<unk>  <unk>  is a type of chronic<unk> <unk>  which does not fulfill any other diagnosis. There is no consensus as to a globally accepted definition, and there is even controversy as to whether the term should be continued to be used. Both the International Headache Society (IHS) and the International Association for the Study of<unk>  (IASP) have adopted the term persistent idiopathic<unk> <unk>  (PIFP) to replace<unk> . In the 2nd Edition of the International Classification of Headache Disorders (ICHD-2), PIFP is defined as "persistent<unk> <unk>  that does not have the characteristics of the cranial neuralgias ... and is not attributed to another disorder." However, the term<unk>  continues to be used by the World Health Organization's 10th revision of the International Statistical Classification of Diseases and Related Health Problems and remains in general use by clinicians to refer to chronic<unk> <unk>  that does not meet any diagnostic criteria and does not respond to most treatments. The main features of<unk>  are: no objective signs, negative results with all investigations/ tests, no obvious explanation for the cause of the<unk> , and a poor response to attempted treatments.<unk>  has been described variably as a medically unexplained symptom, a diagnosis of exclusion, a psychogenic cause of<unk>  (e.g. a manifestation of somatoform disorder), and as a neuropathy.<unk>  is usually burning and continuous in nature, and may last for many years. Depression and anxiety are often associated with<unk> , which are either described as a contributing cause of the<unk> , or the emotional consequences of suffering with unrelieved, chronic<unk> . For unknown reasons,<unk>  is significantly more common in middle aged or elderly people, and in females.<unk>  odontalgia (AO) is very similar in many respects to<unk> , with some sources treating them as the same entity, and others describing the former as a sub-type of<unk> . Generally, the term AO may be used where the<unk>  is confined to the teeth or gums, and<unk>  when the<unk>  involves other parts of the face. As with<unk> , there is a similar lack of standardization of terms and no consensus regarding a globally accepted definition surrounding AO. Generally definitions of AO state that it is<unk>  with no demonstrable cause which is perceived to be coming from a tooth or multiple teeth, and is not relieved by standard treatments to alleviate dental<unk> . Depending upon the exact presentation of<unk>  and<unk>  odontalgia, it could be considered as craniofacial<unk>  or orofacial<unk> . It has been suggested that, in truth,<unk>  and AO are umbrella terms for a heterogenous group of misdiagnosed or not yet fully understood conditions, and they are unlikely to each represent a single, discrete condition.
Atypical facial pain
Nablus mask-like facial syndrome
Necrospermia
Symmastia
Dogger Bank itch
Pellagra
Trypophobia
Focal hyperhidrosis