Approach to the Patient with Facial Pain



Approach to the Patient with Facial Pain


Murray S. Flaster



Facial pain is a frequent presenting complaint in the general clinic, the neurology clinic, and in the emergency department. Age, gender, and a detailed description of the pain complaint and accompanying symptoms will frequently suggest the correct diagnosis, whereas history, neurologic, and general physical examination generate a limited differential to help to further focus the investigation. Not infrequently, the patient has already been seen by several providers, often including a dentist, oral surgeon, or otolaryngologist, and testing and interventions have proved unhelpful. Many of these patients have normal or inconclusive imaging and normal examinations.

In this chapter, we will consider trigeminal neuralgia (TN), both idiopathic (classic) and secondary, the much rarer glossopharyngeal neuralgia (GN), migraine, and the trigeminal autonomic cephalgias (TACs), as well as herpetic and post herpetic neuralgia. Temporomandibular joint (TMJ) dysfunction and atypical facial pain (which has been recently renamed persistent idiopathic facial pain [PIFP]) will be briefly considered. Other causes of facial pain including cranial sinusitis, dental caries, acute glaucoma, and other causes of orbital and periorbital pain, temporal arteritis, and arterial dissections will be briefly discussed.

The practitioner should bear in mind that patients with facial pain, especially those with chronicity are frequently distraught, needy, and often quite complex.


I. TRIGEMINAL NEURALGIA

TN is probably the most common of facial pain disorders, and broadly speaking is among the more severe pain disorders known. Patients complain of very brief, electric-like or lancinating pain involving one or more branches of the trigeminal nerve. Typically the second and third divisions of the trigeminal nerve are involved, contiguously or individually. Rarely, the first division may also be involved, but almost never in isolation. The painful jolt lasts for seconds but can recur multiple times, often in bursts. The pain is almost always unilateral, and its overwhelming severity completely and visibly absorbs the patient when it strikes. Most commonly, there is no pain or paresthesias in between lancinating events and the painful episodes can dissipate as unexpectedly as they appear. The syndrome is often episodic, with painful epochs that stretch for weeks or months, and with spontaneous remissions lasting even years. Over time, typically measured in months or years, there appears to be a tendency toward increasing refractoriness to therapies. Very often, the patient will describe a trigger or aggravating feature that includes talking, chewing, brushing of teeth, application of makeup, shaving, casual contact with the effected area, or even a stimulus as subtle as an air current. Chewing and swallowing presents so much difficulty that the patient loses weight and may even suffer dehydration. The sudden, invasive, and miserable nature of TN is captured by the French phrase tic douloureux. In some patients, usually years after symptom onset, pain may become longer lasting with duller, more constant pain supervening together with paresthesias in the affected territory. Patients reporting these more complex pain phenomena may also have less predictable responses to invasive treatment, leading many authors to additionally classify these patients as “atypical TN.”

TN is etiologically divided into classic (or idiopathic) and symptomatic. Symptomatic TN may be due to compressive tumor (meningioma, acoustic neuroma, and epidermoid), infiltrative neoplasm, or to an inflammatory process, particularly multiple sclerosis. Other cited etiologies include vascular malformations, brainstem ischemia, facial trauma, and arteritis. Bilaterality strongly implies a secondary cause although most symptomatic TN cases are unilateral. Younger
age favors a secondary cause but classic TN has been described in younger patients. The etiology of classic TN remains uncertain, but most authorities believe that demyelinative damage at the root entry zone due to vascular compression is causal. Neuroimaging studies, specifically MRI may show a secondary cause in up to 15% of cases and at least one neuroimaging study should be encouraged regardless of how typical a patient’s presentation may appear. High-field strength, high-resolution diffusion-tensor MR may be able to identify both the offending vessel and intrinsic change within the nerve, and so eventually become a reliable means of confirming classic TN.

TN has a prevalence of 3 to 6 per 100,000 becomes more frequent with age, particularly after age 60 and is nearly twice as frequent in women. Still, there is no completely secure clinical profile unequivocally establishing classical TN. On the other hand, neither involvement of the first division of the trigeminal nerve nor refractoriness to therapy should be considered completely reliable indicators of symptomatic TN. Most importantly, continuous pain or paresthesias or an abnormal neurologic examination prompts a thorough search for a symptomatic cause.

The general recommendation for initial therapy beyond analgesics is oral antiepileptic drug (AED), with carbamazepine most commonly considered first line therapy and where initial favorable response rates in classic TN approach 90%. Treatment with carbamazepine becomes less effective over time, partly due to increased hepatic elimination (autoinduction) but likely involving other, less understood mechanisms. Other agents including oxcarbamazepine, lamotrigine, gabapentin, or baclofen can be effective in monotherapy or as add on therapies. Familiarity with these agents, their side effects, and drug-drug interactions on the part of the treating physician are recommended.

