Abstract 462: Watershed Shift Phenomenon in MCA Occlusion Patient After Direct Revascularization Surgery

Introduction Direct revascularization procedures, such as superficial temporal artery to middle cerebral artery (STA‐MCA) bypass, are commonly performed to restore cerebral blood flow in patients with intracranial stenosis. While the primary aim of this surgery is to alleviate ischemic symptoms, unexpected post‐operative changes, such as the watershed shift phenomenon, can complicate patient's neurologic recovery and affect neurological outcomes. In this case report we present a case where occurrence of a watershed shift phenomenon in a patient following STA‐MCA bypass surgery, affecting immediate post‐operative neurologic status, requiring post‐surgical management. Method A 66‐year‐old male patient presented with a recurrent dysarthria and right side weakness. Patient showed was selected for a STA‐MCA bypass. Pre‐operative imaging (MRI and MRA) indicated compromised blood flow in the distal MCA territory. Direct revascularization surgery was performed, and the performed successfully. Results Post‐surgery, the patient demonstrated significant improvement in her neurological function. However, on POD#1, the patient showed sudden dysarthria, and MR diffusion showed acute infarction on Lt temporal lobe. Symptom was relieved shortly after fluid therapy, but on POD#3 patient showed sudden decrease in mentality and MRI showed newly developed signs of hyperperfusion syndrome, which was soon recovered with blood pressure control. On POD #6 patient showed sudden global aphasia and disorientation. Brain CT angiography and perfusion showed good patency of anastomosis site, but decreased CBF, delayed TTD on temporal lobe adjacent to it, which suggested watershed shift phenomenon. Systolic blood pressure was controlled to 160~180mmHg strictly, and patient recovered from global aphasia. Blood pressure was gradually normalized, and patient was discharged without any neurologic sequlae. Conclusion In this case we present the importance of monitoring potential watershed shift phenomenon following STA‐MCA bypass surgery. While immediate post‐operative improvements can be expected, neurovascular dynamics should be continuously evaluated to address any unexpected complications that may arise. It is important to keep in mind that such complications may occur in post‐operative patients who underwent direct revascularization surgery.