Chronic facial pain patients can be a vexing problem for physicians. In large part, the frustration is due to the lack of knowledge concerning the cause, pathophysiology, and psychology of many of these conditions. The situation has given rise to the expression medically unexplained illness and has been applied to describe syndromes such as those discussed in this article. The term is intended to convey not only the notion that the cause is unknown, but also that understanding of these syndromes is certain to undergo extensive modification in the future.

Chronic facial pain patients frequently wander from clinician to clinician leaving behind a trail of disappointment and even irritation for all involved. This situation is not surprising because medicine has focused relatively little attention on chronic facial pain. With the exception of trigeminal neuralgia, physicians have traditionally relegated the treatment of most chronic facial pain disorders to dentistry. Even in the case of trigeminal neuralgia, most patients undergo unnecessary dental procedures before obtaining a proper diagnosis.<sup>18 Loeser J.D. The management of tic douloureux Pain 1977 ;  3 : 155

Cliquez ici pour aller à la section Références</sup> Ostensibly the decision to refer patients for dental care is based on the notion that these disorders require special dental expertise outside the scope of conventional medical training. There is little evidence to support this viewpoint. Moreover, physicians assume that traditional dental treatments (i.e., biteplates or bite adjustment) are reasonably effective; they are not.

Further complicating matters are the difficulties regarding differential diagnoses. Often the disorders themselves appear similar to one another. So too, do the sufferers, who are frequently middle-aged, are predominantly female, and report elevated rates of depression when compared with their demographic counterparts. In contrast to many medical illnesses, numerous chronic pain disorders lack diagnostic laboratory tests. This lack frequently contributes to delays in arriving at the correct diagnosis. In the absence of a gold standard, accurate diagnosis depends on history, physical examination, and such often overlooked tools as clinical epidemiology.

Familiar sources of facial pain, such as sinusitis and earache, are not discussed. This article provides the reader with the basic tools required to diagnose and treat patients suffering from the most prevalent medically unexplained chronic facial pain syndromes. All of these treatments can be carried out by the primary care physician, thus saving patients unnecessary delay in pain relief. The four medically unexplained disorders discussed are (1) the temporomandibular pain and dysfunction syndrome (TMJ), (2) deafferentation pain (also called orofacial phantom pain, atypical facial pain), (3) glossodynia (also called burning mouth syndrome), and (4) trigeminal neuralgia. The terminology used here is that of the International Association for the Study of Pain (IASP).<sup>23 Merskey H., Bogduk N. Classification of Chronic Pain Seattle: IASP Press (1994). 

Cliquez ici pour aller à la section Références</sup>