Electronystagmography
As electronystagmography (ENG), a basis is known in Neurology , ear, nose and throat , and ophthalmology applied investigation method for registering and determination faster nystagmiformer eye movements with the aid of glued electrodes .
Indications
Electronystagmography is used for the objective assessment of the oculomotor and vestibular system in patients with dizziness or balance disorders. It is the most widely used clinical test to check balance function. In addition, in ophthalmology, in particular neuro- ophthalmology, it represents a sub-area of electrooculography that is used to diagnose and determine a pathological, non-vestibular nystagmus .
principle
The human equilibrium system continuously registers the spatial position and all movements of the body and body parts. The spatial information is necessary, among other things, to coordinate eye movements . In this way, when the spatial position changes, the eyes are kept stable and undisturbed vision is made possible. A complex interplay of various processes in the vestibular and visual system as well as afferents from the spinal cord and the brainstem reflexes (especially vestibulo-ocular reflex ) is necessary for balance and vision . Many of these functions can be tested in the ENG.
The ENG examination therefore includes:
- Examination of eye movements ( optokinetic nystagmus ): The patient should e.g. B. track moving objects with his eyes, the movements are documented. The correct functioning of the eye muscles and the nerves supplying them is a prerequisite.
- Examination of the reaction of the equilibrium system to position or storage
- Examination of the reaction of the equilibrium system to caloric stimulation
Malfunctions are expressed as pathological nystagmus . Modern ENG systems are computer-controlled - from the generation of stimuli, registration of the response via electrodes to automatic evaluation.
preparation
The prerequisite for performing an ENG is that the patient has sufficient eyesight. Before the examination, a thorough anamnesis is taken and the patient is informed or instructed. Possible undesirable effects that can occur with ENG are dizziness and nausea.
options
The ENG can provide important information on the medical history and the symptoms described by the patient and often enables a diagnosis. A comparison of individual test components (e.g. caloric and positional nystagmus ) can indicate the rough localization of the dysfunction (e.g. peripheral balance disorder vs. central balance disorder). A precise localization of lesions in the equilibrium system is not possible with the ENG alone.
A normal ENG does not rule out the presence of a disturbance in the vestibular system. Certain medications can affect the test result.
alternative
As an alternative to electron nystagmography, video nystagmography (VNG), recording eye movements with a video camera and infrared oculography (IROG) are becoming increasingly popular.
literature
- Literature list in the online catalog of the Berlin State Library
- Claus-F. Claussen , Manfred von Lühmann: The electronystagmogram and the neurootological characteristic diagnostics. Instructions for practical examination and therapy of vertigo sufferers. edition m + p, Hamburg et al. 1976.
- Claus-F. Claussen, Gottfried Aust, Wolf Dieter Schäfer, Irmentraut von Schlachta: Atlas of the electronystagmography. Atlas of neurootological examination techniques. Registration curves, evaluation of findings, dizziness diagnostics. edition m + p dr. werner rudat & co nachf., Hamburg 1986, ISBN 3-922326-30-7 .
Individual evidence
- ↑ Thömke F. Eye movement disorders. 3rd, updated and expanded edition. Bad Honnef, Hippocampus 2016
- ↑ Rudolf Sachsenweger (Ed.): Neuroophthalmology. 3rd, revised edition. Thieme, Stuttgart 1982, ISBN 3-13-531003-5 , pp. 66, 219.
- ↑ Herbert Kaufmann (Ed.): Strabismus. With the collaboration of Wilfried de Decker et al. Enke, Stuttgart 1986, ISBN 3-432-95391-7 , p. 405.
