CC

A 32-year-old female presents with a 2.5-month history of daily jaw pain, headache, and ringing ears that is worse in the evenings, and she especially has constant stiffness in the mornings.

HPI

The patient reports that the pain is dull while resting but could be severe, especially during chewing or yawning. Tension and pain around the jaw and neck areas are constantly present, especially in the mornings, and worsen throughout the day (characteristic of myofascial pain dysfunction [MPD]). When asked to point to the regions of pain, she readily identifies the areas over her left masseter muscle. Chronic fatigue, headaches, and neck and shoulder pain were overwhelming with deprived sleep quality. (Decreased sleep quality and interruptions are also typical findings for MPD. Likewise, neck and shoulder pain and headaches are very common findings with MPD.) Chewy or hard food makes the pain worse. (Increasing pain and muscle fatigue during mastication are typical findings in MPD.) Sensitivity on the teeth is also present while chewing. (Because of clenching or bruxing, overloaded occlusal forces would cause teeth sensitivities and might also end with occlusal trauma of cracks on the related teeth.) Besides the migraine-like headaches, the patient reveals anxiety caused by a high level of stress in her life. (Work-, school-, or social life–related stress can cause or exacerbate MPD.) She denies any current or prior history of clicking or popping sounds (which are seen only with internal joint derangements) or crunchy sounds during jaw movements (specific finding of degenerative changes of the temporomandibular joint [TMJ]). She is not aware of any parafunctional habits, such as bruxing or clenching. (Bruxing is grinding of the teeth, and clenching is isometric constriction of masticatory muscles without moving the mandible. Many patients may be unaware of nocturnal or even daytime bruxism or clenching. While grinding their teeth, bruxers might have a higher chance to be recognized by their partners or household. However, while clenching, no sound can be noticed during sleep. Therefore, identification of a clenching parafunction could be difficult. Also, patients with nocturnal bruxing or clenching are characteristically worse on waking and improve over the course of the day. Patients with TMJ dysfunction (TMD) might present with MPD, internal joint derangements, migraine, dizziness, or ringing ear problems (Stechman-Neto J, Porporatti AL, Porto de Toledo I, 2016) at the same time. Such an intricate clinical presentation might misdirect the clinician. In such cases, a detailed pain description with the distribution, frequency, quality, and duration of pain as well as triggering factors should be investigated in detail. At the same time, presentation of any TMJ-related symptoms, such as clicking or crepitation, should be thoroughly identified. In advanced stages, TMD can not only limit jaw functions but also decrease life quality and nutrition because of debilitating pain.

PMHX/PDHX/medications/allergies/SH/FH

The patient’s medical and dental histories revealed sleep deprivation and acid reflux. The patient’s social life is uneventful. On the patient inquiry form, there is a question to evaluate their general stress level on a scale from zero to 10. Her career is highly stressful. She scores her stress level 7 to 8 of 10 with these job-related issues. (Stress, anxiety, and depression disorders are a risk factor for MPD.) She works as a human resource associate and has a high-volume job with several decision-making tasks. Also, the patient claims that she also works from home and spends at least 4 to 5 hours with her laptop. No remarkable family history is noted.

Examination

General. The patient is a well-developed adult female and looks slightly anxious in general.

Maxillofacial. There is no asymmetry, and no lymph nodes are palpable. On palpation, there is tenderness of the masseter, sternocleidomastoid, and trapezius muscles. (The masseter and temporalis muscles are the most involved muscle in MPD.) There is no TMJ capsular tenderness (other than primary TMJ diseases such as infection, inflammation, or traumatic injuries, pain with palpation around the joint is less likely) and no clicks or crepitus. The patient has a maximal incisal opening of 18 mm with a soft end feel, which can be stretched to 26 mm with pain. (Limited opening because of muscle guarding that can be slowly stretched to a normal opening is consistent with MPD.) There is no deviation or deflection while opening the mouth. (Deviation is characteristic finding for anterior disc dislocation with reduction [ADDwR] and deflection is for anterior disc dislocation without reduction [ADDwoR].) Her left and right lateral excursions are 9 and 8 mm, respectively. The remainder of her physical examination is noncontributory.

