Last week, we discussed situations where it is reasonable to perform monothermal (one temperature, two total) caloric irrigations instead of the traditional bithermal (two temperatures, four total) irrigations. I also posed the question, “When is it okay to skip calorics?” This is not as easy to answer as the monthermal versus bithermal question, but let’s think through it.
There is one large group of patients that the guidelines are pretty straightforward. The clinical practice guideline for BPPV recommends against performing vestibular function tests in patients already diagnosed with BPPV. In offices performing VNG’s, the typical and recommended test protocol puts oculo-motor and positional tests before caloric testing. If the Dix-Hallpike positional test is positive for BPPV, the next step should be Canalith Repositioning, not caloric testing. If the patient’s symptoms are resolved after repositioning, they most likely do not need caloric testing. If any vestibular type symptoms persist after repositioning, then additional vestibular function tests, including but not limited to caloric irrigation, are indicated.
In offices doing more comprehensive vestibular function evaluations, the decision process gets trickier because you have a lot more information to consider. I understand that my approach may not apply to the many clinics that do not have rotational chair (RC) available, but I have found that performing RC as the first step in the battery of tests helps me quickly judge whether the patient most likely has a vestibular deficit, or not. This approach has been studied by Arriaga et al in 2005. So, in describing the patients below, keep in mind that they had normal RC exams.
Let me give you a couple of examples where I think it is okay to skip caloric irrigation testing:
Patient #1: A 64 year old male with complaints of lightheadedness and transient loss of balance when he first stands up. He has no symptoms while sitting or lying down, and the lightheadedness and loss of balance improve after about one or two minutes. His medications include Lisinopril and Lasix. His RC, oculo-motor and positional tests are normal, and he has a significant drop in blood pressure when he stands up. The blood pressure comes back to baseline at about three minutes.
Patient #2: A 55 year old female with a history of diabetes. She complains of numbness and tingling in her feet, but is unfamiliar with the term “neuropathy.” She has no symptoms while sitting or lying down, but feels unsteady and at risk for falling whenever she is on her feet. The imbalance is worse in the dark. Her RC, oculo-motor and positional tests are normal. Her platform posturography test (CDP) indicates that she is very reliant on her vision and makes poor use of tactile information from the lower extremities.
In both of these examples, caloric testing is not the logical next step. Caloric testing poses little risk, but it is time consuming and unpleasant for the patient. Patient #1 would be better served by an explanation of orthostatic hypotension and a referral back to the physician that prescribed the above medications. Patient #2 would be better served by a referral to neurology or physical therapy for assessment for possible peripheral neuropathy of the lower extremities.
Photo courtesy of http://theromanticvineyard.com/2013/03/27/7-things-we-dont-do-to-hurt-our-marriage/