A Wearable Device Providing a Visual Fixation Point for the Alleviation of Motion Sickness Symptoms.

OBJECTIVES: Motion sickness (MS) can be problematic for many military operations. Some pharmaceutical countermeasures are effective but can lead to side effects. Non-pharmaceutical countermeasures vary in effectiveness and can require time to be beneficial (e.g., desensitization). Previous research suggests that visual fixation can alleviate MS symptoms. In the current experiment we tested the effectiveness of a user-worn device that provides a visual fixation point that moves with the user. METHODS: Fourteen subjects viewed the interior of a rotating optokinetic drum (60°/s) through a visor that displayed either a clear view of the scene (control) or the scene with a fixation point (experimental). After 5 minutes of viewing, symptoms were assessed using (1) the Simulator Sickness Questionnaire that yields four scores (total, nausea, oculomotor, and disorientation) and (2) a 0 to 10 MS overall scale. RESULTS: Viewing the fixation point resulted in significantly lower scores for all measures. Control condition scores were as much as 400% higher than when the fixation point was viewed. CONCLUSIONS: A wearable device that presents a visual fixation point that moves with the user may reduce MS. The device's portability suggests that it may be suitable for some military operations, and additional research in the field is warranted.

The relationship between vestibular function and topographical memory in older adults.

Research during the past two decades has demonstrated an important role of the vestibular system in topographical orientation and memory and the network of neural structures associated with them. Almost all of the supporting data have come from animal or human clinical studies, however. The purpose of the present study was to investigate the link between vestibular function and topographical memory in normal elderly humans. Twenty-five participants aged 70 to 85 years who scored from mildly impaired to normal on the Montreal Cognitive Assessment (MoCA) received three topographical memory tests: the Camden Topographical Recognition Memory Test (CTMRT), a computerized topographical mental rotation test (TMRT), and a virtual pond maze (VPM). They also received six vestibular or oculomotor tests: optokinetic nystagmus (OKN), visual pursuit (VP), actively generated vestibulo-ocular reflex (VOR), the sensory orientation test (SOT) for posture, and two measures of rotational memory (error in degrees, or RM°, and correct directional recognition, or RM→). The only significant bivariate correlations were among the three vestibular measures primarily assessing horizontal canal function (VOR, RM°, and RM→). A multiple regression analysis showed significant relationships between vestibular and demographic predictors and both the TMRT (R = 0.78) and VPM (R = 0.66) measures. The significant relationship between the vestibular and topographical memory measures supports the theory that vestibular loss may contribute to topographical memory impairment in the elderly.

Controlling motion sickness and spatial disorientation and enhancing vestibular rehabilitation with a user-worn see-through display.

OBJECTIVES/HYPOTHESES: An eyewear mounted visual display ("User-worn see-through display") projecting an artificial horizon aligned with the user's head and body position in space can prevent or lessen motion sickness in susceptible individuals when in a motion provocative environment as well as aid patients undergoing vestibular rehabilitation. In this project, a wearable display device, including software technology and hardware, was developed and a phase I feasibility study and phase II clinical trial for safety and efficacy were performed. STUDY DESIGN: Both phase I and phase II were prospective studies funded by the NIH. The phase II study used repeated measures for motion intolerant subjects and a randomized control group (display device/no display device) pre-posttest design for patients in vestibular rehabilitation. METHODS: Following technology and display device development, 75 patients were evaluated by test and rating scales in the phase II study; 25 subjects with motion intolerance used the technology in the display device in provocative environments and completed subjective rating scales, whereas 50 patients were evaluated before and after vestibular rehabilitation (25 using the display device and 25 in a control group) using established test measures. RESULTS: All patients with motion intolerance rated the technology as helpful for nine symptoms assessed, and 96% rated the display device as simple and easy to use. Duration of symptoms significantly decreased with use of the technology displayed. In patients undergoing vestibular rehabilitation, there were no significant differences in amount of change from pre- to posttherapy on objective balance tests between display device users and controls. However, those using the technology required significantly fewer rehabilitation sessions to achieve those outcomes than the control group. CONCLUSIONS: A user-worn see-through display, utilizing a visual fixation target coupled with a stable artificial horizon and aligned with user movement, has demonstrated substantial benefit for individuals susceptible to motion intolerance and spatial disorientation and those undergoing vestibular rehabilitation. The technology developed has applications in any environment where motion sensitivity affects human performance.

Anterior canal benign paroxysmal positional vertigo: an underappreciated entity.

