Indomethacin-responsive hemicrania continua-like headache secondary to cavernous sinus inflammatory pseudotumor: a case report

Hemicrania continua (HC) is a rare trigeminal–autonomic cephalalgia characterized by continuous, strictly unilateral headache with ipsilateral cranial autonomic symptoms (CAS) and complete response to indomethacin. Although typically considered a primary headache disorder, various structural and vascular lesions may produce secondary HC phenotypes. We report a case of indomethacin-responsive, HC-like headache caused by a cavernous sinus inflammatory pseudotumor (IPT). A 54-year-old man presented with a 2-month history of continuous, right-sided headache accompanied by ipsilateral CAS. The headache resolved completely with indomethacin treatment; however, persistent focal neurological deficits prompted further diagnostic evaluation. Electrophysiological testing demonstrated abnormalities in the right trigeminofacial reflex pathway, and subsequent brain magnetic resonance imaging (MRI) revealed enhancing lesions in the right cavernous sinus and orbital apex, which were consistent with an IPT. Corticosteroid therapy resulted in a complete clinical recovery with near-complete radiological resolution. This case demonstrates that complete indomethacin responsiveness does not exclude a secondary etiology. This finding highlights the vital role of contrast-enhanced MRI and electrophysiological testing when atypical neurological features are present.