From the Guidelines
Determining the seizure threshold for ECT involves using the dose titration method, which is the preferred approach, especially in adolescents, as it allows for the establishment of an adequate dose of electrical impulse while minimizing cognitive impact. This method involves starting with a low electrical dose and gradually increasing it during the first session until a seizure occurs, with increments of 40% to 60% at 30-second intervals, and a maximum of four stimulations permitted 1. The goal is to produce an EEG seizure lasting 30 to 90 seconds, which is considered adequate for therapeutic purposes.
Key Considerations
- The dose titration method is recommended over formula-based approaches, such as the "half age method", as it has been studied in adults and its relevance to adolescents is not known 1.
- Seizure threshold varies widely among individuals, but a high seizure threshold is not typically a problem associated with adolescents, who tend to have a lower seizure threshold characteristic of young people 1.
- Electrode placement and electricity dose strongly influence clinical outcome, with the poorest treatment response found with low-dose unilateral treatment 1.
- Medications, such as anticonvulsants and benzodiazepines, can raise the seizure threshold, while caffeine and theophylline can lower it, and anesthetic agents like methohexital and etomidate can facilitate seizures compared to propofol 1.
Recommendations
- Use the dose titration method to determine the seizure threshold for ECT in adolescents.
- Start with a low electrical dose and gradually increase it until a seizure occurs.
- Aim for an EEG seizure lasting 30 to 90 seconds.
- Consider the effects of medications and anesthetic agents on seizure threshold.
- Reassess seizure threshold as needed during the ECT course, as it may increase with successive treatments.
From the Research
Determining Seizure Threshold for ECT
To determine the seizure threshold for Electroconvulsive Therapy (ECT), several methods can be employed, including:
- Titration method: This involves gradually increasing the electrical stimulus until a seizure is induced 2, 3.
- Age-based method: This method uses the patient's age to estimate the seizure threshold, as age has been shown to be a significant factor influencing threshold 2, 4.
- Fixed high-dose method: This method involves using a standard high dose of electrical stimulus for all patients, regardless of their individual seizure threshold 3, 4.
Factors Influencing Seizure Threshold
Several factors can influence the seizure threshold, including:
- Age: Older patients tend to have higher seizure thresholds 2, 4.
- Gender: Male patients may have higher seizure thresholds than female patients 4.
- Electrode placement: Bilateral electrode placement tends to result in higher seizure thresholds than unilateral placement 2, 4.
- Anesthetic drugs and concurrent psychotropics: These can affect the seizure threshold, although the exact mechanisms are not fully understood 2.
- Morphological characteristics: Certain physical characteristics, such as brain structure and function, may also influence the seizure threshold 2.
Seizure Threshold Values
Studies have reported a wide range of seizure threshold values, with a mean of around 68-111 mC for unilateral ECT and 111-221 mC for bilateral ECT 4. However, it is essential to note that these values can vary significantly between individuals and may need to be adjusted based on individual patient responses 2, 3.
Importance of Seizure Threshold Determination
Determining the seizure threshold is crucial for effective and safe ECT treatment, as it allows for the optimization of the electrical stimulus dose and minimizes the risk of adverse effects 2, 5. Regular retitration of the seizure threshold may also be necessary, especially during maintenance ECT, to ensure that the treatment remains effective and safe 5.