Effects of Galvanic Vestibular Stimulation on Visual Verticality and Standing Posture Differ Based on the Polarity of the Stimulation and Hemispheric Lesion Side in Patients With Stroke

Introduction: There is growing evidence supporting the relationship of vertical misperception and poor balance control with asymmetrical standing posture in patients with stroke. Although the vestibular system has been shown to be responsible for vertical misperception and balance disorders, the effect of galvanic vestibular stimulation (GVS) on both vertical misperception and postural asymmetry after stroke remains elusive. The aim of this study was to investigate the effects of GVS on visual verticality and postural asymmetry after stroke and to clarify whether the effects differ depending on the polarity of the stimulation and hemispheric lesion side.Methods: We measured the subjective visual vertical (SVV) and body weight distribution on each foot in an upright stance in 24 patients with a hemispheric stroke (10 with a left hemisphere lesion and 14 with a right hemisphere lesion) and nine age-matched healthy controls. During the measurements, bipolar GVS (1.5 mA) was applied over the bilateral mastoid processes in three stimulation conditions: contralesional-anodal and ipsilesional-cathodal vestibular stimulation, ipsilesional-anodal and contralesional-cathodal vestibular stimulation, and no stimulation. To examine whether GVS modulates visual verticality and standing posture, SVV and weight-bearing in the three conditions were analyzed.Results: During no stimulation, the SVV deviated to the contralesional side in patients with a right hemisphere lesion, while more weight-bearing was observed on the ipsilesional limb than on the contralesional limb in both patient groups than in the controls. The SVV was modulated by reversing the polarity of GVS in all the groups when the cathodal stimulus side was either ipsilateral or contralateral to the lesion while the ipsilesional-cathodal vestibular stimulation reduced weight-bearing asymmetry in only the patients with a right hemisphere lesion.Conclusions: These findings demonstrate that the effects of GVS on the SVV and standing posture differ depending on the polarity of GVS and the hemispheric lesion side. Patients with a right hemisphere lesion have difficulty maintaining their preferred standing posture under visual verticality modulation evoked by GVS. The application of GVS may clarify whether the vestibular system has neural redundancy after stroke to suppress any effects of the stimulation, including modulation of the visual verticality, on balance.

Anticipatory Motor Planning and Control of Grasp in Children with Unilateral Spastic Cerebral Palsy

Children with unilateral spastic cerebral palsy (USCP) have impairments in motor planning, impacting their ability to grasp objects. We examined the planning of digit position and force and the flexibility of the motor system in covarying these during object manipulation. Eleven children with a left hemisphere lesion (LHL), nine children with a right hemisphere lesion (RHL) and nine typically developing children (controls) participated in the study. Participants were instructed to use a precision grip with their dominant/less affected hand to lift and keep an object level, with either a left, centered or right center of mass (COM) location. Digit positions, forces, compensatory torque and object roll where measured. Although children with USCP generated a compensatory torque and modulated digit placement by lift-off, their index finger was either collinear or higher than the thumb, regardless of COM location, leading to larger rolls after lift-off especially for the RHL group. The findings suggest that while the kinetics of grasp control is intact, the kinematics of grasp control is impaired. This study adds to the understanding of the underlying mechanisms of anticipatory planning and control of grasp in children with USCP and may provide insights on how to improve hand function in children with USCP.

The Relevance of Right and Left Hemisphere Classification to Predict Cognitive Outcome After Stroke

Introduction: Stroke is the fifth leading cause of disability-adjusted life years (DALYs) in the world. Cognitive impairment is one of the disabilities found in the acute phase of stroke and persists in long-term outcomes which can be assessed using the Mini-Mental State Examination (MMSE). However, a clinical classification to predict the cognitive outcome remained unclear. This study is aimed to identify differences of MMSE results in stroke patients between right and left hemisphere lesions to ensure the mentioned location classifications may contribute to cognitive outcome prediction.Method: With the cross-sectional analytic observational design, 32 acute phase patients hospitalized in the Neurology Department Soetomo General Hospital from October–December 2019 were assessed using the Indonesian version of MMSE with purposive sampling and analyzed using the chi-square test.Result: There was no significant difference between MMSE scores in right or left hemisphere lesion. This might happen because (1) MMSE was insensitive and not a domain-specific test; (2) a more specific infarct location was needed to predict cognitive outcome post-stroke, including microarchitecture of the brain especially those involved in the cortico-striato-thalamocortical loop.Conclusion: The right or left hemisphere lesion classification did not contribute significantly to predict cognitive impairment.

Memory monitoring and memory control in chronic stroke patients Dissociated processes

ABSTRACT. Memory problems are common in stroke patients, although little is known about how accurately chronic stroke patients can monitor and control memory processes. Objective: The performance of memory and metamemory in stroke patients and healthy controls were investigated, as well as dissociation between performances. Methods: 10 adults with right hemisphere lesion (mean [M] age=53.2 [SD=9.7]), 10 with left hemisphere lesion (M age=60.4 [SD=6.6]) and 20 healthy participants (M age=56.5 [SD=9.3] with no neurological disease, matched for sex, age and years of education participated in a multiple-case design study. Participants completed a metamemory experimental paradigm, as well as immediate and delayed word recall and recognition tasks. Results: Data indicated that 10 out of the 20 patients presented significantly lower scores compared to controls, two of which had global deficits (functional association). Functional dissociations between memory monitoring (judgments of learning, JOL), control (allocation of study time) and capacity (cued-recall task) among patients were found for eight cases, suggesting these processes are independent. Conclusion: These findings reveal stroke patients may have specific metamemory impairment and can contribute to the understanding of cognitive models of metamemory processing.

Positive Correlation between Left Hemisphere Lesion and Erectile Dysfunction in Post-Stroke Patients

BACKGROUND: Stroke is a serious health condition and the leading cause of disability, including erectile dysfunction (ED). The mechanisms and factors that predict ED in stroke are not fully elucidated. Several studies have shown a relationship between the location of the lesion in stroke with the onset of ED. The left hemispheric lesion was believed to disrupt the parasympathetic nervous system which is responsible for the regulation of erection. Stroke attack in this region therefore can be the underlying reason for ED. However, there are still contradictory findings in this area, and very few studies attempted to look at this problem, particularly among Asian male. AIM: We would like to evaluate the association between left hemisphere lesion after ischemic stroke and the subsequent risk of developing ED. METHODS: The study was conducted in the neurology polyclinic of Sanglah and Wangaya Hospital from February to August 2013. Subjects are all post-stroke patients who visited the neurology polyclinic of Sanglah and Wangaya Hospital that met inclusion and exclusion criteria. RESULTS: There is a significant positive correlation (p < 0.05) between left hemisphere lesions and ED in stroke patients with a correlation coefficient (r) = 0.361 which means weak correlation and p = 0.032. CONCLUSION: Left hemisphere lesions positively correlated with ED in stroke patients. Further longitudinal research is needed to see whether left hemisphere lesion in post-stroke patients is a risk factor for ED.