Altered Visual and Proprioceptive Spatial Perception in Individuals with Parkinson’s Disease

Abstract

Difficulties in the integration of visual, vestibular, and somatosensory information in individuals with Parkinson’s disease (PD) may alter perception of verticality. Accordingly, in this cross-sectional study, we analyzed PD patients’ ( n = 13) subjective visual vertical (SVV) and subjective haptic vertical (SHV) perceptions and compared them to those of healthy controls ( n = 14). We compared SVV and SHV findings among participants with PD, healthy controls, and cutoff points of normality based on prior research literature, using the parametric nonpaired t test (at p < .05) and Cohen’s d (at d > 0.8) to determine clinical relevance. We analyzed SVV with the bucket test and SHV with the rod rotations task in clockwise and counterclockwise directions. We calculated Pearson correlations to analyze the association between verticality tests and the most clinically affected body side. We calculated both the percentage of A-effect (expression of body tilt underestimation to the midline) and E-effect (expression of body tilt overestimation in the upright position). Individuals with PD showed greater variability in right SHV supination compared to the healthy control participants ( p = .002). There was greater clinical relevance in right (as opposed to left) SVV ( d = 0.83), right (as opposed to left) SHV pronation ( d = 0.91), and left (as opposed to right) SHV pronation ( d = 0.88). We observed a higher proportion of E-effect in individuals with PD. A significantly higher proportion of patients with PD, compared to patients in past literature, had right SHV pronation ( p = .001), left SHV pronation ( p = .023), right SHV supination ( p = .001), left SHV supination ( p = .046), and left SHV pronation ( p = .046). Thus, subjective visual and proprioceptive perception of verticality is altered in patients with PD, compared to individuals without PD.

Perception of verticality in the post-COVID-19 condition correlates to infection severity

“…This study demonstrated that individuals with post-COVID-19 condition that were hospitalized showed less accurate performance for SVV and SHV than non-hospitalized individuals. Studies have evaluated the perception of verticality in individuals with acquired 36 and degenerative 31 diseases of the central nervous system (CNS). However, no previous studies have examined this variable in individuals with long-term COVID.…”

“…[42][43][44][45] In addition, more severely ill patients undergoing hospitalization have a greater storm of pro-inflammatory cytokines in the acute phase, with an increased risk of developing a neurodegenerative condition. 46,47 Neurodegenerative processes can alter long-term verticality, 31 graviceptive information perception due to the reduced activity of somatosensory cortical areas. It can also be inferred that changes in verticality observed in this study may have been caused by changes in the peripheral nervous system.…”

“…Any abnormal sensation (hyperesthesia, hypoesthesia, or dysesthesia) in the evaluated regions compared to the face (neutral region) was considered to be “altered” in the test. 31…”

“…The participants were divided into 2 groups: hospitalized patients with post-COVID-19 (hospitalized group) and nonhospitalized patients with post-COVID-19 (non-hospitalized group). They were assessed using the sit-to-stand test, [24][25][26] grip strength, [27][28][29][30] painful and tactile sensory assessment, 31 visual acuity, 32 vestibular assessment, [33][34][35] verticality perception by subjective visual vertical (SVV), [36][37][38][39] and subjective haptic vertical (SHV) tests. [38][39][40] All clinical tests were performed by an authorized and trained researcher.…”

“…Any abnormal sensation (hyperesthesia, hypoesthesia, or dysesthesia) in the evaluated regions compared to the face (neutral region) was considered to be "altered" in the test. 31 Visual Acuity. Visual acuity was assessed in a standardized manner using a Snellen chart placed 6 m away from the individual, who was then asked to read the letters arranged on the chart.…”