wherein death of the pulpal tissue is inevitable and root canal therapy is required, and (2) reversible pulpitis, wherein removal of the pathology (eg, dental caries) will allow the pulpal tissue to return to normal. Periodontal disorders involve the supporting structures of the teeth, such as the bone, periodontal ligament, and cementum. Pericoronitis, or soft tissue inflammation and infection around a partially erupted tooth, is the most frequent periodontal inflammation that causes headache. Pericoronitis can present both acutely with 3 to 4 days of dental pain in settings such as wisdom tooth eruption, or chronically with recurrent episodes of infection and pain (71). Chronic dental pain is more likely to be associated with headache. Resolution or treatment of dental disease may improve long-standing refractory headache (72).
Atypical odontalgia, which presents as medically unexplained dental pain, has been linked with headache and may have a migrainous etiology (88). Graff-Radford and Solberg have defined atypical odontalgia as pain in or near a tooth with no obvious organic cause (31).
In the International Classification of Headache Disorders, atypical odontalgia represents a subgroup of persistent idiopathic facial pain (36). The major diagnostic criteria for atypical odontalgia are (1) dentoalveolar pain with no local cause, (2) continuous pain that lasts more than 4 months, (3) hyperesthesia, and (4) an equivocal somatosensory block (34). The minor criteria include an effective sympathetic block, positive thermogram, and a history of trauma (32). The lack of dental pathology, lack of change in pain over time, and lack of improvement with therapy help distinguish atypical odontalgia from pulpal pain (53).
Temporomandibular joint disorders. Functional disorders with pain in the anatomic region of the temporomandibular joint (TMJ) and associated musculature are referred to as temporomandibular disorders (52). The most frequent presenting symptom of temporomandibular disorders is pain, usually localized in the muscles of mastication, the preauricular area, or the temporal areas, and can occur unilaterally (if the temporomandibular complex is the primary cause of pain) or bilaterally (if muscular involvement is predominant) (36). The pain is characteristically aggravated by jaw function and may radiate to the neck, face, and head. Additional characteristics are limited or asymmetric jaw movements and locking on jaw opening. Painful clicking, popping or grating sounds in the TMJ when opening and closing the mouth are frequent presenting symptoms. A sudden, major change in the occlusion may be an indication of osseous changes within the joint.
The diagnosis of TMJ disorder is primarily clinical and is confirmed by physical examination. Ultrasound and MRI exams may increase diagnostic yield (09). Biomarkers for disease activity, including cytokine-like gland-derived vascular endothelial growth factor from the joint, may be emerging (38).
Headache is common in patients with TMJ disorders, and the attacks tend to be more frequent and more severe (66). The association of temporomandibular disorders and headache may be directly related to TMJ pathology (12; 29; 25; 79). Alternatively, it is possible that primary headache disorders cause TMJ dysfunction (07). Another hypothesis is that headache is an associated symptom of temporomandibular disorders, possibly triggered by the disorder, but not etiologically related. It may be that increased afferent activity within the trigeminal system due to temporomandibular disorders may trigger attacks, increasing headache frequency but not causing them directly.
Pain in the TMJ is frequently myofascial in origin. It has been postulated that pain from myofascial trigger points can generate and maintain both episodic and chronic headache, but the exact pathophysiology is not well understood due to the complexity of pain referral mechanisms in myofascial syndromes (21). Myofascial pain of the muscles of mastication may be more contributory to headache than myofascial pain of the neck and shoulder muscles.
Migraine. It is important to recognize migraine as a cause of dental pain to avoid unnecessary dental procedures (62). Lovshin was the first to describe migraine as facial pain that could occur in the absence of headache (48). Sometimes called “facial migraine” or “lower-half migraine,” pain affecting the second and third divisions of the trigeminal nerve, with often underrecognized migrainous features, is not uncommon. However, unrecognized, it leads patients to seek treatment from a variety of physicians specializing in fields other than headache including otolaryngologists, dentists, ophthalmologists, and oral maxillofacial surgeons. Approximately 12% of patients evaluated for facial pain in a London rhinology clinic were diagnosed as having migraine (20). More interesting is that 47% of these patients with migraine had migraine isolated to the second division of the trigeminal nerve (20). A larger German study found that about 9% of 517 migraine patients experienced pain in the lower half of the face in addition to migraine (98). Moncada and Graff-Radford described a case of exertional migraine presenting as toothache (58). Facial or “lower-half” migraine usually responds to typical migraine treatments (65). Researchers have examined a subset of orofacial pain syndromes that are classifiable as vascular and predominantly affect intraoral structures (40). In rare cases, migraine is associated with the dystonic disorder hemifacial spasm, possibly due to vascular compression of the facial nerve at the root exit zone (08).
