Delayed Diagnosis of a Ruptured Distal Posterior Inferior Cerebellar Artery (PICA) Dissecting Aneurysm Presenting as Craniocervical Junction and Spinal Subdural Hematoma.

Posterior inferior cerebellar artery (PICA) dissecting aneurysms are rare and typically present with subarachnoid hemorrhage (SAH) or ischemic symptoms, with a high risk of rebleeding in the acute phase. This case presents an atypical ruptured PICA aneurysm with a hematoma confined to the craniocervical junction and cervical cord, leading to a delayed diagnosis - a 41-year-old male with an atypical presentation of headache and neck pain without neurological deficits. Initial magnetic resonance imaging (MRI) revealed a hematoma extending from the craniocervical junction to the cervical spinal cord without intracranial SAH, leading to misdiagnosis as spinal subdural hematoma. As symptoms worsened, further investigation with MRI and digital subtraction angiography (DSA) uncovered a ruptured PICA-dissecting aneurysm. The patient underwent successful endovascular coil embolization with parent artery occlusion. This case highlights the importance of considering PICA-dissecting aneurysms in craniocervical junctions and spinal cord hemorrhage, even in the absence of typical intracranial SAH. It underscores the need for a high index of suspicion and comprehensive vascular imaging for timely diagnosis and treatment in atypical cases.