Recognizing uncommon headache syndromes.

Uncommon headache syndromes can be classified into two broad categories: (1) urgent conditions, including subarachnoid hemorrhage, giant cell arteritis and bacterial meningitis, and (2) special syndromes, such as cluster headache, migraine with aura and headache caused by benign intracranial hypertension. In this article, uncommon headaches are differentiated from the common migraine and the tension headache, which fall into a third category. If a neurologic abnormality is detected during the physical examination, aggressive medical diagnostic intervention is required. Because of its cost, neuroimaging should be reserved for specific situations that herald life-threatening or acutely reversible conditions; it should not be used in the work-up of nonspecific headache. The diagnosis of common headaches can be simplified by considering tension and common migraine syndromes to exist at different points on a headache spectrum.