Trigeminal autonomic cephalalgias. Cluster headache, which, along with paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks (SUNCT and SUNA), and hemicrania continua make up the trigeminal autonomic cephalalgias. All trigeminal autonomic cephalalgias are characterized by unilateral head pain and have either one or both of the following: conjunctival injection and/or lacrimation, nasal congestion and/or rhinorrhea, eyelid edema, forehead and facial sweating, miosis and/or ptosis, and/or a sense of restlessness or agitation (36). Hemicrania continua, SUNCT (short-lasting unilateral neuralgiform headache with conjunctival injection and tearing), and SUNA (short-lasting unilateral neuralgiform headache with cranial autonomic symptoms) typically have not been reported to involve the oromandibular structures. The other trigeminal autonomic cephalalgias have been reported to present with dental pain as described below.
Cluster headache. Cluster headache typically has features of severe unilateral orbital, supraorbital, and/or temporal pain lasting 15 to 180 minutes, ipsilateral autonomic symptoms involving the conjunctiva, pupil, eyelid, nose, ear, or forehead, and restlessness or agitation (36). However, cluster headache can also present with orofacial pain. Sixty-five percent of 42 patients with cluster headache received unnecessary dental treatments because of the facial presentation of the pain (14). Others reported 3 patients with episodes of orofacial pain compatible with cluster headache (64).
Paroxysmal hemicrania. Paroxysmal hemicrania is characterized by at least 20 attacks over at least 1 year of severe unilateral orbital, supraorbital, and/or temporal pain lasting 2 to 30 minutes accompanied by ipsilateral autonomic symptoms involving the conjunctiva, pupil, eyelid, nose, ear, or forehead (36). This disorder can also present as orofacial pain. Delchano and Graff-Radford described 2 patients with chronic paroxysmal hemicrania who complained, primarily, of tooth pain that radiated to the maxillo-temporal regions (22). Both patients were well controlled with indomethacin. Multiple cases of paroxysmal hemicrania within the orofacial area have been reported in the dental literature (11).
Cranial neuralgias and facial pain syndromes. The International Headache Society’s International Classification of Headache Disorders third edition lists several causes of cranial and facial pain (36). These include:
• Pain attributed to a lesion or disease of the trigeminal nerve
Of these, pain attributed to a lesion or disease of the trigeminal nerve (trigeminal neuralgia, trigeminal neuropathy) and burning mouth syndrome are most frequently encountered in clinical practice and will be highlighted in this article.
Trigeminal neuralgia and pre-trigeminal neuralgia. Pain attributed to a lesion or disease of the trigeminal nerve is characterized by recurrent unilateral brief electric shock-like pains (36). The pain is abrupt in onset and termination. The location of the pain is limited to the distribution of one or more divisions of the trigeminal nerve (ophthalmic, maxillary, or mandibular). In trigeminal neuralgia the pain is most often present in the maxillary or mandibular branches (36). Painful trigeminal neuropathy presents with facial pain in the territory of the trigeminal nerve. In trigeminal neuralgia, the pain is triggered by innocuous stimuli but can also present with a concomitant constant pain (36). Painful trigeminal neuropathy, unlike trigeminal neuralgia, is continuous or near continuous and is described as burning or squeezing. Facial pain from trigeminal neuralgia or painful trigeminal neuropathy is often misdiagnosed as being caused by dental problems. Merrill and Graff-Radford described 61 patients, 19 with pre-trigeminal neuralgia and 42 with trigeminal neuralgia, who received more than 100 unnecessary dental treatments prior to appropriate diagnosis and treatment (54).
