scholarly journals Head movement kinematics are altered during gaze stability exercises in vestibular schwannoma patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lin Wang ◽  
Omid A. Zobeiri ◽  
Jennifer L. Millar ◽  
Michael C. Schubert ◽  
Kathleen E. Cullen
Keyword(s):  
Standard Of Care ◽  
Head Movements ◽  
Vestibular Loss ◽  
Gaze Stabilization ◽  
Head Kinematics ◽  
Gaze Stability ◽  
Post Surgery ◽  
Before And After ◽  
Healthy Control ◽  
Clinical Measures

AbstractGaze stability is the ability of the eyes to fixate a stable point when the head is moving in space. Because gaze stability is impaired in peripheral vestibular loss patients, gaze stabilization exercises are often prescribed to facilitate compensation. However, both the assessment and prescription of these exercises are subjective. Accordingly, here we quantified head motion kinematics in patients with vestibular loss while they performed the standard of care gaze stability exercises, both before and after surgical deafferentation. We also correlate the head kinematic data with standard clinical outcome measures. Using inertial measurement units, we quantified head movements in patients as they transitioned through these two vestibular states characterized by different levels of peripheral damage. Comparison with age-matched healthy control subjects revealed that the same kinematic measurements were significantly abnormal in patients both pre- and post-surgery. Regardless of direction, patients took a longer time to move their heads during the exercises. Interestingly, these changes in kinematics suggest a strategy that existed preoperatively and remained symmetric after surgery although the patients then had complete unilateral vestibular loss. Further, we found that this kinematic assessment was a good predictor of clinical outcomes, and that pre-surgery clinical measures could predict post-surgery head kinematics. Thus, together, our results provide the first experimental evidence that patients show significant changes in head kinematics during gaze stability exercises, even prior to surgery. This suggests that early changes in head kinematic strategy due to significant but incomplete vestibular loss are already maladaptive as compared to controls.

Vestibular Gaze Stabilization: Different Behavioral Strategies for Arboreal and Terrestrial Avians

2005 ◽  
Vol 93 (3) ◽  
pp. 1165-1173 ◽  
Author(s):  
Asim Haque ◽  
J. David Dickman
Keyword(s):  
Avian Species ◽  
Head Movements ◽  
Head Motion ◽  
Behavioral Strategies ◽  
Specific Behavior ◽  
Gaze Stabilization ◽  
High Frequencies ◽  
Gaze Stability ◽  
Species Specific

In birds, it is thought that head movements play a major role in the reflexive stabilization of gaze and vision. In this study, we investigated the contributions of the eye and head to gaze stabilization during rotations under both head-fixed [vestibuloocular (VOR)] and head-free conditions in two avian species: pigeons and quails. These two species differ both in ocular anatomy (the pigeon has 2 distinct foveal regions), as well as in behavioral repertoires. Pigeons are arboreal, fly extended distances, and can navigate. Quails are primarily engrossed in terrestrial niches and fly only short distances. Unlike the head-fixed VOR gains that were under-compensatory for both species, gaze gains under head-free conditions were completely compensatory at high frequencies. This compensation was achieved primarily with head movements in pigeons, but with combined head and eye-in-head contributions in the quail. In contrast, eye-in-head motion, which was significantly reduced for head-free compared with head-fixed conditions, contributed very little to overall gaze stability in pigeons. These results suggest that disparity between the stabilization strategies employed by these two birds may be attributed to differences in species-specific behavior and anatomy.

Recovery of Gaze Stability During Vestibular Regeneration

2008 ◽  
Vol 99 (2) ◽  
pp. 853-865 ◽  
Author(s):  
Asim Haque ◽  
Mridha Zakir ◽  
J. David Dickman
Keyword(s):  
Dynamic Recovery ◽  
Normal Function ◽  
Temporal Sequence ◽  
Vestibular Loss ◽  
Gaze Stabilization ◽  
Bilateral Vestibular Loss ◽  
Gaze Stability ◽  
Total Lack ◽  
Movement Stability ◽  
Abnormal Behaviors

