The neuropsychiatric phenotype in CACNA1A mutations: a retrospective single center study and review of the literature.

BACKGROUND AND PURPOSE: CACNA1A encodes the α1 subunit of the neuronal calcium channel P/Q. CACNA1A mutations underlie three allelic disorders: familial hemiplegic migraine type 1 (FHM1), episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6). A clear-cut genotype-phenotype correlation is often lacking since clinical manifestations may overlap. Several case reports have described cognitive and behavioral features in CACNA1A disorders, but studies in larger case series are lacking. METHODS: Genetically confirmed CACNA1A cases were retrieved from the database of the ataxia outpatient clinic of the Department of Neurology at Innsbruck Medical University. Clinical charts and neuropsychological test results were retrospectively analyzed. In addition, a review of the literature including only genetically confirmed cases was performed. RESULTS: Forty-four CACNA1A cases were identified in our database. Delayed psychomotor milestones and poor school performance were described in seven (four FHM1, three EA2) and eight (three FHM1, five EA2) patients, respectively. Psychiatric comorbidities were diagnosed in eight patients (two FHM1, six EA2). Neuropsychological testing was available for 23 patients (11 FHM1, 10 EA2, two SCA6). Various cognitive deficits were documented in 21 cases (all patients except one SCA6). Impairments were predominantly seen in figural memory, visuoconstructive abilities and verbal fluency. In the literature, an early psychomotor delay is described in several children with EA2 and FHM1, whilst reports of cognitive and psychiatric findings from adult cases are scarce. CONCLUSIONS: Neuropsychiatric manifestations are common in episodic CACNA1A disorders. In the case of otherwise unexplained developmental delay and a positive family history, CACNA1A mutations should be considered in the differential diagnosis.

Safety assessment of jumps in ski racing.

The influence of important parameters on the flight trajectory for jumps in downhill World Cup races was investigated. To quantify the impact injury risk at landing, the parameter equivalent landing height (ELH) was introduced, which considered a variable slope inclination during the landing movement. Altogether, 145 runs at four different jumps in World Cup races and trainings were recorded and analyzed. A simulation model was developed to predict the flight phase of the skier. Drag and lift areas were selected by parameter identification to fit the simulation trajectory to the two-dimensional data from the video analysis. The maximum values of the ELH which can be absorbed with muscle force was taken from the study of Minetti et al. for elite female and male ski racers. A sensitivity analysis based on the four jumps showed that ELH is mainly influenced by takeoff angle, takeoff speed, and the steepness of the landing surface. With the help of the developed simulation software, it should be possible to predict the ELH for jumps in advance. In case of an excessive ELH, improvements can be made by changing the takeoff inclination or the approach speed.

Consensus paper: management of degenerative cerebellar disorders.

Treatment of motor symptoms of degenerative cerebellar ataxia remains difficult. Yet there are recent developments that are likely to lead to significant improvements in the future. Most desirable would be a causative treatment of the underlying cerebellar disease. This is currently available only for a very small subset of cerebellar ataxias with known metabolic dysfunction. However, increasing knowledge of the pathophysiology of hereditary ataxia should lead to an increasing number of medically sensible drug trials. In this paper, data from recent drug trials in patients with recessive and dominant cerebellar ataxias will be summarized. There is consensus that up to date, no medication has been proven effective. Aminopyridines and acetazolamide are the only exception, which are beneficial in patients with episodic ataxia type 2. Aminopyridines are also effective in a subset of patients presenting with downbeat nystagmus. As such, all authors agreed that the mainstays of treatment of degenerative cerebellar ataxia are currently physiotherapy, occupational therapy, and speech therapy. For many years, well-controlled rehabilitation studies in patients with cerebellar ataxia were lacking. Data of recently published studies show that coordinative training improves motor function in both adult and juvenile patients with cerebellar degeneration. Given the well-known contribution of the cerebellum to motor learning, possible mechanisms underlying improvement will be outlined. There is consensus that evidence-based guidelines for the physiotherapy of degenerative cerebellar ataxia need to be developed. Future developments in physiotherapeutical interventions will be discussed including application of non-invasive brain stimulation.

Relationship between jump landing kinematics and peak ACL force during a jump in downhill skiing: a simulation study.

Recent data highlight that competitive skiers face a high risk of injuries especially during off-balance jump landing maneuvers in downhill skiing. The purpose of the present study was to develop a musculo-skeletal modeling and simulation approach to investigate the cause-and-effect relationship between a perturbed landing position, i.e., joint angles and trunk orientation, and the peak force in the anterior cruciate ligament (ACL) during jump landing. A two-dimensional musculo-skeletal model was developed and a baseline simulation was obtained reproducing measurement data of a reference landing movement. Based on the baseline simulation, a series of perturbed landing simulations (n = 1000) was generated. Multiple linear regression was performed to determine a relationship between peak ACL force and the perturbed landing posture. Increased backward lean, hip flexion, knee extension, and ankle dorsiflexion as well as an asymmetric position were related to higher peak ACL forces during jump landing. The orientation of the trunk of the skier was identified as the most important predictor accounting for 60% of the variance of the peak ACL force in the simulations. Teaching of tactical decisions and the inclusion of exercise regimens in ACL injury prevention programs to improve trunk control during landing motions in downhill skiing was concluded.

