5.3.1 ECT indications, benefits, risks and outcomes

What ECT is and where it came from

Electroconvulsive therapy (ECT) uses a controlled electrical stimulus to induce a generalised seizure under general anaesthesia and muscle relaxation.

• Convulsive therapy entered psychiatry in the 1930s, and chemically induced seizures came first.

• Meduna induced seizures with camphor in 1934.

• Cerletti and Bini induced seizures electrically in Rome in 1938.

Indications

The National Institute for Health and Care Excellence (NICE) limits ECT to three conditions. Severe or resistant conditions outside this list have no NICE-supported place for ECT.

• Malignant catatonia, with autonomic instability, hyperthermia and rigidity, is an emergency, and ECT should not wait until benzodiazepine dose escalation is exhausted.

• Other recognised uses are neuroleptic malignant syndrome, schizoaffective disorder and refractory seizures.

• Dissociative, functional and personality conditions are not indications.

• ECT is not routine treatment for moderate depression or schizophrenia.

Severe and resistant depression

• Severe depression that has failed adequate antidepressant trials, with poor oral intake, calls for ECT next, including in older adults, because it works within days to weeks.

• In treatment-resistant depression ECT has the strongest evidence, giving better response and remission than high-frequency repetitive transcranial magnetic stimulation (rTMS) with a similar drop-out rate.

• Vagus nerve stimulation is used only after other options, including ECT, and stimulant augmentation has limited evidence.

Predictors of response

• Psychotic features, such as mood-congruent delusions, are the most reliable clinical predictor of good response in depression, with the highest response and remission rates.

• Melancholic features have equivocal predictive value.

• Older age, shorter episodes and previous response to ECT also predict better outcome, while chronic illness and repeated treatment failure predict lower response.

Efficacy

The UK ECT Review Group's 2003 meta-analysis found:

• Remission after first-line ECT for severe depression is around 60 to 80%.

• Evidence for short-term benefit is stronger than for lasting remission.

Dose and electrode placement

• Stimulus dose relative to seizure threshold decides how well unilateral ECT works: dosing well above threshold improves response, as NICE's appraisal recognised, but increases cognitive impairment.

• Changing placement, adding a third weekly session, shortening the pulse or using a sine wave does not improve response to unilateral ECT.

• Bilateral (bitemporal) placement causes more cognitive impairment than right unilateral, which spares autobiographical memory.

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Cognitive adverse effects

Memory disturbance is the commonest adverse effect of ECT, and it takes both anterograde and retrograde forms.

• Retrograde loss of recent autobiographical memory is the commonest and most persistent memory effect.

• It shows a temporal gradient, sparing remote memories, and recovers slowly and usually almost completely.

• Implicit and semantic memory are relatively spared.

• Anterograde difficulty retaining new information generally improves over days to weeks after the course.

• Standard tests usually return to baseline within weeks, but patients may still report autobiographical gaps, so take their complaints seriously.

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Somatic and physical adverse effects

• Brief postictal confusion is common.

• Deaths are rare, at a few per 100,000 treatments.

• A brief parasympathetic response can cause bradycardia or asystole, followed by tachycardia, hypertension and rises in cerebral blood flow and intracranial pressure.

• Prolonged seizures and status epilepticus need prompt treatment.

Contraindications

• No contraindication is absolute.

• Relative contraindications are conditions that the seizure's haemodynamic and cerebral effects make dangerous now, not conditions that are old, stable or merely assumed to exclude ECT.

• They include recent myocardial infarction, unstable angina, cerebral aneurysm or vascular malformation, raised intracranial pressure, recent intracerebral haemorrhage and major anaesthetic risk.

• An unsecured cerebral aneurysm is dangerous because the seizure raises blood pressure, cerebral blood flow and intracranial pressure.

• These conditions may change the timing, technique or monitoring rather than rule ECT out.

• Untreated severe depression and catatonia cause dehydration, malnutrition, thrombosis, aspiration and suicide, so weigh ECT's risks against those of illness continuing.

Pregnancy

• Severe illness in pregnancy is a first-line circumstance for ECT.

• Upper gastrointestinal changes of pregnancy raise the risk of aspirating gastric contents under the general anaesthetic.

• The haemodynamic, renal and protein-binding changes of pregnancy are real but do not matter for ECT anaesthesia.

Relapse and continuation treatment

• Nortriptyline plus lithium is the drug regimen with established trial evidence.

• Continuation ECT is given at decreasing frequency.

• Plan continuation care before the acute course ends, and keep monitoring cognition.