Many motion related behaviors, such as gaze stabilization, balance, orientation, and navigation largely depend on a properly functioning vestibular system. After vestibular insult, many of these responses are compromised but can return during the regeneration of vestibular receptors and afferents as is known to occur in birds, reptiles, and amphibians. Here we characterize gaze stability in pigeons to rotational motion during regeneration after complete bilateral vestibular loss via an ototoxic antibiotic. Immediate postlesion effects included severe head oscillations, postural ataxia, and total lack of gaze control. We found that these abnormal behaviors gradually subsided, and gaze stability slowly returned to normal function according to a temporal sequence that lasted several months. We also found that the dynamic recovery of gaze function during regeneration was not homogeneous for all types of motion. Instead high-frequency motion stability was first achieved, followed much later by slow movement stability. In addition, we found that initial gaze stability was established using almost exclusive head-response components with little eye-movement contribution. However, that trend reversed as recovery progressed so that when gaze stability was complete, the eye component had increased and the head response had decreased to levels significantly different from that observed in normal birds. This was true even though the head-fixed VOR response recovered normally. Recovery of gaze stability coincided well with the three stage temporal sequence of morphologic regeneration previously described by our laboratory.

scholarly journals Multimodal Integration After Unilateral Labyrinthine Lesion: Single Vestibular Nuclei Neuron Responses and Implications for Postural Compensation

2011 ◽  
Vol 105 (2) ◽  
pp. 661-673 ◽  
Author(s):  
Soroush G. Sadeghi ◽  
Lloyd B. Minor ◽  
Kathleen E. Cullen
Keyword(s):  
Time Course ◽  
Vestibular Nuclei ◽  
Head Movements ◽  
Neuronal Responses ◽  
Vestibular Loss ◽  
Relative Contribution ◽  
Lower Extremity Muscle ◽  
Before And After ◽  
Late Stages ◽  
Passive Movements

Plasticity in neuronal responses is necessary for compensation following brain lesions and adaptation to new conditions and motor learning. In a previous study, we showed that compensatory changes in the vestibuloocular reflex (VOR) following unilateral vestibular loss were characterized by dynamic reweighting of inputs from vestibular and extravestibular modalities at the level of single neurons that constitute the first central stage of VOR signal processing. Here, we studied another class of neurons, i.e., the vestibular-only neurons, in the vestibular nuclei that mediate vestibulospinal reflexes and provide information for higher brain areas. We investigated changes in the relative contribution of vestibular, neck proprioceptive, and efference copy signals in the response of these neurons during compensation after contralateral vestibular loss in Macaca mulata monkeys. We show that the time course of recovery of vestibular sensitivity of neurons corresponds with that of lower extremity muscle and tendon reflexes reported in previous studies. More important, we found that information from neck proprioceptors, which did not influence neuronal responses before the lesion, were unmasked after lesion. Such inputs influenced the early stages of the compensation process evidenced by faster and more substantial recovery of the resting discharge in proprioceptive-sensitive neurons. Interestingly, unlike our previous study of VOR interneurons, the improvement in the sensitivity of the two groups of neurons did not show any difference in the early or late stages after lesion. Finally, neuronal responses during active head movements were not different before and after lesion and were attenuated relative to passive movements over the course of recovery, similar to that observed in control conditions. Comparison of compensatory changes observed in the vestibuloocular and vestibulospinal pathways provides evidence for similarities and differences between the two classes of neurons that mediate these pathways at the functional and cellular levels.

scholarly journals Effects of vestibular neurectomy and neural compensation on head movements in patients undergoing vestibular schwannoma resection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Omid A. Zobeiri ◽  
Gavin M. Mischler ◽  
Susan A. King ◽  
Richard F. Lewis ◽  
Kathleen E. Cullen
Keyword(s):  
Vestibular Schwannoma ◽  
Normal Subjects ◽  
Head Movements ◽  
Head Motion ◽  
Vestibular Loss ◽  
Vestibular Neurectomy ◽  
Time Points ◽  
Head Kinematics ◽  
Kinematic Measures ◽  
Vestibular Damage

AbstractThe vestibular system is vital for maintaining balance and stabilizing gaze and vestibular damage causes impaired postural and gaze control. Here we examined the effects of vestibular loss and subsequent compensation on head motion kinematics during voluntary behavior. Head movements were measured in vestibular schwannoma patients before, and then 6 weeks and 6 months after surgical tumor removal, requiring sectioning of the involved vestibular nerve (vestibular neurectomy). Head movements were recorded in six dimensions using a small head-mounted sensor while patients performed the Functional Gait Assessment (FGA). Kinematic measures differed between patients (at all three time points) and normal subjects on several challenging FGA tasks, indicating that vestibular damage (caused by the tumor or neurectomy) alters head movements in a manner that is not normalized by central compensation. Kinematics measured at different time points relative to vestibular neurectomy differed substantially between pre-operative and 6-week post-operative states but changed little between 6-week and > 6-month post-operative states, demonstrating that compensation affecting head kinematics is relatively rapid. Our results indicate that quantifying head kinematics during self-generated gait tasks provides valuable information about vestibular damage and compensation, suggesting that early changes in patient head motion strategy may be maladaptive for long-term vestibular compensation.