Imaging

A panoramic radiograph is the baseline screening examination of choice. Although it cannot diagnose MPD, it provides an overview of the teeth and bony structures to rule out other possible pain sources, such as impacted wisdom teeth, dental infection focuses, or osteoarthritis of TMJ. Magnetic resonance imaging (MRI) and computed tomography (CT) scans are ordered based on the clinical suspicion of pathology in conjunction with MPD (see Chapter 67 ). However, MRI and CT are not indicated when MPD is the sole clinical diagnosis. The panoramic radiograph in the current patient reveals no odontogenic or osseous pathology.

Labs

Laboratory tests are not indicated in the workup of MPD unless associated with other suspected or diagnosed medical conditions (e.g., rheumatoid arthritis or neuromuscular disorders). A suspicion of temporal arteritis or any infection possibility would warrant further laboratory testing (erythrocyte sedimentation rate and C-reactive protein as markers of inflammation) and biopsy of the superficial temporal artery. Similarly, patients with metabolic or genetic disorders should have relevant laboratory workup.

Assessment

As shown in the patient’s history, progressive pain description is characteristic in MPD. Similarly, female predilection is also a characteristic indicator for its diagnosis (Bueno CH, Pereira DD, Pattussi MP, 2018). Besides a detailed clinical examination, history of chief complaints, and the patient’s demographic information, social and family histories (Fillingim RB, Slade GD, Diatchenko L, 2011); the presence of stress, anxiety, and depression; and posture issues play an important role for the diagnosis of MPD. Similarly, our patient presented SADD, which was diagnosed and treated by her family doctor. Because the prevalence of TMD is reported between 7.3% and 30.4% in teenagers and up to 31% for adults and older adult patients (Valesan LF, Da-Cas CD, Réus JC, 2021) (Christidis N, Lindström Ndanshau E, Sandberg A, 2019), the volume of this patient population cannot be underestimated. As in our patient example, the adult age group is one of the most commonly affected groups. Because of unsuccessful treatment attempts, repetitive chair times, and economic constraints of the patient or the clinician, unfortunately, this patient group might be frustrated. Even this deadlock condition could aggravate their pain intensity and functional restrictions. It has well documented that females have two to four times more TMD-related issues than male patients. Moreover, patients with MPD present with high stress, anxiety, or depression in their histories. Therefore, patients with TMD need to be asked about the presence of stress-related factors in detail. Similarly, some posture-related problems can originate or worsen the present TMD issues. With this regard, for any stress-related issues and occupation-related poor posture correlation, there should be a part spared in the questionnaire form in TMD evaluation.

Main causes of MPD are as follows.

• 1.

  Psychologic or social distress–related stress (Koukoulithras, Plexousakis, & Kolokotsios, 2021; Ohrbach & Michelotti, 2018), anxiety, depression disorder (SADD). Autonomic nervous system response to emotional disorders or stressing factors causes increased muscle tone, which is the cause of bruxing and clenching. Similarly, gastroesophageal reflux disease, gastric ulcers, sleep deprivation, palpitations, tachycardia, hypertension, burnout, and chronic fatigue syndrome are similar autonomic nervous system–related symptoms that can help in the identification of patients under high stress. These problems should be addressed on the patient’s questionnaire or forms. The presence of high stress is not only a good diagnostic indicator for MPD but is also another determining factor in the development of the treatment plan. Patients should be acknowledged about their SADD-guided increased muscle tension cycle. During the first session, this relationship between their psychosocial condition and MPD must be clearly explained to the patient so they realize that addressing this issue is critical. SADD is the most challenging factor to eliminate for a successful TMD treatment outcome.

• 2.

  Postural problems (Koukoulithras I, Plexousakis M, Kolokotsios S, 2021) originating from occupational or social situations, such as long-time computer or telephone use or heavy physical activities. Such factors can solely initiate the MPD or can worsen the symptoms synchronously with other factors in the long run. During clenching or bruxing parafunctions, not only the masticatory muscles receive high muscle tones, but also the neck and shoulder muscles such as the trapezius and sternocleidomastoid cervical muscles contribute the constriction activity because of increased muscle tone controlled by autonomic nervous system upregulation. Thus, staying in a nonergonomic position during occupational or recreational activities puts more load on the neck and shoulder muscles in patients with MPD. To relieve the muscle constrictions or tetanus episodes at the neck and shoulder area, posture corrections should be recommended to the patient during their daily activities. Referral to a physiotherapist or occupational therapist should also be considered.

• 3.

