Defined boundaries of the<unk>  region. International Classification of Diseases (ICD-11) is a new classification coming into effect as of January 1, 2022. It includes chronic secondary headaches and<unk> . The classification has been established by a close cooperation between International Association for the Study of Pain (IASP), World Health Organization (WHO) and the International Headache Society (IHS). There are 4 main classifications prior to ICD-11 which attempt to classify the causes of<unk> . * The International Classification of Headache Disorders third edition (ICHD-3), a publication by the International Headache Society. https://ichd-3.org/ * The Classification of Chronic Pain Second Edition (Revised), a publication by the International Association for the Study of Pain. *<unk> : Guidelines for Assessment, Diagnosis, and Management, Fifth Edition by American Academy of<unk>  (AAOP): www.aaop.org. * The Research Diagnostic Criteria for Temporomandibular Disorders (see TMD). It has also been suggested that the most basic etiologic classification of<unk>  is into the following 3 groups: # Primarily somatic, arising from musculoskeletal (e.g. TMD pain or periodontal pain) or visceral structures (e.g. pulpal pain or pain from the salivary glands), and transmitted via an intact pain transmission and modulation system. # Primarily neuropathic, which occurs as a result of abnormal or damaged pain pathways, e.g. a surgical or traumatic injury to a peripheral nerve. # Primarily psychological, which is rare (See: psychogenic pain)
Orofacial pain
Periocular injection
Periorbital hyperpigmentation
Tinnitus
Gastroptosis
Enophthalmos
Ear pain
Subconjunctival injection