Facial Pain

Facial pain most often originates from diseased teeth or sinuses. Provocation of dental pain by hot, cold or sweet foods is typical. Acute maxillary sinusitis usually generates a blackish-green, thick, purulent nasal discharge. The pain of nasopharyngeal carcinoma may resist diagnosis until cranial nerve abnormalities appear, deep, dull maxillary paint that waxes and wanes throughout the day best characterizes its early presentation. When differentiation occurs, a burning quality becomes superimposed until finally, diplopia appears. This would be the typical picture of pain produced by a malignancy in the nasopharynx. The ill-founded idea that nondescript pain of the face which often has a burning quality fulfills a never-validated criterion for a psychogenic illness (“atypical facial pain”) is perplexing.

There is no evidence that suggests that pain intensity has diagnostic value; whereas the pains of trigeminal neuralgia and cluster headache are often intense, the differential diagnostic probabilities are unaffected by such quantitative considerations.

Patients with atypical facial pain will often rub the affected areas; those with trigeminal neuralgia will not.

Beware of diagnosis by stereotype. In my experience this is the most common error leading to the misdiagnosis of “atypical facial pain.” Stereotyping a disorder is useful to etch it in one’s mind, but it is important to remind oneself that stereotypes are man-made and the disorders we deal with usually are not. Of all the disorders to be discussed below, trigeminal neuralgia probably conforms to its stereotype more often than any other; but this is a fairly common cause of facial pain, so that if exceptions to the stereotype occur with even a five percent incidence, one will see many patients who are not stereotypic. Therefore, there seems to be little reason to categorize such a patient’s problem as “atypical” trigeminal neuralgia. The latter designation is sometimes confused with atypical facial pain, a designation that should be stubbornly resisted. Most patients referred to me with a that diagnosis have been examples of trigeminal neuralgia, carotidynia, the chronic form of cluster headache , or have had occult jaw bone microabscesses.

In the clinical analysis of pain, the aspect that adds the greatest specificity to the differential diagnostic probabilities is whether or not provocative factors have been identified. Facial pain worsening or appearing de novo in response to cold wind is characteristic of trigeminal neuralgia, and also occurs on occasion in facial migraine and cluster headaches. Pain paroxysms appearing during a meal are important to analyze further. It is the chewing, the swallowing or the taste of the food that is the stimulus? Chewing is a clue pointing toward trigeminal neuralgia, temporomandibular joint dysfunction, or giant cell arteritis (“jaw claudication”), whereas swallowing and taste provocation points toward glossopharyngeal neuralgia. Pain upon swallowing is a common symptom among patients with carotidynia (the inflamed carotid artery abuts the esophagus), and is the classic trigger for the rare superior laryngeal neuralgia. The provocation of pain by alcohol ingestion, exertion, sleep lack or excess, or in association with menses-all point to a migrainous mechanism. Provocative factors must be elicited by direct questioning, and it must be made clear to the patient that it is important to determine whether any pain is ever produced by such factors. Most patients respond in the negative when this issue is initially raised. Many assume that they’re being asked about a common, consistent factor that is causing their pain and most of their attacks either are not provoked by an identifiable factor, or are provoked only inconsistently. It is useful to point out to patients that inconsistently is the rule regarding prevocational factors and that their suspicions regarding provocation are of interest.

Neuralgic disorders are characterized by refractory periods that follow paroxysms of pain. Does the application of a cold stimulus to a tooth repeatedly induce pain as it the case with a diseased tooth? Or is pain elicited but once and then not again as in trigeminal neuralgia?

Patients with chronic pain are often depressed-largely because of a painful problem that has not been alleviated. The idea that recognition of depression in a patient with facial pain somehow adds up to a diagnosis of a typical facial pain has never been validated, contrary assertions notwithstanding. Personalized highlights of some of the causes of facial pain follow.