Effect of vestibular rehabilitation on passive dynamic visual acuity

2008 ◽  
Vol 18 (2-3) ◽  
pp. 147-157
Author(s):  
Matthew Scherer ◽  
Americo A. Migliaccio ◽  
Michael C. Schubert
Keyword(s):  
Visual Acuity ◽  
Exercise Program ◽  
Home Exercise ◽  
Dynamic Visual Acuity ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Gaze Stability ◽  
Before And After ◽  
Vestibulo Ocular Reflex ◽  
Head Impulses

While active dynamic visual acuity (DVA) has been shown to improve with gaze stabilization exercises, we sought to determine whether DVA during {passive} head impulses (pDVA) would also improve following a rehabilitation course of vestibular physical therapy (VPT) in patients with unilateral and bilateral vestibular hypofunction. VPT consisted of gaze and gait stabilization exercises done as a home exercise program. Scleral search coil was used to characterize the angular vestibulo-ocular reflex (aVOR) during pDVA before and after VPT. Mean duration of VPT was 66 ± 24 days, over a total of 5 ± 1.4 outpatient visits. Two of three subjects showed improvements in pDVA with a mean reduction of 43% (LogMAR 0.58 to 0.398 and 0.92 to 0.40). Our data suggest improvements in pDVA may be due in part to improvements in aVOR velocity and acceleration gains or reduced latency of the aVOR. Each subject demonstrated a reduction in the ratio of compensatory saccades to head impulses after VPT. Preliminary data suggest that active gaze stability exercises may contribute to improvements in pDVA in some individuals.

scholarly journals Continuous Head Motion is a Greater Motor Control Challenge than Transient Head Motion in Patients with Loss of Vestibular Function

2021 ◽  
pp. 154596832110347
Author(s):  
Lin Wang ◽  
Omid A. Zobeiri ◽  
Jennifer L. Millar ◽  
Wagner Souza Silva ◽  
Michael C. Schubert ◽  
...  
Keyword(s):  
Motor Control ◽  
Head Movement ◽  
Acute Stage ◽  
Head Movements ◽  
Head Motion ◽  
Cycle Duration ◽  
Vestibular Loss ◽  
Gaze Stability ◽  
Kinematic Measures ◽  
Control Challenge

Background. The vestibular system is vital for gaze stability via the vestibulo-ocular reflex, which generates compensatory eye motion in the direction opposite to head motion. Consequently, individuals with peripheral vestibular loss demonstrate impaired gaze stability that reduces functional capacity and quality of life. To facilitate patients’ compensatory strategies, two classes of gaze stabilization exercises are often prescribed: (i) transient (eg, ballistic) and (ii) continuous. However, the relative benefits of these two classes of exercises are not well understood. Objective. To quantify head motion kinematics in patients with vestibular loss while they performed both classes of exercises. Methods. Using inertial measurement units, head movements of 18 vestibular schwannoma patients were measured before and after surgical deafferentation and compared with age-matched controls. Results. We found that the head movement during both classes of exercises paralleled those of natural head movement recorded during daily activities. However, head movement patterns were more informative for continuous than transient exercises in distinguishing patients from healthy controls. Specifically, we observed coupling between kinematic measures in control subjects that was absent in patients for continuous but not transient head motion exercises. In addition, kinematic measures (eg, cycle duration) were predictive of standard clinical measures for continuous but not transient head motion exercises. Conclusions. Our data suggest that performing continuous head motion is a greater motor control challenge than transient head motion in patients with less reliable vestibular feedback during the sub-acute stage of recovery, which may also prove to be a reliable measure of progression in vestibular rehabilitation protocols.