Glossopharyngeal neuralgia is characterized by a unilateral, brief, stabbing pain in the territory of the glossopharyngeal nerve and auricular and pharyngeal branch of the vagus nerve (36). Pain is localized in the base of the tongue, tonsillar fossa, beneath the angle of the jaw, or ear. It can occur concurrently with trigeminal neuralgia.
Neck tongue syndrome is characterized by immediate-onset, unilateral, sharp or stabbing, and usually severe occipital and/or upper neck pain (36). The pain is brought on by sudden rotatory head movement and is accompanied by abnormal sensation and/or posture of the ipsilateral tongue.
Burning mouth syndrome. Burning mouth syndrome describes oromucosal pain (tongue, mouth, or entire oral cavity), described as tender, burning, tingling, hot, or numb, mainly involving the anterior two thirds of the tongue, without identifiable cause (43; 59; (36). Pain can present with allodynia with tooth brushing (15). It can also be described as a tingling, pricking, pins and needles, numbness, itching, and electrical sensations (15). Associated symptoms can include dysgeusia and xerostomia (36).
Contact point headache. Contact point headache or “Sluder neuropathy” results in unilateral head or facial pain and is often localized to the upper teeth or mouth. The cause is believed to be irritation of the anterior ethmoid nerve or sphenopalatine ganglion, and the pain usually starts after an infection. Septal abnormalities may contribute to pain, and radiofrequency thermocoagulation may be effective in some cases (63). In patients with radiologic evidence of contact point headache, surgical treatment may be effective in reducing pain severity or frequency (01). Unilateral pain or a good response to topical lidocaine may predict good outcomes with endoscopic management (76). However, these radiologic abnormalities are not rare nor necessarily a good predictor of headache causality (39).
Dental disease. The prognosis of dental disease causing face pain is excellent. Dental problems seldom produce long-term or significant disability. Infection is usually local and does not produce systemic complications.
Temporomandibular disorders. Treatment can be effective, and there are few long-term residual problems. It is reassuring for patients with temporomandibular disorders to know that these problems rarely persist beyond the fourth decade. Patients who are not responsive to physical medicine approaches should not be considered surgical candidates automatically; rather, behavioral factors that perpetuate the disorder should be considered.
Migraine. There are a variety of preventive and episodic treatments available for migraine. Risk factors of transitioning from episodic (attacks occurring less than 15 days/month) to chronic migraine include obesity, medication overuse, stressful life events, and sleep disorders (13; 84).
Trigeminal autonomic cephalalgias. Of the trigeminal autonomic cephalalgias, cluster headache is the most prevalent, and its prognosis better studied. About 80% to 90% of patients with cluster headache have episodic cluster headache, whereas 10% to 15% of patients with cluster headache have chronic cluster headache (CCH) (99). Ten percent of patients with episodic cluster headache transform to chronic cluster headache (99). On the other hand, about a third of patients with chronic cluster headache can revert to episodic cluster headache (99). The length of time between cycles can increase as a patient ages, and a patient may note that their cluster headache is “improving” (99).
Cranial neuralgias and facial pain syndromes. The prognosis of cranial neuralgias varies widely and typically depends on if they are primary or secondary (for example, due to a space occupying lesion, or a vascular compression). There are generally both episodic forms of the neuralgias and pain syndromes, with refractory periods in between attacks, but they can also transition to chronic forms with concomitant chronic pain in between attacks.
The cause of toothache is often infection of the dental and periodontal tissues and typically presents as nociceptive and inflammatory pain (70). Pain referral from extradental structures (as in primary headache disorders or cranial neuralgias) typically results from activation of the trigeminovascular system. The trigeminovascular system receives sensory information from and can sensitize nerve branches that innervate parts of the mouth, parts of the ear, extracranial skin, and parts of the meninges, which is carried by cranial nerves VII (the facial nerve), IX (the glossopharyngeal nerve), and X (the vagus nerve) (23; 61). The trigeminal nucleus caudalis converges with the dorsal horn cells of the upper cervical cord. Sensitization of the trigeminal nucleus caudalis results in dysfunction in central neural processing and pain modulation. Because of the relationship of the trigeminal nucleus caudalis to many other cranial and cervical nerves, the pain referral pattern may be confusing and can include face, periorbital, and upper neck pain. Therefore, one must always keep in mind that when local dental pathology cannot be found, referral from other sources may explain the pain.
