Abstract
One of the enigmas of primary headache (that is, when headache is not just a symptom of some other disease but the disease itself) has always puzzled us: Why head pain? Why have we never heard of attacks of pulsating leg pain or an arm pain, which may last two days and comes with specific accompanying symptoms – and these painful attacks bother patients for most of their life? One could answer that this kind of syndrome needs a well vascularized tissue, but then why do we not have patients who have regular “spleen attacks” or “liver attacks” that come in bouts that last, let’s say, 20 minutes and occur several times a day? The obvious answer would be that the trigeminal nerve – possibly the trigemino-vascular system – must be involved to enable humans to have such specific and well-defined attacks, and that trigeminal pain physiology may be quite distinct from spinal pain physiology.
But then, what is so special about headaches? What is so basically different between pain in the first and second or third division of the trigeminal nerve? There must be some fundamental difference between the ophthalmic and the maxillary and mandibular branch of the trigeminus, otherwise dentists would have patients who report regular differentiated tooth pain attacks and always complete remission in between without any obvious dental cause such as caries or trauma. The ophthalmic division of the trigeminal nerve must have an exclusive and outstanding role in the trigemino-vascular system, and it is this physiological role that renders this system prone to respond to attacks from the limbic system.
The above line of argument assumes that there are indeed no patients with such tooth pain attacks without any known dental cause. But how can we really be sure? Any kind of facial or dental pain is primarily seen by dentists, and any kind of head pain is usually referred to neurologists. The only exception is probably trigeminal neuralgia, which is a pain in the orofacial region but which is treated mainly by neurologists. And although the international classification of headache disorders acknowledges facial pain and emphatically endorses the cooperation with facial pain specialists, the field of facial pain is somewhat neglected by headache specialists – and vice versa. It is only for a decade or so that we have known about facial migraine and facial trigemino-autonomic headaches, and there may well be patients with attack-wise toothaches or facial pains that are syndromes in their own right. It may be that we just have not looked hard enough. Or that we have not shared information well enough – that we have not talked to our fellow colleagues from whom we might learn so much – because if a facial pain has its source not in the teeth, or periodontium, or temporomandibular joints, or masticatory muscles, it may belong to a new disease entity. But because we know so little about these syndromes, such pains have been oversimplified and called “atypical facial pain” in the past, which is now termed “PIPF” (idiopathic persisting facial pain). Huge efforts have been made in the last 20 years and indeed the field of facial pain has advanced greatly. Perhaps the most success so far has been achieved in the classification of temporomandibular disorders, and we are at the brink of a new and generally accepted facial pain classification. The ultimate winners of all this are the patients, and now is the right time to join forces.
This is the spirit that facilitated this special issue of Cephalalgia. Experts in the field got together and compiled authoritative reviews of all aspects of facial pain. Because cross-talk between the disciplines is so important, we are very grateful to all the authors and you will see that all articles are by experts of the IHS and IASP collaboratively. It has been great fun to set up this special issue, and we hope that it will plant a seed from which a better understanding, new research projects, and lastly new therapies for facial pain may emerge.