Adipokines as Potential Biomarkers in the Neurorehabilitation of Obese Stroke Patients

2020 ◽  
Vol 17 (4) ◽  
pp. 437-445
Author(s):  
Irene Ciancarelli ◽  
Giovanni Morone ◽  
Marco Iosa ◽  
Stefano Paolucci ◽  
Loris Pignolo ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Functional Recovery ◽  
Functional Independence Measure ◽  
Functional Independence ◽  
Enzyme Linked Immunosorbent Assay ◽  
Stroke Patients ◽  
Rehabilitation Outcomes ◽  
Before And After ◽  
Forward Stepwise ◽  
Clinical Measures

Background: Limited studies concern the influence of obesity-induced dysregulation of adipokines in functional recovery after stroke neurorehabilitation. Objective: To investigate the relationship between serum leptin, resistin, and adiponectin and functional recovery before and after neurorehabilitation of obese stroke patients. The adipokine potential significance as prognostic markers of rehabilitation outcomes was also verified. Methods: Twenty obese post-acute stroke patients before and after neurorehabilitation and thirteen obese volunteers without-stroke, as controls, were examined. Adipokines were determined by commercially available enzyme-linked immunosorbent assay (ELISA) kits. Functional deficits were assessed before and after neurorehabilitation with the Barthel Index (BI), modified Rankin Scale (mRS), and Functional Independence Measure (FIM). Results: Compared to controls, higher leptin and resistin values and lower adiponectin values were observed in stroke patients before neurorehabilitation and no correlations were found between adipokines and clinical outcome measures. Neurorehabilitation was associated with improved scores of BI, mRS, and FIM. After neurorehabilitation, decreased values of Body Mass Index (BMI) and resistin together increased adiponectin were detected in stroke patients, while leptin decreased but not statistically. Comparing adipokine values assessed before neurorehabilitation with the outcome measures after neurorehabilitation, correlations were observed for leptin with BI-score, mRS-score, and FIM-score. No other adipokine levels nor BMI assessed before neurorehabilitation correlated with the clinical measures after neurorehabilitation. The forward stepwise regression analysis identified leptin as prognostic factor for BI, mRS, and FIM. Conclusions: Our data show the effectiveness of neurorehabilitation in modulating adipokines levels and suggest that leptin could assume the significance of biomarker of functional recovery.

Two conditions to fully recover dynamic canal function in unilateral peripheral vestibular hypofunction patients

2021 ◽  
pp. 1-15
Author(s):  
Michel Lacour ◽  
Alain Thiry ◽  
Laurent Tardivet
Keyword(s):  
Crucial Role ◽  
Recovery Process ◽  
Head Impulse Test ◽  
Additional Parameter ◽  
Vestibular Loss ◽  
Horizontal Canal ◽  
Lateral Canal ◽  
Gaze Stability ◽  
Vestibular Hypofunction ◽  
Anterior Canal

BACKGROUND: The crucial role of early vestibular rehabilitation (VR) to recover a dynamic semicircular canal function was recently highlighted in patients with unilateral vestibular hypofunction (UVH). However, wide inter-individual differences were observed, suggesting that parameters other than early rehabilitation are involved. OBJECTIVE: The aim of the study was to determine to what extent the degree of vestibular loss assessed by the angular vestibulo-ocular reflex (aVOR) gain could be an additional parameter interfering with rehabilitation in the recovery process. And to examine whether different VR protocols have the same effectiveness with regard to the aVOR recovery. METHODS: The aVOR gain and the percentage of compensatory saccades were recorded in 81 UVH patients with the passive head impulse test before and after early VR (first two weeks after vertigo onset: N = 43) or late VR (third to sixth week after onset: N = 38) performed twice a week for four weeks. VR was performed either with the unidirectional rotation paradigm or gaze stability exercises. Supplementary outcomes were the dizziness handicap inventory (DHI) score, and the static and dynamic subjective visual vertical. RESULTS: The cluster analysis differentiated two distinct populations of UVH patients with pre-rehab aVOR gain values on the hypofunction side below 0.20 (N = 42) or above 0.20 (N = 39). The mean gain values were respectively 0.07±0.05 and 0.34±0.12 for the lateral canal (p <  0.0001), 0.09±0.06 and 0.44±0.19 for the anterior canal (p <  0.0001). Patients with aVOR gains above 0.20 and early rehab fully recovered dynamic horizontal canal function (0.84±0.14) and showed very few compensatory saccades (18.7% ±20.1%) while those with gains below 0.20 and late rehab did not improve their aVOR gain value (0.16±0.09) and showed compensatory saccades only (82.9% ±23.7%). Similar results were found for the anterior canal function. Recovery of the dynamic function of the lateral canal was found with both VR protocols while it was observed with the gaze stability exercises only for the anterior canal. All the patients reduced their DHI score, normalized their static SVV, and exhibited uncompensated dynamic SVV. CONCLUSIONS: Early rehab is a necessary but not sufficient condition to fully recover dynamic canal function. The degree of vestibular loss plays a crucial role too, and to be effective rehabilitation protocols must be carried out in the plane of the semicircular canals.

