Optokinetic Tracking: I am Confused

I am feeling a little vulnerable this week. I am not a lawyer thank goodness, but the quote, “Never ask a question if you don’t already know the answer” can also apply to someone who writes blogs, or books, or teaches courses, or simply wants to understand why we do what we do.

That leads to the second part of my vulnerability this week. I have been performing Optokinetic tracking as part of the VNG battery for years, on thousands of patients. In my practice we have the ability to do full field stimulation in the rotary chair room, but not everybody needs or gets a rotary chair. So let’s restrict this discussion to those patients who get the Optokinetic tracking test in the VNG room, using the light bar.  So, my concern is “What am I accomplishing?”

In the early years, I just did the VNG test battery as recommended because those recommending surely knew more than I. But over the years, I noticed a few things. First, hardly anyone ever fails the Optokinetic tracking test, and if they do, Smooth Pursuit tracking is also abnormal. Second, if the Optokinetic tracking test is the only abnormality, I can’t remember even one situation where that uncovered a previously unknown cerebellar disorder. Third, a lot of smart people criticize the use of a light bar as they claim it is an inadequate stimulus to provoke “true” optokinetic stimulation.

So, that leads to another personal dilemma. This has nothing to do with the clinical aspects, but rather with my role as advisor to the American Academy of Audiology at the American Medical Association where billing codes and procedural language are developed. Consider these three facts:

  1. Optokinetic tracking is now part of the bundled code. 
  2. Medicare reimbursement has been cut dramatically and we are already seeing a nearly 40% drop in performance of this test since 2007. (Decreased reimbursement results in decreased utilization. You can count on it).
  3. My understanding is that it would cost several thousand dollars to upgrade current VNG systems using a light bar to allow for full field stimulation. The last thing we want is to drive even more people away from performing vestibular evaluations, which is exactly what would happen if full field Optokinetic stimulation was required.

Finally, what is the purpose of the Optokinetic tracking test? Is it a screening test or a diagnostic test for possible cerebellar dysfunction? If it is a screening test, does that change our thinking on acceptable sensitivity and specificity? Let that marinate for a few days, and I will be back next week with others thoughts on this subject.

 

 

About Alan Desmond

Dr. Alan Desmond is the director of the Balance Disorders Program at Wake Forest Baptist Health Center, and holds an adjunct assistant professor faculty position at the Wake Forest School of Medicine. In 2015, he received the Presidents Award from the American Academy of Audiology.