Shepard, Neil T.

ObjectiveTo determine the sensitivity and specificity of ocular and cervical vestibular evoked myogenic potentials (VEMPs) in the diagnosis of superior semicircular canal dehiscence (SCD) and to describe the VEMP response characteristics that are most sensitive to SCD and compare the findings to previous reports.Study DesignCase series with chart review.SettingTwo tertiary neurotologic referral centers.Subjects and MethodsCervical and ocular VEMP peak‐to‐peak amplitudes and thresholds from 39 adult patients older than 18 years with surgically confirmed SCD were compared with 84 age‐matched controls.ResultsUsing receiver operating characteristic (ROC) curves, cervical VEMP (cVEMP) amplitudes, cVEMP thresholds, and ocular VEMP (oVEMP) amplitudes had areas under the curve of 0.731, 0.912, and 0.856, respectively, all of which were statistically significant (P <. 0001). For cVEMP thresholds, at the clinical equivalent ≤85‐dB normalized hearing level (nHL) threshold, the sensitivity and specificity were 97.3% and 31.3%, respectively. At the ≤70‐dB nHL threshold, the sensitivity and specificity were 73.0% and 94.0%, respectively. For oVEMP amplitudes >12.0 µV, the sensitivity and specificity were 78.6% and 81.7%, respectively.ConclusionData from this multicenter study suggest that both cVEMP thresholds and oVEMP amplitudes remain good diagnostic tests for identifying SCD, with each test dependent on a number of factors. The sensitivity and specificity of these individual tests may vary slightly between centers depending on testing parameters used.

Objective (1) To characterize long‐term dizziness following observation, microsurgery, and stereotactic radiosurgery (SRS) for small to medium‐sized vestibular schwannoma (VS) using a validated self‐assessment inventory; and (2) to identify clinical variables associated with long‐term dizziness handicap. Study Design Cross‐sectional observational study. Setting Two independent tertiary academic referral centers: one located in the United States and one in Norway. Subjects and Methods All patients with sporadic VS of less than 3 cm who underwent primary microsurgery, SRS, or observation between 1998 and 2008 were identified. Subjects were surveyed via a postal questionnaire using the Dizziness Handicap Inventory (DHI) and a VS symptom questionnaire. Results The overall survey response rate was 79%. A total of 538 respondents (mean age, 64 years; 56% female) were analyzed, and the mean time interval between treatment and survey was 7.7 years. Pretreatment variables associated with greater dizziness handicap included female sex, older age, larger tumor size, preexisting diagnosis of headache or migraine, and symptoms of dizziness predating treatment. Significant posttreatment features strongly associated with poor long‐term DHI scores included frequency and severity of ongoing headache. On multivariable analysis, treatment modality did not influence long‐term dizziness handicap. Conclusion At a mean of approximately 8 years following treatment, over half of patients with VS reported ongoing dizziness. The authors have identified several baseline features that may help predict the risk of lasting dizziness. Treatment modality does not appear to influence long‐term DHI score. We found a strong association between posttreatment headache and poor dizziness handicap. Future study is needed to further define this relationship.

PurposeRecent research on head shake posturography has demonstrated a modest increase in sensitivity to identifying peripheral vestibular system asymmetry when horizontal head movements were added to portions of the standard Sensory Organization Test (SOT) battery. However, limitations with respect to the head shake protocol were outlined, and usable data for assessing performance could not be established. The purpose of this study was to test a change in protocol for use of head shake SOT to address the noted limitations.MethodForty participants ranging in age from 20 to 79 years with no history of dizziness completed Conditions 2 and 5 of the SOT portion of computerized dynamic posturography on EquiTest equipment, while maintaining head still as well as 4 horizontal head movement velocity tasks.ResultsSlope of a linear regression fit to 6 performance points was used to characterize each participant. Spearman’s ranked correlation (r) indicated a significant relationship between the slope of the line representing a decline in performance with age (r= −.52,p= .0006).ConclusionsThe head shake modification showed a trend in increasing the separation of normal individuals across age and eliminated the limitations addressed in earlier research. Future research will investigate the head shake modification for identifying vestibular peripheral system asymmetries.

PurposeTo determine the sensitivity of a head shake modification to the Sensory Organization Test (SOT) of dynamic posturography in identifying (a) those patients with unilateral, peripheral vestibular hypofunction as indicated by caloric irrigation findings and (b) those patients who report that head movements provoke disruption in postural control.MethodA prospective, single-blinded, random selection methodology was used with 91 patients stratified by the presence or absence of a significant caloric asymmetry and by the presence or absence of head movement provoked symptoms (independent variables). Postural control performance, as measured by EquiTest during the standard test and a head shake modification, served as the dependent variables.ResultsReceiver operating characteristic curves demonstrated only minor improvement in sensitivity (a) with the head shake modification for unilateral peripheral asymmetry and (b) for identification of those with complaints of head movement provoked imbalance.ConclusionsThe head shake modification to standard SOT increased the test sensitivity to identification of patients with unilateral, peripheral vestibular hypofunction and those with head movement provoked symptoms. However, this occurred with low specificity, resulting in no significant improvement in overall performance with this head shake protocol. Suggestions for further research to improve the performance of the head shake modification of SOT for clinical application are discussed.