According to the International Headache Societies (IHS) Classification of Headache (1) , classic migraine must fulfil the following diagnostic criteria: A. At least 5 attacks fulfilling criteria B-D B. Headache attacks lasting 4-72 hours (untreated or unsuccessfully treated) C. Headache has at least two of the following characteristics: 1. Unilateral location 2. Pulsating quality 3. Moderate or severe pain intensity 4. Aggravation by or causing avoidance of routine physical activity (e.g. walking or climbing stairs) D. During headache at least one of the following: 1. Nausea and/or vomiting 2. Photophobia and phonophobia E. Not attributed to another disorder
The classification of headache is based on the outward symptoms, or how the headache presents in the clinic. This poses difficulties. Later in the classification the IHS describe clinical features of cervicogenic (coming from the neck) headache as including mechanical exacerbation of pain and unilaterality (fulfilling criteria C above), nausea/vomiting, photophobia. If the attack lasts 4-72 hours it can present in identical fashion to classic migraine. This has created confusion in finding a diagnosis and has led the President of the IHS to conclude: "Headache of cervical origin and migraines often show similar clinical presentations." (2)
If migraine is defined by the way it looks, and it can look identical to cervicogneic headache, how can a migraine possibly be diagnosed without excluding the cervical spine? This relates directly to criteria E. Not attributed to another disorder. Unfortunately criteria E usually gets as far as some type of investigation to rule out significant pathology like tumours, and may include a general assessment of the neck.
What is required is an expert examination of the upper cervical spine to eliminate the spine as a cause.
(1) IHS (2004) The International Classification of Headache Disorders (II). Cephalalgia, 24 (S1) (2) Goadsby PJ, Bartsch T (2005) Anatomy and physiology of pain referral patterns in primary and cervicogenic headache disorders. Headache Currents;10:42-48.