Question
Is it possible to do a Fistula test using computerized dynamic posturography and your office tympanometer? I know there are some manufacturers with specific equipment designed to be an addition to your CDP machine, but I am inquiring as to just the regular old tympanometer.....What protocol would you use, and what CPT code for billing? Or, is this not advisable?
Answer
Yes, one could do the CDP Pressure Test (we prefer this name because the test documents abnormal couplings between the middle and inner ear spaces, which may or may not be caused by a fistula) with an office tympanometer. If one used this method, one could run 3 trials of condition 5 without pressure stimulation, and 2 sets of 3 trials each, while stimulating one ear, for a total of nine trials. One could use both the three condition 4 and the three condition 5 trials (6 trials total) and two consecutive tests to obtain the necessary minimum of 9 trials total. Of course, it would be best to randomize trials among control, left, and right ear stimuli.
There are several problems with this approach. One, is that control over the stimulus onset, waveform, and amplitude is limited. Another problem is that the patient knows when an ear is being stimulated. Finally, a positive response can be judged only by observing gross increases in sway over the 20-second stimulus trials, compared to the control trials. If trials have been randomized, the operator will have to manually record the conditions of each trial and then manually score the results on a trial by trial basis.
With the hardware/software automated system, brief stimuli (1.5 sec) are delivered at random times. Tubes are inserted in both ears so that stimulus deliveries can be randomized between the two ears. Control trials are interspersed at random between the stimulus trials. Then, sway responses are stimulus onset averaged and analyzed to document changes in sway correlated with the brief stimuli. Onset averaged results are then compared to averages of the control trials. We perform two types of analysis to identify significant differences between control and stimulus trials. First, amplitude differences between control and stimulus trials are analyzed for statistical significance. Second, autocorrelations are performed to quantify the extent and significance of any synchronization between stimulus and sway response onsets. These are more reliable methods for determining a positive response.
I don't have good information on billing...sorry.
Dr. Lewis M Nashner is currently President and CEO of Neurocom International, Inc. He is past Senior Scientist and Chairman of the Neurological Sciences Institute, Oregon Health & Sciences University, and remains an Adjunct Professor of Physiology at that institution. During his research career, Dr Nashner published extensively in the area of human motor control and human balance. Since founding Neurocom, his research has focused primarily on clinical applications for technology in diagnosis and treatment of balance and mobility disorders.