Evidence-Based Reviews

Electroconvulsive therapy: How modern techniques improve patient outcomes

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Refinements have decreased memory loss, other adverse effects while retaining efficacy



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Electroconvulsive therapy (ECT) has remained one of the most effective treatments for major depressive disorder (MDD) since it was introduced >70 years ago.1 ECT’s primary indication is severe, treatment-resistant MDD but sometimes it is used to treat other disorders, including bipolar mania and schizophrenia. In ECT, electrical current is delivered to a patient’s brain via electrodes placed on the scalp to induce a seizure while the patient is under anesthesia and a muscle relaxant. ECT’s exact mechanism of action for MDD is unknown, but researchers believe it may relieve depressive symptoms by regulating functional disturbances in relevant neural circuits.2

Research has shown that 64% to 87% of patients with severe MDD respond to ECT, with response rates as high as 95% for patients with MDD with psychotic features.3-5 Although patients may respond more quickly, 6 to 12 sessions typically are required to resolve a severe depressive episode.2

Despite ECT’s proven effectiveness, several factors have limited its widespread use, including limited access and expertise, adverse cognitive effects such as memory impairment, and negative public perception based on how ECT was administered decades ago.2 This article describes current methods of administering ECT, and how these changes have helped minimize these concerns while retaining efficacy.

Modern ECT practices

Since ECT was first used in the 1930s, clinicians have made many modifications to improve its efficacy and safety. Refinements to how ECT is administered include changing waveform parameters, individualizing dosing to seizure threshold, and altering electrode placement.6,7

Pulse width. Most ECT devices used today feature a constant-current output stimulator8 that allows continuous current regulation.7 Total charge, in millicoulombs (mC), is the common metric.7 Pulse width is a commonly altered waveform parameter in ECT delivery. Most research supports administering repeated brief or ultra-brief pulses (0.5 to 2 milliseconds), which is associated with greater charge efficiency and fewer side effects than traditional sine wave ECT dosing.8,9 Using a brief or ultra-brief pulse width increases clinical efficiency and decreases side effects because it focuses the stimulus on brain regions that regulate mood while limiting stimulation of brain regions involved in cognitive functioning.7 With brief-pulse stimulus, a patient’s cognitive performance may return to baseline levels within 3 days of treatment.6 Increasing evidence demonstrates that using a larger number of pulses with a brief pulse width and amplitude enhances ECT’s antidepressant effects while reducing unwanted neurocognitive side effects.7

Dosing and duration. In terms of clinical efficacy, how much the electrical stimulus exceeds a patient’s seizure threshold— the minimum amount of electrical charge that induces a generalized CNS seizure10—is more important than the absolute intensity of the stimulus.1 The degree to which the stimulus should exceed the seizure threshold depends on electrode placement, which is described below.

Acute therapy patients typically receive 2 to 3 treatments each week,11,12 culminating in 12 to 18 treatments.8,12 The optimum number of sessions administered is determined by the ratio of clinical improvement to the severity of cognitive adverse effects.3

Electrode placement. Spatial targeting of stimulus is crucial to maximize therapeutic benefits and minimize side effects. Concerns about cognitive side effects have led to variations in electrode placement to minimize the amount of brain parenchyma affected by electrical discharge (Table).1,7,8 The most commonly used placements are:

  • bitemporal (BT)—electrodes are placed midline between the eye and ear on both sides of the head
  • right unilateral (RUL)—1 electrode is positioned just lateral to the vertex and the other at the right temple.7
When given in doses close to a patient’s seizure threshold, RUL ECT offers only modest effects, but at suprathreshold doses—eg, 6 times the seizure threshold—it is as effective as BT placement1 but avoids cognitive disruption.9 Patients who do not respond to several seizures with RUL placement often are switched to BT to enhance clinical response.8 In BT ECT, stimulus is administered at 1.5 times the patient’s threshold levels. Exceeding these values is unlikely to increase efficacy, but can contribute to adverse effects.1


ECT electrodes: Bitemporal vs right unilateral placement

BTElectrodes are placed midline between the eye and ear on both sides of the headStimulus is administered at 1.5 times a patient’s seizure threshold. Often used for patients who do not respond to several seizures with RUL
RUL1 electrode positioned just lateral to the vertex and the other at the right templeWhen stimulus is administered in doses 6 times a patient’s seizure threshold, RUL is as effective as BT but avoids cognitive disruption. Offers only modest effects when stimulus is administered in doses close to a patient’s seizure threshold
BT: bitemporal; ECT: electroconvulsive therapy; RUL: right unilateral
Source: References 1,7,8


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