Search

The impact of vibrotactile feedback of the gravity vector, provided by a “balance” belt worn around the waist, was evaluated in 39 patients with a severe bilateral vestibular loss, confirmed by extensive laboratory testing and suffering from a low quality of life, mainly due to imbalance. The mobility and balance score (MBS) of all patients prior to the use of the belt was equal or less than 5 out of a scale of 10. Thirty-one out of the 39 patients experienced the effect of the belt on their balance and mobility as positive in a preselection trial of 2 h in the hospital. The 31 positive responders then used the belt for 1 month in daily life. The average MBS increased significantly from 4.2 to 7.9 (paired T test, T = 9.82, p

Maģistra darbs ir uzrakstīts angļu valoda uz 47 lapām. Tas satur 28 attēlus, 2 tabulas un 42 atsauces uz literatūras avotiem. Maģistra darba mērķis ir nodemonstrēt optometrisko rehabilitācijas metožu ietekmi uz infantilu idiopātisko nistagmu (IIN). Desmit pacientiem ar IIN (30 ± 14 g.) tika veiktas sekojošas ārstēšanas metodes: prizmas ar bāzi uz āru, krāsotas kontaktlēcas (zīlītes diametrs 5 mm), audio-biofīdbeka metode. Pirms un pēc ārstēšanas tika novērtēts redzes asums un kontrastredze tālumā un stereoredze tuvumā ar labāko subjektīvo korekciju, nistagma apmlitūda un frekvence. Rezultāti parādīja, ka visas ārstēšanas metodes vienādi ietekmēja redzes asuma, nistagma amplitūdas un frekvences izmaiņas. Nenovēroja nozīmīgu saistību starp nistagma parametru izmaiņu un redzes asuma uzlabošanos., This thesis is written in English and consists of 47 pages. It contains 28 figures, 2 tables, and 42 references. The aim of this study was to show the results of the optometric rehabilitation techniques in cases of infantile idiopathic nystagmus (IIN). Ten patients with IIN (30 ± 14 y.) had the following treatments: base-out prisms, colored contact lenses (pupil diameter of 5 mm), audio-biofeedback. Binocular visual acuity and binocular contrast sensitivity with the best correction at far, stereopsis with the best correction at near, the amplitude and frequency of nystagmus were evaluated before and after every treatment. All treatment techniques equally affected changes in visual acuity, nystagmus amplitude and frequency. No significant relation was observed between changes in nystagmus parameters and the improvement in visual acuity. Subjective evaluations of the patients preferred the effect of audio-biofeedback.

Objective Cerebellar ataxia essentially includes deficient postural control. It remains unclear whether augmented sensory information might help cerebellar patients, as the cerebellum underlies processing of various sensory modalities for postural control. Here, we hypothesized that patients with cerebellar degeneration can still exploit audio‐biofeedback (ABF) of trunk acceleration as a real‐time assistive signal to compensate for deficient postural control. Methods Effects on postural sway during stance were assessed in an ABF intervention group versus a no‐ABF disease control group (23 vs. 17 cerebellar patients) in a clinico‐experimental study. A single‐session ABF paradigm of standing plus short exergaming under ABF was applied. Postural sway with eyes open and eyes closed was quantified prior to ABF, under ABF, and post ABF. Results Postural sway in the eyes closed condition was significantly reduced under ABF. Both benefit of ABF and benefit of vision correlated with the extent of postural sway at baseline, and both types of sensory benefits correlated with each other. Patients with strongest postural sway exhibited reduced postural sway also with eyes open, thus benefitting from both vision and ABF. No changes were observed in the no‐ABF control group. Interpretation Our findings provide proof‐of‐principle evidence that subjects with cerebellar degeneration are still able to integrate additional sensory modalities to compensate for deficient postural control: They can use auditory cues functionally similar to vision in the absence of vision, and additive to vision in the presence of vision (in case of pronounced postural sway). These findings might inform future assistive strategies for cerebellar ataxia.

The importance of sensory feedback for postural control in stance is evident from the balance improvements occurring when sensory information from the vestibular, somatosensory, and visual systems is available. However, the extent to which also audio-biofeedback information can improve balance has not been determined. It is also unknown why additional artificial sensory feedback is more effective for some subjects than others and in some environmental contexts than others. The aim of this study was to determine the relative effectiveness of an audio-biofeedback system to reduce postural sway in stance in healthy control subjects and in subjects with bilateral vestibular loss, under conditions of reduced vestibular, visual, and somatosensory inputs. This audio-biofeedback system used a threshold region and nonlinear scaling parameters customized for each individual, to provide subjects with pitch and volume coding of their body sway. Audio-biofeedback had the largest effect on reducing the body sway of the subjects with bilateral vestibular loss when the environment provided limited visual and somatosensory information; it had the smallest effect on reducing the sway of subjects with a vestibular loss when the environment provided full somatosensory information. The extent that all subjects substituted audio-biofeedback information for their loss of sensory information was related to the extent that each subject was visually dependent or somatosensory-dependent for their postural control. Comparison of postural sway under a variety of sensory conditions suggests that patients with profound bilateral loss of vestibular function show larger than normal information redundancy among the remaining senses and with audiobiofeedback audio-biofeedback of trunk sway . The results support the hypothesis that the nervous system uses augmented sensory information differently depending both on the environment and on individual proclivities to rely on vestibular, somatosensory or visual information to control sway.

This paper introduces a prototype audio-biofeedback system for balance improvement through the sonification using trunk kinematic information. In tests of this system, normal healthy subjects performed several trials in which they stood quietly in three sensory conditions while wearing an accelerometric sensory unit and headphones. The audio-biofeedback system converted in real-time the two-dimensional horizontal trunk accelerations into a stereo sound by modulating its frequency, level, and left/right balance. Preliminary results showed that subjects improved balance using this audio-biofeedback system and that this improvement was greater the more that balance was challenged by absent or unreliable sensory cues. In addition, high correlations were found between the center of pressure displacement and trunk acceleration, suggesting accelerometers may be useful for quantifying standing balance.