A Prospective Study on Electronystagmography (ENG) to Detect Vestibular Disorders Using Simplified GUI

A Prospective Study on Electronystagmography (ENG) to Detect Vestibular Disorders Using Simplified GUI

Natarajan Sriraam (M.S. Ramaiah Institute of Technology, Bangalore, India), Namitha Shivakumar (Accenture Services Pvt. Lt., Chennai, India), Poonam R. (Accenture Services Pvt. Lt., Bangalore, India) and Shamanth Dharmappa Y. (Accenture Services Pvt. Lt., Bangalore, India)
Copyright: © 2016 |Pages: 14
DOI: 10.4018/IJBCE.2016010105
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Abstract

Electronystagmography (ENG) refers to the clinical test that monitors the involuntary movements of the eye due to an effect called Nystagmus. The procedure is also used to detect disorders of inner ear that are responsible for vertigo and imbalance. In clinical practice, various tests such as caloric test, calibration test, gaze test, pendulum tracking test, opto-kinetics test, positional test and Rhomberg's test were generally performed to diagnose the vestibular dysfunction. Such procedure were found to be very time consuming and cumbersome for the patients. This prospective study investigates the screening of the vestibular dysfunction by integrating the readymade hardware unit with a compact software tool to reduce the clinical test duration. Electrooculography (EOG) based physiological signal is used to record the eye movements during ENG. The proposed research study aims in developing a simplified procedure towards the analysis of ENG signals. The proposed methodology not only helps in reducing the time for performing such procedures but also helps in reducing the discomforts to the subject. The procedure showed the effectiveness in terms of recognizing the required biomarkers for various activities. For the pilot study, 25 healthy male and 25 female test subjects in the age group of 19-21 years were considered. Experimental set up was arranged to record EOG signals with all activities with time duration of 10 minutes. Two features namely spike rhythmicity and auto regressive feature using Burg's method were extracted from the recorded raw signal. A typical Elman feedback neural network was introduced to perform the binary classification to identify the pattern, (Nystagmus left ear-Nystagmus right ear, Vertical-Horizontal and Gaze-Pendulum) respectively. An overall classification accuracy (CA) of 93.8% was achieved that confirms the effectiveness of the test required to detect nystagmus. The system needs to be validated with large experimental data to confirm the accuracy for clinical screening and validation.
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Introduction

The term Electronystagmography (ENG) refers to the physiological recordings related to movements of retina and nystagmus during fixation and its impact during the vestibular, visual as well as positional stimulation (Heide et al., 1999). Specifically ENG is the reflection of the involuntary rapid movements of the eye in response to the numerous external stimuli. If nystagmus does not occur on stimulation, a problem may exist within the ear, nerves that supply the ear, or certain parts of the brain. This test may also be used to distinguish between lesions in various parts of the brain and nervous system. After the initial clinical examination and simple tests of equilibrium have been completed, the nystagmographic investigation begins with tests for the presence of spontaneous or positional nystagmus on the posture table. These are followed by the caloric tests. Calibration of the eye movements is carried out first to obtain a measure of the eye movements, which are expressed in degrees of rotation of the eyes and translated into mm. deviation of the tracing. The patient looks from a certain distance to two points on the wall alternately, shifting his gaze in the horizontal plane. The distance between these two points is chosen so that the eyes travel through an area of about 20° from one to the other. Calibration in the vertical plane is done similarly in the vertical axis. For better understanding, a short brief note is given on the various testing procedure

Water Caloric Test

In this test, pure cold water is poured or injected to any one of the ear. The stimulation of water in the ear is well picked by the EOG electrodes and in due turn eye moves rapidly from side to side. The procedure is extended to the other ear too.

Calibration Test

In this test, the subject need to track the traces of the light at a five-six feet distance from eyes. The movement of the pupil is monitored during this procedure.

Gaze Test

In this test, the subject is asked to either sit or lie down and look into the fixed light without any bodily movement. The light is placed in front of the subject or to the side. This test is an indicator of how subject keep the eye fixed on to a target without any involuntary eye movements.

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