Leg Dominance Effects on Postural Control When Performing Challenging Balance Exercises.

Leg dominance reflects the preferential use of one leg over another and is typically attributed to asymmetries in the neural circuitry. Detecting leg dominance effects on motor behavior, particularly during balancing exercises, has proven difficult. The current study applied a principal component analysis (PCA) on kinematic data, to assess bilateral asymmetry on the coordinative structure (hypothesis H1) or on the control characteristics of specific movement components (hypothesis H2).

Complexity, Composition, and Control of Bipedal Balancing Movements as the Postural Control System Adapts to Unstable Support Surfaces or Altered Feet Positions.

The current project investigated the dynamics of postural movements and muscle activity during balancing with feet-together and feet-apart positions on different support surfaces (firm surface (FS), modified- and conventional balance boards). We hypothesized that movement complexity and muscle activation would increase with increased balance-task difficulty, and that differences in the composition and control of postural movements between bipedal wide- and narrow-based balancing would be observed in all surface conditions. We applied a principal component analysis (PCA) to decompose postural movement trajectories of 26 active-young adults into sets of movement components (principal movements; PMs).

Leg Dominance as a Risk Factor for Lower-Limb Injuries in Downhill Skiers-A Pilot Study into Possible Mechanisms.

Leg dominance has been reported as one potential risk factor for lower-limb injuries in recreational downhill skiers. The current study proposed and tested two possible mechanisms for a leg dominance effect on skiing injuries-imbalance of the knee muscle strength and bilateral asymmetry in sensorimotor control. We hypothesized that the knee muscle strength (Hypothesis 1; H1) or postural control (Hypothesis 2; H2) would be affected by leg dominance.

Changed Temporal Structure of Neuromuscular Control, Rather Than Changed Intersegment Coordination, Explains Altered Stabilographic Regularity after a Moderate Perturbation of the Postural Control System.

Sample entropy (SaEn) applied on center-of-pressure (COP) data provides a measure for the regularity of human postural control. Two mechanisms could contribute to altered COP regularity: first, an altered temporal structure (temporal regularity) of postural movements (H1); or second, altered coordination between segment movements (coordinative complexity; H2). The current study used rapid, voluntary head-shaking to perturb the postural control system, thus producing changes in COP regularity, to then assess the two hypotheses.

PManalyzer: A Software Facilitating the Study of Sensorimotor Control of Whole-Body Movements.

Motion analysis is used to study the functionality or dysfunctionality of the neuromuscular system, as human movements are the direct outcome of neuromuscular control. However, motion analysis often relies on measures that quantify simplified aspects of a motion, such as specific joint angles, despite the well-known complexity of segment interactions. In contrast, analyzing whole-body movement patterns may offer a new understanding of movement coordination and movement performance.

The Effect of Cognitive Resource Competition Due to Dual-Tasking on the Irregularity and Control of Postural Movement Components.

Postural control research suggests a non-linear, n-shaped relationship between dual-tasking and postural stability. Nevertheless, the extent of this relationship remains unclear. Since kinematic principal component analysis has offered novel approaches to study the control of movement components (PM) and n-shapes have been found in measures of sway irregularity, we hypothesized (H1) that the irregularity of PMs and their respective control, and the control tightness will display the n-shape.

Biomechanics in posture space: Properties and relevance of principal accelerations for characterizing movement control.

Human movements, recorded through kinematic data, can be described by means of principal component analysis (PCA) through a small set of variables representing correlated segment movements. The PC-eigenvectors then form a basis in the associated vector space of postural changes. Similar to 3D movements, the kinematics in this posture space can be quantified through 'principal' positions (PPs), velocities (PVs) and accelerations (PAs).

Effects of a cognitive dual task on variability and local dynamic stability in sustained repetitive arm movements using principal component analysis: a pilot study.

In many daily jobs, repetitive arm movements are performed for extended periods of time under continuous cognitive demands. Even highly monotonous tasks exhibit an inherent motor variability and subtle fluctuations in movement stability. Variability and stability are different aspects of system dynamics, whose magnitude may be further affected by a cognitive load.

Postural reconfiguration and cycle-to-cycle variability in patients with work-related musculoskeletal disorders compared to healthy controls and in relation to pain emerging during a repetitive movement task.

Background: Movement variability in sustained repetitive tasks is an important factor in the context of work-related musculoskeletal disorders. While a popular hypothesis suggests that movement variability can prevent overuse injuries, pain evolving during task execution may also cause variability. The aim of the current study was to investigate, first, differences in movement behavior between volunteers with and without work-related pain and, second, the influence of emerging pain on movement variability.

Age Effects in Postural Control Analyzed via a Principal Component Analysis of Kinematic Data and Interpreted in Relation to Predictions of the Optimal Feedback Control Theory.

Optimal feedback control theory suggests that control of movement is focused on movement dimensions that are important for the task's success. The current study tested the hypotheses that age effects would emerge in the control of only specific movement components and that these components would be linked to the task relevance. Fifty healthy volunteers, 25 young and 25 older adults, performed a 80s-tandem stance while their postural movements were recorded using a standard motion capture system.

How does lower limb dominance influence postural control movements during single leg stance?

The main purposes of the current study were to examine bilateral asymmetry in postural control during single-leg standing between the dominant and non-dominant legs using a novel analysis approach based on principal component analysis (PCA). It was hypothesized that the asymmetry might manifest as differences in the coordinative structure (control strategies), or as differences in the frequency or regularity of corrective interventions of the motor control system. The static and dynamic leg dominance of 26 active young adults (14 males and 12 females) was determined from their preferred leg for dynamic and for static tasks.

