The impact of early perfusion CT measurement after extracranial-intracranial bypass surgery

OBJECTIVE: The early postoperative period after extracranial-intracranial bypass surgery carries the risk of hypo- as well as hyperperfusion. The purpose of this study is to evaluate early perfusion computerized tomography (PCT) after revascularization to assess the hemodynamic balance.

METHODS: Standard cerebral bypass surgery was performed on ten patients, and PCT measurement within 6 h after surgery was performed and analyzed.

RESULTS: The hemisphere with reduced cerebral vascular reserve (CVR) showed a regional cerebral baseline blood flow (CBF) of 5.58 ± 1.69 and a regional cerebral baseline blood volume (CBV) of 2.41 ± 0.76 before surgery. Mean transit time (MTT) was 4.16 ± 0.9 s and time to peak (TTP) 3.25 ± 1.62 s. After the procedure values changed significantly (p < 0.05) in eight patients who had no complications. Patency rate was documented in all patients by angiography. One patient showed a decrease of CBF and CBV and an increase of MTT and TTP. Clinically the patient developed a transient hemiparesis immediately after surgery. Another patient showed the expected increase in CBF and CBV; however, MTT and TTP also increased. A delayed hemiparesis probably related to hyperperfusion occurred with improvement in the follow-up.

CONCLUSION: This pilot study demonstrates that early PCT parameters can provide immediate and detailed information about hemodynamic parameters and seems to have a predictive value regarding the morbidity of hypo- or hyperperfusion in patients after cerebral bypass surgery.