14: Facial pain

Facial pain

14.1 Assessment of a patient suffering from orofacial pain

Assessment of orofacial pain requires eliciting as much information from the patient as possible. The basic information you need must include:

• the nature of the pain: encourage the patient to describe the pain in their own words by the use of open questions rather than supplying them with a list of descriptors of pain from which to select; the latter can be useful if a patient is finding it particularly difficult to describe their pain. The use of a 0 to 10 scale can assist patients in expressing the severity of their pain with 0 being pain free and 10 representing the worst pain that the patient has ever experienced

• when the pain first began

• the duration of each episode of pain

• the frequency of the painful episodes: how often do episodes of pain occur; what is the longest and shortest time the patient has been symptom free

• the site(s) affected: ask the patient to point to the source of the pain and/or outline the area affected by it; does the pain radiate to other areas? Is it confined to the distribution of a particular nerve(s) or does it cross anatomical boundaries, for example the midline?

• initiating factors: anything that the patient remembers occurring immediately before or at the same time as the start of their symptoms

• precipitating factors: anything which now seems to induce the patient’s symptoms

• exacerbating factors: anything which makes the patient’s symptoms worse

• ameliorating factors: anything which relieves, either partially or totally, the patient’s symptoms

• associated signs and symptoms

• previous investigations

• previous treatment

• relevant medical/dental/social/family history.

Much of this information will emerge naturally, in most cases, by simply asking the patient to tell you about their pain. Verbal and non-verbal communication skills should be used to encourage the patient to tell their story in a way that is mutually beneficial. At the end of the consultation, the patient should feel that they have been able to impart information that they believed to be relevant and the dentist should have guided them through this process to yield up the information required to reach a differential diagnosis.

A thorough extraoral (including the temporomandibular joint and muscles of mastication) and intraoral examination (see Chapter 2) is obviously mandatory. Additional components of the examination procedure may be required depending on the differential diagnosis, for example assessment of cranial nerve function in patients presenting with symptoms of trigeminal neuralgia. The differential diagnosis will be based on a combination of the outcome of the examination and history. The special investigations that are carried out (these may not always be necessary) will be aimed at clarifying the differential diagnosis and should be carefully tailored to fulfil this purpose, not used as a general screening procedure.

While this chapter will not be considering those diseases of the teeth and their supporting structures that give rise to orofacial pain, it is important to stress that dentists need to be particularly skilled in excluding such structures as the source of the patient’s pain. The principal causes of pain arising from the teeth and their supporting structures are listed below, with reference to the appropriate sections of this book and its companion volume (Master Dentistry Volume 2, edited by Heasman). You must know the signs of symptoms of these conditions and apply this knowledge when reaching a differential diagnosis in the case of a patient with orofacial pain.

14.2 The neuralgias

Trigeminal neuralgia

Two types of trigeminal neuralgia have been defined: classical (CTN) and symptomatic (STN). By definition, the latter type is characterised by the presence of a structural abnormality.

The majority of cases (>85%) of trigeminal neuralgia are of classic type (CTN). Compression of the trigeminal nerve in the region of the dorsal root entry zone (DREZ) by a blood vessel has emerged as the leading cause of CTN. In STN, this compression is the result of a structural lesion such as a tumour or vascular malformation. Demyelination secondary to multiple sclerosis also falls within the definition of STN.

Clinical presentation

Medical management

The therapy of choice is carbamazepine. Reduction or complete resolution of symptoms following its use is considered to be virtually diagnostic of trigeminal neuralgia. However, it should be prescribed cautiously, starting at a dose of 100 mg twice or three times daily and increasing slowly until the patient’s symptoms are controlled. This is usually achieved at between 200 and 400 mg three times daily. Gradual increase in dosage is important as elderly patients are particularly susceptible to carbamazepine’s many side-effects. Some of these, for example nausea, ataxia and dizziness, make taking carbamazepine completely unacceptable to the patient or significantly limit its dose. Others, including leucopenia, thrombocytopenia and skin reactions, necessitate its withdrawal; patients should be informed of the signs and symptoms of these conditions when the drug is prescribed. Full blood count, liver and renal function tests should ideally be carried out prior to its prescription and at regular intervals during at least the first months of treatment. Individuals of Han Chinese or Thai origin should be tested for HLA-B∗ 1502 allele and, if positive, carbamazepine should not be prescribed as a result of the risk of development of Stevens–Johnson syndrome. If withdrawal of carbamazepine proves to be necessary, oxcarbazepine provides an alternative. Should the dose of carbamazepine be limited, the antiepileptic lamotrigine may be added or used an alternative.

Surgical management

Although the evidence base for surgical interventions is weak, microvascular decompression (MVD) appears to have the best outcome and is emerging as the preferred option in those patients who are fit for open surgery. In this procedure, the offending blood vessel is lifted away from the trigeminal root and permanently repositioned. In comparison to peripheral destructive procedures such as neurectomy or central destructive procedures such as percutaneous radiofrequency thermocoagulation, MVD has a low rate of complications. It is, however, important that MVD is performed sooner rather than later as success declines with duration of trigeminal neuralgia symptoms. This is leading to a change in approach with clinicians raising the awareness of patients to the possibility of surgical intervention much earlier in the medical treatment phase rather than as a last resort. Gamma knife stereotactic surgery provides an alternative to MVD in those patients for whom surgery is contraindicated. Other central procedures include retrogasserian glycerol injection, compression or radiofrequency thermocoagulation. The above procedures have largely replaced peripheral treatment options although local anaesthetic injected into the trigger zone will provide temporary relief of symptoms (bupivacaine has a longer duration of action) and is useful in confirming the diagnosis.

Glossopharyngeal neuralgia

Glossopharyngeal neuralgia is an extremely uncommon condition.

Clinical presentation

Preherpetic neuralgia

Development of the classic vesicles of herpes zoster (Chapter 11; Fig. 14.1) is, in some cases, preceded by facial pain. This leads to the diagnosis being made retrospectively in many cases.

Postherpetic neuralgia

Postherpetic neuralgia occurs in about 10% of patients who have had herpes zoster infection and it persists in approximately 5%.

14.3 Pain of vascular origin

Migraine

Cluster headaches

Jan 9, 2015 | Posted by in Oral and Maxillofacial Pathology | Comments Off on 14: Facial pain
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