Pupillary Response as Assessment of Effective Seizure Induction by Electroconvulsive Therapy

Summary

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.

Abstract

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.

Introduction

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 ....

Protocol

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.......

Discussion

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.......

Materials

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