Novel characterization of subjective visual vertical in patients with unilateral spatial neglect

Do we need to consider head-on-body position, starting roll position and presence of visuospatial neglect when assessing perception of verticality after stroke?

BACKGROUND AND OBJECTIVE

Considering various factors that influence the accuracy of the Subjective Visual Vertical (SVV) and Subjective Postural Vertical (SPV), standardization of assessment methods is needed. This retrospective study examined the contribution of Head-on-Body (HOB) position, starting roll position (SRP) and visuospatial neglect (VSN) to SVV and SPV constant errors (i.e. deviation from true vertical). Also, the contribution of HOB position and VSN presence to SVV and SPV variability (i.e. intra-individual consistency between trials) was assessed.

METHODS

First-ever unilateral hemispheric stroke survivors (<85 years; <100 days post-stroke) were assessed with three HOB positions (neutral, contralesional, and ipsilesional) and seven starting positions (20°Contralesional to 20° ipsilesional) of the laser bar and tilt chair. Linear mixed models were selected to evaluate the contribution of HOB, SRP, and VSN to SVV/SPV constant errors and variability.

RESULTS

Thirty-four subjects (24 VSN-/10 VSN+) were assessed. A tilted HOB position led to significantly higher constant errors for the SVV and SPV (the latter only in the VSN- group), and an increased SVV variability. SRP only significantly contributed to the SVV constant errors and only in the VSN- group. Furthermore, the presence of VSN resulted in a significantly higher SVV and SPV variability.

CONCLUSIONS

HOB position and the presence of SRP and VSN are important factors to consider during SVV and SPV measurements. Assessment with a neutral HOB position leads to more accurate results. HOB position and SRP influence the results of SVV and SPV differently in individuals with and without VSN, which highlights the relevance of VSN assessment.

Association between spatial neglect and impaired verticality perception after stroke: A systematic review

BACKGROUND

Although most research on spatial neglect (SN) has focused on spatial perception deficits with regard to the lateral (left-right) axis, deficits of spatial perception with regard to the vertical (up-down) axis, such as disturbances in the perception of verticality (e.g., judgement of vertical orientations), have also been suggested.

OBJECTIVE

We aimed to systematically analyse reported associations between SN and characteristics of verticality perception while considering the time post-stroke.

METHODS

PubMed, Web of Science, Scopus, PubPsych and PsycArticles databases were searched on May 24, 2022 for articles written in English that evaluated the association between SN and verticality perception (i.e., the subjective visual vertical [SVV], subjective postural vertical [SPV] and subjective haptic vertical [SHV]) in adults after stroke. Left and right SN were considered and had to be assessed using standardized methods. Data were manually extracted, and risk of bias was assessed with the Newcastle-Ottawa Scale. The tilt of the line/chair relative to the gravitational vector and its direction, together with uncertainty (i.e., variability across measurements), were evaluated.

RESULTS

Thirteen studies were included (431 participants after stroke); at least 191 participants exhibited SN. Mainly the first 3 to 6 months post-stroke were evaluated. SN was associated with SVV misperception, which resulted in larger SVV tilts (mostly in the contralesional direction) and uncertainty in participants with than without SN. SVV tilt magnitudes ranged from a mean/median of -8.9° to -2.3° in SN participants and from -1.6° to 0.6° in non-SN participants, the latter falling within normative ranges. For SPV and SHV measurements, the magnitude of tilt and the uncertainty were insufficiently assessed or results were inconclusive.

CONCLUSIONS

SN was associated with larger SVV tilts and uncertainty, which suggests that SVV misperception is a key feature of SN. This observation highlights the importance of regular SVV assessment in people with SN in clinical practice.

PROSPERO

CRD42019127616.

[The effect of different rotation modes on testing resulting of the subjective visual vertical]

Objective:To investigate the effect of different rotations modes of control rod on testing results of the subjective visual vertical （SVV）. Methods:Twenty-four normal young volunteers were selected for this study, and the control rod of SVV was rotated in clockwise, counterclockwise and any direction at the head tilt-positions of 0°, 45° left and 45° right. The differences of SVV deflection angle values at different rotation modes were analyzed. Results:①The deviation angle values of SVV obtained by rotating the control rod in clockwise, counterclockwise and any direction at the head tilt-positions of 0° were 1.56°±0.21°, 3.05°±0.24°, and 2.16°±0.22°, respectively，and the difference was statistically significant （P<0.05）,the deviation angle value of SVV in clockwise direction was smaller; ②At head tilt-positions of 45° left, the SVV deviation angle values obtained by rotating the control rod in three rotation modes were 2.59°±0.53°, 4.03°±0.51°, and 3.49°±0.54°, respectively, and the difference was statistically significant（P<0.05）,the deviation angle value in the clockwise direction was also smaller; ③At the head tilt-positions of 45° right, the SVV deviation angle values in three modes were 4.68°±0.58°, 7.23°±0.72°, and 5.93°±0.96°, respectively, and the difference was statistically significant （P<0.05）,the deviation value of SVV was also smaller when rotated in the clockwise direction; ④Comparison of SVV deviation angle values in three rotation modes at the head tilt-positions of 45° left and 45° right showed that there was no statistical difference in clockwise and in any direction （P>0.05）, while the difference was statistically significant when rotated in the counterclockwise direction （P<0.05）. Conclusion:Different rotation modes of the control rod during SVV testing will affect the test results. Rotating the control rod in clockwise direction to make the SVV values more accurate is recommended.

Evaluation of subjective vertical perception among stroke patients: a systematic review

BACKGROUND

Verticality misperception is relatively common among patients after stroke, and it may be evaluated in terms of (a) subjective visual vertical (SVV), (b) subjective haptic vertical (SHV) and (c) subjective postural vertical (SPV). To better understand these assessment methods, we conducted a systematic review of the methodological characteristics of different protocols for evaluating SVV, SHV and SPV among individuals after stroke.

OBJECTIVE

To standardize the methodological characteristics of protocols for evaluating verticality perception after stroke.

METHODS

We searched the following databases: PUBMED, regional BVS portal (MEDLINE, LILACS, IBECS, CUBMED, Psychology Index and LIS), CINAHL, SCOPUS, Web of Science, Science Direct, Cochrane Library and PEDro. Two review authors independently used the QUADAS method (Quality Assessment of Diagnostic Accuracy Studies) and extracted data.

RESULTS

We included 21 studies in the review: most (80.9%) used SVV, eight (38.1%) used SPV and four (19.0%) used SHV. We observed high variability in assessments of verticality perception, due to patient positions, devices used, numbers of repetitions and angle of inclination for starting the tests.

CONCLUSION

This systematic review was one of the first to explore all the methods of assessing verticality perception after stroke, and it provides crucial information on how to perform the tests, in order to guide future researchers/clinicians.