Cervical Vertigo means that dizziness is a function of head/on neck motion, rather than due to stimulation of the inner ear by motion or gravity.
The diagnosis of cervical vertigo is presently controversial. While nearly everyone agrees that cervical vertigo exists, very few agree on how it is diagnosed. This page outlines the author's method in diagnosing cervical vertigo. It is not standard practice in ENG testing at the present. From the author's experience, it is the only practical method of diagnosing cervical vertigo.
To diagnose cervical vertigo one must observe something that changes according to movement (position, velocity, acceleration) of the head with respect to the trunk.
The test we are discussing is often called the "Vertebral artery test", or VAT for short. However, with the method that we describe here, this is a misnomer, because the signs that we elicit are generally subtle and are mainly elicited by other processes.
This is how you do it - with the subject sitting upright, the head is rotated gently about the vertical axis to the end point of rotation, and this position is maintained for 30 seconds. During this period the eyes are kept in the center of the orbit, and monitored for development of a nystagmus, as shown below. The eyes are monitored in total darkness. This is most easily done with a VENG system.
|Cervical nystagmus -- see Head-left.|
This figure shows a weak left-beating nystagmus associated with turning the head to the left. There is no nystagmus with head-right or head center.
We recommend repeating this test when positive, to be sure it is reproducible.
In the author's unpublished experience, this pattern frequently is associated with a C5-C6 disk herniation that is abutting the cord. It is rarely encountered in persons with normal cervical MRI scans.
Here we are speculating. When the head is turned 90 degree's on the neck, the spinal cord must also rotate 90 degrees within the spinal canal. We speculate that when there is a disk abutting the cervical cord, and the cord is attempting to rotate, that it presses up against the cord. For unknown reasons, this creates a small nystagmus that is always directed towards the direction of head rotation.
There are some people who have cervical vertigo due to neck spasm and pain. This method does not address this problem.
While the author finds this an immensely useful test, admittedly it is unaccompanied by any literature that might substantiate it's use. A simple blinded trial in which people known to have cervical disks were tested by an examiner blinded to their radiology, would be of considerable interest.