Myofascial Pain Syndrome in the Craniomandibular Region# Jan Dommerholt, PT, MPS* Craniomandibular disorders (CMD) are characterized become chronic pain patients (3-5). Patients with by a combination of symptoms that may include pain, persistent craniomandibular pain without objective tenderness and dysfunction of the temporomandibular clinical or radiographic findings are especially joint, the mouth and the occlusal contacts, the cervical challenging not only to the general dentist, but also to spine, and the muscles of mastication. Patients may orthodontists, oral surgeons, TMJ specialists, and other present with local dentoalveolar pain; muscle pain; clinicians. Some patients may be considered good head, facial and neck pain; sounds during condylar candidates for splint therapy. Others are referred to movements; deviations and limitations of mandibular oral surgeons when common dental procedures fail to movements; altered occlusal relations; parafunctions offer relief. Some frustrated pain patients may even and poor oral habits; and functional limitations of request surgical treatment in an effort to eliminate mastication. Craniofacial pain conditions have special chronic craniomandibular pain (6). emotional and psychological meaning. The face, the It is generally accepted that CMD have a mouth, speech, and other oral functions are essential for multifactorial etiology (7). Although many diseases, nearly all human interactions; craniofacial pain such as dental disease, infections and tumors, can be conditions interfere with such functions and with the associated with pain, most chronic pain problems are ability to communicate. thought to be musculoskeletal in nature. Different Approximately 10% of the general population perspectives of the primary source of pain have passed experience craniomandibular pain (1). The prevalence the revue. Some researchers and clinicians have is estimated to range from 0% to 10% for males and emphasized joint dysfunction (8, 9); others have from 2% to 18% for females. The prevalence in focused more on muscular problems (10-12). The children and adolescents is estimated to range between relation between occlusion and CMD has been the 2% to 6% (2). Pain complaints range from acute and subject of several investigations (13-16). Multiple transient conditions such as toothaches to chronic studies have considered the impact of stress on CMD ailments, such as trigeminal neuralgia and and in particular the impact of stress on pain and temporomandibular disorders. While in the majority of tenderness of the masticatory muscles (17-19). With pain patients, pain decreases over time with or without the advancement of the pain sciences, more and more treatment, for a small percentage the pain complaint emphasis is placed on peripheral and central nervous persists. Similarly to other musculoskeletal pain system sensitization (20-23). problems, between 5% and 15% of all CMD patients # Previously published as Dommerholt, J: “El sindrome de dolor miofasical en la region craneomandibular”. In: Padrós Serrat, E. (ed) Bases diagnosticas, terapeuticas y posturales del functionalismo craniofacial. Madrid, Ripano, 2006: 564-581 * Bethesda Physiocare / Myopain Seminars, 7830 Old Georgetown Road, Suite C-15, Bethesda, MD 20814 – 2440, USA; +301.656.5613 (phone); +301.654.0333 (fax); [email protected] 1 Functional relations with spine dysfunction defined concept of “myofascial pain syndrome” (MPS) need to be considered in the management of patients described by Simons, Travell and Simons (33). MPS is with craniomandibular pain syndromes (24, 25). the main subject of this chapter and can be described as Rocabado has developed a pragmatic approach the sensory, motor, and autonomic symptoms caused by incorporating the intricate relationships between the myofascial trigger points. A myofascial trigger point cervical spine and mandible and temporomandibular (MTrP) is clinically defined as a hyperirritable spot in function. He has demonstrated that centric position can skeletal muscle that is associated with a hypersensitive only be achieved when there is a balance between the palpable nodule in a taut band. The spot is painful on position and movement patterns of the subcranial compression and can give rise to characteristic referred region, the mid and lower cervical spine, the hyoid, and pain, referred tenderness, motor dysfunction, and the mandible (26, 27). A detailed biomechanical autonomic phenomena (33). Although there are many assessment is important. Rocabado’s “pain map” is an peer-reviewed studies and reports in the international excellent tool to determine which joint structures cause medical literature supporting the importance of MTrPs or may contribute to the pain complaint (see in