Electroconvulsive Therapy (ECT)

Electroconvulsive Therapy (ECT) is a medical treatment performed under general anesthesia, in which small electric currents are passed through the brain, intentionally triggering a brief seizure. The indications for treatment with ECT are numerous including for depression, bipolar mania/depression, schizophrenia, and catatonia.


During the late 1930s it was observed that people suffering from both epilepsy and serious mental illnesses exhibited an interesting phenomenon in the aftermath of a seizure. These individuals would have a reduction in psychiatric symptoms, lasting anywhere from days to weeks.[1] Based on these observations, seizures were induced in patients who did not otherwise have epilepsy. It was found that the safest way to accomplish this was by delivering an electrical shock to the head. ECT was used extensively and indiscriminately in the first three decades of it discovery, due to the lack of psychiatric medications at the time (the pre-antipsychotic and antidepressant era). This indiscriminate use came with serious complications and valid concerns: the public view of ECT, characterized in numerous movies (e.g. - One Flew Over The Cuckoo's Nest) portrayed it as an inhumane, horrific, and frightening procedure. This exaggerated portrayal in popular culture unfortunately stigmatized an effective and often life-saving procedure when used in the right patients.

Current Practice

Today, ECT is used effectively to treat severe mood disorders (i.e. - severe depression with melancholic features, psychotic depression, and severe, acute mania). Techniques and safety protocols for administering ECT have also changed dramatically. ECT is now an anesthetic procedure, and requires the use of general anesthesia and muscle relaxants. The patient is therefore fully anesthetized and asleep during the procedure. Serious or persistent side effects now extremely rare. Although, ECT is often considered a treatment of last resort, in most jurisdictions, it remains under-utilized due to stigma. ECT can be extremely effective and, at times, a life-saving procedure. ECT remains a first-line treatment for many psychiatric disorders.[2]

Overall, ECT is very safe and rapid acting. Out of all medical procedures involving anesthesia, it is the lowest risk procedure.[3] The mortality rate from ECT has been estimated to be less than 1 death per 98,000 treatments, which is similar to the background rate associated with anesthetic induction for any surgical procedure.[4] Some studies have shown a lower overall mortality rate from natural causes in inpatients who have received ECT compared to those who did not.[5]

Current indications for ECT include: treatment-refractory and medication-resistant depression, depression with psychotic features, refractory OCD, catatonia, psychosis, Parkinson's Disease, status epiplepticus,[6] severe suicidality, and neuroleptic malignant syndrome.

There are no absolute contraindications to ECT, only relative contraindications.[7] Relative contraindications include: space-occupying cerebral lesions, increased intracranial pressure, recent myocardial infarction, recent cerebral hemorrhage, unstable vascular aneurysms or malformations, pheochromocytoma, and class 4 or 5 anaesthesia risk (ASA IV, ASA V).[8]

ECT treatment ranges between 6 to 18 treatments, and can be delivered 2-3 times per week. Administering ECT only 2 times per week confers a better cognitive profile. If after 12 sessions there is no response, no further ECT should be pursued.

ECT delivers an electrical stimulus, which induces an action potential in the neurons in the brain. Before the invention of newer techniques, older sine wave machines were used. Now, brief pulse or ultra brief pulse ECT is used, which provides a more efficient delivery of electrical energy (see figure 1). The exact mechanism of action of ECT's antidepressant effects remains unknown, and is hypothesized to be due to its effects on various central nervous system functions, including neurotrophic factors, neurotransmitters, hormones, and neuropeptides.

The delivery of the electrical stimuli depends on the placement of the electrodes. The electrodes can be bifrontal, bilateral, or right unilateral (RUL) (see figure 2). Typically, RUL is used because it results in less cognitive side effects.

Sine Wave, Brief Pulse, and Ultra Brief Pulse ECT Fig. 1


ECT affects autonomic nervous system activity, which causes rapid hemodynamic changes. The heart rate goes down (as ECT causes a parasympathetic drive). The effects of ECT on the heart is similar to a brief period of “vigorous exercise.”[9]


During ECT, cortical blood flow increases by up to 300%, which increases intracranial pressure (ICP). Cerebral oxygen demand also increases up to 200% during seizure activity. ECT remains safe in patients with brain tumours and intracranial masses provided that there is not significant cerebral edema (Hence, increased ICP is a relative contraindication).[10] Brain volumes increase with ECT treatment,[11] and there is also an increase in Brain Derived Neurotrophic Factor (BDNF) levels.[12][13] During ECT, the brain will try to achieve homeostasis in response to the electrical current, and will release GABA to suppress seizures.[14] The release of GABA is thought to play a role in the antidepressant effect of ECT as well.

