Temporomandibular Disorders (TMDs) and Chronic Orofacial Pain
- Broad overview of chronic orofacial pain conditions other than TMDs
- Temporomandibular disorders (TMDs)
- Pathological states related to the temporomandibular joint
Surgery of the temporomandibular joint (TMJ) is indicated in only a tiny percentage of those presenting with symptoms from this structure. The TMJ and its supporting structures are however involved in a disproportionate number of referrals for management to oral surgery.
This chapter aims to give the reader a broad overview and understanding of the more commonly presenting chronic orofacial pain conditions with a specific focus on, Temporomandibular disorders (TMDs) which probably account for the largest proportion of the chronic pain referrals to oral surgery.
The chapter will firstly briefly outline the three other commonly presenting chronic orofacial pain conditions in order to allow the reader to distinguish between these and TMDs.
Broad Overview of Chronic Orofacial Pain Conditions Other Than TMDs
This is defined by the International Association of Pain as ‘a sudden, usually unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve’. Triggers often include cold air or tactile stimulation of the area affected, for instance shaving or applying make-up. There is a female preponderance in the fifth and sixth decades of life and it most commonly occurs in maxillary or mandibular division of the trigeminal nerve.
Vascular compression of the trigeminal nerve root can sometimes be identified, while some cases are secondary to pathology such as multiple sclerosis (MS) or intracranial tumours. Cases attributable to vascular compression or with no identifiable pathology are classified as ‘classical’ trigeminal neuralgia, and those with identifiable pathology other than vascular compression are classified as ‘secondary’ trigeminal neuralgia.
A thorough clinical history and examination including cranial nerve testing (see Chapter 1) is necessary before considering magnetic resonance imaging (MRI) to exclude intracranial causes:
- a space occupying lesion
- MS in patients presenting before 40 years of age
- a vascular loop compressing the trigeminal nerve root at the pons.
In the absence of any causative factors on an MRI, the drug of choice remains carbamezapine. Before starting carbamezapine the following tests should be taken: full blood count, urea and electrolytes, and liver function. These will help identify any pre-existing abnormalities and provide a baseline from which to measure any side effects of therapy. Haematinics should be repeated at intervals until therapy is discontinued.
Carbamezapine is started at 100 mg twice daily and increased in 100 mg increments gradually over a number of days until control is achieved. A maximum of 1200 mg/day can be given in divided doses. Alternatives prescribed in specialist centres include oxcarbazepine, gabapentin and phenytoin.
Neurosurgical management involves microvascular decompression, separating the trigeminal root from any vascular loop compressing it. Alternative surgical management includes gamma knife therapy and peripheral nerve procedures.
Burning Mouth Syndrome (BMS)
BMS is defined by the American Academy of Orofacial pain as ‘a common dysaesthesia described as a burning sensation in the oral mucosa’.
The tongue is commonly affected, but any part of the oral mucosa may be involved. Two subtypes have been delineated:
1 primary BMS – where no predisposing or exacerbating pathology, or deficiency can be found.
2 secondary BMS – where pathology or deficiency can be identified as exacerbating or causing the complaint. This subtype has a female preponderance in the fourth to fifth decades of life.
The aetiology of this subtype is unknown, but recently a pathophysiological cascade theory has been proposed.
Factors identified that can exacerbate or cause the complaint include: candidosis; vitamin B12, folate or ferritin deficiency; diabetic neuropathy; inadequate tongue space in complete dentures; drug reactions, e.g. ACE inhibitors; xerostomia.
A thorough clinical history and examination including cranial nerve testing should give a good basis for diagnosis. Any of the factors related to secondary BMS need to be excluded, through careful history and examination, drug history, haematinics, random glucose and microbiological swabs.
If factors related to secondary BMS are present, an appropriate referral should be arranged and the symptoms reviewed following this. If symptoms persist or there is no organic factor identified initially, consideration should be given to referring the patient to a specialist for cognitive behavioural therapy or pharmacotherapy.
A recent systematic review of pharmacotherapy has suggested that topical benzodiazepines may be of merit but that the use of systemic tricyclic antidepressants is not well supported by evidence.
Persistent Idiopathic Orofacial Pain (Atypical Facial Pain, Atypical Odontalgia)
This is defined by the International Headache Society as a ‘persistent facial pain that does not have the characteristics of the cranial neuralgias and is not attributed to another disorder’.
Patients present with poorly localised deep pain that does not follow anatomically defined patterns. The pain normally persists for the majority of the day and lacks consistency in its aggravating or relieving factors, while thorough investigation reveals no overt abnormality. Patients may have had multiple dental treatments to try and remove the pain. There is a female preponderance in the third to fourth decades.
The cause is unknown.
A thorough clinical history and examination including cranial nerve testing to exclude any underlying pathology should be undertaken. An odontogenic cause should be excluded through careful examination, testing and, if indicated, radiographs of the dentition.
If atypical pain is suspected the patient should be referred for specialist opinion and management. Irreversible or invasive procedures should not be undertaken on teeth to try and relieve the pain if the clinical picture, vitality testing or radiographic examination would not support the procedure. Specialist management will involve cognitive behavioural therapy with or without systemic pharmacotherapy, which may involve polypharmacy.
Temporomandibular Disorders (TMDs)
‘A collective term embracing a number of clinical problems that involve the masticatory musculature, the temporomandibular joint and associated structures, or both’ (American Academy of Orofacial Pain).
For the clinician treating TMDs it is paramount to have an appreciation that TMDs are a group of chronic illnesses, which largely follow a benign course and mostly respond favourably to conservative therapy.
TMDs have been previously known by a number of other terms: Costen’s syndrome, pain dysfunction syndrome, facial arthromyalgia, temporomandibular joint dysfunction. These terms are mentioned as some clinicians still persist in using them, although at the time of writing the accepted terminology for the group of conditions is TMDs.
The aetiology of TMDs is still undetermined, although five main factors have been suggested:
- parafunctional activities
- occlusal factors
- deep pain input
- emotional stress (Okeson, 2003).
Invasive treatment of any of these factors in isolation is unlikely to produce success and conservative reversible therapy remains, therefore, the mainstay in treatment of TMDs.
Presentation, Diagnosis and Investigation
Patients can present with a variety of signs and symptoms including:
- clicking or crepitus in the temporomandibular joint (TMJ)
- pain or tenderness in the muscles of mastication or TMJ
- reduced mouth opening
- earache (related to pain in the TMJ)
- headache (related to pain in the temporalis muscles).
There is a larger proportion (20–45%) of the general population with signs and symptoms of TMDs than those that present for treatment (2–4%) and of those presenting the female:male ratio is 7 : 1. The age range of presentation is from the second to fourth decades. Those presenting in higher age ranges should be viewed with a greater degree of suspicion as TMDs are less likely to present late in life and there maybe another causative pathology that is mimicking the symptoms.
Established research diagnostic criteria (RDC) for TMDs take a dual axis approach to diagnosis (axis I – physical; axis II – psychosocial). The RDC/TMD physical diagnosis of TMDs falls into three main groups:
- group I – myofascial pain
- group II – disc displacements
- group III – other common joint disorders.
A modified, quicker, version of the RDC/TMD, the clinical examination protocol for TMD (CEP-TMD) has emerged. The CEP-TMD results in a RDC/TMD physical diagnoses (Box 17.1) and the examination form and process can be viewed online (see Further reading).
Box 17.1 Diagnostic Criteria for the CEP-TMD
Key: Painful muscles
|Myofascial pain with limited opening
Key: Painful muscles + limited movement