LAUSR

Background Hemicrania continua (HC) is a primary headache syndrome characterized by a unilateral, moderate, continuous headache with exacerbations marked by migrainous and cranial autonomic symptoms. However, clinical phenotypes similar to primary HC may be subtended by several disorders. Case report We report the case of a 62-year-old man experiencing, over the previous year, a headache completely consistent with HC and its absolute responsiveness to indomethacin therapy. Later, the patient developed diplopia caused by sixth cranial nerve palsy ipsilateral to headache. In this frame, clinical, laboratory and neuroimaging characteristics supported the diagnosis of idiopathic hypertrophic pachymeningitis (IHP). Conclusions IHP is a rare fibrosing inflammatory disorder leading to a localized or diffuse dura mater thickening. IHP clinical manifestations are a progressively worsening headache and signs related to cranial nerves involvement and venous sinus thrombosis. Here, we report, for the first time, a HC phenotype subtended by IHP.