Spontaneous Intracranial Hypotension: A Rare Etiology of Subarachnoid Hemorrhage.

Subarachnoid hemorrhage (SAH) is a rare complication of spontaneous intracranial hypotension (SIH), and the underlying pathophysiological mechanism linking these two conditions is not yet fully understood. We report the case of a previously healthy 49-year-old female patient who presented with a bilateral fronto-occipital headache that worsened over the course of five days, accompanied by neck pain, nausea, photophobia, and phonophobia. The headache was refractory to analgesic treatment and lessened with recumbency. A brain CT scan revealed a mild SAH on the right Sylvian fissure, while CT angiography (CTA) and digital subtraction angiography (DSA) were unremarkable. MRI demonstrated features consistent with SIH. In this patient, MRI findings supported the hypothesis of brain sag with bridging vein strain as the underlying mechanism. An epidural blood patch was considered but deferred due to spontaneous clinical improvement without recurrence. This case report emphasizes that SIH should be considered in patients presenting with non-aneurysmal SAH, particularly if the headache has orthostatic features.