  Occlusal changes (Okeson JP, 2020). The masticatory muscle system needs to adapt to any acute or chronic changes in the occlusion system. The changes beyond certain physiologic compensation limits or longstanding minor variations can be the reason for MPD. During the assessment, these occlusal changes should also be identified. The clinician should also inquire if the initiation of the patient’s symptoms was after any restoration or orthodontic treatment. For a permanent successful treatment result, these occlusion-related factors should also be addressed with a prosthetic rehabilitation, orthodontic treatment, or orthognathic surgery.

• 4.

  TMJ-related diseases such as ADDwoR or TMJ arthritis might trigger muscle constriction as a response to the pain.

• 5.

  Acute trauma in the muscle tissues might create trigger points after the injury.

• 6.

  Nutritional deficiencies, especially vitamins B ₁ , B ₆ , and B ₁₂ and folic acid could be a factor (Koukoulithras I, Plexousakis M, Kolokotsios S, 2021).

• 7.

  Metabolic disorders, including hypothyroidism, obesity, hypoglycemia, and hyperuricemia, could contribute.

• 8.

  Patients with genetic disorders related to the musculoskeletal system, such as Ehlers-Danlos syndrome, can present with severe MPD (Wang TJ, Stecco A, 2021). Also positive family history is a strong indicator of MPD (Fricton J, 2016) ​(Koukoulithras I, Plexousakis M, Kolokotsios S, 2021).

• 9.

  Inflammatory diseases such as vasculitis, temporal arteritis, fibromyalgia, and infections, can also contribute.

• 10.

  Cancer pain might also trigger MPD (Kalichman L, Menahem I, Treger I, 2019).

Except for acute traumatic injuries, because anterior disk dislocation is caused by the chronic pulling effect of the superior belly off the external pterygoid muscle, the presence of joint-related signs and symptoms should be investigated for all MPD cases. If any clicking, popping, or crepitation sounds, deflection, or deviation during jaw opening cannot be identified, TMJ-related problems can be ruled out until the second evaluation. It is also a remarkable finding that patients with TMJ point out specifically their TMJ areas. However, patients with MPD readily identify a large pain distribution area extending from the head to the neck and shoulder. Similarly, patients with MPD can also present with migraine-type headaches, tinnitus, and dizziness. If the patient has not been evaluated by a neurologist for migraine headaches after the initiation of the treatment, they should be addressed to the related specialist.

Treatment

The current patient was encouraged to manage her stressors more effectively by undergoing counseling for stress management and using biofeedback to reduce muscle tension. Her family physician initiated duloxetine 30 mg/day for minor depression. During the first appointment, the patient was instructed to avoid chewy foods for 2 weeks. At the same time, application of moist heat (using a warm, moist towel) for a few minutes followed by a gentle massage to the affected muscles at least eight times a day was instructed. A methocarbamol 500 mg and ibuprofen 200 mg combination once a day after dinner was prescribed together with pantoprazole. A deprogramming occlusal splint for maxilla with a hard, flat plane was fabricated, and the patient always wore this except while eating or brushing her teeth. The splint was adjusted on the articulator to eliminate interferences during lateral excursions and ensure a 1-mm vertical increase in centric relation.

During the second week followup visit, the patient presented with a nonremarkable improvement and was not able to use methocarbamol because of side effects. Splint adjustment was not needed. She opted to get botulinum toxin (BTX) treatment. A total of 100 U of onabotulinum toxin was reconstituted in 2 mL of 0.9% sodium chloride and benzyl alcohol solution to achieve 5 units/0.1 mL. After reassessment to identify injection spots, 100 U of BTX was administered bilaterally to the masseter, temporalis, and trapezius muscles with a 30-gauge ½-inch needle. For the medial and lateral pterygoid muscles and tendon of the temporalis muscle, a 27-gauge ½-inch needle was used. On each temporalis muscle, BTX was administred on four injection sites. At the anterior part, 2.5 U of BTX was administered; at the middle part, 5 U; at the posterior part 2.5 U, and at its tendon, 5 U of BTX. On both masseter muscles, BTX injection was done at three points, 2 cm apart from each other, and for each point 5 U BTX was given. On each trapezius muscle, two injection points received 5 U BTX for each, 2 cm apart from each other. Also, lateral and medial pterygoid muscles, bilaterally, received 5 U BTX for each muscle. By 2 weeks, the patient was wearing the splint only at night and was able to open to 44 mm, with complete resolution of her pain. She did not require repeat BTX therapy during the first and third month followups.