Phases of ECT
  1. Anesthesia
  2. Muscle relaxant
  3. The electrical stimulus

  5. Post-ictal recovery

It is important to inform patients about the risks and benefits of ECT. Below is a template for informed consent:

  • Ask patient what they understand about ECT
  • Explain procedure (# of treatments, what treatments will consist of, what happens just before and after treatment, how they will feel, how long each session lasts)
  • Explain efficacy (with depression, bitemporal is 65%, RUL is 58%)
  • Cover serious/life threatening risks (1 per 10,000 treatment deaths, risks of general anesthesia)
  • Cover common side effects (confusion, headache, muscle pains, HTN, cardiac changes, nausea, cognitive difficulties - specifically memory 1-2 months prior and after procedure may be “hazy”)
  • Discuss alternate treatment medications (continue with medications, change medications, psychotherapy options)
  • Discuss next steps (work-place adjustment, change to medications prior to treatment course beginning)
  • Limitations with treatment (no driving for 24 hours, time off work/school)
  1. Confirm ID of patient (name, age, patient diagnosis)
  2. Let anesthesia know of medication doses
  3. Assess patient for symptoms since the last treatment
  4. Ensure patient is NPO at least 8 hours prior to treatment
  5. Confirm ECT parameters
  6. Set parameters on the machine
  7. Obtain BP/HR/O2 sat/ECG monitoring
  8. Prep skin and scalp
  9. Prep ECT electrodes
  10. Place EEG monitoring electrodes appropriately
  11. Anesthesia to obtain IV access
  12. Anesthesia to administer IV meds
  13. Anesthesia to pre-oxygenate
  14. Ensure appropriate muscle relaxant (wait at least 60 seconds from the administration of succinylcholine)
  15. Anesthesia to place bite block
  16. Place ECT electrodes
  17. Administer stimulus
  18. Monitor motor seizure activity (time, strength)
  19. Monitor EEG seizure (time, resolution, post-ictal suppression)
  20. Anesthesia to ensure appropriate oxygenation, with suction of airway if necessary
  21. Administer any post-treatment medications
  22. Monitor vitas post-treatment
  23. Observe patient for 1 hour post-treatment
  24. Ensure patient is accompanied home once recovery monitoring complete
  25. Ensure documentation complete

ECT can be delivered via three placements: bilateral (bitemporal), bifrontal, or right unilateral placements. Typically, right unilateral ECT is given first due to its favourable cognitive profile. The D’Elia placement (i.e. - Right Unilateral) is the preferred standard for unilateral ECT. Left unilateral ECT can be cognitively sparing in those who rely on right hemispheric function (visual, spatial) for their livelihood.

Bilateral (bitemporal) ECT has a greater incidence of anterograde and retrograde amnesia. Bifrontal ECT may be as effective as bitemporal but is more cognitively advantageous. Ultimately, bilateral ECT should be used if there is greater urgency for improvement or life threatening situations. Also, if unilateral ECT fails after 6 to 10 treatments or there is a history of failure, then one should consider bilateral ECT.

ECT electrode placement Fig. 2

The electrical pulse to be delivered is recommended to be 6 times above the seizure threshold for patients recieving unilateral ECT, and 2.5 times above the seizure threshold for bilateral ECT.[15]

Some medications should be stopped prior to starting ECT, while others should be continued.

Medications indications and contraindications

Medications to continue Medications to stop
Antihypertensives Anticonvulsants (taper dose, or discontinue completely)
Heartburn medications (proton pump inhibitors, H2 blockers) Stimulants (taper and discontinue completely)
Glaucoma medications Lithium (discontinue 36-48 hours prior to treatment, there is a risk of developing delirium while on lithium)
Neuroleptics/Anti-psychotics (Haloperidol, clozapine, risperidone - may be beneficial in combination with ECT) MAOIs (consider dose reduction)
Antidepressants Benzodiazepines (should be held by 17:00, the day before each ECT treatment)


