Contenido del CD adjunto

Temporomandibular disorder (TMD) is an umbrella classification that includes ailments of the temporomandibular joints (TMJs) and masticatory muscles. TMD-related facial pain has been found to occur in 4% to 12% of the population, and severe symptoms are reported by 10% of subjects. Some signs or symptoms of TMD are extremely common, joint clicking, for example, is found in 20% to 30% of the population. However, only 3% to 11% are assessed as needing treatment. These figures are compatible with the data on the percentage of individuals who seek treatment (1.4%–7%). Masticatory muscle and TMJ tenderness were found in 15% and 5%, respectively, of a large population examined.4However, muscu- lar tenderness was self-reported by only about a third of these, sug- gesting that many patients have asymptomatic muscle tenderness.

Signs and symptoms of TMD have been found in all age groups, peaking in 20- to 40-year-olds. Signs of TMD have been described in children and adolescents but are usually mild. In a group of adolescents, treatment need was assessed at 7%.5TMDs may also occur in edentulous patients. Accumulated evidence suggests that symptoms in the elderly may be lower than in the general popula- tion, but some studies show a slight elevation in the prevalence of some signs (e.g., joint sounds, limited mouth opening) in this age group.6_{There is a female preponderance of TMD signs and symp-} toms, especially of muscular origin. Most studies also report that the vast majority of patients (up to 80%) who seek treatment are females7(Tables 17–5and17–6).

Masticatory Myofascial Pain

The diagnosis of masticatory myofascial pain (MMP) is based on the history and clinical examination of the patient. MMP is char- acterized by regional, unilateral pain around the ear, the angle/body of the mandible, and the temporal region (seeTable 17–5). Referral patterns include intraoral, auriculotemporal, supraorbital, and maxillary areas, depending on the muscles involved and the inten- sity of the pain. Pain is aggravated during jaw function, with tran- sient spikes of pain occurring spontaneously. In addition to pain, there may be deviation of the mandible on opening, fullness of the ear, dizziness, and soreness of the neck, particularly if muscle trigger 126 Chapter 17  OROFACIAL PAIN

Table 17^ 5.Current Diagnosis of Temporomandibular Disorders

Diagnosis Pain Intensity Primary Location Referral Clinical Symptoms Examination Findings Imaging

MMP Moderate Angle of mandible,

temporal, periauricular

Depending on involved muscles: forehead, neck, and intraoral regions Continuous pain, exacerbated on chewing Difficulty in chewing Acute malocclusion: clinically unverifiable

Tender pericranial, masticatory and cervical muscles

Myofascial trigger points

Deviation and limitation of mouth opening Ethyl chloride spray onto muscle relieves

pain and increases mouth opening

Not relevant

ADDwR Moderate to severe

Periauricular Ear, angle of mandible Pain on chewing Joint sounds

Tender TM joint, associated with reciprocal clicking

Deviation to affected side on mouth opening May have pain on loading the joint by biting

a hard stick contralaterally

MRI or arthrography: displaced articular meniscus (reducing)

ADDwoR Moderate to severe

Periauricular Ear, angle of mandible Pain on chewing

May report a history of joint sounds

Unable to fully open mouth

Very tender TM joint. Deviation to affected side and limitation of mouth opening. Pain on loading the joint by biting a hard stick contralaterally. MRI or arthrography: displaced articular menisus (non-reducing) DJD Moderate to severe

Periauricular Ear, angle of mandible Muscles of

mastication Headache, neck pain

Pain and difficulty with chewing

Stiffness of the jaws; usually worse in the evening but not particularly severe in the morning (if so, lasts <30 min)

Very tender TMJ; may occur bilaterally Usually associated with crepitation in the

affected joint

There may be no initial correlation between clinical and imaging findings

Pain on loading the joint by biting a hard stick contralaterally. Plain radiographs or CT: may be degenerative changes with microcystes, hypercortication and osteophyte formation IJD Moderate to severe

