Abstract
Nummular headache is characterized by mild to moderate, pressure-like head pain exclusively in a small, rounded or oval area without underlying structural lesions. Either during symptomatic periods or interictally, the affected area shows a variable combination of hypoesthesia, dysesthesia, paresthesia, tenderness or discomfort. The particular topography and signs of sensory dysfunction suggest that nummular headache is an extracranial headache probably stemming from epicranial tissues such as the terminal branches of sensory nerves. Apart from nummular headache, other headaches and neuralgias such as idiopathic stabbing headache, trochleitis, supraorbital neuralgia, external compression headache, nasociliary neuralgia, occipital neuralgias, and auriculotemporal neuralgia have temporal or spatial features that suggest a peripheral (extracranial) origin, i. e. stemming from the bone, scalp, or pericranial nerves. Common to these disorders is a focal localization or a multidirectional sequence of paroxysms, paucity of accompaniments, tenderness on the emergence or course of a pericranial nerve or on the tissues where pain originates, and possible presence of symptoms and signs (including effective treatment with locally injected anesthetics or corticosteroids) of nerve dysfunction. These observations led to the emergence of a conceptual model of head pain with an epicranial origin that we propose to group under the appellation of epicranias (headaches and pericranial neuralgias stemming from epicranial tissues). Nummular headache is the paradigm of epicranias. Epicranias essentially differ from other primary headaches with an intracranial origin and features of visceral pain, i. e. splanchnocranias that are characterized by a painful area wider than that of epicranias, no clear borders, presence of autonomic features, regional muscle tension, and driving of the process from the brain and brainstem.