Dear Editor:

Electroconvulsive therapy (ECT) is a medical treatment that involves the electrical stimulation of the brain under general anesthesia. This treatment modality has been utilized worldwide for over 80 years.1 According to the American Psychiatric Association, ECT is indicated for major depression, mania, and schizophrenia.2 Unfortunately, there are occasions in which a psychiatrist is unable to elicit a therapeutic seizure during a treatment session. Male gender, advanced age, and medications, such as mood stabilizers, are factors that increase the seizure threshold.3 In such cases, a missed seizure or brief seizure (less than 15 seconds in duration) presents as a challenge for the psychiatrist. A review of the literature indicates that ketamine might be an alternative anesthetic agent in the treatment of ECT.4–6 Although methohexital is the preferred anesthetic agent due to its safety, effectiveness, and cost, ketamine might serve as an alternative option. In the following case report, we present the utilization of ketamine as an adjunctive anesthetic agent in the treatment of ECT. Ketamine was selected due to its proconvulsant properties compared to other anesthetics.5,7

The patient is a 38-year-old man hospitalized in the state hospital with a diagnosis of schizophrenia, and his psychotic symptoms consisted of auditory hallucinations, paranoid delusions, and psychotic agitation. The patient continued to present with these psychotic symptoms for six years despite trials of various antipsychotic medications and adherence to haloperidol (up to 60mg/day) for the past six years and clozapine (up to 900mg/day) for the past three years. Due to the lack of clinical improvement on a combination of antipsychotic medications, the patient was referred for treatment with ECT. At the start of his ECT treatments, the patient was taking clozapine 850mg/day, haloperidol 30mg/day, and haloperidol decanoate 300mg/month. Furthermore, the patient was not ordered other medications, such as mood stabilizers that might influence the seizure threshold.

The patient was treated on the Thymatron System IV, with a pulse width of 0.5 milliseconds. Other treatment parameters include bilateral stimulus electrode placement, 1mg/kg of methohexital as the anesthetic agent and 1mg/kg of succinylcholine as the muscle relaxant. We utilized the age-based dosing method in attempt to establish the seizure threshold. We failed to establish the seizure threshold on five consecutive attempts over the course of one week. Despite hyperventilation and a titration of the stimulus dose up to 252mC, we were unable establish the seizure threshold. 

At the next treatment session, the patient received adjunct ketamine 0.5mg/kg in the form of an intravenous (IV) bolus in addition to 1mg/kg of methohexital. The other treatment parameters remained the same. We were able to obtain a therapeutic seizure of 20 seconds or greater on electroencephalogram with a stimulus dose of 330mC. The patient received a total of 19 therapeutic ECT treatments with this treatment protocol. The patient also responded well to these treatments and reported a significant decrease in auditory hallucinations and did not appear to be distressed about his delusions. Furthermore, there has been a significant decrease in the number and severity of behavioral incidents. In the month prior to his ECT treatments, the patient was often placed in seclusion and/or restraints after 12 separate incidents of hurting staff secondary to his psychotic symptoms. In contrast, the patient did not engage in any behavioral incidents during the period in which he received therapeutic ECT treatments. 

The utilization of ketamine for ECT to treat depressive disorders remained a topic of interest.4–6,8 Unfortunately, the literature on ketamine for ECT to treat treatment-resistant psychotic disorders is limited. We elected to not utilize ketamine as the sole anesthetic agent due to its potential risk of hypertension, tachycardia, and hallucinations.7 The authors were initially concerned about the potential worsening of psychotic symptoms in our patient with schizophrenia. However, our case provides support for the safe use of ketamine as an adjunctive anesthetic agent in the treatment of ECT. Future considerations include the utilization of ketamine as the sole anesthetic agent for ECT to treat treatment-resistant psychotic disorders.


  1. Gazdag G, Ungvari GS. Electroconvulsive therapy: 80 years old and still going strong. World J Psychiatry. 2019;9(1):1–6.
  2. American Psychiatric Association. The Practice of Electroconvulsive Therapy: Recommendations for Treatment, Training, and Privileging: A Task Force Report of the American Psychiatric Association. 2nd ed. Washington, DC: American Psychiatric Association; 2001.
  3. van Waarde JA, van Oudheusden LJ, Verwey B, et al. Clinical predictors of seizure threshold in electroconvulsive therapy: a prospective study. Eur Arch Psychiatry Clin Neurosci. 2013;263(2):167–175. 
  4. Zisselman M, Zitzmann W. A Role for ketamine in electroconvulsive therapy. J ECT. 2019;35(4):e57.
  5. Krystal AD, Weiner RD, Dean MD, et al. Comparison of seizure duration, ictal EEG, and cognitive effects of ketamine and methohexital anesthesia with ECT.  J Neuropsychiatry Clin Neurosci. 2003;15(1):27–34.
  6. Gamble JJ, Bi H, Bowen R, et al. Ketamine-based anesthesia improves electroconvulsive therapy outcomes: a randomized-controlled study. Can J Anaesth. 2018;65(6):636-646.
  7. Kellner CH. ECT Technique. Handbook of ECT: A Guide to Electroconvulsive Therapy for Practitioners. Cambridge: Cambridge University Press; 2018:68–69.
  8. Fernie G, Currie J, Perrin JS, et al. Ketamine as the anesthetic for electroconvulsive therapy: the KANECT randomised controlled trial. Br J Psychiatry. 2017;210(6), 422–428.

With regards,

Chong Yang, DO; Carolina A Klein, MD; Alaric Frazier, MD

All authors are with th Department of State Hospitals-Napa in Napa, California.

Funding/financial disclosures. The authors have no conflict of interest relevant to the content of this letter. No funding was received for the preparation of this letter.