Periauricular Ear, angle of mandible Headache, neck pain

Pain and difficulty with chewing

Stiffness of the jaws and pain in the muscles Jaw stiffness is particularly

severe in the morning and lasts > 30 min

Very tender, often swollen, TMJ Usually associated with crepitation in the

affected joint May occur bilaterally

TMJ involvement usually occurs in advanced stages of generalized inflammatory arthritides

Joint destruction may lead to an anterior open bite

Depending on underlying disorder associated with autoimmune or hematologic

abnormalities Destruction of articular surfaces Often similar radiographic picture as in DJD

ADDwR, anterior disk displacement with reduction; ADDwoR, anterior disk displacement without reduction; CT, computed tomography; DJD, degenerative joint disease; IJD, inflammatory joint disease; MMP, masticatory myofascial pain; MRI, magnetic resonance imaging; TM, temporomandibular; TMJ, temporomandibular joint.

12 7 V CH R O N IC P A IN : NO NC ANCE R P A IN

points are present. Pain is dull, heavy, tender, and rarely, throbbing, and the severity may fluctuate during the day but is moderate; the average pain duration is about 5.5 hours. Some patients experience the most intense pain in the morning (21%) or late afternoon (79%), and others have no fixed pattern. Pain-free days may be reported, and fortunately, the pain rarely wakes the patient. MMP has been clearly shown to be a chronic or fluctuating pain condi- tion; over 5 years, 31% of patients suffered continuous MMP, 36% experienced recurrent pain, and 33% remitted.8

Examination usually reveals limited active mouth opening (<40 mm, interincisal). Forced (passive) opening by the examiner may reveal a slightly increased opening. Tenderness to palpation is usu- ally present in masticatory muscles unilaterally, and it is a distin- guishing feature of MMP patients. The masseter is the muscle most commonly involved (>60%), the medial pterygoid and temporalis muscles are tender in about 40% to 50% of cases, commonly uni- laterally. The sternocleidomastoid, trapezius, and suboccipital mus- cles are usually tender in 30% to 45% of patients, very often bilaterally. Typically, there are localized tender sites and trigger points in muscle, tendon, or fascia. A hypersensitive bundle or nodule of muscle fiber of harder than normal consistency is the physical finding most often associated with a trigger point. Trigger points may be associated with a twitch response when sti- mulated. In addition, trigger point palpation may also provoke a characteristic pattern of regional referred pain and/or autonomic symptoms. Referral to the teeth may be prominent and may often cause misdiagnosis as dental pathology.

Pain Associated with theTMJ

The most common conditions associated with pain of the TMJ are internal derangements, which may be painful when associated with joint inflammation (Fig. 17–1andTable 17–5). More rarely, degen- erative joint disease (DJD) or inflammatory arthritic diseases may affect the TMJ. Often, these TMJ entities are comorbid with muscle pain, usually MMP, and thus require a combined treatment

approach. More rarely, the TMJ may be affected by infectious or metabolic arthritides which are not be dealt with in this chapter.

Internal derangement signifies an abnormal anatomic relation between the condylar head and the articular disk when the teeth are in normal occlusion. In most cases, the disk is anteriorly displaced (seeFig. 17–1B).

AnteriorDiskDisplacementwithReduction(seeFig. 17–1B and C) During mouth opening, the condyle on the affected side meets the posterior band of the anteriorly displaced disk, encounters some resistance, then moves under the disk proper (reduction). During closing, the condyle will slip off the anteriorly positioned disk and return into the glenoid fossa. The sound that the condyle makes on mounting the disk during opening and then slipping off during closing causes the characteristic reciprocal clicking of anterior disk displacement with reduction (ADDwR). Patients with ADDwR may be totally asymptomatic and report only joint clicking or popping sounds that may or may not bother them. ADDwR may, however, be symptomatic with pain that is associated with chewing, particularly hard foods. The affected TMJ may be tender to palpa- tion. Although pain is usually mild, it may become moderate to severe with VAS scores of 6 to 7. When the disk is displaced uni- laterally, the mandible will deviate to the affected side during open- ing until the first click occurs—this signifies ‘‘reduction’’ or a return to normal relationship. Mouth opening then continues undeviated and is usually not limited; there may be some pain at maximal opening.