Trigeminal Neuralgia

The syndrome of trigeminal neuralgia may result form a focal demyelinative lesion of the trigeminal nerve at any point in its course. The pain mechanism probably originates within the brainstem, the result of disinhibition of a central pain-gate. Cerebellopontine angle tumors are present in 4-5 percent of patients with the syndrome so that magnetic resonance imaging is necessary for nearly all of these patients. The pain is paroxysmal, appearing and reaching maximal intensity without latency; it is nearly always analogous to “electric-shocks” which occur in staccato, “machine gun” volleys. The pain is nearly always triggered by certain maneuvers that include talking, chewing and brushing the teeth. Trigger zones are areas of the face which when lightly touched can evoke a pain paroxysm. These are present in perhaps half of these patients. Patients are rarely wakened from sleep by pain in contrast with glossopharyngeal neuralgia. Very rarely does trigeminal neuralgia spontaneously cease completely, so that lifelong treatment is necessary. However, there is usually a cluster tempo to the disorder in that temporary remissions lasting months and even years are the rule. At least one remission of 6 months or more occurs in over 50 percent of patients. During these remissions, medications can be stopped. A central pathogenesis of pain after a trigger point is stimulated, and latency between stimulation of a trigger point and the appearance of pain. Moreover, the central mechanisms and depress excitatory mechanisms in the spinal trigeminal nucleus caudalis. At the cellular level, the drugs block membrane sodium channels responsible for the generation of the action potential under conditions of repetitive neuronal firing. Optimal medical treatment should be addressed aggressively and critically within a period of 5 to 6 months. If pain control is suboptimal, serious consideration of the surgical options should be given before advancing age increases the risks. If carbamazepine, phenytoin, and baclofen alone and in combination fail, clonazepam and valproate ought to be implemented. Oxcarbazepine (Trileptal) at 1200 – 2400 mg/ day has been reported to be effective when carbamazepine has failed. If these, too, fail, the side effect profiles of pimozide and tocainide should be compared to the risks of surgery. A highly useful measure in treating any neuralgic disorder is the administration of 250 mg of phenytoin intravenously over 5 minutes. This procedure, albeit uncontrolled, has consistently stopped trigeminal neuralgia pain within 5 minutes in over 75 patients. Pain relief usually lasts 1-2 days, but sometimes several days. This can be a highly useful maneuver that can be repeated, while awaiting drug doses to reach therapeutic levels. Trigeminal neuralgia and hemifacial spasm appearing homolaterally is known as tic convulsive and is almost inevitably associated with pathological processes in the posterior fossa, particularly anomalous, ecstatic or aneurysmal blood vessels. Moreover, the concurrent appearance of homolateral trigeminal neuralgia and cluster headache usually involves the maxillary area of the face and is known as the cluster-tic syndrome. It is notoriously refractory to medical treatment. Posterior fossa microvascular decompression of the trigeminal nerve or trigeminal rhizotomy has often been necessary.

Glossopharyngeal Neuralgia

Although pathogenesis and treatment are quite similar, the clinical presentations of glossopharyngeal and trigeminal neuralgia are dissimilar. Both disorders occur in combined form, concurrently and homolaterally in 10 percent of patients with glossopharyngeal neuralgia. Paroxysmal pain occurs unilaterally in relationship to the ear, tonsil, larynx and tongue. Pain appears quite abruptly and persists for several seconds to one minute or so, often ending abruptly (“square wave” pain). There is often a dull, deep, continuous pain at the affected site. Vigorous coughing attends the paroxysms in 10 per cent of patient; occasionally hoarseness persisting for several minutes occurs after severe pains. Remissions are usually dramatic, lasting months to years between bouts. Swallowing cold liquids is the commonest trigger pain paroxysms. Skin trigger zones are only infrequently present, occurring within the external auditory canal, at the lateral aspect of the neck, and the pre- or postauricular areas. Spraying topical lidocaine upon the oropharynx stops the pain in 90 percent of patients; the diagnosis is clearly affirmed when a positive test is obtained.

Carotidynia

There appears to be two forms of this disorder an acute form which results in a monophasic illness that lasts for one two weeks and tends not to recur; and a chronic form that appears to be a variant of migraine and is responsive to anti-migraine measures. Both forms are common and are highly responsive to the administration of coritcosteroids. Carotid artery tenderness and overlying soft tissue swelling are the findings common to both. 5/5 patients with the acute syndrome who underwent MR imaging of the neck had abnormal enhancing tissue surrounding the symptomatic carotid artery.

