Wendy J. Carender

Determining the preferred modality for real-time biofeedback during balance training

Vestibular rehabilitation therapy has been shown to improve balance and gait stability in individuals with vestibular deficits. However, patient compliance with prescribed home exercise programs is variable. Real-time feedback of exercise performance can potentially improve exercise execution, exercise motivation, and rehabilitation outcomes. The goal of this study is to directly compare the effects of visual and vibrotactile feedback on postural performance to inform the selection of a feedback modality for inclusion in a home-based balance rehabilitation device. Eight subjects (46.6±10.6years) with peripheral vestibular deficits and eight age-matched control subjects (45.3±11.1years) participated in the study. Subjects performed eyes-open tandem Romberg stance trials with (vibrotactile, discrete visual, continuous visual, and multimodal) and without (baseline) feedback. Main outcome measures included medial-lateral (M/L) and anterior-posterior mean and standard deviation of body tilt, percent time spent within a no-feedback zone, and mean score on a comparative ranking survey. Both groups improved performance for each feedback modality compared to baseline, with no significant differences in performance observed among vibrotactile, discrete visual, or multimodal feedback for either group. Subjects with vestibular deficits performed best with continuous visual feedback and ranked it highest. Although the control subjects performed best with continuous visual feedback in terms of mean M/L tilt, they ranked it lowest. Despite the observed improvements, continuous visual feedback involves tracking a moving target, which was noted to induce dizziness in some subjects with vestibular deficits and cannot be used during exercises in which head position is actively changed or during eyes-closed conditions.

Persistent positional nystagmus: a case of superior semicircular canal benign paroxysmal positional vertigo?

Involvement of the superior semicircular canal (SSC) in benign paroxysmal positional vertigo (BPPV) is rare. SSC BPPV is distinguished from the more common posterior semicircular canal (PSC) variant by the pattern of nystagmus triggered by the Dix‐Hallpike position: down‐beating torsional nystagmus in SSC BPPV versus up‐beating torsional nystagmus in PSC BPPV. SSC BPPV may be readily treated at the bedside, which is a key component in excluding central causes of down‐beating nystagmus. We present an unusual video case report believed to represent refractory SSC BPPV based on the pattern of nystagmus and the absence of any other central signs.

Strategies to Distinguish Benign Paroxysmal Positional Vertigo from Rotational Vertebrobasilar Ischemia

Vertigo provoked by head rotation is a classic symptom of rotational vertebrobasilar ischemia (RVBI). Inner ear disease can cause positional vertigo and mimic RVBI. We review the case of a patient with vertigo consistently triggered by leftward head rotation when supine. Computed tomography angiogram and dynamic arteriogram failed to show compression of the vertebral arteries with head rotation. Further evaluation revealed benign paroxysmal positional vertigo (BPPV) as the underlying etiology. Treatment of her BPPV led to complete resolution of her symptoms. A succinct overview of this common otologic disorder is provided, and strategies to help distinguish it from RVBI are discussed.

Dizziness Symptom Type Prevalence and Overlap: A US Nationally Representative Survey.

BACKGROUND The traditional approach to dizziness encourages providers to emphasize the type of dizziness. However, symptom types might substantially overlap in individual patients, thus limiting the clinical value of this approach. We aimed to describe the overlap of types of dizziness using a US nationally representative sample. METHODS The 2008 US National Health Interview Survey was examined for prevalence and overlap of types of dizziness. The data were also separately examined among people who otherwise had typical features of traditionally vertigo-based disorders (ie, benign paroxysmal positional vertigo and Menieres disease). Data analysis also included exploratory factor analysis. RESULTS Twelve-month prevalence of problems with dizziness or balance was 14.8%, representing 33.4 million individuals. The mean number of dizziness symptoms was 2.4 (95% confidence interval [CI], 2.3-2.4), with 61.1% reporting more than one type. Of subjects who otherwise had typical features of traditionally vertigo-based disorders, the mean number of dizziness types was 3.1 (95% CI, 3.0-3.3), and only 24.6% (95% CI, 21.0%-28.7%) reported vertigo as the primary type. Exploratory factor analysis found that symptom types loaded onto a single factor without other clinical or demographic variables. CONCLUSIONS Substantial overlap of dizziness types exists among US adults with dizziness. People otherwise having features of traditionally vertigo-based disorders also typically report multiple dizziness types and do not typically report vertigo as the primary type. Symptom types correlate more strongly with each other than with other clinical or demographic variables. These findings suggest that the traditional emphasis on dizziness types is likely of limited clinical utility.