Anterior Disk Displacement without Reduction (seeFig. 17–1C and D)

In anterior disk displacement without reduction (ADDwoR), the condyle is unable to mechanically pass under the disk, and there- fore, there is no reduction. Attempts to open the mouth further induce pain located over the joint and are usually associated with no increased opening. The joint is generally very tender to palpation.

Table 17^6.Current Therapy of Temporomandibular Disorders

Diagnosis Treatment Options

MMP Physical: Home or institutional physiotherapy to maintain muscle strength and mobility and restore normal mouth opening. Spray (with ethyl chloride) and stretch exercises. Biofeedback, soft laser, physical self-regulation program (breathing training, postural relaxation, and proprioceptive reeducation).

Soft diet: For acute cases, a soft diet allows the muscles to rest.

Bite appliance: Flat occlusal appliance made of hard acrylic. Adjusted intraorally to maintain even contacts. Usually worn only during sleep.

Pharmacologic: Acute cases may be treated with analgesics or NSAIDs: Paracetamol/acetaminophen 250–500 mg qid; naproxen 500 mg bid; ibuprofen 200–400 mg qid. Chronic cases may require tricyclic antidepressants: amitriptyline (10–35 mg daily), cyclobenzaprine (10–30 mg/day), clonazepam (0.5 mg daily), or gabapentin (2700–3600 mg daily). Psychological: Cognitive behavioral therapy.

Trigger point injection: Lidocaine (2%), mepivacaine (3%), or procaine injection into muscle trigger points. TMJ pain Physical: As above.

Bite appliance: Repositioning appliances have been advocated to recapture the disk; however, they fail to do so in the long term, so we suggest flat appliances as above. Some data suggest that contacts on the posterior region of the bite plate may lead to off-loading of the joint and may be used initially. Readjustment of the plate to allow full contacts should be performed to prevent occlusal changes.

Pharmacologic: NSAIDs are usually required to reduce symptoms. Comorbid MMP should be treated concomitantly, as above.

Arthrocentesis: Is able to restore mouth opening in disk displacement without reduction and may improve symptoms in other intra-articular disorders.

Surgery: Either arthroscopic or open is reserved for resistant cases or cases with other clear indications for surgery (hyperplasia, ankylosis).

MMP, masticatory myofascial pain; NSAIDs, nonsteroidal anti-inflammatory drugs; TMJ, temporomandibular joint. 128 Chapter 17  OROFACIAL PAIN

Analysis of fluids obtained from the upper joint space during arthrocentesis reveals proinflammatory cytokines so that an active inflammatory process is present. Pain in ADDwoR may become quite severe with VAS scores of 7 to 9 and will severely affect the patient’s functional capabilities. The patient will present with limited mouth opening (20–25 mm) and a sharp deviation to the affected side when asked to open the mouth. Onset is usually acute and may be preceded by a history of ADDwR. In some patients, there may be a slow transition from ADDwR to ADDwoR. The patient has a consistent reciprocal click but reports that, at times, sudden-onset restricted mouth opening occurs with no click. Mandibular movements often relieve this situation, and the patient returns to ADDwR; this condition is simply termed ADDwR with intermittent locking. If ADDwoR is untreated, a degree of physio- logic adaptation occurs whereby the articular tissues are stretched and the patient may therefore present with minimally limited mouth opening (30–35 mm) accompanied by a lesser degree of deviation.

DJD

DJD is a chronic noninflammatory disease that affects the articular cartilages of synovial joints, particularly load-bearing ones.

