Emotional responses during unilateral amobarbital anesthesia: differential hemispheric contributions?

To explore (1) effects of test and subject variables in determining euphoric and dysphoric responses during unilateral amobarbital anesthesia and (2) which cerebral areas contribute to the emotional responses.

Incidence of euphoric and dysphoric reactions during left- and right-sided amobarbital anesthesia of the internal carotid artery (ICA) and selective anesthesia of the middle cerebral (MCA) and the posterior cerebral (PCA) artery was recorded. The sample comprised 270 Norwegians (6-61 years), and a total of 562 injections were performed under conditions endeavoring to calm down the patients.

The overall incidence of observed emotional responses during ICA anesthesia was 21.5%, euphoric reactions being about 10 times more frequent than dysphoric. The incidence of euphoric reactions, however, was not significantly higher under right- than under left-sided anesthesia, and dysphoric reactions were not more frequent under left- than under right-sided anesthesia. Indeed, 13 patients showed elevated mood under both right- and left-sided anesthesia. Anesthesia of the territories of ICA and MCA gave rise to similar results, while no cases of mood change were observed under selective PCA anesthesia.

It is concluded that unilateral amobarbital anesthesia as such, irrespective of side, may trigger both euphoric and dysphoric responses. The relative frequency obtained is influenced importantly both by the emotional responsiveness of the subjects and the emotional climate of the test situation. Finally, it is suggested that brain regions supplied by the PCA contribute less to modulation of euphoric and dysphoric responses than those supplied by the MCA or the ICA.