Transcranial Doppler ultrasound: a new method of monitoring hemispheric anesthetization during the intracarotid amobarbital procedure.
BACKGROUND
Electroencephalography (EEG) is traditionally used to assess the duration of hemispheric anesthetization and to monitor return of function in the anesthetized hemisphere during the intracarotid amobarbital procedure (IAP), but EEG changes are not consistently seen. The authors evaluated the role of continuous transcranial Doppler (TCD) monitoring as an alternative to EEG.


METHODS
The authors performed both continuous TCD monitoring and EEG during the IAP in 10 patients with medically intractable partial epilepsy. Mean velocities were monitored continuously in both middle cerebral arteries (MCAs), and changes in MCA velocities on continuous TCD monitoring were time locked with the EEG changes.


RESULTS
The average mean MCA velocities were within normal limits bilaterally (50-85 cm/s) in all patients at baseline. Mean MCA velocites increased in all patients to 95-115 cm/s at the start of the test when the patients were asked to raise their hands and start counting. After injection of sodium amobarbital, mean MCA velocities in all patients dropped dramatically on the ipsilateral side to values of 12-39 cm/s and returned to the baseline average value when the hemiparesis recovered. In 8 patients, the duration of delta activity on EEG coincided with the time interval during which the mean MCA velocities were low on TCD monitoring. In 2 patients, despite the presence of hemiparesis clinically and a drop in mean MCA velocities on the ipsilateral side on continuous TCD monitoring, EEG remained normal on the ipsilateral side.


CONCLUSIONS
Continuous TCD monitoring may be a more sensitive method than EEG in determining the duration of hemispheric anesthetization during IAP. Because the items for assessment of memory are presented during the period of hemispheric anesthetization, TCD may be useful in more precisely defining the time window for memory testing.
Acharya
Vinita J
VJ
Department of Neurology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. acharya@pitt.edu
Acharya
Jayant N
JN
Tegeler
Charles H
CH
Morris
Pearse
P
Meads
Dana
D
O'Donovan
Cormac A
CA
D000654:Amobarbital / Q000008:administration & dosage* / Q000494:pharmacology; D001783:Blood Flow Velocity; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology / Q000601:surgery; D002339:Carotid Arteries; D004569:Electroencephalography / Q000187:drug effects; D004828:Epilepsies, Partial / Q000601:surgery*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000494:pharmacology; D007269:Injections, Intra-Arterial; D008568:Memory / Q000187:drug effects / Q000502:physiology; D008991:Monitoring, Physiologic / Q000379:methods*; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D017585:Ultrasonography, Doppler, Transcranial
D006993:Hypnotics and Sedatives; D000654:Amobarbital