The role of sensory augmentation for people with vestibular deficits: Real-time balance aid and/or rehabilitation device?

This narrative review highlights findings from the sensory augmentation field for people with vestibular deficits and addresses the outstanding questions that are critical to the translation of this technology into clinical and/or personal use. Prior research has demonstrated that the real-time use of visual, vibrotactile, auditory, and multimodal sensory augmentation technologies can improve balance during static and dynamic stance tasks within a laboratory setting. However, its application in improving gait requires additional investigation, as does its efficacy as a rehabilitation device for people with vestibular deficits. In some locomotor studies involving sensory augmentation, gait velocity decreased and secondary task performance worsened, and subjects negatively altered their segmental control strategies when cues were provided following short training sessions. A further question is whether the retention and/or carry-over effects of training with a sensory augmentation technology exceed the retention and/or carry-over effects of training alone, thereby supporting its use as a rehabilitation device. Preliminary results suggest that there are short-term improvements in balance performance following a small number of training sessions with a sensory augmentation device. Long-term clinical and home-based controlled training studies are needed. It is hypothesized that sensory augmentation provides people with vestibular deficits with additional sensory input to promote central compensation during a specific exercise/activity; however, research is needed to substantiate this theory. Major obstacles standing in the way of its use for these critical applications include determining exercise/activity specific feedback parameters and dosage strategies. This paper summarizes the reported findings that support sensory augmentation as a balance aid and rehabilitation device, but does not critically examine efficacy or the quality of the research methods used in the reviewed studies.

Refractory Positional Vertigo With Apogeotropic Horizontal Nystagmus After Labyrinthitis: Surgical Treatment and Identification of Dysmorphic Ampullae.

Objectives To describe the rationale, intraoperative details, and histopathologic findings discovered when treating an unusual case of apogeotropic horizontal canal positional vertigo with a transmastoid labyrinthectomy. Patient A single case report. Intervention Therapeutic. Main Outcome Measures Resolution of apogeotropic nystagmus and improvement of positional vertigo. Results The apogeotropic variant of horizontal canal positional vertigo can be a difficult entity to treat. This report describes a patient who developed profound sensorineural hearing loss and vertigo after an acute left labyrinthitis. Ten months later, she developed vertigo with apogeotropic positional nystagmus involving the left horizontal semicircular canal. Particle repositioning maneuvers and vestibular physical therapy were unsuccessful. In addition, she developed intermittent positional vertigo affecting the ipsilateral vertical semicircular canals. Given the persistence of her vertigo, multiple canal involvement, and patient preference for definitive treatment, a transmastoid labyrinthectomy was performed. Intraoperatively, the ampulla of the horizontal canal as well as that of the other canals was grossly abnormal as later confirmed on histology. After surgery, her apogeotropic nystagmus and vertigo resolved, and her balance ability gradually improved to a highly functional level. Conclusion This case illustrates a unique form of positional vertigo that developed and persisted after acute labyrinthitis. Conservative measures were unsuccessful and a transmastoid labyrinthectomy documented dense inflammatory tissue involving all three ampullae. We postulate that the post-labyrinthitic inflammatory changes resulted in mass loading of the membranous ampullae, causing abnormal nystagmus patterns and positional vertigo, which resolved after the labyrinthectomy.

