Symptomatic Vasospasm Refractory to Clazosentan after Subarachnoid Hemorrhage of Ruptured Vertebral Artery Dissecting Aneurysm: Clinical Implications from Two Contrasting Cases

Clazosentan prevents vasospasms after aneurysmal subarachnoid hemorrhage (SAH). However, clinical data on patients with SAH with ruptured vertebral artery dissecting aneurysms (VADAs) are limited. We report the case of a 49-year-old male patient with mild-grade (WFNS grade 1) thick and diffuse (modified Fisher grade 3) SAH who underwent endovascular trapping of a ruptured VADA, resulting in a poor functional outcome with a modified Rankin Scale score of 4 due to severe symptomatic vasospasm refractory to clazosentan, requiring repeated rescue endovascular therapies and chronic communicating hydrocephalus. A retrospective analysis of the clot density in the basal and Sylvian cisterns, assessed by the Hounsfield unit (HU) values of serial CT scans, in this patient showed persistent higher values, distinct from another VADA case that showed a decline in HU values with a good clinical course. These results imply the limited effectiveness of clazosentan in cases of thick and diffuse SAH after a ruptured VADA, even in good-clinical-grade patients treated with less invasive modalities. The HU values may become a simple quantitative marker for predicting symptomatic vasospasms and chronic hydrocephalus.