Journal of Vestibular Research - Volume 21, issue 5

Authors: Cohen, Helen S. | Gottshall, Kim R. | Graziano, Mariella | Malmstrom, Eva-Maj | Sharpe, Margaret H. | Whitney, Susan L.

Article Type: Research Article

Abstract: The Barany Society Ad Hoc Committee on Vestibular Rehabilitation Therapy has developed guidelines for developing educational programs for continuing education. These guidelines may be useful to individual therapists who seek to learn about vestibular rehabilitation or who seek to improve their knowledge bases. These guidelines may also be useful to professional organizations or therapists who provide continuing education in vestibular rehabilitation. We recommend a thorough background in basic vestibular science as well as an understating of current objective diagnostic testing and diagnoses, understanding of common tests used by therapists to assess postural control, vertigo and ability to perform activities of …daily living. We recommend that therapists be familiar with the evidence supporting efficacy of available treatments as well as with limitations in the current research. Show more

Keywords: Vestibular rehabilitation, occupational therapy, physical therapy, training

DOI: 10.3233/VES-2011-0424

Citation: Journal of Vestibular Research, vol. 21, no. 5, pp. 243-250, 2011

Authors: Laurens, Jean | Valko, Yulia | Straumann, Dominik

Article Type: Research Article

Abstract: Visuo-vestibular interactions in monkeys can be accurately modelled using the classical Raphan and Cohen's model. This model is composed of direct vestibular and visual contributions to the vestibulo-ocular reflex (VOR) and of a velocity storage. We applied this model to humans and estimated its parameters in a series of experiments: yaw rotations at moderate (60°/s) and high velocities (240°/s), suppression of the VOR by a head-fixed wide-field visual stimulus, and optokinetic stimulation with measurements of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN). We found the velocity storage time constant to be 13 s, which decreased to 8 s during visual …suppression. OKAN initial velocity was 12% of the OKN stimulus velocity. The gain of the direct visual pathway was 0.75 during both visual suppression and OKN; however, the visual input to the velocity storage was higher during visual suppression than during OKN. We could not estimate the time constant of the semicircular canals accurately. Finally, we inferred from high-velocity rotations that the velocity storage saturates around 20–30°/s. Our results indicate that the dynamics of visuo-vestibular interactions in humans is similar as in monkeys. The central integration of visual cues, however, is weaker in humans. Show more

Keywords: Vestibular, sensorimotor, semicircular canal, reflex, modelling, oculomotor

DOI: 10.3233/VES-2011-0425

Citation: Journal of Vestibular Research, vol. 21, no. 5, pp. 251-266, 2011

Authors: Honaker, Julie A. | Shepard, Neil T.

Article Type: Research Article

Abstract: Adequate function of the peripheral vestibular system, specifically the vestibulo-ocular reflex (VOR; a network of neural connections between the peripheral vestibular system and the extraocular muscles) is essential for maintaining stable vision during head movements. Decreased visual acuity resulting from an impaired peripheral vestibular system may impede balance and postural control and place an individual at risk of falling. Therefore, sensitive measures of the vestibular system are warranted to screen for the tendency to fall, alerting clinicians to recommend further risk of falling assessment and referral to a falling risk reduction program. Dynamic Visual Acuity (DVA) testing is a computerized …VOR assessment method to evaluate the peripheral vestibular system during head movements; reduced visual acuity as documented with DVA testing may be sensitive to screen for falling risk. This study examined the sensitivity and specificity of the computerized DVA test with yaw plane head movements for identifying community-dwelling adults (58–78 years) who are prone to falling. A total of 16 older adults with a history of two or more unexplained falls in the previous twelve months and 16 age and gender matched controls without a history of falls in the previous twelve months participated. Computerized DVA with horizontal head movements at a fixed velocity of 120 deg/sec was measured and compared with the Dynamic Gait Index (DGI) a gold standard gait assessment measurement for identifying falling risk. Receiver operating characteristics (ROC) curve analysis and area under the ROC curve (AUC) were used to assess the sensitivity and specificity of the computerized DVA as a screening measure for falling risk as determined by the DGI. Results suggested a link between computerized DVA and the propensity to fall; DVA in the yaw plane was found to be a sensitive (92%) and accurate screening measure when using a cutoff logMAR value of > 0.25. Show more

Keywords: Falling risk, Dynamic Visual Acuity, vestibular function test, balance disorders, vestibulo-ocular reflex

DOI: 10.3233/VES-2011-0427

Citation: Journal of Vestibular Research, vol. 21, no. 5, pp. 267-276, 2011

Authors: Mohammad, Maha T. | Whitney, Susan L. | Marchetti, Gregory F. | Sparto, Patrick J. | Ward, Bryan K. | Furman, Joseph M.

Article Type: Research Article

Abstract: The purpose of the study was to investigate the test-retest reliability and response stability of the Dynamic Visual Acuity (DVA) and Gaze Stabilization Test (GST) in patients with vestibular disorders. Twenty-nine patients with vestibular disease (16–78 years) participated. Subjects performed the GST and DVA in pitch and yaw planes, twice in one session and once after 7–10 days. The GST output is the maximum head velocity at which the patient was able to identify orientation of the letter E. The DVA output is the change in visual acuity when moving the head compared to static acuity. Subjects indicated their level …of dizziness and visual blurring using a visual analog scale. Within- and between-sessions intraclass correlation coefficients ranged between 0–0.5 for the DVA and GST measures, with better correlations for within-session assessments. Response stability (standard error of measurement / mean) of the GST ranged between 21–32% and the DVA ranged between 25–69% with vertical DVA being most influenced by measurement error. Subjects' symptoms did not correlate with performance on either test. The current test protocol needs refinement to enhance reliability and stability in persons with vestibular disorders. Show more

Keywords: Vestibulo-ocular reflex, gaze stabilization test, dynamic visual acuity

DOI: 10.3233/VES-2011-0430

Citation: Journal of Vestibular Research, vol. 21, no. 5, pp. 277-288, 2011

Authors: Uehara, Natsumi | Tanimoto, Hitoshi | Nishikawa, Tasuku | Doi, Kiyoshi | Katsunuma, Sayaka | Kimura, Hidehito | Kohmura, Eiji | Nibu, Ken-ichi

Article Type: Research Article

Abstract: Objective: To evaluate vestibular function after unilateral acoustic neuroma surgery via a retrosigmoid approach. Methods: Thirty-eight patients were tested using caloric irrigation, static posturography, and the Dizziness Handicap Inventory (DHI) before, and one week to nine months after surgery. Results: Twenty-six patients were categorized as a response group and 12 as a no-response group on the basis of preoperative caloric irrigation findings. The posturographic parameters and DHI scores at one week after surgery showed significant deterioration in the response group, but not in the no-response group. However, they recovered to the preoperative baseline at 3 months …after surgery. The posturographic parameters and DHI scores for older patients tended to be worse than those for younger patients at 6 and 9 months after surgery. Conclusion: Patients in whom caloric responses are retained preoperatively show a temporary disturbance of balance after removal of acoustic neuroma. Disequilibrium after surgery ameliorates to the preoperative baseline within three months due to vestibular compensation, regardless of preoperative vestibular function. It is possible that poorer vestibular compensation may facilitate incomplete recovery in older patients after surgery. Show more

Keywords: Vestibular compensation, vestibular function, acoustic neuroma, posturography, Dizziness Handicap Inventory, retrosigmoid approach

DOI: 10.3233/VES-2011-0429

Citation: Journal of Vestibular Research, vol. 21, no. 5, pp. 289-295, 2011