Dental disease. Inflammation (sometimes due to infection) is the typical pathogenesis for dental pain. Inflamed, painful tissues are often swollen, hot, red, and limited in function. When acute pain occurs in the dental structures, patients may complain of referred pain and tenderness in adjacent structures. Regarding atypical odontalgia, Sicuteri and colleagues described the relationship of atypical odontalgia with headache and suggested a neurovascular etiology (88). Patients with atypical odontalgia also have abnormal somatosensory function, as measured by quantitative sensory testing (46) and prolonged allodynia to cold stimulation (101). This suggests that atypical odontalgia, like migraine, involves sensitization of higher order neurons.
When examined on functional MRI, stimulation of the affected area produces changes in areas of pain processing such as the thalamus and insular, somatosensory, and prefrontal cortices (56). A deafferentation mechanism, perhaps sympathetically maintained, may also be the cause of atypical odontalgia based on the high frequency of associated trauma, the equivocal effect of somatic block, and the positive effects of sympathetic block (33; 34). As in migraine, there is thought to be some correlation with underlying psychosocial factor and atypical odontalgia; high levels of depression and resentment have been found to be predictive for development atypical odontalgia (17).
Temporomandibular disorders. The TMJ is a diarthrodial synovial joint. It is characterized by 2 compartments separated by fibrous discs. The movements in the joint are both rotational and translational. The first 25 mm of mouth opening involve rotation of the condyle within the fossa. The second 25 mm involve translation of the disc condyle complex along the articular eminence.
The temporomandibular disorders are classified into joint-related problems (arthrogenous) and muscle disorders (myogenous). Most problems occur in combination but may present as isolated problems.
Temporomandibular joint pain can be caused by inflammation within the joint and is complicated by dysfunctions of the intracapsular portions (ligaments and disc). Inflammation of the TMJ may occur in conjunction with internal derangements or incoordination of the disc condyle and temporal bone. Joint noise present on movement may be due to anatomical changes of any of the articulating surfaces or to remodeling from micro- or macrotraumas. Noise may also be present when the disc is displaced (usually anteriorly and medially). Mandibular manipulation or movement results in a clicking or popping noise as the condyle moves under the disc during translation of the disc condyle complex along the articular eminence. As the teeth come back together, noise can again be noted. This condition is called an anterior displaced disc with reduction. These situations can be painful when they are accompanied by associated intracapsular inflammation. Local anesthetic or steroid injection decreases the pain and aids in localizing the pathology. When the mandible cannot move beyond the displaced disc, the condition is called a closed lock or anterior displaced disc without reduction. A closed lock may require manual manipulation with local anesthetic or arthroscopic intervention.
TMJ inflammation is usually associated with degenerative changes (seen on bony imaging). Inflammation secondary to systemic arthritis is rare. Rheumatoid arthritis and psoriatic arthritis do affect the TMJ; standard serology for these conditions will confirm the diagnosis.
Other etiologic factors for temporomandibular disorders include bruxism, trauma, occlusal interferences, and emotional stressors (12; 02; 49; 26; 27; 82; 80; 83). Berlin and Dessner reported that treating bruxism reduced headaches and suggested that treating functional disturbances of the masticatory system and reducing the forces that bruxism produces on the musculoskeletal system decreases pain. Because bruxism is such a common problem, it is difficult to regard it as a common cause of headache (86; 87).
The relationship of temporomandibular disorders and migraine is well-established and supported by clinical studies. Temporomandibular disorders are extremely common in those with both migraine and tension-type headache in those presenting for evaluation (Silva et al 2014). As in migraine, there is also a strong relationship to mood disorders such as anxiety (69). Triggers for temporomandibular disorders, such as chewing gum, may also trigger headache or migraine (45). Finally, estrogen receptors are present not only in the TMJ and masseter, but also in the trigeminal mesencephalic nucleus (06). Modulation of pain by estrogen may explain why temporomandibular disorders are more common in women than men.
