Secondary Nummular Headache: A New Case Series and Review of the Literature.

Background: Nummular headache (NH) is defined in the International Classification of Headache Disorders (ICHD) by the presence of localized pain circumscribed to a small round area of the scalp, not better accounted by any other diagnosis. As in many other primary headache disorders, secondary cases might occur. To date, 13 secondary cases have been published. We aim to present a long series of secondary NH and review the literature of symptomatic NH.

Patients And Methods: Retrospective analysis of an observational prospective cohort in a headache unit located in a tertiary hospital. We included patients that fulfilled ICHD criteria and were attributed to a secondary cause. We describe the clinical characteristics, the underlying causes, and the response to treatment.

Results: We included 274 NH patients; eight of them (2.9%) were considered secondary. In one patient the underlying cause was subcutaneous, as for six cases the lesion was located in the bone (two hemangiomas, one osteoma, three different types of cysts), and in one was intracranial but closely related with internal diploe (cavernoma). Among our patients with secondary NH, a preventive therapy was not always needed and, when required, gabapentin or onabotulinumtoxinA were used with positive response.

Conclusions: Secondary NH phenotype overlaps primary NH. Therefore, we recommend routine imaging study in every NH patient. Concerning treatment, it was not necessary to remove the underlying lesion to control the pain and many cases responded to the same prophylactics as primary NH cases.