There is considerable malpractice litigation associated with bilateral vestibular loss, as many patients develop this condition after exposure to toxic drugs. Some patients with bilateral vestibular loss, in an attempt to improve their chances during the litigation, exaggerate the extent of their inner ear deficit. The purpose of this page is to help clinicians as well as attorneys sort out "true" vestibular deficits from "facticious" vestibular deficits. We hope that the result of this page will be to help establish the true picture.
Malingering, like other forms of deceit, is detected through observation of inconsistency. Inconsistency is most easily detected when there is a combination of subjective and objective measures. In malingering, the modifiable (subjective) tests are poorer than the unmodifiable (objective) tests.
For bilateral vestibular loss, the astute clinician needs to know what is expected of symptoms, signs and test results, as a function of time, over at least several years, as well as the limits of normal for all of the tests. This should also be known for different ages of people -- mainly persons up to 65 years old, and persons 65 or older. The clinician also needs to know about the effects of common medications on the vestibular system, and the effects of ototoxins on other parts of the ear (such as hearing).
The author of this page, Dr. Timothy Hain, uses the following criteria to develop a judgement as to whether or not there is a component of exaggeration to a patients clinical picture.
We will use the following abbreviations for tests:
This table documents the usual patterns seen in persons with gentamicin ototoxicity.
|Test||Normal||Acute (3 mo)||1 year||2 years|
|ECTR||6 seconds||< 6 sec||< 6 sec||< 6 sec|
|DIE||0-2 lines loss||7 lines||4 lines||3 lines|
|ROT||Normal gain and phase, TC > 12||Reduced gain, increased phase, TC < 7||Increased phase, TC < 7, gain close to normal||Increase phase, Tc < 7, normal gain|
|ENG||Normal TR (20 or higher)||TR < 20||TR < 20||TR < 20|
|VEMP||Amplitude > 70||< 70, typically 20 or 0||< 70, 20 or less||< 70, 20 or less|
|AUD||Normal or age pattern||No difference||No difference||No difference|
|CDP||Composite > 70||Composite < 70, vestibular pattern, possibly aphysiologic||Composite < 70, vestibular pattern, not aphysiologic||Composite < 70, vestibular pattern, not aphysiologic|
|DRV||Driving||Not driving||Occasional driving||Driving during day|
Persons attempting to exaggerate their deficits, simply do not follow this timetable. They do not improve with time, they have more deficits one tests that they understand and can modify (such as posturography) than tests that require no cooperation (such as VEMP testing). By noting these inconsistencies, inferences can be made concerning true vestibular function. All of these values change with age, and again, an astute clinician must know what to expect over time.
On the other hand, sometimes people do not completely "follow the program" with respect to this complex timetable. They may have other problems than inner ear, there may be "noise" in their testing results, and the interaction with age can be tricky.
Note that this table does not have a column for > 2 years. Persons who "grow up" with bilateral vestibular loss, such as when it is present from birth, often do much better. They can look very normal in the light, they are not disabled by their deficit.