Occlusal interferences are by far the most controversial aspect of etiology and treatment in temporomandibular disorders and related headache. In a review based on a series of studies, Seligman and Pullinger (86; 87) indicated little, if any, relationship of occlusal factors to temporomandibular disorders (85). Several investigators have concluded, based on treatment outcome, that occlusal problems are important etiologic factors in headache (49; 25; 82; 83). An adolescent study found that occlusal appliance therapy was more effective than formal relaxation therapy for the treatment of temporomandibular disorders (94). However, malocclusion is not a primary etiologic factor in temporomandibular disorders in many subjects studied (Akeel and Jasser 1999). A 2-year study of girls who required orthodontic treatment showed that orthodontic treatment did not significantly change the course of temporomandibular symptoms compared with a group of untreated patients with the same malocclusion and a group with normal occlusion (37). Another study suggested that occlusal interferences actually worsen clinical symptoms in persons with an established TMJ diagnosis (97).
Migraine and primary headache disorders. In primary headache disorders, pain is thought to originate from sensitization of the trigeminovascular system (23; 61). Activation of trigeminal nociceptors (sensory receptors that perceive pain or harm), which innervate specific intracranial vascular and meningeal structures, results in sensitization of the trigeminal ganglia. Trigeminal ganglia activation results in the release of inflammatory neuropeptides, including CGRP, neurokinin A, and substance P into perivascular nerve endings. This release triggers neurogenic inflammation, which consists of vasodilation, plasma protein extravasation, degranulation of mast cells, and platelet aggregation. Neurogenic inflammation results in the sensation of pain that is unilateral and throbbing and aggravated by movement. Importantly, the trigeminal ganglion also receives input from all branches of the trigeminal nerve, which includes ophthalmic, maxillary branches, and mandibular branches innervating the face and mouth. Heightened activation of the trigeminal ganglia can sensitize these branches of the trigeminal nerves, resulting in orofacial pain. In addition, the mandibular nerve (a branch of the trigeminal nerve) supplies motor function to the masseter muscle as well as sensory functions and could account for the “jaw tightness” seen in many patients with migraine.
If signals to the trigeminal ganglia continue, the trigeminal nucleus caudalis is activated (23; 61). Activation of the trigeminal nucleus caudalis results in dysfunction in central neural processing and pain modulation and can present with orofacial pain. The resulting head pain from central sensitization is persistent and more refractory to treatment. Because the trigeminal nucleus caudalis also receives input from the extracranial skin, it is also often superimposed with pain of the extracranial skin, which results in scalp tenderness and cutaneous (skin) allodynia. In addition, the trigeminal nucleus caudalis receives input from deep tissues around the eye. Activation of the trigeminal nucleus caudalis, which occurs in central sensitization, is also thought to produce the referred pain of migraine around the eye.
Trigeminal autonomic cephalalgias. Dysregulation of the hypothalamus, the trigeminal nerve, and the parasympathetic system are all critical in the pathophysiology of trigeminal nucleus caudalis and result in orofacial pain and autonomic symptoms (100; 57). Signals from various structures, including the hypothalamus, activate the thalamus, which then activates the superior salivatory nucleus and results in activation of the trigeminal-autonomic reflex (100; 57; 89). The reflex results in pain from trigeminal nerve (mostly the ophthalmic branch, V1) activation and autonomic symptoms (lacrimation, rhinorrhea, and conjunctival injection) from the parasympathetic activation. The parasympathetic reaction is facilitated by a sympathetic deficit (miosis, ptosis), which is inherent to trigeminal nucleus caudalis.
Cranial neuralgias and facial pain syndromes. Cranial neuralgias and facial pain syndromes can be due to neurovascular compression, secondary lesions due to multiple sclerosis, space occupying lesions, or other causes such as skull base bone deformities, connective tissue disease, arteriovenous malformations, dural arteriovenous fistulas, genetic neuronal hyperexcitability, or idiopathic (no cause identified). In burning mouth syndrome, tongue biopsy suggested an etiology of trigeminal small-fiber sensory neuropathy as a cause of burning mouth syndrome (43). Secondary burning mouth syndrome can occur from candidiasis, lichen planus, hyposalivation, medications, anemia, vitamin B12 or folic acid deficiencies, Sjögren syndrome, or diabetes (36).