clinical practice, many of these reports are not Rocabado’s chapter in this book for a more detailed included in major medical library indices. Fortunately, description of his approach). several prominent researchers are now investigating In addition to a biomechanical joint MTrPs and the results of many of these studies support assessment, clinicians need to include a detailed the theoretical foundations and clinical applications. evaluation of the muscles in the cervical and Nevertheless, there is a substantial lack of basic craniomandibular region. Numerous studies of scientific studies; in general, MTrPs are underexplored craniomandibular muscle pain and dysfunction have by research investigators (34). incorporated the “research diagnostic criteria for A better understanding and working temporomandibular disorders” by Dworkin and knowledge of MTrPs and MPS will provide dentists, LeResche, which include a section on muscle orthodontists, oral surgeons, and other clinicians with dysfunction (28). The research criteria were developed an effective approach to relieve human suffering, and to classify and quantify both the physical and contribute significantly to their patients’ quality of life. psychosocial components of temporomandibular If MTrPs are not considered in the differential dysfunction. Although the criteria are widely used in diagnosis, a common cause of patients’ pain complaints dental research, they are remarkable simplistic where it will be overlooked (34, 35). MPS should be considered involves muscle dysfunction. The section “Axis I, with any pain syndrome in the head, neck, face, and Group I, Muscle Disorders” of the criteria includes only TMJ area (12, 33, 36). Dentists need to be aware that two options to describe muscle dysfunction: tender apparent dental or TMJ pain does not necessarily have muscles with or without limited mouth opening. a dental or joint origin (37). The inclusion of the word “diagnostic” in the Myofascial pain tends to be dull, poorly title of Dworkin and LeResche’s classification criteria localized, and deep, in contrast to the precise location may be interpreted that the criteria can be used in of dental pain and cutaneous pain. Muscles can refer clinical practice. However, research criteria do not pain to other deep somatic structures, such as fascia, necessarily provide a mechanism for clinical diagnosis. joints, viscera, and other muscles (38). Clinically, For example, MTrPs, myositis, and other less common referred pain is confusing to many clinicians, as conditions affecting muscles, such as myoadenylate frequently, patients complain more of pain in the deaminase deficiency or fascioliasis can not be referred pain zone and not necessarily of pain in the diagnosed using the research criteria. Therefore, immediate area of a MTrP. Signs and symptoms Dworkin and LeResche’s criteria do not provide any suggestive of non-odontogenic pain include an starting points to treat patients with craniomandibular inadequate local dental cause for the pain; a recurrence muscular dysfunction in clinical settings, even though of pain in spite of reasonable dental therapy of the tooth they have been validated for research purposes (29-32). or TMJ; poor lasting pain relief after local anesthetic blocking; positive findings with Rocabado’s pain map; Myofascial Pain Syndrome postural abnormalities such as forward head posture; In the dental literature, muscle pain with or and other pain problems, such as chronic and recurrent without limits in mouth opening is commonly referred headaches and widespread chronic pain conditions. to as “myofascial pain dysfunction syndrome,” a Patients with MPS usually have a history of somewhat unfortunate term, as it is often confused and acute or chronic muscle overload. In dental practice, used interchangeably with the more practical and better MPS is commonly seen in patients with a history of 2 bruxism or clenching (12, 39-41). A common The second edition summarizes significant progress in iatrogenic cause of MPS occurs when patients are the understanding of the pathophysiological basis of the required to keep their mouths open for prolonged clinical presentations associated with MTrPs. The periods of time during dental procedures (42). Patients manuals have been translated into six different with MPS in the head-neck region often are unable to languages, including Spanish. Several other MTrP relax their muscles in between contractions, i.e., the manuals have been published in Switzerland, the masseter, sternocleidomastoid and trapezius muscles. United States and the UK (46, 55, 56). The muscles are in continuous contracture, which can Several assessment and treatment approaches result in muscle ischemia, fatigue and pain (23, 43, 44). have emerged