Preoperative cerebral perfusion SPECT identify patients at risk for transient neurological deterioration after STA-MCA bypass surgery

Transient neurological deterioration (TND) is one of the most fatal complications after extracranial-intracranial bypass surgery and it has been assumed to be caused by transient hyperperfusion. This study was performed to evaluate the relationship between TND and preoperative cerebral perfusion status on brain SPECT to identify patients who are at risk of TND following superficial temporal artery middle cerebral artery (STA-MCA) bypass surgery. Sixty patients who underwent STA-MCA bypass surgery were enrolled. The resting cerebral blood flow (CBF) and cerebral vascular reserve (CVR) after acetazolamide challenge were measured before and 10 days after surgery using Tc-99m ethylcysteinate dimmer SPECT. Moreover, the CBF was measured on the third day postoperation. Follow up perfusion SPECT 6 month after surgery were obtained in 42 patients. With the use of the statistical parametric mapping and probabilistic brain atlas, the counts for the MCA territory were calculated for each image and statistical analyses were performed. In 6 of 60 patients (10%), TND occurred after surgery. The average CBF on the third postoperative day was significantly higher than the preoperative CBF (p 0.003). Furthermore, in 42 patients who had brain SPECT in the 6 months following operation, cerebral perfusion in the 6 months post operation was still higher than that observed before the operation. The increase in CBF from the preoperative day to the third postoperative day negatively correlated with preoperative perfusion (correlation coefficient = -0.66, p 0.0006). In TND patients, basal CBF on preoperative SPECT was significantly lower (p=0.01), and the changes in CBF on the third day after surgery was significant higher (p = 0.008). However, CVR did not significantly correlate with the increased perfusion after operation. The preoperative CBF and the subsequent changes in CBF after operation can help identify the risk of TND after STA-MCA bypass surgery