Part II: When the test results
and the history don’t match
Of course, sometimes the history is anything but clear. Another basic rule (again, not always true) is that, if after ten to fifteen minutes of questions you have no idea what is wrong with the patient, there is a very good chance that there is some psychological component. At the very least, your chances of providing a firm diagnosis at the end of the exam are reduced.
Another issue is when the patient provides a very clear description of their symptoms, you are pretty sure what is wrong, yet your tests don’t support your theory. This is the case quite often with BPPV. We did a study years ago that showed that about 40% of patients with active BPPV will have a negative Dix-Hallpike exam as a result of fatiguing the response by excessive head movement while traveling to their appointment. Just because the Dix- Hallpike is negative, you should never rule out BPPV if the symptom profile fits.
I use the Romberg and Tandem gait tests a bit unconventionally. I use these two together to get an idea of whether the patients is having difficulty sensing movement (as would be the case with a vestibular disorder, or peripheral neuropathy) or if they are having difficulty generating movement (as would be the case with a cerebellar or orthopedic disorder). Whenever the ENG reveals unexpected abnormalities on the ocular motor portion of the exam, I will double check for significant cerebellar dysfunction by checking for abnormal tandem gait and/or dysdiadochokinesia on rapid alternating hand movements. Abnormal responses support the likelihood of cerebellar dysfunction and the need for neurological evaluation or neuro-imaging.