Transient hyperperfusion after superficial temporal artery/middle cerebral artery bypass surgery as a possible cause of postoperative transient neurological deterioration

BACKGROUND: This study was designed to investigate the relationship between transient neurological deterioration and changes in cerebral perfusion after superficial temporal artery/middle cerebral artery (STA-MCA) bypass. METHODS: Clinical characteristics of the patients with postoperative transient neurological deterioration were analyzed in 120 STA-MCA bypass procedures for ischemic cerebral diseases, such as atherosclerotic disease and moyamoya disease. Serial brain single-photon emission computed tomography (SPECT) was performed on 25 patients before surgery and on the third and tenth postoperative days. The hemispheric perfusion on SPECT was calculated semi-quantitatively using statistical parametric mapping and a probabilistic brain atlas. RESULTS: Among 120 procedures, there were 4 permanent postoperative neurological deficits (3.3%) and 20 postoperative transient neurologic deteriorations with unknown etiology (17%). In 25 patients analyzed for postoperative perfusion changes, cerebral perfusion increased on the third postoperative day and the increased perfusion negatively correlated with preoperative perfusion (correlation coefficient = -0.77; p < 0.001). Temporal changes and the location of transient hyperperfusion on SPECT correlated with the time course and neurological deficits associated with postoperative transient neurological deterioration in 3 patients. CONCLUSIONS: Postoperative transient relative hyperperfusion is a common phenomenon and may be one of the causes of postoperative transient neurological deterioration after STA-MCA bypass surgery for ischemic cerebral diseases.This study was supported by a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (grant No. A06-0171-B51004-06N1-00040B)