Prototype tests of vertical and torsional alignment nulling for screening vestibular function

BACKGROUND

We have developed a non-invasive, behavioral measure of ocular alignment using a computer tablet, colored lenses, and touch screen software.

OBJECTIVE

The goal of this study was to determine if these tests differentiate healthy controls from patients with vestibular disorders.

METHODS

In the vertical alignment nulling test (VAN), subjects were asked to adjust a horizontal line that was offset vertically from a fixed horizontal line. In the torsional alignment nulling test (TAN) subjects were asked to adjust a line that was rotationally offset (i.e. clockwise) from a fixed horizontal line. We measured VAN and TAN in 14 healthy controls and 8 patients with known vestibular disorders.

RESULTS

Patients had significantly worse scores than controls on TAN, (mean 2.2 vs 0.75, p = 0.01), and no differences for scores compared to controls on VAN, (mean 0.4 vs 0.8, p = 0.07).

CONCLUSIONS

These results suggest that TAN, and possibly VAN, have potential for identifying misalignments in ocular position. After further technical development these tests might be useful in the future for screening patients in facilities that are not equipped to perform cervical and ocular vestibular evoked myogenic potentials.

Analysing the effect of crystal size and structure in highly efficient CH3NH3PbI3 perovskite solar cells by spatially resolved photo- and electroluminescence imaging

CH3NH3PbI3 perovskite solar cells with a mesoporous TiO2 layer and spiro-MeOTAD as a hole transport layer (HTL) with three different CH3NH3I concentrations (0.032 M, 0.044 M and 0.063 M) were investigated. Strong variations in crystal size and morphology resulting in diversified cell efficiencies (9.2%, 16.9% and 12.3%, respectively) were observed. The physical origin of this behaviour was analysed by detailed characterization combining current-voltage curves with photo- and electroluminescence (PL and EL) imaging as well as light beam induced current measurements (LBIC). It was found that the most efficient cell shows the highest luminescence and the least efficient cell is most strongly limited by non-radiative recombination. Crystal size, morphology and distribution in the capping layer and in the porous scaffold strongly affect the non-radiative recombination. Moreover, the very non-uniform crystal structure with multiple facets, as evidenced by SEM images of the 0.032 M device, suggests the creation of a large number of grain boundaries and crystal dislocations. These defects give rise to increased trap-assisted non-radiative recombination as is confirmed by high-resolution μ-PL images. The different imaging techniques used in this study prove to be well-suited to spatially investigate and thus correlate the crystal morphology of the perovskite layer with the electrical and radiative properties of the solar cells and thus with their performance.

Strategies for balance rehabilitation: fall risk and treatment

Identification of fall risk for patients with known vestibular hypofunction is important because it affects the management and the level of independence of these patients. Patients with bilateral vestibular loss, overall, have a greater incidence of falls than the general community-dwelling population over the age of 65 years. In younger patients, the incidence of falls may be related to severity of vestibular loss and to overconfidence or a lack of caution in activities. Preliminary reports suggest that vestibular rehabilitation can reduce the fall risk in patients with vestibular loss.

Role of central preprogramming in dynamic visual acuity with vestibular loss

OBJECTIVE

To determine the contribution of central preprogramming of eye movements to dynamic visual acuity (DVA) during head movement in patients with vestibular hypofunction.

STUDY DESIGN

Prospective, clinical study.

SETTING

Tertiary care, academic hospitals.

PARTICIPANTS

Twenty-six healthy subjects and 20 patients with unilateral (UVL) and 7 with bilateral vestibular loss (BVL) (age range, 20-86 years).

INTERVENTIONS

Diagnostic interventions, including caloric and rotational chair testing.

MAIN OUTCOME MEASURE

Measurements of DVA during predictable (DVA-predictable) and unpredictable (DVA-unpredictable) head movements using a computerized test.

RESULTS

There was a difference between DVA-predictable and DVA-unpredictable scores in all groups (P<.02). The difference between DVA-predictable and DVA-unpredictable scores for the BVL group was significantly greater than that for the other groups (P<.005). Age was a significant factor in DVA-unpredictable scores for the healthy subjects (P<.001) and UVL group (P<.02). Comparisons of DVA between groups were significant (P<.03), with the following exceptions: UVL group for head movements toward the unaffected side for DVA-predictable and DVA-unpredictable scores, compared with healthy subjects, and UVL group for head movements toward the affected side for DVA-predictable scores, compared with the BVL group.

CONCLUSIONS

Unpredictable head movements cause a greater decrement in visual acuity than do predictable head movements. This suggests that central programming of eye movements and/or efference copy contributes to gaze stability during predictable head movements in healthy subjects and patients with vestibular hypofunction. Patients with BVL use central programming of eye movements to maintain gaze stability more than do healthy subjects or patients with UVL.

Falls in patients with vestibular deficits

OBJECTIVE

To determine to what extent patients with vestibular hypofunction experience falls.

STUDY DESIGN

Prospective clinical study.

SETTING

Outpatient tertiary care facility in a university.

PATIENTS

Patients with unilateral (n = 70) and bilateral (n = 45) vestibular hypofunction, confirmed on vestibular function testing, aged 24 to 89 years.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Incidence of falls.

RESULTS

There was a significant difference in the incidence of falls reported since the onset of the vestibular deficit by patients with unilateral (UVL) and bilateral (BVL) vestibular hypofunction. The incidence of falls for BVL was significantly greater than that for UVL. The incidence of falls for UVL was not different from that expected in a community-based population when age was considered. The incidence of falls for BVL was significantly greater than that reported for the general population aged 65 through 74 years (51.1% for BVL, 25% for community-dwelling individuals) but was significantly less than expected for persons aged > or =75 years (18.2% for BVL, 49% for community-dwelling individuals). The lower incidence of falls in patients with BVL aged > or =75 years may be related to the use of assistive devices and to a decrease in risky behavior. All patients with serious injury were from the UVL group, and all were >65 years old. The incidence of fall-related injuries requiring medical attention among patients with UVL was similar to that in community-dwelling individuals.

CONCLUSIONS

Falls are an important consequence of bilateral vestibular hypofunction, and patients should be counseled about the increased risk of falling. Assistive devices should be considered, especially for persons aged >65 years with BVL.

Vestibular rehabilitation of patients with vestibular hypofunction or with benign paroxysmal positional vertigo

Since the initial introduction of exercises as a treatment for patients with vestibular deficits, there have been numerous clinical reports on the benefits of treatment. Clinical reports, however, are of limited use as a basis for treatment because, without a control group, they offer only interesting descriptions of the patient populations. Fortunately, several prospective, randomized studies on the treatment of patients with vestibular hypofunction or with benign paroxysmal positional vertigo have been published recently, adding to the small number of previous publications. This review will examine the information provided by those studies. Advances in the use of outcome measures, assessment of otolith function and treatment of related balance problems are also presented.

Visual-Vestibular Habituation and Balance Training for Motion Sickness

Background and Purpose. This case report describes physical therapy for motion sickness in a 34-year-old woman. The purpose of the report is twofold: (1) to provide an overview of the literature regarding motion sickness syndrome, causal factors, and rationale for treatment and (2) to describe the evaluation and treatment of a patient with motion sickness. Case Description and Outcomes. The patient initially had moderate to severe visually induced motion sickness, which affected her functional abilities and prevented her from working. Following 10 weeks of a primarily home-based program of visual-vestibular habituation and balance training, her symptoms were alleviated and she could resume all work-related activities. Discussion. Although motion sickness affects nearly one third of all people who travel by land, sea, or air, little documentation exists regarding prevention or management.