Radiographic evidence of DJD is very common (14%–44%) in asymptomatic individuals, but only 8% to 16% will have clinically detectable disease. DJD affects women, particularly after the age of 40 to 50. Pain is located in the TMJ and periauricularly and may spread to adjacent structures. Patients complain of difficulty in chewing, jaw stiffness, and tiredness. Jaw stiffness is usually more severe in the evening. The TMJ and muscles of mastication are very tender. Mouth opening is restricted and deviates to the affected side; crepitation is generally present. Imaging often reveals sub- chondral bone sclerosis, flattening, lipping (osteophyte formation), and microcyst formation. DJD may occur after trauma to the TMJ and may be more severe in its clinical presentation than its primary counterpart.

Inflammatory Joint Disease

The TMJ may be involved in the clinical presentation of a number of systemic arthritides including rheumatoid and psoriatic arthritis. In most cases, the patient is already diagnosed, and TMJ involve- ment is a sign of increasing disease severity. The management of such cases, therefore, involves the addition of selected TMD-specific therapies to the existing treatment. The TMJ may be very painful, at times swollen, and will limit function. Imaging reveals joint destruc- tion similar to that observed in DJD but often more rapid in its progression. Laboratory findings may include a raised erythrocyte sedimentation rate, anemia, leukocytosis, and the presence of autoantibodies.

Treatment

Not all patients with acute TMDs will develop a chronic pain dis- order. Predictors of chronicity include high initial pain intensity, high disability score, higher scores of emotional distress, the pres- ence of myofascial pain (versus TMJ disorders), and female gender. Patients developing chronicity also differ significantly in numerous biopsychosocial variables (e.g., they suffer from more current anx- iety disorders, mood disorders, and somatization disorders).

Treatment of TMDs with a variety of conservative methods consistently results in high (75%–90%) success rates. In general, treatment is aimed at palliation and is based on clinical diagnosis; because the etiology is unclear, no treatment is curative. Extensive research shows that there are no compelling data to support any intervention as capable of TMD eradication or modification. Moreover, conservative therapies are consistently successful and in no way inferior to more invasive or irreversible procedures such as surgery, occlusal adjustment, and prosthetic rehabilitation. The data thus support a conservative approach to the management of TMDs. This is reinforced by findings that the natural history of TMD includes an extensive number of patients who will either substantially fluctuate or remit over time and rarely progress to severe pain.

Treatment aims in TMD patients include reducing pain, restor- ing function and range of motion, decreasing or eliminating aggra- vating or contributing factors, and increasing bite comfort and muscle strength. In addition, we aim to reduce psychological distress, restore social functioning, and cease or prevent drug abuse. The assessment of treatment outcome is based on accurate assessment of pain intensity and frequency and the evaluation of changes in psychosocial comorbidity.

Therapy for TMDs falls into a number of categories: physical, pharmacologic, psychological, trigger point injection (for MMP), TMJ arthrocentesis, or TMJ surgery and is often multidisciplinary. Treatment of TMD very often combines conservative interventions, and different centers have variable protocols depending on patients’ signs and symptoms and clinician’s preferences. Treatment dura- tion is generally 4 to 6 months but may be longer in selected cases (seeTable 17–6).

Closed Maximal Opening

normal ADDwR ADDwoR A C B D 1 2 3 4

Figure 17^1.Internal derangements of the temporomandibular

joint. A, Normally when the mouth is in the closed position, the

condyle lies below the articular disk. B, Mouth opening begins with rotational movement followed by translation of the condyle over the eminence to the maximal opening, which is usually 40 mm or more; movement is fully coordinated with the disk.C, In ADDwR, the disk is anteriorly located relative to normal, often the condyle is located under the posterior attachment. During opening, the condyle reduces (resumes a normal position) under the disk and full opening is unlimited and characterized by a normal condyle/disk relation.D, In ADDwoR, the disk is anteriorly located relative to normal but is unable to reduce during opening; mouth opening remains limited and the disk remains anteriorly displaced, even at maximal opening (usually < 30mm). Movement is thus on the posterior attachment.1, condyle; 2, articular disk, 3, posterior attachment; 4, fossa; 5, eminence; ADDwoR, anterior disk displacement without reduction; ADDwR, anterior disk

displacement with reduction.

