Contralateral cerebral blood flow velocity changes after intracarotid amobarbital injection

Background and Purpose. The intracarotid amobarbital procedure (IAP) leads to a prompt decrease in ipsilateral middle cerebral artery (MCA) mean blood flow velocity (MFV). Little is known about contralateral MFV changes. Methods. The authors investigated bilateral MCA MFV using transcranial Doppler sonography (TCD) in 8 patients with epilepsy undergoing IAP. Measurements were excluded from analysis if angiography revealed any signs of interhemispheric cross-flow. Results. Within 64 seconds after amobarbital injection, ipsilateral MFV decreased to a mean of 44.4% ± 7.5% of baseline value (P < .01). In the absence of interhemispheric cross-flow and within 68 seconds, contralateral MFV decreased to 83.1% ± 7.9% (P Α .01). Conclusions. The observed decrease of contralateral MFV was not caused by amobarbital cross-perfusion. A possible underlying mechanism may be interhemispheric deafferentation.