Diagnosis
There are several tests for testing the nystagmus, which are usually performed by an ENT physician. First, the patient is placed on a swivel chair, which is then accelerated. This results in a slowly beating eye nystagmus, first against the direction of rotation, followed by a rapid return movement in the direction of rotation.
With this action, the body tries to produce an image on the retina that is as complete as possible, just like when fixing the surroundings from a moving train. If the swivel chair is now stopped, the direction of the nystagmus changes. This is mainly due to the inertia of the endolymph in the organ of equilibrium, which is responsible for the balance.
This nystagmus can also be observed in a healthy person and can be visualized with so-called Frenzel glasses. These special glasses, which are put on the patient, enable an exact representation of the eye movements by means of a very strong refraction of the eyes. Thus, even a very fine beating nystagmus will be well represented by these glasses.
In order to prevent the examinee from fixing a point through the glasses, he or she is prevented from doing so by a glare lamp. The caloric test is another possibility to test the nystagmus. Here, the patient receives either cold water with a temperature of approx.
25 degrees or warm water with a temperature of approx. 40 degrees into the external auditory canal. This causes an irritation of the vestibular organ and triggers a nystagmus.
The brain is faked a rotation by this temperature change, which immediately leads to a jerk nystagmus by the vestibulo-ocular reflex (VOR). Why this temperature difference leads to the triggering of a nystagmus is still largely unknown. In space, numerous attempts have been made to find out, under exclusion of the earth’s gravitational force.
Symptoms
For the person in whom a nystagmus is triggered, there are initially no symptoms if it is a physiological nystagmus. In general, a nystagmus goes completely unnoticed and is embedded in everyday situations in which certain points are fixed. However, as soon as the nystagmus is not physiological but pathological, moderate to severe symptoms may occur.
In the case of non-physiological nystagmus, a rotational movement is simulated, which is registered by the brain. This causes severe dizziness, which is usually the first symptom of a pathological nystagmus. The dizziness is usually of a spinning nature.
In the case of very severe dizziness, the patient may also suffer from severe disturbances of balance that lead to the point where he or she is no longer able to stand on his or her own legs. Furthermore, a frequent accompanying symptom of severe dizziness is also severe nausea, which can lead to vomiting. Patients with a pathological nystagmus are in a very poor state of health and urgently need diagnostic and therapeutic help.
