Nummular headache after trans-sphenoidal surgery: a referred pain-based headache syndrome.

Nummular headache (NH) is a newly categorized primary headache characterized by a consistent location, shape and size of painful area in each attack. The etiopathogenesis is entirely unknown. Currently, the peripheral theory of epicranial neuralgia is accepted more widely than the central theory but it cannot fully explain the clinical picture. We report a patient who suffered from a relapsing and remitting course of NH at the high parietal area and vertex shortly after resection for pituitary prolactinoma via a trans-sphenoidal approach. There was no focal trophic change or paresthesia but a mild allodynia in the painful area. The patient did not exhibit trigeminal sensory disorder or cranial trauma thoroughly. The pain responded well to gabapentin. Therefore, physicians should be aware of postoperative NH, which is amenable to treatment. The findings in our patient support a dual mechanism of NH and suggest that central NH is a form of referred pain.