History and physical examination are used to diagnose migraine headaches (Cutrer 2012; Katsarava 2012; NHF 2012; Walling 2011; Goldman 2011; Univ. of Maryland Medical Center 2012).
Migraine headache is often misdiagnosed as sinus headache or tension-type headache (NHF 2012). This is especially true when the headache complaints are not accompanied by the typical features of migraine such as nausea, light/sound sensitivity, and exacerbation upon physical activity (Cutrer 2012).
Some less common but potentially more serious disorders including subarachnoid hemorrhage, intracranial mass lesions, cerebral vasculitis, and others can cause migraine-like symptoms. Therefore, it is important that your doctor rule out other possible causes of headache, especially in the absence of history of migraine (Merck Manual 2012; Kwiatkowski 2009; Bope 2012; Ferri 2012).
When physicians are not sure that migraine is the proper diagnosis, tests such as computerized tomography (CT), magnestic resonance imaging (MRI), and a spinal tap (lumbar puncture) may be used to help rule out other possible conditions (Mayo Clinic 2012; Kwiatkowski 2009).