Atypical Facial Pain

Continuous unilateral, deep, aching pain sometimes with a burning component and devoid of features outlined for the disorders considered previously is commonly regarded as atypical facial pain. However, deep, dull continuous pain is the type of pain that is commonly encountered in a variety of diseases. Some of these patients eventually turn out to have disorders such as vascular lesions of the brainstem, nasopharyngeal carcinoma or squamous cell carcinoma of the facial skin that has migrated perineurally intracranially. In these two latter instances, facial pain may antedate cranial nerve dysfunction by several months. Therefore, a better designation for this syndrome is “facial pain of unknown cause”; as knowledge is advance, other causes of pain will undoubtedly be uncovered.

Referred Facial Pain from Lung Carcinoma

There are nearly 30 reports of homolateral facial pain as a nonmetastic complication of pulmonary carcinoma. Facial pain has abated following local irradiation of the lung in nine patients or local surgery in three, supporting the likelihood that this is not a chance coincidence. The pain is deep and aching, usually temporo-aural in location, and often right-sided. The close anatomic relationship of the right vagus nerve to mediastinal lymph nodes has been offered as a possible explanation for the dextral dominance. Most of the tumors have been adenocarcinomas, but squamous cell and small cell tumors also have been encountered.

Maxillary and Mandibular Bone Cavities

A major advance in elucidating the cause of pain in a substantial proportion of these patients has been made by Roberts and his colleagues and by Ratner et al. These investigators have found radiologically undetectable infected maxillary or mandibular bone cavities at previous tooth extraction sites in tow large series of patients with “atypical facial pain.” They used an injection of local anesthetic into a tooth extraction site as a diagnostic test; if facial pain repeatedly disappeared following such an injection, curettage of the jaw bone and antibiotic treatment were then implemented. Twenty-three patients were treated in the uncontrolled series of Ratner et al. and 14 were pain-free or nearly pain-free after treatment and followed for nine months to over four years. Microscopic examination of the bone and low grade inflammation. A complex mix of aerobic and anaerobic flora were cultured in virtually all cases. Jaw bone curettage is an outpatient procedure that is usually completed within an hour.

Post-Traumatic Facial Pain

More than half the patients with non-descript facial pain report its onset after trauma to the face, often surgical trauma. Orbital enucleations, sinus procedures, and complicated dental extractions are the commonest procedures that antedate the appearance of pain. Fortunately, for the large majority of these patients, their pain problem is self-limited: within one to five years it subsides whether symptomatic treatment is effective or not (Raskin, unpublished observations). The mechanism underlying this disorder presumably involves activation of central pain transmission pathways.

Facial Pain of Unknown Cause

A small proportion of patients with nondescript facial pain develop their syndromes without provocation of any sort, and defy further diagnostic analysis. They are invariably depressed as are the vast majority of patients with chronic pain, but the notion that depression is the cause of their pain is unconvincing. It is certainly true that drugs which are in general use as antidepressants are effective for most of the patients, but to argue that the effectiveness of such drugs establishes the mechanism as depression is solecistic.

TREATMENT

The tricyclic drugs and phenelzine are effective in about 80 percent of patients with facial pain of traumatic or unknown cause. I begin with amitriptyline. Twenty milligrams daily is begun and then over weeks, if tolerated, the dosage is slowly elevated if necessary to 250 mg. The majority of patients will receive at least some benefit from this drug and require no further pharmacotherapy. If pain relief is insufficient, phenelzine is added, 30 mg at bedtime and increased by 15 mg daily each week until pain relief or 75 mg daily is achieved. The two drugs are continued for at least six weeks before a judgment is formed as to final benefit. If phenelzine is poorly tolerated or ineffectual, amitriptyline is maintained and to it is added serially valproic acid, and finally, perphenazine or fluphenazine. Very few patients do not achieve substantial pain attenuation using aggressive pharmacotherapy as outlined above.
Should a prominent burning quality attend a patient’s facial pain syndrome, a series of homolateral stellate ganglion blocks may be useful.

Low intensity laser therapy is also effective in treating these disorders.

Low Intensity Laser Therapy (LILT)

The low intensity Laser (LILT) sends photons (light) into the injured tissues and can penetrate two to three inches to treat affected areas. It uses a natural enhancement of the cellular machinery that can and has been dynamically measured in published studies to promote healing without burning affected tissue .Once the photons find the injured tissues, they stimulate and energize the cells to repair and strengthen at a remarkable rate. The treatment does not hurt, takes about 30 minutes and is very cost advantageous.

Wellness Program

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