Jessie N. Patterson

Effects of Hand Placement Technique on the Video Head Impulse Test (vHIT) in Younger and Older Adults

Objective To investigate the effects of hand placement techniques on the video head impulse test (vHIT) responses (i.e., gain, velocity) in older and younger adults and to determine intra-rater and inter-rater reliability of the horizontal vHIT. Design Descriptive, reliability study. Setting University research laboratory. Subjects Forty healthy adults grouped by age with negative history of current or previous vestibular diseases between the ages of 20 and 88 years (mean = 46.60, standard deviation 23.20). Main Outcome Measures Three examiners each used two hand placement techniques (chin and head) to elicit the horizontal vHIT responses. Both the examiner and hand placement orders were counterbalanced to account for order and fatigue effects. The outcome measures of interest were vHIT gain and velocity. Results A two-way between-subject factorial analysis of variance revealed a significant main effect for hand placement technique and gain response. Mean values for vHIT gain were higher for head technique. Significant main effects were observed for the velocity response for hand placement technique and age group. Mean velocity values were higher for chin technique and lower velocities were observed in the older age group. Intra- and inter-rater reliability scores were consistent for gain values; however, poor to fair inter-rater reliability scores were observed for velocity values. Conclusion It is suggested that clinical sites select one hand placement technique for the measure to provide consistency of protocol. Establishing clinical norms using the one selected method to verify reliability within and across clinicians is suggested before examination with a disordered population.

Examining postconcussion symptoms of dizziness and imbalance on neurocognitive performance in collegiate football players

Objective This study examined the effects of symptom reports of dizziness and imbalance on cognitive function in concussed collegiate football players. Design Retrospective, descriptive. Setting University athletic medicine facility. Subjects Twenty-seven collegiate football players were included in the final analysis: 16 with symptoms of dizziness/imbalance resulting from concussion and 11 without dizziness/imbalance resulting from concussion. Main Outcome Measures Participants completed the Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) at baseline, at 1 to 2 days postconcussion and 5 to 7 days postconcussion. The ImPACT neurocognitive assessment consists of 6 modules, yielding 4 composite scores: verbal memory, visual memory, visual-motor processing speed, and reaction time. In addition, it includes a postconcussion symptom scale total score. Results Results revealed that participants with reports of dizziness and imbalance had significantly lower scores on the ImPACT composite scores; however, these individuals also had an overall higher symptom inventory. When accounting for the additional postconcussion symptoms, time was the only significant effect. Conclusion Dizziness and imbalance are common symptoms postconcussion; however, these symptoms did not predict performance on acute ImPACT scores. Further research is needed to understand the mechanisms causing postconcussion symptoms, including symptoms of dizziness and imbalance, and influence on outcomes postconcussion.

Gaze stabilization test asymmetry score as an indicator of previous concussion in a cohort of collegiate football players

Objective:Vestibular dysfunction may lead to decreased visual acuity with head movements, which may impede athletic performance and result in injury. The purpose of this study was to test the hypothesis that athletes with history of concussion would have differences in gaze stabilization test (GST) as compared with those without a history of concussion. Design:Cross-sectional, descriptive. Setting:University Athletic Medicine Facility. Participants:Fifteen collegiate football players with a history of concussion, 25 collegiate football players without a history of concussion. Intervention:Participants completed the dizziness handicap inventory (DHI), static visual acuity, perception time test, active yaw plane GST, stability evaluation test (SET), and a bedside oculomotor examination. Main Outcome Measures:Independent samples t test was used to compare GST, SET, and DHI scores per group, with Bonferroni-adjusted alpha at P < 0.01. Receiver operating characteristic curve analysis and area under the curve (AUC) were used to assess the clinical performance of the GST and SET. Results:Athletes with previous concussion had a larger GST asymmetry score [mean (M) = 12.40, SD = 9.09] than those without concussion (M = 4.92, SD = 4.67; t (18.70) = −2.955, P = 0.008, 95% CI, −12.79 to −2.18, d = −1.37). Clinical performance of the GST (AUC = 0.77) was better than the SET (AUC = 0.61). Conclusions:Results suggest peripheral vestibular or vestibular–visual interaction deficits in collegiate athletes with a history of concussion. The results support further research on the use of GST for sport-related concussion evaluation and monitoring. Clinical Relevance:Inclusion of objective vestibular tests in the concussion protocol may reveal the presence of peripheral vestibular or visual–vestibular deficits. Therefore, the GST may add an important perspective on the effects of concussion.

Modified head shake sensory organization test: Sensitivity and specificity

The Sensory Organization Test (SOT) of Computerized Dynamic Posturography (EquiTest™ equipment) is a valuable tool for investigating how an individual uses balance system sensory input (vestibular, vision, proprioception/somatosensory) to maintain quiet stance; however, it is limited as a screening tool for identifying peripheral vestibular system dysfunction. Previous research has shown that adding horizontal head-shake to portions of the standard SOT battery improved the identification of peripheral vestibular system asymmetry; however, flaws in the methods were noted. The objective of this work was to evaluate the sensitivity and specificity of the modified head-shake SOT (HS-SOT) protocol for identification of peripheral vestibular system lesion. Fifteen patients with chief complaint of instability, vertigo, and/or lightheadedness, with and without a caloric unilateral weakness (UW) and fifteen age-matched healthy controls were included in the final analysis. Ten of the 15 patients demonstrated a caloric UW≥25%. Participants completed standard conditions 2 and 5 of SOT with head still and during four horizontal head-shaking tasks (i.e., HS-SOT2-60°/s, HS-SOT2-120°/s, HS-SOT5-15°/s, and HS-SOT5-60°/s). Average equilibrium scores decreased as condition difficulty increased (SOT2, HS-SOT2-60°/s, HS-SOT2-120°/s, SOT 5, HS-SOT5-15°/s, and HS-SOT5-60°/s) for each group; as expected, a lower decline was noted for controls (slope=-6.59) compared to patients (slope=-11.69). The HS-SOT5-15°/s condition was superior for identifying peripheral vestibular asymmetry (AUC=0.90 sensitivity=70%, specificity=100%), with the strongest correlation to caloric UW% (rs=-0.743, p=0.000006). HS-SOT5-15°/s appears to be a promising screening measure for peripheral vestibular asymmetry.