Orofacial pain. Twelve point two percent of American adults have experienced dental pain in the last 6 months, and it was a primary complaint in 2.95% of people presenting to the emergency departments from 1997 to 2000 (44).
Dental disease. The prevalence of pericoronitis is reported to be 81% and occurs primarily in the third decade (71). Atypical odontalgia occurs in 3% to 6% of patients following endodontic treatment. There is a female predominance, and it occurs primarily in the fifth decade (53). The frequency and epidemiology of headache and tooth pain is unknown. Headache is usually a secondary phenomenon, and it does not pose a significant diagnostic dilemma.
Temporomandibular disorders. Temporomandibular disorders affect approximately 5% to 12% of the population (81). However, epidemiologic studies of temporomandibular disorders typically have not differentiated headache from facial pain specifically, and there is still overlap between headache attributed to temporomandibular disorder due to muscular tension and tension-type headache (36). This should not deter clinicians from managing headaches using proven treatments aimed at the temporomandibular structures, but it should caution against drawing the conclusion that if treatment is effective, the cause is temporomandibular disorder (12; 02). New research diagnostic criteria for temporomandibular disorders (RDC/TMD) axis 1 and axis 2 criteria have been established by the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group to allow for more controlled and comparable research (81).
Migraine. Migraine affects 38 million people in the United States (12% of the overall population); an estimated 4 million people in the United States have chronic migraine. Global estimates are generally higher (16). Chronic migraine affects 1% to 2% of the global population; 2.5% of persons with episodic migraine progress to chronic migraine each year (16).
Trigeminal autonomic cephalalgias.
Cluster headache. Cluster headache is the most common trigeminal autonomic cephalalgias, occurring in about 2 per 1000 individuals. This number likely reflects underdiagnosis of the disease (99).
Cranial neuralgias and facial pain syndromes.
Trigeminal neuralgia and burning mouth syndrome. Trigeminal neuralgia is the best studied of all the cranial neuralgias. It has an annual incidence around 5.9 per 100,000 person-year (female) and 3.4 per 100,000 person-year (male) (41). Per reports, prevalence of burning mouth syndrome has a wide range in general populations from 1% to 15% (50). It is different to characterize the prevalence of many cranial neuralgias and facial pain syndromes due to nonspecific diagnosis or characterization of these rarer disorders.
Dental disease. Prevention of dental disease is achieved through comprehensive oral hygiene programs. Education and the use of fluorides have dramatically curtailed the problems of dental decay. However, once disease is present, removal or infection control is essential (24).
The differential diagnosis of toothache is summarized in Table 2. One must consider pains arising in the tooth and those arising outside of the dentition and referred to this area.
Pain arising in the tooth
Pain arising outside of the tooth
• Atypical odontalgia
Diagnostic workup of local dental pathology includes inspecting the tooth for carious lesions, testing sensitivity to percussion, and examining vitality. X-ray imaging is useful in diagnosing caries and periapical pathology. The majority of atypical odontalgia patients do not have radiologic evidence of bone destruction, but the use of cone-beam CT may detect more abnormalities than plain radiographs (68). MRI imaging studies do not appear to improve diagnostic accuracy or demonstrate significant inflammation (67).
A more extensive workup may be required when chronic dental pain is present. The common tests to exclude dental disease must be performed, but cranial nerve screening, temporomandibular examination, and myofascial examination should also be done. Cervical spine evaluation can be performed if needed. These tests will rule out additional pathological processes. Differential blockade may be useful for those pains that are not musculoskeletal in origin (93). This can be a diagnostic neural blockade and diagnostic pharmacologic blockade. Diagnostic neural blockade is best achieved with a double-blind, placebo-controlled format. If this is not possible, repeated procedures are required. The basic purpose of the diagnostic block is to differentiate sensory from sympathetic pain mechanisms. Phentolamine infusions are useful in diagnosing sympathetically maintained pain.
Although physical exam findings remain essential in the diagnosis of temporomandibular disorders and migraine, MRI may be useful to assess lateral pterygoid muscle volume. The lateral pterygoid muscle is difficult to palpate and hypertrophy of this muscle is associated with migraine and temporomandibular disorders (47).
