Effects of superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis on the cerebrospinal fluid gas tensions and pH in hemodynamically compromised patients.

Abstract

This study was aimed to directly measure cerebrospinal fluid (CSF) gas tensions and pH before and after STA-MCA anastomosis for occlusive carotid artery diseases to investigate its direct effects on the ischemic brain. This study included 9 patients who underwent STA-MCA anastomosis on the basis of CBF studies. About 1 mL of CSF was collected before and after bypass procedures, and CSF pH, CSF PO₂, and CSF PCO₂ were measured with a blood gas analyzer. As the controls, the CSF was collected from 6 patients during surgery for unruptured cerebral aneurysm. CSF PO₂ and CSF PCO₂ were expressed as the ratio to PaO₂ and PaCO₂, respectively. Before bypass procedure, CSF PO₂/PaO₂ was 0.88 ± 0.16, being lower than the controls (1.10 ± 0.09; P = 0.005). CSF PCO₂/PaCO₂ was 0.93 ± 0.13, being higher than the controls (0.84 ± 0.06; P = 0.039). Ipsilateral-to-contralateral CBF ratio had a positive correlation with CSF PO₂/PaO₂ (P = 0.0028) but a negative correlation with the CSF PCO₂/PaCO₂ (P = 0.0045). STA-MCA anastomosis increased CSF pH from 7.402 ± 0.133 to 7.504 ± 0.126 (P = 0.0011) and CSF PO₂/PaO₂ from 0.88 ± 0.16 to 1.05 ± 0.26 (P = 0.018) but decreased CSF PCO₂/PaCO₂ from 0.93 ± 0.13 to 0.70 ± 0.17 (P = 0.0006). The severity of cerebral ischemia before surgery is intensely reflected in the gas tensions and pH of the CSF. STA-MCA anastomosis carries dramatic effects on CSF gas tensions and pH in hemodynamically compromised patients. CSF would be a valuable surrogate biomarker to monitor the severity of cerebral ischemia.