Vestibular rehabilitation following surgical repair for Superior Canal Dehiscence Syndrome: A complicated case report

ABSTRACT Superior Canal Dehiscence Syndrome (SCDS) causes auditory and vestibular symptoms. Following surgical repair of the dehiscence, patients often experience dizziness and imbalance. This case report describes a postoperative vestibular exercise program, focusing on the principles of central compensation and habituation, and how it was modified for a patient with delayed progress secondary to strabismus and visual vertigo. A 63-year-old male with history of strabismus eye surgery, right hearing loss, aural fullness, and sensitivity to loud sounds was referred for vestibular rehabilitation (VR). He was seen for one preoperative and six postoperative PT visits over eight months. Outcome measures two weeks postoperative were as follows: Dizziness Handicap Inventory (DHI) 38/100; Timed Up & Go (TUG) 9.92 seconds; Dynamic Gait Index (DGI) 16/24; and a 3-line difference in Dynamic Visual Acuity (DVA). Improved outcomes at discharge included: DHI 18/100; TUG 6.87 seconds; DGI 23/24; and 1-line difference in DVA. He was able to return to work and previously enjoyed recreational activities. Postoperative vestibular rehabilitation programs are functionally and symptomatically beneficial following surgical repair for SCDS. Deviations from expected recovery should be addressed to achieve optimal outcomes as demonstrated in this complicated case report.

Determining inertial measurement unit placement for estimating human trunk sway while standing, walking and running

Inertial measurement units (IMU) are often used to estimate medial-lateral (M/L) trunk sway for assessing and treating gait disorders, and IMU sensor placement is an important factor effecting estimation accuracy. This study tracked multi-segment spine movements during standing and ambulation tasks to determine optimal IMU placement. Ten young healthy subjects, wearing markers placed along the spine, left/right acromion, and left/right posterior superior iliac spine performed standing and walking trials in a motion capture laboratory. Results showed that movement at the spine location T7-T8 most closely matched the clinical definition of M/L trunk sway for standing trials (0.5 deg error) and at the spine location T9-T10 for walking trials (1.0 deg error), while movement at the lower spine L2-L4 tended to be the least accurate for standing and ambulation tasks (1.5 deg error and 4.0 deg error, respectively). Based on these results, a second study was performed to develop and validate a trunk sway estimation algorithm during walking trials with a single optimally-placed IMU. IMU trunk sway estimation was compared to the clinical definition of trunk sway from motion capture markers and showed root-mean-square errors of 2.5 deg and peak trunk sway errors of 2.0 deg. The results of this study suggest that IMUs should be placed on the mid-back to reduce errors associated with spine movements not matching clinically-defined M/L trunk motion.

Nystagmus Discordance with 2-Dimensional Videonystagmography in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo

Objective The Dix-Hallpike test is a standard component of the videonystagmography test battery and can diagnose posterior semicircular canal benign paroxysmal positional vertigo. The purpose of this study is to determine the prevalence of discordant, equivocal, and concordant nystagmus tracings in active posterior semicircular canal benign paroxysmal positional vertigo when compared directly with the eye video. Study Design Case series with chart review of patients diagnosed with posterior semicircular canal benign paroxysmal positional vertigo by 2-dimensional videonystagmography from August 1, 2007, to August 1, 2012. Setting A tertiary vestibular test laboratory. Subjects and Methods Ninety-six adults (4 had bilateral involvement) with posterior semicircular canal benign paroxysmal positional vertigo were included. A total of 100 videos with accompanying videonystagmography tracings were reviewed to determine nystagmus trajectory as well as globe position. Descriptive statistics were used to describe prevalence. Fisher exact test was used to compare proportions. Results Sixty-two percent of cases involved benign paroxysmal positional vertigo of the right posterior semicircular canal, while 38% involved the left posterior semicircular canal. The prevalence of discordant, equivocal, and concordant tracings was 65% (65/100), 29% (29/100), and 6% (6/100). All tracing errors involved the horizontal channel. There was no association between tracing accuracy and the ear of involvement or globe position (P > .05). Conclusions Two-dimensional videonystagmography tracings are not reliable for identifying nystagmus trajectory in posterior semicircular canal benign paroxysmal positional vertigo.