Modeling the ski-snow contact in skiing turns using a hypoplastic vs an elastic force-penetration relation.

A ski-snow interaction model is presented. The force between ski and snow is decomposed into a penetration force normal to the snow surface, a shear force parallel to it, and friction. The purpose of this study was to investigate the benefits of a hypoplastic vs an elastic contact for penetration in the simulation of skiing turns. To reduce the number of influencing factors, a sledge equipped with skis was considered. A forward dynamic simulation model for the sledge was implemented. For the evaluation of both contact models, the deviation between simulated trajectories and experimental track data was computed for turns of 67 and 42 m. Maximum deviations for these turns were 0.44 and 0.14 m for the hypoplastic contact, and 0.6 and 7.5 m for the elastic contact, respectively. In the hypoplastic contact, the penetration depth of the ski's afterbody maintained nearly the same value as the part under maximum load, whereas it decreased in the elastic contact. Because the shear force is proportional to the penetration depth, the hypoplastic contact resulted in a higher shearing resistance. By replacing the sledge with a skier model, one may investigate more complex skier actions, skiing performance, or accident-prone skiing maneuvers.

Impact of environmental factors on knee injuries in male and female recreational skiers.

In alpine skiing, the knee represents the dominant injury location with marked gender differences. Snow, slope and weather conditions as well as altitude and low temperatures are thought to influence the prevalence of knee injuries. Therefore, ski patrol injury reports were used to compare gender-specific prevalence of knee injuries with regard to several environmental factors including the actual air temperatures. A total of 1039 non-contact knee injuries were reported with a corresponding prevalence of knee injuries of 44.4% (males: 30.1%; females: 57.4%). Temperature quartiles of all recorded injuries were calculated to compare gender-specific prevalence of knee injury with regard to temperatures. Comparing the first quartile (mean temperature -11°C) with the fourth quartile (mean temperature +3°C), the prevalence of knee injury in female skiers was higher at low ambient temperatures (61% vs 50%, odds ratio: 1.60, 95% confidence interval: 1.16-2.22; P=0.005) while no such association was found for male skiers. Additionally, knee-injured females showed a twofold prevalence when skiing during snowfall compared with females with other injuries (15.4% vs 8.6%; P=0.001). No other environmental factor showed a significant association with the gender-specific prevalence of knee injury. In conclusion, low ambient temperature and snowfall are important environmental risk factors for knee injuries in female skiers.

ACL injury mechanisms and related factors in male and female carving skiers: a retrospective study.

In recreational alpine skiing, ACL injury risk is 3 times greater in females. However, since the introduction of carving skis ACL injury risk seems to have decreased. No study has yet investigated the distribution of ACL injury mechanisms in male and female carving skiers. Therefore, the aim of the study was to investigate potential gender specific differences of ACL injury mechanisms and related factors among carving skiers. In total, 220 recreational carving skiers (59 males and 161 females) suffering from an ACL injury volunteered for this study. Demographic data, skiing ability, equipment related and environmental factors, circumstances and causes for the fall, and type of fall (injury mechanisms) were collected by questionnaire. The forward twisting fall is the most reported ACL injury mechanism in both gender (p=0.672) accounting for 54% of all injuries, although male and female skiers differed significantly with regard to circumstances of fall (p=0.001) and actions when ACL injury occurred (p=0.04). Bindings not releasing at the time point of accident occurred 2.6 times more with females than with males (p=0.005). The forward twisting fall seems to have become the dominant ACL injury mechanism both in male and female recreational skiers since the introduction of carving skis.

Interaction of potential intrinsic and extrinsic risk factors in ACL injured recreational female skiers.

The aim of this study was to investigate the interaction of potential intrinsic and extrinsic risk factors in ACL injured recreational female skiers. 93 female recreational skiers who had suffered a non-contact ACL injury and 93 age-matched controls completed a self-reported questionnaire relating to intrinsic risk factors (menstrual history, BMI, previous knee injuries, self reported weekly sports participation) and extrinsic risk factors (type of ski used, time of last binding adjustment, snow condition, weather and slope difficulty). A logistic regression model revealed the following independent ACL injury risk factors for female recreational skiers: icy snow conditions (odds ratio, 24.33; 95% confidence interval, 6.8-86.5, P<0.001), skiing during snowfall (odds ratio, 16.63; 95% confidence interval, 1.8-152.1, P=0.013), use of traditional skis (odds ratio, 10.49; 95% confidence interval, 2.0-54.5, P=0.005), and preovulatory phase of menstrual cycle (odds ratio, 2.59; 95% confidence interval, 1.2-5.5, P=0.013). In conclusion, ACL injuries in female recreational skiers are the result of a complex interaction of intrinsic and extrinsic risk factors.

Fine mapping of T-cell immunoglobulin mucin domain gene 1 failed to detect a significant association with multiple sclerosis.

