What is ENG ?
Electronystagmography (ENG) is an important test done to evaluate patients with vertigo, dizziness and balance problems. The study of eye movements provides a lot of information about the functioning of the brain and the balance system. ENG is used to second eye movements in different conditions and with different tests. By analyzing these movements, we are able to understand the area affected by the disorder.
ENG detects eye movements by virtue of a change in the cornea – retinal potential during these movements. The changes in potential are picked up by surface electrodes placed near the eyes of the patient. Findings of ENG must be correlated with the history given by the patient and other neuro –ontological tests to identify the cause of vertigo or dizziness.
Videonystagmography(VNG) is the most non-invasive, accurate, reliable and affordable way of evaluating the vestibular and oculomotor systems. This technology is used for observation, measurement and analysis of eye movement during various oculomotor and vestibulartests.Thisequipment eradicatesthe issue ofmyogenicandelectricalnoiseseeninENG. Itevaluatesperipheralandcentralvestibularfunctions VNGhasauserfriendlybinoculargoggledesign What is VNG ?
Difference between ENG & VNG? ENG VNG Uses electrodes to record corneo–retinalpotential. The detailed finding of oculomotortestsnotpossible. Direct recording of eye movements with infrared cameras. Eachoculomotortestlikegaze, saccades,smoothpursuit,skew deviation and optokinetic stimulation can be studied in detail. Continued…
Difference between ENG & VNG?
ENG VNG
Reviewing and replaying tests not possible.
Able to record horizontal eye movements. Vertical eye movement recording is not very accurate.Cannotrecordtorsion.
Able to replay tests, visualize in slow motion and review videos.
Able to record eye movements in horizontal and vertical planes with high precision and graphically present the nystagmus with slow-wave velocity and a number of beats.
Torsional eye movements are well presented on video.
Tests Conducted During ENG and VNG Examination
Test for spontaneous nystagmus – Nystagmus is the jerky oscillatory movement of the eyes caused by disturbances in the balance system. In many cases, this nystagmus cannot be accurately diagnosed by naked eye examination. VNG examination allows high resolution magnified imaging of eye movements.
Test for gaze – This test checks the ability to hold gaze at a point. Patients with balance disorders may have problems in holding their eyes steady on a fixed point.
Saccades – This test checks the ability to move the eyes and appropriately focus on another object of interest
Smooth pursuit – A light moving like a pendulum is presented to be followed by the patient with eye movements without moving the head. The ability to track it with the required velocity and precision is measured.
Other tests done – include skew deviation, hyperventilation, vibration, valsalve and optokinetic stimulation.