There is general agreement that patients refractory to medical therapy should be considered for surgical intervention although evidenced-based data are sparse and broad agreement on how soon to seek surgical alternatives is lacking. A very effective approach with high rates of immediate pain relief and very effective long-lasting benefit involves craniotomy with microscopic vascular decompression (MVD) at the trigeminal root. Highresolution MRI has been employed to detect these offending vessels and predict successful MVD but reliability of these methods remains incomplete. Perioperative and postoperative complications occur, but are infrequent in the hands of experienced neurosurgeons. Less invasive partial destructive procedures include radiofrequency thermal rhizotomy, done very commonly and percutaneous balloon microcompression and less frequently, chemical rhizotomy. Stereotactic radiosurgery should be considered when patient infirmity or patient preference weighs against open surgery. The percutaneous procedures offer degrees of initial pain relief similar to that of MVD but also modestly less reliable sustained benefit. Complications potentially include deafferentation syndromes (anesthesia dolorosa or corneal hypoesthesia with keratitis) hearing loss or CSF leak. In the case of the least invasive nonmedicinal approach, stereotactic radio surgery, the patient must be made aware that pain relief will not become effective for a mean interval of about 1 month. Many experienced neurosurgeons are of the opinion and that too many patients have suffered for too long before being referred for definitive interventional therapy. The role of invasive therapy in patients with multiple sclerosis remains more controversial.

We stress that interventional procedures are effective in patients with classic TN but in patients with other causes of facial pain or frankly equivocal cases of TN, invasive procedures are wisely avoided or approached with appropriate circumspection.


II. GLOSSOPHARYNGEAL NEURALGIA

GN is similar to TN in that it presents with unilateral lancinating pain involving the posterior-lateral aspect of the throat (tonsil), the posterior aspect of the tongue, the ear, or larynx and as is the case for TN, remains a clinical diagnosis. Swallowing is a typical trigger as are speech or cough. The lancinating pain appears in some patients to trigger a coughing fit. A rare variant accompanied by syncope has been described which through presumed influence on vagus nerve outflow can cause recurrent brady-arrhythmia and even asystole. Like TN, GN may remit or relapse spontaneously but it is a far rarer disorder, with an estimated frequency of between 1/10th and 100th that of TN. It may be either idiopathic or
symptomatic. Symptomatic causes include tumors of the skull base, infection, an expansile vertebral artery due to large atheroma, or malformation of the skull base. Otolaryngologic evaluation as well as neuroimaging evaluation is recommended. Elimination of triggered pain by the application of topical anesthetic may help support the diagnosis. Microvascular compression is considered the underlying cause of idiopathic GN by many authorities and so a surgical approach is often recommended if medical therapy is ineffective. Highresolution MRI lends some support to the theory of microvascular compression. In many cases, severity of GN may be milder relative to TN and in some instances, patient assurance has proved a sufficient remedy.


III. HERPES ZOSTER (HZ) NEURALGIAS

The acute or chronic neuralgia resulting from the segmental (dermatomal) recrudescence of herpes virus in the dorsal root ganglia is quite distinct clinically from TN and is generally readily recognized acutely by a characteristic, topographically distinct, unilateral rash. Because involvement of the trigeminal ganglion in reactivated latent herpes virus infection is common, HZ is a frequent cause of facial pain, especially in the elderly.

HZ has an overall incidence of between 1.5 and 3 per 1,000 annually, but this incidence rises to up to 6.5 per 1,000 by age 60 and up to 11 per 1,000 by age 70. Between 20% and 40% of all individuals will experience HZ in their lifetime. HZ affecting the first division of the trigeminal nerve (HZ ophthalmicus) is the second most common form of HZ, second only to the involvement of the thoracic dermatomes and comprises 10% to 20% of all HZ cases. The second and third divisions of the trigeminal nerve are rarely if ever affected in isolation. HZ begins with a prodrome that includes fatigue and malaise, headache and photophobia, rarely fever but very frequently includes a vague sensory prodrome in the involved dermatome that consists of tingling paresthesias, sometimes burning paresthesias, sometimes lancinating paresthesias, and sometimes allodynia. The HZ induced paresthesias are sensed as surface, dermatomal phenomena but a perceived deeper discomfort described as muscle or bone ache or even visceral pain referred to as myotomal phenomena in the older literature also occurs and can be severe. After a period of about 1 to 5 days, the typical rash (shingles), first maculopapular, and then frankly vesicular appears, restricted to a primary dermatome and parts of the immediately contiguous dermatomes. As the rash advances, the pain may worsen, and pruritus develops. The pain is mixed and unrelenting; a lancinating component may be prominent but never singular. A patient’s scratching will alter the appearance of the rash, with excoriations obscuring vesicles and it is therefore important to remain watchful for secondary bacterial infection. Bilateral or multifocal involvement is seen only in the immune compromised. Rarely, patients perceive a prodrome including sensory symptoms without evidence of rash. (This phenomenon together with the sequelae of HZ in the absence of observed rash have been termed “zoster sine herpete.”) The rash generally subsides over a period of 30 days; pain generally declines with it, but in 10% to 20% of patients, the pain persists beyond 30 days. This persistent pain syndrome termed postherpetic neuralgia (PHN) is the most common complication of HZ.

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Aug 18, 2016 | Posted by in NEUROLOGY | Comments Off on Approach to the Patient with Facial Pain

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