LAUSR

Introduction Pretruncal non-aneurysmal subarachnoid hemorrhage (PNSAH; also called perimesencephalic hemorrhage or perimesencephalic pattern angiographically-negative SAH) is a distinct subtype of SAH characterized by focal SAH in the pretruncal cisterns with limited extension into the Sylvian fissures and an excellent prognosis [1–7]. The etiology of PNSAH is not entirely clear, but the culprit vessels of PNSAH include the anterior pontomesencephalic vein, the perforating arteries of the basilar artery or its branches, and the basilar artery itself. The focal hemorrhage pattern, nonexistence of vasospasm, and good prognosis have led many to suggest PNSAH is venous in origin, which is corroborated by its association with primitive anatomical variants of the venous drainage system [8–11], vein of Galen stenosis [12], deep venous or dural sinus thrombosis [13–15], low angle of basilar artery bifurcation [16], and high cerebral blood flow on computed tomography (CT) perfusion scans [17]. Rarely, PNSAH may be arterial in origin, as has been documented by reports of PNSAH in association with a basilar artery fenestration aneurysm [18], intramural basilar hematomas [19], and perforating artery rupture [19, 20]. In rare cases, a pretruncal hemorrhage pattern may be the presenting symptom of uncommon vascular malformations, such as a pontine or cerebellar venous angioma or capillary telangiectasia [21, 22], leading many to perform digital subtraction angiography or magnetic resonance imaging of the brain and spine to rule out these lesions. We report a case of PNSAH in the setting of a cerebrospinal fluid (CSF) leak in the cervical spine. We hypothesize that our patient sustained a minor trauma that provoked a dural tear and acute CSF hypovolemia, ultimately resulting in an acutely engorged pretruncal vein which subsequently ruptured.