For primary headache or cranial neuralgias, secondary causes such as demyelinating disease, space-occupying lesions, vessel abnormalities, and local or systemic disorders should be ruled out (36).
Dental disease. Dental problems are best managed with conventional dental therapies and rarely produce any long-term or significant disability. Atypical odontalgia may respond to multiple treatments, such as tricyclic antidepressants with or without phenothiazines (51). Medication used for other types of pain may be effective, as demonstrated by a clinical trial in which duloxetine 60 mg produced significant clinical improvements in 2 weeks (60). Onabotulinum toxin A, discussed below, has been shown to be helpful in treating atypical odontalgia as well (19).
Temporomandibular disorders. Temporomandibular disorders should be treated with symptomatic management and removal of the precipitating and perpetuating factors. This process allows the affected system to regulate and repair itself. This requires monitoring signs and symptoms carefully and adjusting the treatment according to the level of dysfunction. Temporomandibular disorders are usually self-limiting and resolve with or without treatment (28). For this reason, most patients do not require aggressive, irreversible, and expensive treatments. The patient who has failed all conventional treatments should be managed in the same manner as any patient with chronic pain. Further invasive and irreversible treatments should be avoided. These patients often require a multidisciplinary pain management approach.
Temporomandibular disorders usually require a number of management modalities, which are discussed below:
(1) Patient education and home care form the backbone of treatment for temporomandibular disorders. This program requires a detailed explanation of the problems the patient faces and the effects of perpetuating factors; this clarification enables the patient to play a part in his or her therapy. The home program requires instruction on what can be chewed without provoking pain.
(2) More research is needed for behavior modification and psychosocial interventions for treatment of temporomandibular disorders (03; 74). Such interventions could address poor postural and oral habits. Stress can be reduced through biofeedback, self-hypnosis, or other relaxation techniques.
(3) Pharmacotherapy is helpful in the treatment of temporomandibular disorders (35). Analgesics or anti-inflammatory agents should be prescribed on a time-contingent and non-pain-contingent basis. Pharmacotherapy should be performed carefully. Anti-inflammatory, analgesic, muscle relaxant, and serotonergic (antidepressant) medications may be effective in the management of temporomandibular disorders.
(4) There is weak evidence for the use of physical therapy. Numerous devices and modalities are available, all of which must be used with care. Posture education helps to alter jaw position and minimizes diurnal clenching or excess strain on other muscles. Stretching exercises help maintain range of motion and aid in neuromuscular re-education. Splinting and resultant muscular hyperactivity can be reduced with stretching along with cold vapocoolant sprays for distraction. Iontophoresis, therapeutic ultrasound, moist heat, and ice may be useful. Transcutaneous electrical nerve stimulation (TENS) relieves pain and reduces muscle hyperactivity. High-frequency, high-intensity TENS reduced myofascial pain significantly better than placebo or low-frequency TENS in 1 study (30), and TENS can be useful in combination with other treatment modalities (75).
(5) Appliance therapy is a physical medicine technique used to manage temporomandibular disorders. Appliances are hypothetically meant to eliminate occlusal disharmony, prevent attrition, reduce bruxism and parafunction, prevent pain associated with masticatory muscle dysfunction, and correct internal derangement. The reduction of painful symptoms is well documented (18). These appliances are usually worn at night and occasionally during the day. Many different appliances are described in the literature, but 2 types are used most often. The first is the stabilization appliance, which has a flat surface of hard acrylic that covers all surfaces of either the maxillary or mandibular teeth. It appears to distribute the forces evenly and relax the elevator muscles (18). The second type is the repositioning appliance, which has been used in disc displacement. By producing translation of the condyle without rotation (protrusion), one can continually reduce the anterior displacement. It was thought that holding the jaw in this position with the aid of a repositioning appliance would allow remodeling and permanent reduction of the anterior displacement. Although there was initial enthusiasm for this technique, long-term effectiveness was achieved in only 36% of patients. A drawback of repositioning therapy is a resultant posterior open bite that sometimes requires extensive orthodontic or prosthodontic treatment to reestablish posterior tooth contact. Prior to performing this treatment on carefully selected patients, informed consent regarding the possible treatment side effects must be obtained.
