Frequency and characteristics of spinal bleeding sources in non-traumatic angiogram-negative subarachnoid hemorrhage

Introduction: Angiogram-negative subarachnoid hemorrhage (AN-SAH) accounts for 5-15% of spontaneous SAH. This study aims to analyze the frequency and characteristics of spinal bleeding sources in patients with AN-SAH. Methods: 140 patients suffering from AN-SAH treated at our institution from 2012 to 2022 were included in this retrospective cohort study. Results: 52.1% were diagnosed with perimesencephalic SAH, 35.0% with non-perimesencephalic SAH and 12.9% with CT-negative SAH (diagnosed by lumbar puncture). Additional MRI identified a spinal bleeding source in 4 patients (2.86%). These patients presented with local spine pain or neurological deficits (RR 3.9706 [95%-CI: 0.7272-21.6792]; p<0.001) and were younger (mean difference 14.85 years [95%-CI: 0.85-28.85; p=0.038]) compared to patients without a spinal bleeding source. Conclusions: AN-SAH caused by spinal pathology is rare. This study indicates that craniocervical and holospinal MRI should be considered in AN-SAH, especially for young patients with AN-SAH who present with back pain or neurological deficits.