Vestibulo-ocular Systems Research Articles

How often is neck and vestibulo-ocular physiotherapy treatment recommended in people with persistent post-concussion symptoms? A retrospective analysis

BackgroundPersistent post-concussion symptoms (PPCS) are complex, and typically involve multidisciplinary assessment and management. The neck and vestibulo-ocular systems are recognised as potential contributors to PPCS, yet it is not clear how often treatment for these systems is warranted. ObjectivesTo explore how often neck and vestibulo-ocular treatment is received or recommended in people with PPCS. DesignRetrospective chart review. MethodDe-identified clinical service data for the calendar year of 2017 were extracted from a single concussion service provider in Dunedin, New Zealand. A summary of the individual assessments and treatments received were extracted and used to determine how often cases were considered to require physician or neuropsychological assessment; and how often cases received or were recommended neck and/or vestibulo-ocular physiotherapy treatment. Results/findings147 cases were included in this study. Physician assessment was considered required in 25 cases (17%), and neuropsychological assessment in 90 cases (61%). For physiotherapy, neck treatment was received or recommended in 80 cases (54%), and vestibulo-ocular treatment in 106 cases (72%). Notably, this included 59 cases (40%) where both neck and vestibulo-ocular treatment were received or recommended. ConclusionsThe high proportion of cases receiving or recommended neck and vestibulo-ocular treatment strongly suggests both these systems often contribute to PPCS, often in overlap. While based on retrospective data, these findings highlight the value of routine neck and vestibulo-ocular examination in the assessment and management of PPCS. Further prospective study would be beneficial to explore these proportions in more detail and in other regions.

Adaptive control: A review of the ability to acquire and maintain high sensorimotor performance

When the relationship which relates us to the environment through vision, often named visual mapping, is durably modified, our behaviour is altered at sensory, motor and cognitive levels. The brain has the ability through the so-called adaptive control to progressively decrease the motor errors despite visual image alteration. Adaptive control in both the visuo-manual and the vestibulo-ocular systems is reviewed. A parallel is tentatively made between adaptation to ordinary optical alterations (resulting from the use of refraction-corrective glasses) in the visual mapping of these two systems and the adaptation to more complex visuo-motor relationships experienced by people working in virtual environments.

視標追跡眼運動と半規管眼運動の相互作用について

Impaired smooth pursuit eye movements may be corrected by saccades to repair visual errors during an eye tracking test (ETT).However, in this study, most of the cases that showed a saccadic pattern during ETT demonstrated smooth eye movements in a pendular rotation test (PRT) with the eyes open and fixed at the stand still target in lightness due to interaction between the visuoocular and vestibuloocular systems. The incidence and character of the two kinds of induced eye movements in horizontal ETT and PRT with the eyes open were investigated.Investigated were thirty one cases among out-patients in the Neuro-Otological Clinic of Kitasato University Hospital in 1996. All cases showed saccadic patterns in ETT, fulfilling the following criteria: each half period to the right and left containing three or more saccades with a maximum amplitude of four or more degrees. Only 3 cases or 10% of the 31 patients showed saccadic pattern in PRT with the eyes open.The saccadic index (S.I.) (maximum amplitude multiplied by the number of saccades) was calculated in each case. The combined SI of both directions was between 75.8 to 100.6 in the 3 cases who had saccadic pattern in PRT with the eyes open. VOR gains remained in the low range (0.40 to 0.57). However, cases who showed high S.I. in ETT, but had smooth pursuit eye movement in PRT with the eyes open showed a high VOR gain. We concluded that most cases of saccadic pattern in ETT showed smooth eye movements in PRT with the eyes open and fixed at the target due to a high VOR gain, but in 10% of cases no increase was recorded due to a failure of vestibular compensation.

Do the saccadic system and the vestibulo-ocular reflex of monkeys share a common neural integrator?

A common ‘neural integrator’ has been hypothesized to perform mathematical integration of velocity-coded inputs for all oculomotor subsystems. Studies in cats suggested that the integrators for some subsystems may be differentially affected by drugs. Our tests in macaques show that the fixation is unaffected and saccadic and vestibulo-ocular systems are affected in parallel. Thus, the common integrator hypothesis cannot be ruled out on the basis of these results.

The cerebellar nodulus and ventral uvula control the torsional vestibulo-ocular reflex

1. The vestibulo-ocular reflex (VOR) was investigated in rhesus monkeys before and after surgical ablation of the cerebellar nodulus and ventral uvula. The lesion resulted in an alteration of the torsional VOR: compensatory eye movements were poor in the low frequency range and the time constant was reduced to values comparable to those of primary semicircular canal afferents. In addition, animals permanently lost their ability to generate torsional optokinetic nystagmus (OKN). 2. The effects of the lesion on the torsional VOR differed from those observed in the horizontal and vertical vestibulo-ocular systems. While the vertical VOR and OKN were unaltered, the horizontal VOR and OKN were characterized by increased time constants and smaller phase leads during low frequency head oscillations. 3. These results suggest that the cerebellar nodulus and/or ventral uvula exert a distinct and specific dynamic control on the torsional vestibulo-ocular and optokinetic reflexes. Such specific effects on the torsional system could reflect a functional segregation of the vestibulo-cerebellum in terms of the controls of torsional versus horizontal and vertical slow phase eye movements.

Dynamic characteristics of the visuo-, vestibulo- ocular system

A pendular rotation test was carried out to investigate the dynamic characteristics of the vestibuloocular system. The purpose of. this study was as follows : (1) In normal subjects, to calculate the transfer function (TF) of the right and the left vestibulo-ocular systems. (2) In patients with a unilateral labyrinth, to calculate the TF of rightward and leftward eye movements separately, and to detect vestibular asymmetry.The subject was asked to sit a rotating chair. A sinusoidal pendular rotation was given to the subject with eyes open in the dark. Chair rotation was made as random as possible. The chair (head) and eye movements were recorded. The TF was calculated with head velocity as input and eye velocity as output. For the calculation autoregressive analysis was used. Prior to the calculation, saccadic eye movements were eliminated from the eye movements. In normal subjects, the eye velocity curve was divided into eye movements induced by the right labyrinth and those induced by the left labyrinth. In patients, the eye velocity curve was divided into rightward eye movement and leftward eye movements. The TF was calculated by using these eye movements as output. The results were displayed as Bode plots.In normal subjects, gain diagrams of the vestibuloocular system indicated frequency dependent gain enhancement from 0.01 to 2.2 Hz at the rate of 4.2 dB/decade. In the Bode plots of the right and the left vestibulo-ocular systems, the gain decreased to 5 dB at 0.1 Hz, compared with that of the vestibuloocular system.In patients, gain diagrams of the unilateral vesti-bule-ocular system were the same as the gain of the unilateral vestibulo-ocular system in normal subjects. Patients who were examined within a few months after the onset of disease, showed that the gain of eye movement toward the healthy labyrinth was low, in the frequency range from 0.01 to 0.1 Hz, compared to that in the opposite direction. In patients who were examined more than 3 months after onset, these differences of gain were not detected.

Eye-head coordination with laterally "modulated" gaze field.

Discrimination of peripheral targets is possible with progressive lenses if visual strategy is changed. However, there is a penalty in response time. This penalty is reduced after adaptation. This adaptation involves making earlier and more rapid head movements on the one hand, and recalibrating the saccadic and vestibulo-ocular systems on the other hand. These changes enable subjects to gaze directly through a zone of the lenses where discrimination is possible. This adaptation also consists of learning to use information from blurred images. In this way visual processing can begin earlier.