Investigation on the Value of Bilateral Index (BIS) Monitoring for Magnetic Seizure Versus Electroconvulsive Therapy

Electroconvulsive therapy (ECT) has been shown to be an effective treatment for patients suffering from depression, who do not respond to medical treatment. However it is often dismissed by patients, who feel uncomfortably about the application of electric shocks to their heads. In 2000, magnetic seizure therapy (MST) has been introduced which uses magnetism instead of electricity to evoke convulsions. MST seems to be as effective as ECT in terms of its antidepressant potency but may be associated with less severe cognitive side effects. Control of anaesthesia during seizure therapy is demanding since light anesthesia might be associated with awareness, whereas deep anesthesia impedes the antidepressant effect of the convulsion. Therefore, Bispectral index (BIS) monitoring is frequently used to tailor anaesthesia for ECT, however little is known about BIS following MST. The investigators hypothesize that in comparing MST with ECT, (a) patients show a faster increase in BIS and that (b)less left-right differences occur in BIS.