The treatment of patients with MPD begins with the correct diagnosis and the identification of underlying etiologic factors. Besides the symptomatic conservative therapy, the treatment plan must address the cause, if possible.

Regardless, conservative therapy is generally the first-line treatment unless other identifiable associated diagnoses (impacted wisdom teeth, infection, severe internal derangements, degenerative joint disease, tumors) are present that are thought to exacerbate the symptoms of MPD. However, in general, conservative treatment often results in significant improvement on resolution of the MPD in the short term. Conservative treatment options include reassurance, stress management, posture correction, relaxation and stretch exercises, biofeedback, deprogramming occlusal splint use, application of heat or icing, massage therapy, nonsteroidal antiinflammatory drugs (NSAIDs), and muscle relaxants. Because of abuse potential, prescription of anxiolytics should preferably be referred to the patient’s family physicians, and counseling must be done with caution. Following the conservative therapy instructions, the patient should be followed up within 2 to 4 weeks. During their second visit, an occlusal splint adjustment can be done as needed. Reassessment of pain and function should update the treatment plan. Patients with an improvement should continue the conservative treatment measures by tapering down the frequency and amounts and maintain the occlusal splint use as long as the bruxing or clenching problem continues.

The core management strategy for long-term success is based on the elimination of the cause, SADD factors, postural and occlusal corrections, and infections or pathologies. Patients presenting with SADDs should be addressed to their physicians to learn management by either counseling or medical treatment, if necessary, with anxiolytics or antidepressants. Awakening the patient’s self-awareness about daily minor stress management is one of the major steps in treatment. Neither the patient nor the clinician should expect a successful result without eliminating this component.

Patients who do respond to an occlusal splint and have a significant malocclusion should consider orthodontic treatment with or without orthognathic surgery. These modalities may offer a long-term solution to MPD, but such major surgical interventions are irreversible and have complication risks.

Trigger point injections with sham dry needling, saline, or lidocaine injections could be beneficial in patients with acute pain conditions. For acute or severe MPD-related pain relief, a local anesthetic is injected directly into the trigger points on the muscles. This can provide temporary or sometimes permanent resolution of muscle pain–related spasm (Tantanatip A, Patisumpitawong W, Lee S, 2021). However, patients should be informed that the pain could return when the local anesthesia effect is gone. Frequent repetitions of trigger point injections might end up with physical trauma on the muscle tissue (Gattie E, Cleland JA, Snodgrass S, 2017).

Patients with MPD who are refractory to all conservative approaches or cannot tolerate NSAIDs or muscle relaxants can be considered for onabotulinum toxin therapy. It may also be possible to improve MPD with injection of botulinum toxin into the muscle to reduce muscle activity and related occlusal forces. This may need to be repeated every 3 to 12 months because of the temporary effect of the botulinum toxin. Patients who can achieve SADD management, posture correction, or occlusal adjustment within this period might not need to repeat the botulinum toxin injections. Regeneration of the nerve endings at the motor endplate of the neuromuscular junction is responsible for cessation of the clinical effects. Excessive muscle activity alone may not explain most cases of MPD, and the response to botulinum toxin is not predictable. Intraarticular procedures, including arthrocentesis, arthroscopy, and arthroplasty, have no place in the management of isolated MPD.

Complications

Because the nature of the conservative treatment protocol consists of noninvasive techniques, complications are relatively uncommon and are mostly related to the failure of available treatments to alleviate pain, the side effects of medications, or difficulties with occlusal splint therapy.

Nonsteroidal antiinflammatory drugs are often helpful and carry no risk of physiologic dependence, although gastrointestinal irritation or bleeding, platelet dysfunction, increased blood pressure, and decreased renal function are potential complications. The use of some muscle relaxants and anxiolytics can be associated with dependence and abuse, which are compounded by the frequently chronic and recurrent nature of MPD. The most common complain about the muscle relaxants are drowsiness, concentration problems, and stomach upset.

