Classifying head,face and oral pain

The diagnosis of head and orofacial pain (OFP) is confounded by the proximity between the relevant structures: The eyes, nose, ears, mouth (teeth, tongue), paranasal sinuses, the brain and associated tissues. The shared innervation and blood supply, the trigeminovascular system, suggests that pains from this region are part of the same fabric. Not loosely related, but an intimately woven system with intricate, overlapping pain pathophysiologies, symptomatology and referral patterns. Yet, while closer collaboration will enhance diagnosis and management, the professions dealing with head and face pain remain relatively isolated. It is taking far too many of us, far too long to correctly diagnose some of our patients with facial pain (1).

One of the major underlying factors driving misdiagnosis is consistently “location”. To emphasize this point, primary pains with features that are reminiscent of migraine or cluster headache occurring exclusively in the lower two-thirds of the face and intraorally have been well documented. Pain location may be driving consultation choices, skewing who is seeing these “atypical” patients. Our patients know where it hurts … but not where the “hurt” originates from. Understanding that the source of pain may not equate with pain location is our purview; our responsibility.

As a result, far too many patients with atypically-located migraines (2,3), cluster headaches (4), or other trigeminal autonomic cephalgias (5) suffer from misdiagnosis by those involved in their care, including primary physicians and dentists, neurologists, and otolaryngologists. Regional myofascial pain (one of the temporomandibular disorders [TMDs]) has complex head, face and intraoral referral patterns that cause widespread misdiagnosis. To clarify, OFP is no rarity and affects around a quarter of the general population, with about 10% being chronic (6). Painful TMDs are quite prevalent, affecting 4.6% of the population (6.3% in women, 2.8% in men) (7). Add to that the unclear number of oral and facial presentations of other primary headaches such as migraine (8).

We therefore need an updated and integrated classification that defines the individual sources of pain in the oral, facial and head region. Such a classification would allow the multi-professional team involved in the management of our patients in pain a resource for accurate diagnosis. The International Classification for Headache Disorders (9) is the best and most comprehensive system I know of, but for oral and facial pain it is lacking. There have been changes within ICHD-3 that draw attention to some of the facial presentations of primary headaches. Are these sufficient? In view of the continuing diagnostic difficulties, and the need to increasingly involve professions such as otolaryngology and dentistry, we believe there should be more focused sub-classifications for these entities. To make ICHD-3 better, we need the TMDs and other orofacial pains to be individually recognized and included, and more stress placed on facial variants of primary headaches. While these are technically all headaches, we must address the need for a more comprehensive description of pains in the lower two-thirds of the head. This classification would form the basis for improved education of relevant healthcare professionals and hopefully improved diagnosis.

There is widespread commitment to the integration of oral, facial and head pains. The International Association for the Study of Pain (IASP) has recently approved a renamed special interest group (SIG): The OroFacial and Head Pain (OFHP) SIG. It is as revolutionary as it is completely logical. This group will complement the International Headache Society (IHS) with the distinctive scientific resources the IASP has to offer. Together with the IHS, the American Academy of OFP and the International Network for Orofacial Pain and Related Disorders Methodology (previously the International RDC-TMD Consortium Network), the OFHP-SIG is examining orofacial pain issues and designing a classification. Only good may come of this interaction. Based on a strong foundation of classification, we may proceed to the much-needed research into oral and facial pain syndromes and their management. Certainly, Cephalalgia is an excellent forum to submit such work.

We must collaborate, in the interest of the people we serve: Our patients. The African proverb comes to mind: “If you want to go fast, go alone. If you want to go far, go together”. Let’s go far.