Current concepts in chronic post-traumatic headache.

Over the years, there has been much confusion and conflict regarding when a post-traumatic headache (PTH) should be classified as chronic. Chronic pain usually is described as pain persisting for longer than 6 months. For many years, a chronic PTH was considered to be a headache lasting longer than 2 months. Some useful definitions and criteria were published in 2003 by the International Headache Society, in the Second Edition of the Classification and Diagnostic Criteria for Headache Disorders. These criteria are reviewed and discussion follows regarding the problem of when a chronic PTH should be classified as permanent. This becomes very important in a medical-legal context. Management of chronic PTH often will require a multifactorial approach.