OBJECTIVE: Evaluate the frequency and characteristics of benign paroxysmal positional vertigo (BPPV) arising from involvement of the anterior semicircular canal (AC) as compared with the posterior canal (PC) and horizontal canal (HC). STUDY DESIGN: Prospective review of patients with BPPV. SETTING: Tertiary referral center. PATIENTS: A total of 260 patients who were evaluated for vertigo were identified as experiencing BPPV. INTERVENTIONS: Standard vestibular assessment including the use of electrooculography (EOG) or video-oculography (VOG) was completed on all patients. Based on EOG/VOG findings, the BPPV origin was attributed to AC, PC, or HC involvement secondary to canalithiasis versus cupulolithiasis. Treatment was performed with canalith repositioning maneuvers (CRMs) appropriate for type of canal involvement. RESULTS: For the 260 patients, the positionally induced nystagmus patterns suggested the canal of origin to be AC in 21.2%, PC in 66.9%, and HC in 11.9%. Cupulolithiasis was observed in 27.3% of the AC, 6.3% of the PC, and 41.9% of the HC patients. Head trauma was confirmed in the history preceding the onset of vertigo in 36.4% of the AC, versus 9.2% of the PC and 9.7% of the HC patients (p < 0.001). The number of CRMs completed to treat the BPPV did not differ between canals involved (1.32 for AC, 1.49 for PC, and 1.34 for HC). CONCLUSION: The direction of subtle vertical-beating nystagmus underlying the torsional component is critical in differentiating AC versus PC origin; EOG/VOG aids in accurate assessment of the vertical component for the diagnosis of canal involvement. AC involvement may be more prevalent than previously appreciated, particularly if the examiner does not appreciate the vertical component of the nystagmus or the diagnosis is made without the assistance of EOG/VOG. Head trauma history is significantly more frequent in AC versus other forms of BPPV, and patients with a history of head trauma should be examined closely for AC involvement. CRM is as successful for treatment of AC BPPV as for other types of BPPV.

A comparison of screening methods in school-aged children.

OBJECTIVE: We sought to compare the findings of 3 different hearing screening methods in school-aged children. STUDY DESIGN AND SETTING: Prospective testing of second- and third-grade students in their schools was carried out. METHODS: Three hundred children (599 ears) were screened by using 3 test modalities, pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), and tympanometry. RESULTS: All of the tests were normal in 532 ears (89%), and all were abnormal in 12 ears (2%). Tympanometry yielded the most abnormalities (8.3%), and pure-tone testing demonstrated the fewest (3.3%), with a positive rate of 6.3% for DPOAE testing. False-positive rates were 1.2%, 4.2%, and 6.4% for pure tones, DPOAE, and tympanometry, respectively, when normal results on pure-tones or DPOAE were taken to represent true hearing. CONCLUSION/SIGNIFICANCE: We continue to recommend pure-tone testing as an effective screening method, with follow-up by using otoacoustic emissions in those who fail the pure-tone test.

Preliminary ossiculoplasty results using the Kurz titanium prostheses.

OBJECTIVE: Limitations in biocompatibility and hearing improvement with ossicular chain reconstruction prostheses are addressed with new, lightweight titanium prostheses designed to maximize visualization of the capitulum and footplate regions. The effectiveness of these new prostheses is being tested in a prospective multicenter study. STUDY DESIGN: Prospective case series. SETTING: Multicenter (8 sites), primarily tertiary private practice or academic otologic clinics. PATIENTS: A convenience sample of 31 patients undergoing ossiculoplasty, with 16 partial ossicular chain reconstructions using the Bell prosthesis and 15 total reconstructions using the Aerial prosthesis. INTERVENTION: Ossiculoplasty using new Kurz titanium prostheses. Cartilage was interposed between the tympanic membrane and the prosthesis. MAIN OUTCOME MEASURES: Air-bone gap for pure tone average and 3,000 and 4,000 Hz, assessed preoperatively and 3 months, 6 months, and 12 months postoperatively; percent of patients obtaining an air-bone gap of

Electrocochleography in Retrosigmoid Vestibular Nerve Section for Intractable Vertigo Caused by Meniere's Disease.

Interest in electrocochleography has increased in recent years because of the discovery of an elevated summating potential to action potential amplitude ratio (SP/AP ratio) in patients with endolymphatic hydrops caused by Meniere's disease or perilymph fistula. It was the purpose of this investigation to determine whether the intraoperative SP/AP ratio will decrease after vestibular nerve section in patients with intractable Meniere's disease. Fourteen patients with medically intractable classic Meniere's disease underwent retrosigmoid vestibular nerve section. Intraoperative transtympanic electrocochleography was performed with alternating click stimuli presented at 95 dB HL. In all patients the SP/AP ratio was recorded before the skin incision ("baseline" condition) and after the dura was closed ("closing" condition). Statistical analysis was applied to the recorded data. In 11 (79%) patients, the SP/AP ratio was found to be elevated above 0.30 in the baseline state. In 13 (93%) patients, the SP/AP ratio decreased more than 25% after the nerve was sectioned. These results were highly statistically significant (p < 0.001). We conclude that the SP/AP ratio does decrease in patients with Meniere's disease after undergoing retrosigmoid vestibular nerve section and offer a possible explanation. (Otolaryngol Head Neck Surg 1997;116:593-6.).