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Pupillary responses (light reflex) were measured for assessment of adequate seizure induction by electroconvulsive therapy using an automated infrared pupillometer immediately after electrical stimulation. Constriction ratio was calculated and compared with seizure quality.
Electroconvulsive therapy (ECT) is reported to be effective for severe neuropsychiatric disorders. In ECT, electrical stimulation is applied to the brain, inducing seizure activity. Adequate seizure induction with ECT is associated with seizure duration, symmetrical high amplitude waveforms during slow-wave activity, postictal suppression, and activation of the sympathetic nervous system. Sympathetic nervous system activation is influenced by anesthetic agents or cardiovascular drugs during ECT. Pupillary responses can reflect sympathetic nervous activity or the degree of brain damage. Pupillary response measurement can be conducted in a simple, precise, and objective way using an automated infrared pupillometer, enabling the measurement of pupil diameter (mm) to two decimal places. The white light used for measuring light reflexes is not overly bright, and patients do not typically report discomfort. Pupillary light reflexes were measured before anesthesia induction and immediately after electrical stimulation using this equipment. Pupil diameter is typically enlarged after brain damage or sympathetic nervous activation. Adequate seizure induction using ECT could induce pupillary enlargement immediately after electrical stimulation. In the current method, the constriction ratio of pupil size was calculated automatically and compared with seizure quality. Pupillary responses immediately after electrical stimulation may provide a useful assessment of the efficacy of seizure induction with ECT.
Electroconvulsive therapy (ECT) is considered an effective treatment for severe neuropsychiatric disorders, including refractory psychosis, bipolar disorder, and depression1. In ECT, an electrical current is applied to the brain to induce a seizure under general anesthesia2. Although the mechanisms underlying ECT remain unclear, its antidepressant effects have been attributed to seizure-induced changes in neurotransmitter levels, improved neuroplasticity, increased functional connectivity, and an increase in the plasmatic production of brain-derived neurotrophic factor3. It has also been reported that ECT facilitates serotonin-, norepinephrine- and dopamine-mediated neurotransmission4. These findings suggest that ECT could cause activation of the sympathetic nervous system. Previous studies have evaluated adequate seizure induction by ECT using seizure duration, symmetrical seizure amplitude, postictal suppression, and activation of the sympathetic nervous system4,5. Among these factors, increased activation of the sympathetic nervous system cannot be measured using electroencephalography. Detection of sympathetic nervous system activation is dependent on increased blood pressure (BP) and heart rate (HR). However, these hemodynamic parameters do not always reflect sympathetic responses because of the administration of antihypertensive drugs to prevent cardiac events during ECT and anesthetic agents, which affect sympathetic nervous function.
Pupillary responses can reflect the degree of brain damage6. Thus, pupillary mydriasis is indicated for severe brain damage6. Artificial seizures induced by electrical stimulation constitute an abnormal state of brain activity. Thus, evaluating the pupillary response immediately after ECT may be useful for assessing the efficacy of ECT because ECT may also influence pupillary responses7. However, measuring pupillary responses in busy clinical situations, as in the current case, is often difficult. To address this issue, a measurement method using an infrared quantitative pupillometer could help to measure pupillary responses easily, accurately, objectively and reproducibly. Quantitative pupillary assessment methods are superior to those obtained manually at the bedside, even by experienced nurses and physicians8. The proposed method for measuring pupillary reactivity using an automated infrared pupillometer could be useful for detecting the degree of seizure or sympathetic nervous activation. In a previous study, we reported that the pupillary light reflex was related to the efficacy of seizure by ECT9. Specifically, we found that pupillary diameter was not changed after light stimulation, remaining enlarged when adequate seizure was induced. Thus, the aim of the proposed method is to measure the light reflex using an automated infrared pupillometer immediately after electrical stimulation. The proposed method is easy to perform, enabling any clinician, not only psychiatrists, to evaluate the efficacy of seizure induction using ECT.
The study protocol was approved by the institutional clinical research ethics committee of Kyushu University, Fukuoka, Japan (IRB: Clinical Research number #28-77). Although the measurement of pupillary reaction is an essential and standard clinical procedure during anesthesia, informed consent was obtained for this research. Patients with cataract, glaucoma, intraocular lenses, or insulin-dependent diabetes mellitus were excluded because their pupillary responses may be abnormal.
1. Preparation for Electroconvulsive Therapy
2. Preparation for anesthesia
NOTE: All patients underwent ECT in the same room, at the same time of day.
3. Anesthesia
4. Electroconvulsive Therapy Procedure
Portable pupillometer devices are produced by several companies. These devices are typically conveniently sized and can be operated with one hand (Figure 1A), enabling examiners to accurately detect pupillary responses by pressing a button. Infrared light is used to detect the pupillary edge automatically (Figure 1B), accurately representing pupillary data (Figure 1C). This device m...
Automated infrared pupillometer devices have been used to measure pupillary reactions in clinical situation12. However, to our knowledge, no previous studies have used this equipment for detecting the efficacy of seizure induction by ECT. Resting pupil diameter size differs between patients, but constriction ratio provides an objective measure. Thus, we selected the constriction ratio change, not the diameter size change. Additionally, small changes of pupillary diameter can only be measured using...
The authors have nothing to disclose.
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Name | Company | Catalog Number | Comments |
Npi-100/automated infrared pupillometer | NeurOptics | ||
Thymatron IV system | Somatics Inc. | ||
Thymapads™ | Somatics Inc. | EPAD-C | |
BIS Quatro sensor | medtronic | ||
Non invasive blood pressure cuff | Nihon Koden | YP-713T | |
VBM tourniquet9000 | Medizintechnik GmbH | ||
EEG | Somatics Inc. | ECEF-4 | |
ECG | Somatics Inc. | ELDSC-9 | |
EMG monitoring lead | Somatics Inc. | ELDS-BR | |
Finger probe | Nihon Koden | TL-201T | |
Npi-200/automated infrared pupillometer | NeurOptics |
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