Time Course of a Misperception of Verticality and Its Characteristics in Post-stroke Participants

Little is known about the time course of verticality perception after stroke. This study aims to assess:

* The time course of verticality perception (Subjective Visual, Haptic and Postural Vertical; resp., SVV, SHV, SPV);
* The longitudinal interaction of the recovery of spatial disorders (e.g., different types of neglect, lateropulsion) with verticality perception;
* The longitudinal interaction of motor function and outcomes (such as paresis, sitting balance and standing balance) and verticality perception.

The participants will be repetitively assessed during the subacute phase post-stroke, to evaluate the time course of:

* The SVV, SHV and SPV;
* Spatial disorders (visuospatial and personal neglect, lateropulsion)
* Motor function (lower limb strength, sitting and standing balance, functionality in ADL, trunk performance)

For a correct vertical alignment of the body with the gravitational vector, the patient must be able to accurately perceive verticality. Estimation of verticality is a complex process, suggested to be based on internal references derived from the integration of multisensory input (e.g. visual, vestibular and somatosensory). Due to a brain lesion, this complex process can be hampered, resulting in a deviation of the subjective vertical.

Different modalities of verticality perception can be assessed, including the Subjective Visual (SVV), Haptic (SHV) and Postural (SPV) Vertical. Previous studies reported a deviation of the subjective vertical in post-stroke patients. These deviations are associated with poorer balance performance. However, some stroke participants have more difficulties with accurately estimating a vertical position as compared to others. This increased magnitude is often seen in participants with lateropulsion or spatial neglect.

Although previous studies showed an increased deviation of the subjective vertical in post-stroke patients, little is known about the recovery of this misperception of verticality. Especially in patients with spatial disorders (e.g., lateropulsion or (different subtypes of) neglect), there is clear lack of studies assessing the longitudinal recovery of a misperception of verticality. Knowledge about the spontaneous recovery of a deviated verticality perception and its association with spatial disorders, will give insights in the role of a misperception of verticality in these disorders.

Although disturbances in perceiving verticality and decreased balance performance seems to be related, it is unclear how these disturbances exactly impacts balance and functional outcome. A longitudinal interaction between verticality perception and motor function will be evaluated.

Participants will be recruited from rehabilitation hospital Revarte (Edegem) or AZ Monica (Antwerp). Participants will be included at 3 or 5 weeks post-stroke and evaluation will take place at 3, 5, 8 and 12 weeks post-stroke. Also, in healthy participants the SVV, SHV and SPV will be evaluated to obtain normative data.

The outcome measures contain:

* Perception of verticality: SVV, SHV, SPV;
* Combination of pen-and-paper tasks and computerized tests to asses visuospatial and personal neglect;
* Clinical scales to evaluate lateropulsion;
* Clinical scales to evaluate motor function (lower limb strength, sitting balance, standing balance, functionality in ADL, trunk performance);
* Instrumented analysis to assess sitting and standing balance.

For the data-analysis Linear Mixed Models will be used, to evaluate study results and mean change over time.

Eligibility Criteria:
Inclusion Criteria:

* First-ever, MRI- or CT-confirmed, ischemic or hemorrhagic supratentorial stroke;
* Able to give written informed consent.

Exclusion Criteria:

* Bilateral lesions;
* Vestibular dysfunction, symptomatic orthostatic hypotension or other pre-existing neurological conditions that could interfere with the assessments;
* Inability to understand and follow basic verbal instructions;
* Hemianopsia or other visual field deficits (glasses or corrective lenses are allowed)

And a group of healthy controls to obtain normative data. These participants are eligible for inclusion if they are between 18 and 90 years old and do not suffer from vestibular dysfunction, symptomatic orthostatic hypotension or other neurological conditions that could interfere with the assessment.