(6) Occlusal therapy is based primarily on anecdotal study. There is no research supporting a direct relationship between occlusal interferences and temporomandibular disorders. A metaanalysis found very low-quality evidence for the use of noninvasive splints or bruxism to reduce pain in temporomandibular disorders (73). Therefore, occlusal therapy should not be undertaken when acute symptomatology is present but kept in the context of dental maintenance (35).
(7) Surgery is used extensively in the treatment of temporomandibular disorders. Before the advent of endoscopic procedures, arthrotomy was the traditional approach to joint surgery. The TMJ can now be examined with the arthroscope, but its use should be limited to situations where less invasive techniques are insufficient for diagnosis. This would include the need for biopsy or confirmation of a diagnostic finding. The best indication for treatment is the anterior displaced disc without reduction (closed lock). Arthroscopic treatment has been reported to be effective for other intracapsular problems, including synovitis, deviation in form, osteoarthritis, and hypo- and hypermobility (77; 78). Further long-term studies are required. Open surgery is performed for bony ankylosis and neoplasia but remains controversial in disc displacement. Surgery is not indicated for treating inflammation. Provided that the goals of surgery are not overestimated, there is scope for improvement in certain areas. Surgery does not restore diseased tissue to normal, and patients should be made aware of this prior to surgery.
(8) OnabotulinumtoxinA has been studied for a myriad of conditions causing orofacial pain, including temporomandibular disorders, atypical odontalgia, and trigeminal neuralgia. Although the complete mechanisms of action of onabotulinumtoxinA are not understood, the evidence suggests that it prevents release of local nociceptive neuropeptides and excitatory neurotransmitters (91; 19). OnabotulinumtoxinA also may act to decrease pain sensitivity and lower peripheral sensitization by decreasing the translocation of the transient receptor potential vanilloid 1 to neuron cell membranes (19). In temporomandibular disorders, onabotulinumtoxinA can be used prior to surgery and if conservative approaches were ineffective (91). Administration of onabotulinumtoxinA into the muscles of mastication, primarily the masseter, temporalis, and lateral pterygoids muscles, can help relieve pain (91). OnabotulinumtoxinA was also shown to reduce both attack frequency and pain severity in a randomized, double-blind, placebo-controlled trial (96). A study on using onabotulinumtoxinA for atypical odontalgia showed that patients had significant pain relief ranging from pain freedom to intermit mild pain (19). Complications from onabotuliumtoxinA arise from weakness or paralysis in the muscles injected (91; 19).
Migraine and TACs. The treatment for migraine and TACs is discussed extensively in other articles in MedLink Neurology.
Chronic face pain from other causes. There are some interventional procedures that are being studied for atypical face pain from other causes. Pulsed radiofrquency of the sphenopalatine (pterygopalatine) ganglion in patients with chronic facial pain syndromes, showed benefit and reduced opioid use; 21% reported complete pain relief, and 65% had subjectively rated their pain relief between good and moderate (95; 10; 04). Implanted peripheral nerve field stimulators (PNFS) in patients with intractable facial pain due to trigeminal neuralgia and painful trigeminal neuropathy have also shown promise (42).
Anesthesia carries little risk, but intubation may result in loss of teeth or augmentation of the temporomandibular disorders in patients with loose teeth or temporomandibular disorders. Specific informed consent should be obtained prior to anesthesia. Appropriate screening of patients with temporomandibular disorders should include the following:
(1) Measurement of mouth opening
Simy Parikh MD
Dr. Parikh of The Jefferson Headache Center at Thomas Jefferson University has no relevant financial relationships to disclose.See Profile
Stephen D Silberstein MD
Dr. Silberstein, Director of the Jefferson Headache Center at Thomas Jefferson University, receives honorariums from Abbie, Curelator, Ipsen Therapeutics, Lundbeck Biopharmaceuticals, Supernus Pharmaceuticals, and Theranica for consulting. He is also the principal investigator for clinical trials conducted by Amgen, ElectroCore Medical, and Teva.See Profile
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