Effects of device on video head impulse test (vHIT) gain

Background: Numerous video head impulse test (vHIT) devices are available commercially; however, gain is not calculated uniformly. An evaluation of these devices/algorithms in healthy controls and patients with vestibular loss is necessary for comparing and synthesizing work that utilizes different devices and gain calculations. Purpose: Using three commercially available vHIT devices/algorithms, the purpose of the present study was to compare: (1) horizontal canal vHIT gain among devices/algorithms in normal control subjects; (2) the effects of age on vHIT gain for each device/algorithm in normal control subjects; and (3) the clinical performance of horizontal canal vHIT gain between devices/algorithms for differentiating normal versus abnormal vestibular function. Research Design: Prospective. Study Sample: Sixty‐one normal control adult subjects (range 20‐78) and eleven adults with unilateral or bilateral vestibular loss (range 32‐79). Data Collection and Analysis: vHIT was administered using three different devices/algorithms, randomized in order, for each subject on the same day: (1) Impulse (Otometrics, Schaumberg, IL; monocular eye recording, right eye only; using area under the curve gain), (2) EyeSeeCam (Interacoustics, Denmark; monocular eye recording, left eye only; using instantaneous gain), and (3) VisualEyes (MicroMedical, Chatham, IL, binocular eye recording; using position gain). Results: There was a significant mean difference in vHIT gain among devices/algorithms for both the normal control and vestibular loss groups. vHIT gain was significantly larger in the ipsilateral direction of the eye used to measure gain; however, in spite of the significant mean differences in vHIT gain among devices/algorithms and the significant directional bias, classification of “normal” versus “abnormal” gain is consistent across all compared devices/algorithms, with the exception of instantaneous gain at 40 msec. There was not an effect of age on vHIT gain up to 78 years regardless of the device/algorithm. Conclusions: These findings support that vHIT gain is significantly different between devices/algorithms, suggesting that care should be taken when making direct comparisons of absolute gain values between devices/algorithms.

Examining Effects of Physical Exertion on the Dynamic Visual Acuity Test in Collegiate Athletes

Background: Acute symptoms of dizziness and/or imbalance commonly experienced in athletes postconcussion are speculated to arise from dysfunction at multiple levels (i.e., inner ear or central vestibular system) to appropriately integrate afferent sensory information. Disruption along any pathway of the balance system can result in symptoms of dizziness, decreased postural control function (vestibulospinal reflex), and reduced vestibulo‐ocular reflex function. This may also lead to decreased gaze stability with movements of the head and may account for symptoms of blurred vision or diplopia reported in almost half of athletes sustaining a concussion. Current concussion position statements include measures of postural control to examine changes to the balance system postconcussion. The Balance Error Scoring System (BESS) is a commonly used low‐cost postural control measure for concussion assessment. Although this is a widely used measure for documenting balance function on both immediate (sideline) and recovery monitoring, the BESS has been shown to be affected by physical exertion. Therefore, the BESS may not be the most efficient means of examining functional changes to the balance system immediately after head injury. Dynamic Visual Acuity Test (DVAT) has been found to effectively evaluate and monitor changes to the gaze stability system postinjury. Thus, DVAT may be an additional measure in the concussion assessment battery, as well as an alternative for more immediate sideline assessment to help make objective return‐to‐play decisions. Purpose: The aim of the study was to determine the effects of physical exertion on a clinical vestibular assessment, the DVAT, in collegiate athletes, as a first step in defining the role of this measure in the concussion assessment battery. Research Design: Cross‐sectional, repeated‐measures design. Study Sample: Twenty‐eight healthy collegiate athletes (20 males, 8 females; age = 20.25 ± 1.46 yr, range = 18‐25 yr) volunteered to participate in the study. Data Collection and Analysis: Participants were randomly assigned to complete a 20‐min protocol of physical exertion or rest. DVAT was completed pre‐exertion or rest (pre‐DVAT), immediately following the 20‐min protocol (post‐DVAT I), and again 10 min after the completion of the 20‐min protocol (post‐DVAT II). Ratings of perceived exertion (RPE) and heart rate (HR) were monitored throughout testing. Repeated‐measures analysis of the variance were used to examine the effects of exertion on DVAT. Additionally, intraclass correlation coefficients were used to examine test reliability. Results: No significant main effect was observed for right and left DVAT logarithm of the minimal angle of resolution loss between groups or across time points (p > 0.05). A significant main effect was observed for RPE and HR for groups and time points (p < 0.001), indicating adequate physical exertion and rest. Fair to good reliability (intraclass correlation coefficient values between 0.4 and 0.74) was observed for both rightward and leftward movements of the head across the three time points. Conclusions: Findings from this study suggest that DVAT is not affected by physical exertion and may provide a more immediate assessment of the balance system that may be of use for the sideline concussion assessment. Future studies will be performed to examine additional factors (e.g., background noise, complex visual backgrounds) that may affect DVAT performance in the sideline environment.