Low bispectral index values following electroconvulsive therapy associated with memory impairment

Area of Science:

• Neuroscience
• Anesthesiology
• Psychiatry

Background:

• Electroconvulsive therapy (ECT) is a medical treatment for severe depression.
• Patients undergoing ECT may experience altered consciousness and memory deficits.
• Bispectral index (BIS) monitoring is used to assess anesthetic depth.

Purpose of the Study:

• To investigate the time course of memory recovery and BIS values after ECT.
• To determine the relationship between BIS values and post-ECT amnesia.

Main Methods:

• Five patients with depression undergoing repeated ECT were studied.
• Memory recall for a presented object was assessed at four time points.
• Continuous BIS data were collected until pre-anesthetic levels were reached.
• Receiver operating characteristic (ROC) curve analysis was used to assess BIS-memory associations.

Main Results:

• Patients frequently experienced prolonged periods of low BIS values (50-70) and sleep post-ECT, waking 1-2 hours later.
• All patients could recall the object when BIS values returned to baseline.
• The ROC curve analysis showed a strong association (area under curve = 0.902) between BIS values and memory disturbance.

Conclusions:

• ECT is associated with frequent prolonged periods of low BIS values and sleep post-treatment.
• ECT procedures lead to amnesia, with memory formation impairment linked to low BIS values.
• BIS values returning to pre-anesthetic levels correlate with memory recovery after ECT.