Search Results (5)

Background/Objectives: To evaluate the predictive role of anti-compensatory saccades in diagnosing mild acute unilateral vestibular loss. Methods: Consecutive patients with vertigo who underwent a bedside vestibular evaluation and video head impulse testing of the horizontal semicircular canal at the San Bernardino Outpatient Clinic in Salò, Italy, between 1 January and 30 June 2024 were examined (Group 1). Two control groups were considered: patients with severe unilateral acute vestibular loss (Group 2) and healthy subjects (Group 3). The video head impulse testing patterns of anti-compensatory saccades (amplitude, scattered pattern, and latency) using the suppression head impulse paradigm were analyzed to evaluate their predictive role in identifying horizontal canal dysfunction, even when borderline gain values of the canal’s vestibulo-ocular reflex were present. Results: Group 1 included 74 patients, Group 2 included 20 patients, and Group 3 included 20 healthy, voluntary subjects. The anti-compensatory saccades revealed significant differences in the amplitudes and scattered patterns between the two ears, exclusively in Groups 1 and 2. Conclusions: The anti-compensatory saccades alterations using the suppression head impulse paradigm can predict mild acute unilateral vestibular loss, even when the horizontal semicircular canal’s vestibulo-ocular reflex gain values are mild (lower borderline). Conversely, a borderline asymmetry of the horizontal semicircular canal’s vestibulo-ocular reflex using the classic head impulse paradigm should not be considered a marker of mild acute unilateral vestibular loss when the saccadic pattern is symmetrical using the suppression head impulse paradigm. Further meticulous differential diagnostic investigations are necessary in such cases to effectively diagnose horizontal semicircular canal dysfunction. Full article

Background: The impact of dance training on brainstem-mediated vestibular reflexes remains unclear. This study examined the vestibulo-ocular reflex (VOR) and its suppression during high-speed head movements, which may closely resemble the head-turning speeds used in dancers’ spotting techniques, using the video head impulse test. Methods: Eighteen female college students (mean age: 21 years) were divided into two groups—nine trained dancers (≥six years of dance training) and nine age-matched non-dancers—all without a history of hearing, vestibular, or neurological disorders. VOR function was assessed using the head impulse paradigm (HIMP) and the suppression head impulse paradigm (SHIMP) for right and left lateral stimulation, with minimum head velocities of 150°/s. Results: All participants exhibited VOR measures within normal limits and the VOR gain of dancers did not significantly differ from that of non-dancers. However, most dancers reported a preference for right-sided pirouettes and the right-side SHIMP gain negatively correlated with years of training, suggesting a link between preferred turning direction and VOR suppression ability. Furthermore, dancers with over 15 years of training exhibited earlier anti-compensatory saccade latencies (~75 ms) during SHIMP. Conclusions: Trained dancers maintain a healthy VOR and may develop enhanced voluntary control, enabling more effective VOR suppression. The earlier onset of anti-compensatory saccades suggests neural adaptations in eye–head coordination for high-velocity movements. Given the study’s small sample size and the inclusion of non-fulltime dancers, future research with larger samples of professional dancers is needed for enhanced generalizability. These findings provide preliminary evidence of dance-related neuroplasticity in brainstem-mediated vestibular reflexes and open new research avenues. Full article

Non-motor symptoms in Parkinson’s disease (PD) include ocular, visuoperceptive, and visuospatial impairments, which can occur as a result of the underlying neurodegenerative process. Ocular impairments can affect various aspects of vision and eye movement. Thus, patients can show dry eyes, blepharospasm, reduced blink rate, saccadic eye movement abnormalities, smooth pursuit deficits, and impaired voluntary and reflexive eye movements. Furthermore, visuoperceptive impairments affect the ability to perceive and recognize visual stimuli accurately, including impaired contrast sensitivity and reduced visual acuity, color discrimination, and object recognition. Visuospatial impairments are also remarkable, including difficulties perceiving and interpreting spatial relationships between objects and difficulties judging distances or navigating through the environment. Moreover, PD patients can present visuospatial attention problems, with difficulties attending to visual stimuli in a spatially organized manner. Moreover, PD patients also show perceptual disturbances affecting their ability to interpret and determine meaning from visual stimuli. And, for instance, visual hallucinations are common in PD patients. Nevertheless, the neurobiological bases of visual-related disorders in PD are complex and not fully understood. This review intends to provide a comprehensive description of visual disturbances in PD, from sensory to perceptual alterations, addressing their neuroanatomical, functional, and neurochemical correlates. Structural changes, particularly in posterior cortical regions, are described, as well as functional alterations, both in cortical and subcortical regions, which are shown in relation to specific neuropsychological results. Similarly, although the involvement of different neurotransmitter systems is controversial, data about neurochemical alterations related to visual impairments are presented, especially dopaminergic, cholinergic, and serotoninergic systems. Full article

Saccadic eye movements are directed to the objects of interests and enable high-resolution visual images in the exploration of the visual world. There is a trial-to-trial variation in saccade dynamics even in a simple task, possibly attributed to arousal fluctuations. Previous studies have showed that an increase of fatigue level over time, also known as time-on-task, can be revealed by saccade peak velocity. In addition, pupil size, controlled by the autonomic nervous system, has long been used as an arousal index. However, limited research has been done with regards to the relation between pupil size and saccade behavior in the context of trial-to-trial variation. To investigate fatigue and arousal effects on saccadic and pupillary responses, we used bright and emotional stimuli to evoke pupillary responses in tasks requiring reactive and voluntary saccade generation. Decreased voluntary saccade peak velocities, reduced tonic pupil size and phasic pupillary responses were observed as time-on-task increased. Moreover, tonic pupil size affected saccade latency and dynamics, with steeper saccade main sequence slope as tonic pupil size increased. In summary, saccade dynamics and tonic pupil size were sensitive to fatigue and arousal level, together providing valuable information for the understanding of human behavior. Full article

Vergence eye movements are frequent in every day life and important for depth perception. Yet, studies of vergence in elderly are rare. We examined convergence and divergence between targets placed along median line at 20, 40 or 150 cm. Thirteen elderly (70 ± 11 years) and ten young (25 ± 3 years) adults participated in the study. The gap paradigm (i.e., the fixed stimulus is extinguished prior to target onset) and the overlap paradigm (the fixed stimulus remains illuminated after target onset) were used to elicit reflexive or voluntary eye movements. Latency of convergence and divergence increased with age in both gap and overlap conditions. Both young subjects and elderly showed shorter latency of vergence under the gap condition than under the overlap condition. In the overlap condition, for elderly only, convergence resulted in longer latencies than divergence. In the gap condition express convergence was rare, while express latencies (80–120 ms) were frequent for divergence starting from a near fixation point (at 20 cm). The rates of express divergence were similar for young (23%) and elderly (21%). These results were in line with prior studies of saccades and indicated different aging effects on regular and express latencies. Full article