The Effect of a Home Exercise Program on Visio-Vestibular Function in Concussed Pediatric Patients

ObjectiveTo explore if a home exercise program (HEP) affects visio-vestibular function in concussed pediatric patients.BackgroundA HEP can provide an equitable and cost-effective method for therapy targeted towards visio-vestibular deficits that are common following concussion. It is unclear if pediatric patients prescribed a HEP demonstrate improved visio-vestibular function.Design/MethodsThis observational study included 1,041 patients (59% female; age = 14.0 ± 2.5 years) reporting to a specialty care concussion center for an initial visit ≤28 days post-injury and follow-up ≤60 days post-injury. All patients completed a Visio-Vestibular Examination (VVE) at both timepoints consisting of 9 subtests: smooth pursuit, horizontal/vertical saccades and gaze stability, binocular convergence, left/right monocular accommodation, and complex tandem gait. Patients were prescribed a HEP (1–2 times/day) at initial visit consisting of exercises addressing visio-vestibular deficits. At follow-up, patients reported their progress: (1) has not done the HEP, (2) is currently doing the HEP, or (3) has completed the HEP. Primary outcomes included HEP progress, VVE subtests (normal/abnormal), and total VVE (abnormal = 2 + abnormal subtests). Chi-square tests with Bonferroni corrections were used to determine if abnormal VVE outcomes were associated with HEP status.ResultsAt initial visit, 81 2(77.6%) patients presented with abnormal total VVE. At follow-up, the proportion of abnormal total VVE did not differ among patients not doing the HEP (101 [62.0%]), patients currently doing the HEP (516 [69.0%]), and patients who had completed the HEP (51 [69.0%]). However among VVE subtests, a lower proportion who completed the HEP presented with abnormal smooth pursuit (7.5%), horizontal (3.8%) and vertical (3.8%) saccades, and complex tandem gait (0%) relative to patients currently doing the HEP (p = 0.003) and patients not doing the HEP (p = 0.01).ConclusionsOur findings indicate that patients who completed the HEP presented with improved elements of visio-vestibular function relative to those who did not start or were currently doing the HEP.

Eye Movement Abnormalities in Amyotrophic Lateral Sclerosis

Background and Purpose It is generally believed that eye movements are completely spared in amyotrophic lateral sclerosis (ALS). Although a series of eye movement abnormalities has been recognized in recent years, the findings are highly controversial, and the corresponding pattern has not yet been established. Furthermore, bulbar disabilities should be considered in relation to eye movement abnormalities. The present study aimed to determine whether eye movement abnormalities are present in ALS and, if so, to investigate their characteristics and their association with bulbar disability in ALS patients. Methods Patients with clinically definite, probable or laboratory-supported probable ALS (n=60) and a control group composed of their caregivers (n=30) underwent clinical assessments and standardized evaluations of the oculomotor system using videonystagmography. The gaze test, reflexive saccade test and smooth pursuit test were administered to all subjects. Results Eye movement abnormalities such as square-wave jerks, abnormal cogwheeling during smooth pursuit, and saccade hypometria were observed in ALS patients. Square-wave jerks (p<0.001) and abnormal cogwheeling during smooth pursuit (p=0.001) were more frequently observed in ALS patients than in the control subjects. In subgroup analyses, square-wave jerks (p=0.004) and abnormal cogwheeling during smooth pursuit (p=0.031) were found to be more common in ALS patients with bulbar involvement (n=44) than in those without bulbar involvement (n=16). There were no significant differences in the investigated eye movement parameters between bulbar-onset (n=12) and spinal-onset patients (n=48). Conclusion ALS patients showed a range of eye movement abnormalities, affecting mainly the ocular fixation and smooth pursuit systems. These abnormalities were observed more common in the ALS patients with bulbar involvement. Our pioneering study indicates that the region of involvement could better indicate the pathophysiological essence of the abnormalities than the type of onset pattern in ALS. Eye movement abnormalities may be potential clinical markers for objectively evaluating upper brainstem or supratentorial cerebral lesion neurodegeneration in ALS.

The influence of stimulus and behavioral histories on predictive control of smooth pursuit eye movements

The smooth pursuit system has the ability to perform predictive feedforward control of eye movements. This study attempted to examine how stimulus and behavioral histories of past trials affect the control of predictive pursuit of target motion with randomized velocities. We used sequential ramp stimuli where the rightward velocity was fixed at 16 deg/s while the leftward velocity was either fixed (predictable) at one of seven velocities (4, 8, 12, 16, 20, 24, or 28 deg/s) or randomized (unpredictable). As a result, predictive pursuit responses were observed not only in the predictable condition but also in the unpredictable condition. Linear mixed-effects (LME) models showed that both stimulus and behavioral histories of the previous two or three trials influenced the predictive pursuit responses in the unpredictable condition. Intriguingly, the goodness of fit of the LME model was improved when both historical effects were fitted simultaneously rather than when each type of historical data was fitted alone. Our results suggest that predictive pursuit systems allow us to track randomized target motion using weighted averaging of the information of target velocity (stimulus) and motor output (behavior) in past time sequences.

Central Ocular Motor Disorders: Clinical and Topographic Anatomical Diagnosis, Syndromes and Underlying Diseases

The key to the diagnosis of ocular motor disorders is a systematic clinical examination of the different types of eye movements, including eye position, spontaneous nystagmus, range of eye movements, smooth pursuit, saccades, gaze-holding function, vergence, optokinetic nystagmus, as well as testing of the function of the vestibulo-ocular reflex (VOR) and visual fixation suppression of the VOR. This is like a window which allows you to look into the brain stem and cerebellum even if imaging is normal. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum and rarely the cortex. There is a simple clinical rule: vertical and torsional eye movements are generated in the midbrain, horizontal eye movements in the pons. For example, isolated dysfunction of vertical eye movements is due to a midbrain lesion affecting the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), with impaired vertical saccades only or vertical gaze-evoked nystagmus due to dysfunction of the Interstitial nucleus of Cajal (INC). Lesions of the lateral medulla oblongata (Wallenberg syndrome) lead to typical findings: ocular tilt reaction, central fixation nystagmus and dysmetric saccades. The cerebellum is relevant for almost all types of eye movements; typical pathological findings are saccadic smooth pursuit, gaze-evoked nystagmus or dysmetric saccades. The time course of the development of symptoms and signs is important for the diagnosis of underlying diseases: acute: most likely stroke; subacute: inflammatory diseases, metabolic diseases like thiamine deficiencies; chronic progressive: inherited diseases like Niemann-Pick type C with typically initially vertical and then horizontal saccade palsy or degenerative diseases like progressive supranuclear palsy. Treatment depends on the underlying disease. In this article, we deal with central ocular motor disorders. In a second article, we focus on clinically relevant types of nystagmus such as downbeat, upbeat, fixation pendular, gaze-evoked, infantile or periodic alternating nystagmus. Therefore, these types of nystagmus will not be described here in detail.

Supranuclear Ocular Motor Systems

Properly functioning eye movements facilitate a clear, stable view of the environment. Saccadic eye movements and nystagmus fast phases are 2 types of fast eye movements. Slow eye movements include smooth pursuit, vestibular, optokinetic, and vergence. Reflexive and voluntary conjugate eye movements incorporate cortical, subcortical (basal ganglia), and vestibulocerebellar input to the final common pathways of horizontal and vertical eye movements. The present chapter reviews the anatomy and dysfunction of the supranuclear input to conjugate gaze.