129 V CHRONIC PAIN: NONCANCER PAIN

Physical and Combined Modalities

Most pain physicians with experience in the field of TMD will attest to the success of conservative physical therapy, including muscle exercise, thermal packs, and oral splints. However, few, if any, of these therapies have been subjected to controlled trials. Often, reas- surance and education of the patient combined with simple exer- cises for the TMJ, masticatory, and neck muscles will result in pain alleviation and restored mandibular function.

Muscle tenderness may be also treated with vapocoolant sprays and concomitant stretching—‘‘spray and stretch.’’ This usually induces immediate relief and is often employed as a diagnostic test. Other commonly used techniques such as ultrasound and ther- mal packs have also not been rigorously assessed. Transcutaneous electrical nerve stimulation (TENS), low-level laser, and physical self-regulation (PSR) programs are sometimes effective in TMDs. Many studies indicate the importance of education and self-care in the management of TMDs.9

Occlusal Splints

Flat occlusal splints (relaxation or stabilizing splints) are in wide- spread use and provide even occlusal contacts; these may be con- structed for the upper or lower jaw. There seems to be no difference in effect between flat splints, anterior midline stop devices, and canine guidance splints. We do not recommend partial coverage splints owing to the inherent potential to cause permanent occlusal changes and the lack of evidence for any advantage over flat splints. Meta-analyses consistently demonstrate benefit for oral splints in TMDs in general: both TMJ arthralgia and MMP.10_{The presence} of widespread pain reduces the effectiveness of oral splints and sug- gests that these should be prescribed for patients with regional myo- fascial face pain only. The number needed to treat (NNT) for occlusal appliances in the treatment of TMDs has been calculated: an NNT of 6 for TMJ pain and 4.3 for MMP.10The relatively good success rate and highly conservative nature of splints account for their extensive use. They do, however, entail higher costs than other therapies.

Pharmacologic

NSAIDs are used extensively in the management of pain and dis- ability associated with joint disease. Selective cyclooxygenase (COX)-2 inhibitors and some of the older nonselective COX inhi- bitors have potentially serious side effects on the renal and cardio- vascular system, and long-term therapy is contraindicated. For the treatment of TMDs, calculations of NNTs for drugs versus placebo reveal encouraging figures of 2.7 to 3.5. Ibuprofen (400 mg three times daily) and naproxen (500 mg twice daily) are good choices. In patients with gastrointestinal discomfort, we recommend the addi- tion of antacids (e.g., proton pump inhibitor; omeprazpole). Simple analgesics or combination analgesics (e.g., codeine and paraceta- mol/acetaminophen) may also provide good analgesia and may be safer than NSAIDs.

Amitriptyline at low doses (10–30 mg/day) provides consistent benefit for patients with craniofacial myofascial pain, including predominantly muscular TMDs, and post-traumatic myofascial pain. Clonazepam (0.5 mg daily), a long-acting benzodiazepine with anticonvulsant properties, or cyclobenzaprine (10–30 mg daily), a muscle relaxant, is beneficial in predominantly muscular TMDs. Gabapentin (2700–3400 mg daily) is effective for the treat- ment of MMP with an NNT of 3.4.11

Biobehavioral Therapy

Pain is a subjective experience with important affective, cognitive, behavioral, and sensory components. Outcomes including restora- tion of functional activity, eradication of drug abuse and depen- dency, and rehabilitation of residual emotional distress need to be

addressed. The assessment of psychological distress in MMP patients may be performed with established questionnaires.

Cognitive-behavioral therapy (CBT) is an option that aims at altering negative overt behavior, thoughts, or feelings in chronic