Commentary on “Reliability and Diagnostic Accuracy of Clinical Tests of Vestibular Function for Children”

Abstract

“How could I apply this information?” Clinicians can use the positive and negative likelihood ratios (LR+, LR−) provided in Table 5 to determine the likelihood that a specific child diagnosed with severe to profound sensorineural hearing loss (SNHL) has vestibular hypofunction (VH). We use the example of the 6-year-old child with SNHL in this study who did not undergo reference standard Vestibular Function Testing (VFT) yet had positive results on 4 clinical tests: (1) Head Thrust Test, (2) Dynamic Visual Acuity Test, (3) Modified Clinical Test of Sensory Interaction on Balance total score, and (4) Modified Emory Clinical Vestibular Chair Test with fixation removed. Her pretest probability for VH was 42%, on the basis of the fact that 8 of 19 children with SNHL in this study had VH as diagnosed by VFT. Using a nomogram1 and the LR+ from each clinical test (range, 2.84-5.87), her posttest probability of having VH as diagnosed by VFT would be approximately 65% to 82% (Figure 1). If each clinical test had been negative (LR− range, 0.14-0.38), her posttest probability of having VH as diagnosed by VFT would be approximately 8% to 20% (Figure 2). In this case, the use of a nomogram and the LR of each clinical test provided critical quantitative information that increased certainty that the child had VH to make appropriate referrals for reference standard VFT and determine the most appropriate intervention plan.Fig. 1: Using a nomogram to find the posttest probability of VH based on positive test results. Pretest probability = 42%. MCTSIB total +LR = 5.87, posttest probability = 82%. HTT +LR = 3.25, posttest probability = 70%. DVA +LR = 2.84, posttest probability = 65%. A positive result on each of these 3 clinical tests changes the probability of the child having VH from 42% (pretest) to 65% to 82% (posttest), depending on the test. DVA indicates Dynamic Visual Acuity; HTT, Head Thrust Test; LR, likelihood ratio; MCTSIB, Modified Clinical Test of Sensory Interaction on Balance.Fig. 2: Using a nomogram to find the posttest probability based on negative test results. Pretest probability = 42%. m-ECVCT-fixation removed − LR = 0.38, posttest probability = 20%. HTT − LR = 0.33, posttest probability = 18%. DVA − LR = 0.18, posttest probability = 10%. MCTSIB total − LR = 0.14, posttest probability = 8%. A negative result on each of these 4 clinical tests changes the probability of the child having VH from 42% (pretest) to 8% to 20% (posttest), depending on the test. DVA indicates Dynamic Visual Acuity; HTT, Head Thrust Test; LR, likelihood ratio; MCTSIB, Modified Clinical Test of Sensory Interaction on Balance; m-ECVCT, Modified Emory Clinical Vestibular Chair Test.“What should I be mindful about when applying this information?” Clinicians must be mindful that only 8 participants had VH as diagnosed by reference standard VFT and that the psychometric properties of the 5 clinical tests of vestibular function can only be generalized to 6- to 12-year-old children with severe to profound SNHL from chronic lesions. Furthermore, 13 of 20 participants with SNHL used cochlear implants, yet no mention was made as to whether these children had a higher incidence of VH or whether their implants were on or off during the clinical tests of vestibular function. Barabara Sargent, PT, PhD, PCS University of Southern California Los Angeles, California Jennifer Pate, PT, DPT Los Angeles Children's Hospital Los Angeles, California