Brady Workman is back this week with a review of a very interesting article he brought me a few months ago. It made me rethink our clinical application of VEMP testing to include those patients with unusual complaints that don’t necessarily fit the picture of a typical vestibular disorder.  Here’s Brady.

Recently, I was reading an article discussing the differences in symptoms among adults with canal versus otolith vestibular dysfunction, which raises some important questions for the future of vestibular assessment. As most clinicians know, a detailed case history is essential in establishing a diagnosis of peripheral vestibular dysfunction, with the qualitative nature of the symptoms being important in reaching a final diagnosis.

 

A traditional symptom of peripheral vestibular system dysfunction is rotary vertigo, meaning a sensation of self or environmental motion. Symptoms are then evaluated with objective measures, such as calorics (horizontal canal) or dynamic positioning tests (typically posterior canal) to reach an end diagnosis. In the past, these objective measures have predominately focused on assessment of semicircular canals (head turn sensors), which have different end functions than the otolith organs (linear sensors) of the vestibular system. Therefore, it seems logical that dysfunction of the semicircular canal(s) of the vestibular system may provoke different symptoms than otolith dysfunction. Otolith dysfunction (saccule and/or utricle) may then produce non-typical symptoms, which may still be indicative of peripheral vestibular system damage such as: tilting, pushing/pulling, or rocking sensations due to their contribution in sensing linear acceleration, postural control, and head tilt. It has only been in recent years that assessment of the otolith organs (saccule & utricle) of the vestibular system have become more widely utilized with VEMP testing, so less is known of the effects of their dysfunction.

 

In the aforementioned article, the authors were able to assess individuals with varying pathologies and degrees of vestibular system dysfunction. They were able to successfully categorize individuals based off of their symptomology as having semicircular canal versus otolith involvement using a symptom index of their creation. Individuals with semicircular canal pathology tended to have symptoms of rotary vertigo, while those with otolith damage reported more linear symptoms including pulling/pushing, rocking, or tilting sensations. While all of the individuals were found to be unsteady on their feet, those with otolith organ involvement reported higher handicap due to their symptoms and were at a much higher risk for falling than those with semicircular canal dysfunction only.

 

There were several limitations to this preliminary report, including the small sample size, but this does call for clinicians working with dizzy patients to be more open-minded in what quantifies a symptom of vestibular dysfunction. Linear symptoms such as pulling/pushing, tilting, or rocking sensations may then be appropriate for clinicians to accept as symptoms of vestibular system dysfunction, with differential evaluation necessary to rule in or out otolith involvement. This report further elucidates the need for comprehensive evaluation of the vestibular system, including both the semicircular canals and otolith organs, in order to appropriately direct therapy and/or further referrals for diagnostic evaluation.

 

The current treatment for those identified with unilateral vestibular system damage would be physical therapy designed to stimulate the vestibular system as a means to drive central compensation for the injury. This central compensation is a re-calibration of the vestibular system to make sense of the change in input at the level of the brain. Traditional views of vestibular rehabilitation have focused on stimulating the vestibular ocular reflex through head movements. This type of therapy has been shown to be beneficial, especially in cases of semicircular canal damage. However, in cases of otolith dysfunction it seems that physical therapy targeting postural control and orientation of the head and body may also beneficial, as these appear to be the primary functions of the otolith organs. Currently, there is little evidence to support this claim and further research is necessary in order to determine appropriate diagnosis and therapy options for damaged otolith organs.

 

 

I am about seven weeks out from an acute vestibular neuritis. From a clinician’s point of view, this is a textbook case of acute vestibular syndrome that I have seen hundreds of times. This time, as the patient, my experience has been predictable in some ways, and hard to explain in other ways.

The first thing we do when we see a “dizzy” patient is to try to get a clear understanding of their symptoms to make a correct diagnosis. They often have difficulty finding the right words to describe some of the sensations they experience.  As far as making a diagnosis, I knew within fifteen minutes of onset that I was suffering from an acute vestibular neuritis on the right side.  Looking back, I fit the typical description of two to three days of constant vertigo, followed by persistent disequilibrium and disorientation. I will take this opportunity to try and describe some of the symptoms that don’t fall neatly into categories of vertigo, disequilibrium, or lightheadedness, and some that do.

In my earlier post, I described the acute vertigo.  With gradually decreasing intensity, when my eyes were open the room looked as if things were constantly moving from left to right.  This correlates with the left beating nystagmus I was experiencing. There is no visual symptom related to the fast phase (beating to the left), but during the slow phase of nystagmus to the right, the room visually followed my eye movement. I learned that the vertigo eased up with my eyes closed, and that diazepam was very helpful in allowing me to sleep through most of the first 48 hours. The constant sensation of movement lasted about one week, but I had still had recordable nystagmus in darkness up to three weeks.

Visual Blurring

The ongoing symptoms after the first week are unchanged, but are slowly reducing in intensity. The most obvious is the visual blurring with head movement, known as oscillopsia. During the first couple of weeks, I only had clear vision when my head was still. Over time and with therapy, this has improved to where it is only noticeable with fast head movement to the right, and in the car on bumpy roads. I simply cannot keep my eyes focused on an object in these situations.

Sensory Conflict

I had one scary situation in a parking lot. I did not drive for one month, and started with a few days of just circling my neighborhood. My wife and I decided to go to lunch, and I would try my typical 10 minute work commute. As I pulled into a parking space in the plaza right across from my office, I experience a very disorienting sensory conflict. At the exact instant my car came to a stop, the car next to me started to back out.  Normally, in this situation, my brain would rely on my inner ear to make the quick judgment as to whether I was moving, or the other car was moving. Because I was not getting useful information from the inner ear, I could not tell which one of us was moving. I slammed on the brakes and freaked my wife out a little bit.

Loss of Balance

I am fine as long as I have a target to focus on. I can even run on a treadmill if I stare right at a number or symbol in front of me. If I turn my head while walking, I veer off center. Throughout the day, I have numerous, brief moments of imbalance. I catch myself and have not fallen, but I fear that my luck my run out. I tried hiking a couple of days ago, and working my way down a rocky slope was a bad idea. I am not ready for that yet. I also tried to walk on a floating dock surrounded by choppy water. Bad idea.

Hard to Describe

I have had a few sensations that defy clear explanation, but I will try. When my eyes are closed, and I move my head quickly, there is a sensation that I can best describe as feeling if here is too much liquid space around my brain. It feels like my brain is “sloshing around” in my head. There is occasionally an odd sensation of “pulling” in the back of my head when I move certain ways. I cannot reproduce it at will.

I suspect I have a mild case of right posterior canal BPPV. Inconsistently, but on several occasions, I have experienced a 10 to 15 second burst of mild vertigo shortly after rolling on to my right side. If I open my eyes, there is a visual sense of downward vertical movement, which I suspect indicates I have an up-beating component to my nystagmus.

Rehabilitation

I have been incorporating rehab exercises into my daily activities, with an occasional dedicated session to working on balance. I got some helpful tips from the Physical Therapist that I refer my patients to for vestibular rehabilitation. After recommending vestibular exercises to many patients over many years, I realize that the exercises I demonstrate are a lot more challenging to a person with a vestibular deficit. Now, I understand!