ECT has the best response rate in geriatric depression, patients with a greater severity of illness, psychotic depression, and when there is an absence of personality disorders. In individuals with borderline personality disorder, the rates of ECT response are significantly lower, this is an important risk/benefit consideration that needs to be discussed with patients.[16] The effects of ECT are also dose-dependent, with a better response at higher doses.[17] Patients can expect improvement in symptoms by the third treatment, and achieve remission beginning by the seventh treatment.[18] Suicidal ideation also similarly decreases greatly by around the fourth treatment.[19] ECT also improves quality of life measures significantly for patients post-treatment.[20]

The best and strongest predictor of non-response to ECT is the degree of non-response to previous antidepressant medications. Response rates are about 50% in those who have treatment-resistant depression and up to 90% in treatment-naive patients.[21]

About 50% of patients will relapse with depressive symptoms at the 12-month mark, after a successful course of ECT.[22] Patients who receive ongoing pharmacotherapy have significantly lower relapse rates compared to patients who do not have any treatment post-ECT (most studies were done using venlafaxine and nortriptyline in these studies). Thus it is recommended that patients recieve pharmacotherapy (and psychotherapy) after their first ECT treatment.[23][24] Post-ECT pharmacotherapy should be continued for at least 12-24 months. Antidepressant choice should be the one that the patient responded the best to in the past. In absence of an effective antidepressant, venlafaxine (first choice) or nortriptyline (second choice) should be used.[25]

Maintenance ECT (prophylactic ECT) should be added after an individual has gone through a second course of ECT. In addition to maintenance ECT, augmentation with an antidepressant, plus lithium should be considered.[26] Again, post-ECT pharmacotherapy should be continued for at least 12-24 months.[27] There is evidence to support maintenance ECT as an augmentation treatment to psychopharmacological treatment in mood disorders.[28]

Possible side effects and adverse events from ECT include:

  • Dental injury, orobuccal lacerations (using a bite block prevents this)
  • Post-ictal confusion (lasting 15-60 minutes)
  • Memory loss (retrograde)
  • Subjective memory worsening is reported by a minority of patients (young women are at greater risk of experiencing these symptoms.[29])
  • Headaches
  • Myalgias (Muscle pain in the back is due to succinylcholine)
  • Nausea and vomiting
  • Jaw pain (due to contraction of masseter muscle due to direct electrical contraction)
Memory and Cognition

Cognition is a broad term that encompasses several components, including: attention, anterograde memory (inability to remember any new information), retrograde memory (inability to remember past memory), procedural memory, and reaction time. ECT does have an amnestic effect in particular for retrograde memory. The amnestic effects of ECT are greatest and most persistent for knowledge about the world (impersonal memory) compared with knowledge about the self (personal memory). There is also more cognitive impairment with more frequent ECT administration (i.e. - 2 sessions per week vs. 3 sessions). Overall, ECT is associated with short-term cognitive effects, but cognition eventually returns or surpasses their pre-ECT baseline.[30] The majority of evidence suggests that ECT given over a period of years will not cause cumulative cognitive deficits. There are also reduced rates of dementia in geriatric patients with mood disorders who receive ECT. Most importantly, ECT does not increase the risk of dementia in the elderly, making it a safe and appropriate option.[31]

It is important to note however, in rare cases, individuals can experience significant and distressing memory loss, and this remains an under-researched area in ECT.

  • Never forget: give anesthetic first, and THEN give muscle relaxant
  • An adequate seizure in ECT is one that lasts around or greater than 30 seconds.
  • If the patient has a very brisk seizure with prominent motor activity, a higher dose of succinylcholine should be considered
  • Rocuronium should be considered for patients with prominent myalgia and headaches
  • Anesthetic agents and seizure duration:
    • Increased: Etomidate
    • No Effect: Methohexital, ketamine, remifentanil, alfentanil
    • Shortened: Propofol, midazolam, lorazepam, thiopental, thiamylal, lidocaine
  • Electrode plate placement:
    • Use concave electrode plates for bifrontal (BF) and right unilateral (RUL) ECT
    • Use flat electrode plates for bitemporal (BT)
  • If there is a poor seizure response, you can consider:
    • Administering caffeine can increase the duration of seizures[32]
    • Use hyperventilation to augment seizure duration[33]
    • Increase hydration
  • If there are cognitive side effects from ECT, you can try to:
    • Reduce the frequency of treatments (i.e. - 3x per week to 2x per week)
    • Reduce the stimulus intensity