Nystagmus – a clue to your dizziness

Nystagmus is likely a word you haven’t heard before.  It is the term for an involuntary eye movement that happens when your head is moving.  If you’re looking at a target in front of you and you start turning your head, your eyes will move in the opposite direction of your head movement in order to stay on your target.  This is because of a reflex called your vestibulo-ocular reflex or VOR, and we can thank the VOR for our ability to keep our surroundings in focus when we are moving. 

If you continue to turn your head to the point where your eyes can no longer stay on the target because they’re all the way over to the edge of the socket, your eyes will do a rapid movement to line back up with your head.  This combination of slow movement one way and rapid movement the other way to reset is called a beat of nystagmus. 

How nystagmus can help determine the cause of dizziness

So how can nystagmus be helpful when medical professionals are trying to determine why a person is feeling dizzy?  One of the more common causes of dizziness or vertigo is when the vestibular part of the inner ear that detects head motion isn’t agreeing with the ear on the other side.  This mismatch is normal when the head starts to move, but if it’s happening when the head isn’t in motion due to an abnormality in one inner ear, the brain will be tricked into thinking that the head is moving.  As mentioned, nystagmus is generated by a reflex, so if the brain thinks you’re moving, it’s going to kick in that reflex and nystagmus will be generated, which will make it look and feel like things are moving when they aren’t.

The direction of the nystagmus help indicate a diagnosis

When nystagmus is generated inappropriately by an abnormality, the direction of it (and there are many possibilities) can point to different diagnoses. 

• Some directions of nystagmus indicate that there is some damage or reduced function in an inner ear, as can happen after trauma or inner ear infection. 
• Other types of nystagmus indicate that some of the crystals that we all have in a certain part of the inner ears have gotten into the wrong area – a condition called BPPV or Benign Paroxysmal Positional Vertigo, which is the most common cause of vertigo. 
• Some directions of nystagmus indicate that the issue lies in the parts of the brain that process information from the ears, rather than the ear(s) being the culprit.

Viewing nystagmus with infrared goggles

One challenge is that much of this valuable information cannot be seen in room light beyond the first few days after the onset of symptoms.  Research has shown that around two-thirds of these abnormal eye movements are missed when clinicians assessing dizziness patients test only in room light*.  In conditions where nystagmus is visible in room light, it is often so subtle that it is difficult to determine the exact direction of it with the naked eye. 

A way to see what the eyes are doing in the dark without anything to focus on is required for this tell-tale nystagmus to emerge.  Fortunately, there are special infrared goggles designed to allow medical professionals detect 100% of these abnormal eye movements*, and they are invaluable in the assessment and treatment of people with dizziness disorders.

At Lifemark, almost all of our vestibular therapists utilize the infrared goggles in their evaluation, and have the advanced training required in order to perform and interpret the appropriate goggle tests. 

Do you have nystagmus? And if so, what condition does the direction of it suggest?  Take advantage of the infrared goggle technology to help get to the bottom of what is making you dizzy by booking an appointment with a Lifemark vestibular therapist today! To find a vestibular therapist near you, visit our locations page or book online here.

Reference for both *s above: (Baba et al., 2004; Ozel et al., 2022)