Nummular headache update.

Nummular headache (NH) is a rare headache disorder characterized by focal and well-circumscribed pain fixed within a rounded or oval/elliptical-shaped area of the head, typically 2 to 6 cm in diameter (Grosberg et al. Curr Pain Headache Rep 11:310-2, 2007). The disorder most commonly affects the parietal region and is almost always unilateral and side-locked. The pain is typically characterized as pressure-like, sharp, or stabbing and is usually mild to moderate in intensity. Many patients experience superimposed exacerbations of pain, lasting from seconds to days (Grosberg et al. Curr Pain Headache Rep 11:310-2, 2007). Distortions of sensation including hyperesthesia, hypoesthesia, allodynia, and paresthesias are frequently reported in the affected area. The temporal pattern may be episodic or chronic. Rarely, the disorder may be bifocal or multifocal, affecting various regions of the head simultaneously or in sequence. Treatment with gabapentin, tricyclic antidepressants, or botulinum toxin may be helpful. In this review of the more than 250 cases now reported in the literature, the epidemiology, clinical features, pathogenesis, differential diagnosis, and management of this disorder are discussed.