Reflections on the nosology of cranio-facial pain syndromes.

Orofacial pain syndromes have traditionally been divided into two groups: the typical neuralgias and atypical facial pain. While typical neuralgias are well characterised, the term atypical facial pain (now persistent idiopathic facial pain) covers a variety of poorly defined head and face pains whose aetiological mechanisms are poorly understood. This paper examines the characteristics and nosography of these conditions, and suggests they should not be considered as neuralgias (section 13 of the 2004 IHS classification) but as other primary headaches (section 4).