“Torso Rotation”' experiments. 4: the role of vision and the cervico-ocular reflex in compensation for a deficient VOR

1999 ◽  
Vol 9 (2) ◽  
pp. 89-101
Author(s):  
L.J.G. Bouyer ◽  
D.G.D. Watt
Keyword(s):  
Motion Sickness ◽  
Vestibular Function ◽  
Repeated Exposure ◽  
Head Movements ◽  
Upper Body ◽  
Calibration Data ◽  
En Bloc ◽  
Mean Velocity ◽  
Gaze Stability ◽  
Velocity Gain

Acute, reversible changes in human vestibular function can be produced by exposure to “Torso Rotation” (TR), a method involving the overuse of certain types of simple, self-generated movements. A single session results in multiple, short-lasting aftereffects, including perceptual illusions, VOR gain reduction,gaze and postural instability, and motion sickness. With repeated exposure, motion sickness susceptibility disappears and gaze stability improves. VOR gain continues to be reduced, however. Therefore, another gaze stabilizing system must come into play. Are visual and/or neck inputs involved in this functional compensation? Six subjects participated in this 7-day experiment. Eye and head movements were measured during 2 tests: 1) voluntary “head only” shaking between 0.3 and 3.0 Hz (lights off) and 2) voluntary “head and torso” shaking, moving the upper body en bloc (neck immobilized). Measurements were obtained before and repeatedly after TR. Velocity gain (eye velocity/head velocity) was determined for each of these tests. Each day, mean velocity gain during “head only” shaking in the dark (averaged over 1.0 to 2.0 Hz) dropped significantly after TR ( P < 0.01), with no long-term improvement ( P > 0.9). Similar results, although more noisy, were obtained for “head and torso” shaking. As a control, EOG calibration data confirmed that gaze stability in the light did improve over the 7 days of testing. This experiment demonstrates that the reduction in gaze instability following repeated exposure to TR results from an increased use of vision. It excludes the VOR, the COR, and predictive mechanisms (including efference copy) as contributors. In addition, in the 20 minutes following TR completion, gaze stability recovered less than during previous VOR testing in the dark. These results are compatible with the motion that exposure to TR leads to a change in sensorimotor strategy involving a de-emphasis of vestibular inputs.

Abnormal spinal cord motion at the craniocervical junction in hypermobile Ehlers-Danlos patients

2021 ◽  
pp. 1-7
Author(s):  
Petra M. Klinge ◽  
Abigail McElroy ◽  
John E. Donahue ◽  
Thomas Brinker ◽  
Ziya L. Gokaslan ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Neck Pain ◽  
Craniocervical Junction ◽  
Head Movements ◽  
Ehlers Danlos Syndrome ◽  
Transmission Electron ◽  
Pathogenic Factors ◽  
Healthy Control ◽  
Craniocervical Instability ◽  
Danlos Syndrome

OBJECTIVE The craniocervical junction (CCJ) is anatomically complex and comprises multiple joints that allow for wide head and neck movements. The thecal sac must adjust to such movements. Accordingly, the thecal sac is not rigidly attached to the bony spinal canal but instead tethered by fibrous suspension ligaments, including myodural bridges (MDBs). The authors hypothesized that pathological spinal cord motion is due to the laxity of such suspension bands in patients with connective tissue disorders, e.g., hypermobile Ehlers-Danlos syndrome (EDS). METHODS The ultrastructure of MDBs that were intraoperatively harvested from patients with Chiari malformation was investigated with transmission electron microscopy, and 8 patients with EDS were compared with 8 patients without EDS. MRI was used to exclude patients with EDS and craniocervical instability (CCI). Real-time ultrasound was used to compare the spinal cord at C1–2 of 20 patients with EDS with those of 18 healthy control participants. RESULTS The ultrastructural damage of the collagen fibrils of the MDBs was distinct in patients with EDS, indicating a pathological mechanical laxity. In patients with EDS, ultrasound revealed increased cardiac pulsatory motion and irregular displacement of the spinal cord during head movements. CONCLUSIONS Laxity of spinal cord suspension ligaments and the associated spinal cord motion disorder are possible pathogenic factors for chronic neck pain and headache in patients with EDS but without radiologically proven CCI.

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