原発性頭蓋内低血圧症：二次性頭痛の一般的に見逃される原因

Spontaneous intracranial hypotension (SIH) is an uncommon but important cause of secondary headache that can closely mimic primary headache disorders, often leading to diagnostic delays. We present the case of a 50-year-old woman with a persistent, treatment-resistant orthostatic headache initially misdiagnosed as migraine, sinusitis, and perimenopausal symptoms. Brain MRI revealed a spontaneous subdural hematoma (SDH) along with classical features of SIH, while spinal MRI demonstrated a small longitudinal epidural fluid collection. Conservative management failed to relieve her symptoms; however, sequential non-targeted epidural blood patches (EBP) resulted in significant clinical and radiological improvement, with complete recovery noted at follow-up. This case underscores the importance of considering SIH in patients presenting with atypical or positional headaches, particularly when accompanied by SDH. Early recognition and appropriate intervention are crucial to prevent complications and optimise patient outcomes.