The IASP classification of chronic pain for ICD-11: chronic secondary headache or orofacial pain

This article describes chronic secondary headache and chronic orofacial pain (OFP) disorders with respect to the new International Classification of Diseases (ICD-11). The section refers extensively to the International Classification of Headache Disorders (ICHD-3) of the International Headache Society that is implemented in the chapter on Neurology in ICD-11. The ICHD-3 differentiates between primary (idiopathic) headache disorders, secondary (symptomatic) headache disorders, and OFP disorders including cranial neuralgias. Chronic headache or OFP is defined as headache or OFP that occurs on at least 50% of the days during at least 3 months and lasting at least 2 hours per day. Only chronic secondary headache and chronic secondary OFP disorders are included here; chronic primary headache or OFP disorders are listed under chronic primary pain syndromes that have been described in a companion publication. The subdivisions of chronic secondary OFP of ICHD-3 are complemented by the Diagnostic Criteria for Temporomandibular Disorders and contributions from the International Association for the Study of Pain Special Interest Group on Orofacial and Head Pain and include chronic dental pain. The ICD-11 codes described here are intended to be used in combination with codes for the underlying diseases, to identify patients who require specialized pain management. In addition, these codes shall enhance visibility of these disorders in morbidity statistics and motivate research into their mechanisms.