Occlusal splint therapy is not without complications (especially when the splint is inappropriately designed). Several different types of splints are used by prescribing clinicians, and unfortunately, there are no clear evidence-based guidelines for splint therapy. Different splints include maxillary, mandibular, flat-plane, anterior repositioning, and pivotal splints. Flat-plane occlusal splints, whether maxillary or mandibular, are the most popular and technically the least demanding. Although complications related to conservative splint therapy are uncommon, an incorrectly adjusted splint can result in exacerbation of the preexisting TMJ dysfunction, tooth movement, or the development of new symptoms. Shifted teeth could cause permanent changes of the occlusion and might need correction with orthodontic treatment. Anterior repositioning splints are occasionally useful in patients with class II malocclusions and function by holding the mandible in a forward position; this unloads the richly innervated retrodiscal tissue within the TMJ and helps to reestablish a more normal disk–condyle relationship. This is also another useful tool for the ADDwR and ADDwoR cases to increase interarticular distance to allow reduction of the displaced disk. These splints are likely to be associated with permanent occlusal changes, and considerable clinician experience is required in their use. Pivotal splints are rarely used and are thought to function by decreasing masticatory muscle forces (via periodontally mediated biofeedback). Long-term use of pivotal splints, especially their use during the nighttime, can easily cause extrusions of maxillary or mandibular anterior teeth and an increase in vertical height. Eventually, this can aggravate the occlusal issues and worsen TMD.

After splint therapy, changes in the occlusion can be seen. Before splint therapy, patients might have a centric occlusion–centric relation discrepancy. A flat-plane occlusal splint may eliminate this discrepancy over time, resulting in a less than ideal occlusion when the splint is removed or discontinued. This may necessitate continued splint therapy, occlusal adjustment, orthodontics, or orthognathic surgery.

Repetitive injections of BTX might cause a decreasing effect, and the patient may no longer receive the benefit of BTX. Neutralizing host antibodies against the onabotulinum toxin is shown to be the cause. Proper administration of BTX minimizes the side effects, such as unbalanced muscle tone or chewing force weakness (Jadhao VA, Lokhande N, Habbu SG, 2017). The patient should understand that these are temporary findings. Rarely, a dropped-eyelid appearance might be observed after injections to the anterior part of the temporalis muscle (Ramos-Herrada RM, Arriola-Guillén LE, Atoche-Socola KJ, 2022). So far, no fatalities related to BTX use for MPD have been reported. Bruising and soreness at the injection sites are the most common and minor complications. Use of the smallest-gauge needles (30 or 27 gauge) could minimize these expectations.

Most of all, in case of failure of any therapeutic attempts, the progress of persistence of MPD would lead to internal derangements.

Discussion

Myofascial pain dysfunction is the most common of all TMDs (Fricton J, 2016). Unless there is any underlying systemic cause, it is reversible in the initial stages. MPD can manifest with otologic symptoms and migraine-like headaches. These findings might guide the patient to different specialists at the beginning; however, in a thorough evaluation, all these signs and symptoms are valuable clues to lead to the diagnosis of MPD. Otologic symptoms, such as ringing ears, dizziness, or migraine-like headaches might respond to MPD treatment.

The main muscles of mastication are the masseter, temporalis, and lateral and medial pterygoid muscles. They all function harmoniously during speech and deglutination. As a result of autonomic nervous system upregulation to stress and postural problems in addition to the masticatory muscles, the head, neck, and shoulder muscles might present with increased muscle tone. As with any group of muscles, they are susceptible to inflammation, which may in turn cause pain. This is commonly caused by excessive activity of these muscles, but the exact pathophysiology is likely to be multifactorial. The elimination of the factors causing muscle hyperactivity is mandatory for long-term success. Management of the acute symptoms of MPD is generally similar, regardless of the cause. Besides noninvasive and conservative treatment options, BTX use could be beneficial to minimize muscle tension pain and related muscle relaxant and NSAID use. BTX might aid to break the pain–muscle constriction–pain positive feedback cycle by decreasing muscle relaxation. Counseling with or without antidepressant use should be delegated to the family physician for permanent solutions for patients who have a high SADD-related cause. All possible systemic and local causes should be investigated. Patient acknowledgment and determination to practice the treatment instructions are also vital for a successful outcome. As is often the case, no definitive factors can be identified; consequently, a generic approach using several modalities must be tailored.

In the presence of clicking or popping sounds, clinician should consider dealing with internal joint derangements at the same time as with MPD. Similarly, crepitus during jaw movements together with radiographic changes indicates the need for management of arthritic changes at the same time.