Human Postural Control: Assessment of Two Alternative Interpretations of Center of Pressure Sample Entropy through a Principal Component Factorization of Whole-Body Kinematics.

Sample entropy (SaEn), calculated for center of pressure (COP) trajectories, is often distinct for compromised postural control, e.g., in Parkinson, stroke, or concussion patients, but the interpretation of COP-SaEn remains subject to debate.

Preservation of hearing in bilateral acoustic neurinomas by deliberate partial resection.

With the aim of preserving hearing, 20 acoustic neurinomas in 17 patients with neurofibromatosis 2 were intentionally submitted to an incomplete (80%) tumour removal. In 12 cases this was an operation on the last hearing ear with total deafness of the contralateral ear. If an auditus existed in both ears the better hearing ear was selected for the primary intervention.

Extended middle cranial fossa approach for acoustic neuroma surgery.

The enlarged middle cranial fossa approach was used for removal of acoustic neuromas in 209 cases. Complete tumor removal was accomplished in 96% of cases. Hearing was preserved in 51% of cases, with better results in smaller tumors.

[Function-saving microsurgery in suboccipital removal of large acoustic neuromas].

Various successful approaches are available for acoustic neurinoma surgery, permitting total tumor removal and preservation of cranial nerve function. In smaller and medium sized tumors excellent results can be achieved with respect to facial and cochlear nerve function using the transtemporal approach. For larger tumors similar results can be achieved by the suboccipital approach.

The enlarged middle cranial fossa approach for surgery of the temporal bone and of the cerebellopontine angle.

Due to the fact that the temporal bone has broad segments of bone anterior to and behind the internal auditory canal which are empty of functionally important structures, a broad exposure of the cerebellopontine angle may be obtained from above. This technique is adequate for the management of acoustic neurinomas up to 3 cm in diameter. A low postoperative morbidity and a high percentage of hearing preservation with total tumor removal were obtained in a series of 190 cases.

[Surgical interventions for ameliorating of equilibrium disorders refractory to conservative therapy].

In cases of vertigo resistant to conservative treatment, surgery can be valuable for labyrinthine fistula, perilymphatic fistula, cupulolithiasis and Menière's disease. For instance, covering a labyrinthine fistula by a fascial graft relieves the vertigo in an amazingly short time. Perilymphatic fistula is verified and treated by tympanotomy and is used for patients with special auditory and/or vestibular features.

Evaluation of flunarizine in patients with Menière's disease. Subjective and vestibular findings.

In an open multicentre pilot study, 32 patients affected with Menière's disease were treated with the cerebrally effective calcium antagonist flunarizine for 12 weeks. By means of the so-called vestibular index, the therapeutic results could be documented in a rapid and clear manner; the vestibular index takes into account both the subjective statements of the patients and objective pathological vestibular findings in terms of figures. The mean value of this vestibular index of 32 patients with Menière's disease was 9.

[Caloric evaluation of the vestibular organ in the child--an electronystagmography study for determining age dependence of the vestibulo-ocular response].

The vestibular-ocular reflex was examined after caloric stimulation on 120 healthy children, age 5 to 14 years. The different parameters of the nystagmus such as the beats during the culmination period of 30 s, the velocity of the slow phase and the amplitude and duration of the nystagmus showed a clear correlation to the child's age. The values for the duration of the nystagmus and the number of beats after caloric stimulation increased with respect to age, whereas the other parameters decreased.

[Experience with fibrin glue in type-III tympanoplasty with stapes elevation].

In a retrospective study, type III tympanoplasties with stapes elevation on two groups of patients were compared. In group I (101 patients) the stapes elevations, the temporalis fascia grafts for tympanic membrane reconstruction, the grafts of periosteum and cartilage used for repair defects of the posterior bony meatal wall and the Stacke-II plasty replaced in its original position after tympanoplasty were also fixed with fibrin glue (Tissucol). Group II (control group of 102 patients) was operated with fibrin glue.

[Peripheral vestibular neuropathy and a central vestibular equivalent].

The results of the initial and follow-up examinations of 217 patients with vestibular neuritis and 63 patients with a so called "vestibular neuritis syndrome" were statistically evaluated and quantified using the vestibular index. The results for patients with vestibular neuritis were compared at the different stages to those of patients after neurectomy of the vestibular nerve. The site of the lesion in patients with vestibular neuritis may therefore be in the region of Scarpa's ganglion (retrolabyrinthine).

[Angiomatous malformation of the inner auditory canal with the leading symptoms of vertigo and tinnitus].

A case of a rare arteriovenous malformation in the internal auditory canal is reported. It caused unilateral tinnitus, facial weakness, trigeminal hypesthesia, and vertigo with lateropulsion. The audiological and otoneurological findings together with air-cisternography a CT scan had indicated an intrameatal tumor.

[Removal of acoustic neuromas of the cerebellopontile angle with transtemporal approach by the middle cranial fossa].

The enlarged transtemporal middle fossa approach to the cerebello-pontine angle is adequate for complete removal of acoustic neuromas up to 4.0 cm in diameter (sizes B and C according to Fisch). A description of the surgical technique and the results of 63 operations are presented (13, 23 and 27 tumours of sizes A, B and C respectively).