Imaging-Based Diagnosis of Intracranial Vertebral Artery Dissection Leading to Non-Aneurysmal Subarachnoid Hemorrhage: A Vascular-Neuroimaging Case Report

Background: Intracranial vertebral artery dissection (VAD) is an uncommon but clinically significant cause of non-aneurysmal subarachnoid hemorrhage (SAH). When hemorrhagic, its early mortality is driven largely by the elevated risk of rebleeding. Diagnosis relies heavily on advanced vascular imaging, as clinical manifestations often overlap with those of other causes of acute headache. Case: We report the case of a 57-year-old man with hypertension and type 2 diabetes who presented with sudden, severe holocranial headache and posterior cervical pain immediately following neck hyperextension during public transportation. Initial non-contrast CT revealed a diffuse Fisher II SAH. Digital subtraction angiography demonstrated a dissection flap at the left vertebrobasilar junction with absence of opacification of the posterior inferior cerebellar artery (PICA), in the absence of aneurysms or arteriovenous malformations. MRI confirmed subarachnoid blood and an intramural hematoma signal consistent with arterial wall injury. Conclusion: This case highlights the critical role of multimodal vascular imaging—particularly CT, MRI, and catheter angiography— in diagnosing intracranial VAD presenting as non-aneurysmal SAH. Recognizing characteristic imaging features facilitates timely management, prevents diagnostic delay, and underscores the importance of considering VAD in patients with acute headache and neck pain, especially following biomechanical stress to the cervical segment.