The T-cell immunoglobulin mucin (TIM) gene family encodes receptors on T-cells that regulate Th1- and Th2-cell-mediated immunity. Recently published data implied differential expression of human TIM molecules by mononuclear cells in cerebrospinal fluid of patients with multiple sclerosis (MS) and might therefore be involved in different phases of the pathogenesis of MS. The purpose of this study was to investigate the association of TIM1 gene polymorphism with susceptibility to and clinical progression in MS. In total, 272 patients with MS and 272 sex- and age-matched healthy blood donors from Western Austria were genotyped for 10 single nucleotide polymorphisms (SNPs). Five SNPs were located in the promoter region of TIM1 (rs7702920, rs41297577, rs41297579, rs9313422 and rs34333511). Another five SNPs were selected in exon 4 (rs1553316 and rs12522248) and in the intronic regions 4 and 7 of TIM1 (rs1553318, rs2279804 and rs2277025), respectively. None of these SNPs showed a significant association with MS after correction for multiple comparisons. Haplotype analysis of our data resulted in 11 haplotypes and showed no significant differences between MS patients and controls. Our findings suggest that even fine mapping of TIM1 shows no significant association of this gene with multiple sclerosis.

Calculation of the contact pressure between ski and snow during a carved turn in Alpine skiing.

The macroscopic contact area between ski and snow and the contact pressure are crucial influencing factors for carved turns in Alpine skiing. In the present paper, a simulation model is developed to quantify these factors. The ski is modelled as an Euler-Bernoulli beam with variable cross section, camber, bending and torsional stiffness using measured data from skis. The reaction forces of the snow are decomposed in penetration and shear forces. For the penetration forces a hypoplastic constitutive law is applied incorporating elastic and plastic deformation of the snow at the contact area. For the shear forces metal cutting theory is used. Ski deformation, contact area and contact pressure are computed based on quasi-static equilibrium between forces exerted by the skier and snow reaction forces. Parameter studies are performed to investigate the influence of edging and distributing the load between the inner and outer ski. Higher edging angles as well as loading both skis affected the contact pressure positively by increasing the resistance against shearing. The results of our study agree well with measurement data taken from literature. Based on the results, the importance of actions of the skier during carved turns is concluded.

Factors associated with self-reported risk-taking behaviour on ski slopes.

BACKGROUND: In recent years, discussions have arisen about the potential influence of wearing a ski helmet on an increasing level of risk taking and higher speeds on ski slopes. OBJECTIVE: To evaluate factors associated with self-reported risk-taking behaviour in recreational skiers and snowboarders. METHODS: Speeds of skiers and snowboarders were measured with a radar speed gun and sex, age, nationality, height, weight and helmet use, used type of gear, self-estimated skill level and self-estimated fitness level were recorded. In addition, participants were asked if they considered themselves as cautious or risk-taking skier or snowboarder. RESULTS: In total, 453 skiers (39.6 (14.8) years) and 74 snowboarders (26.4 (9.6) years) have been interviewed. A stepwise forward logistic regression model revealed five independent factors for a risk-taking behaviour on slopes. Adjusted OR and their 95% CI showed that risk takers were <40 years (OR 2.4, 95% CI 1.51 to 3.80), had a higher skill level (OR 2.1, 95% CI 1.25 to 3.50), were more likely males (OR 2.0, 95% CI 1.22 to 3.26), had a lower body mass index (22.8 vs 24.2) and skied with higher speeds (on average 53 vs 45 km/h) compared to cautious skiers. CONCLUSION: Risk-taking behaviour on ski slopes is associated with younger age, higher skiing ability, male sex, lower body mass index and on average higher speeds. Helmet use is not associated with riskier behaviour on slopes. In addition, helmet use has to be recommended because helmet use reduces the risk of head injuries among skiers and snowboarders.

An approach to generate noncontact ACL-injury prone situations on a computer using kinematic data of non-injury situations and Monte Carlo simulation.

ACL-injuries are one of the most common knee injuries in noncontact sports. Kinematic data of injury prone situations provide important information to study the underlying ACL-injury mechanisms. However, these data are rare. In this work an approach is presented to generate injury prone situations for noncontact ACL-injuries on a computer. The injury prone situations are generated by a musculoskeletal simulation model using kinematic data of a non-injury situation and the method of Monte Carlo simulation. The approach is successfully applied to generate injury prone landings in downhill ski racing. The characteristics of the obtained injury prone landings are consistent with video recordings of injury cases.

Effects of arch height of the foot on ground reaction forces in running.

There is a suggested link between running injuries and arch type of the foot. However, a distinct cause and effect relationship has not been established. Feet may be functionally categorized on the basis of arch height. The purpose of this study was to compare selected ground reaction force variables in running for different arch heights. Static height of the medial longitudinal arch was measured using a caliper, arch flattening during running was determined by video analysis, and ground reaction forces during running were recorded from a KISTLER force plate. Thirty-four subjects were divided into three arch height and three arch flattening groups, and single-factor analyses of variance were conducted to compare the groups. Arch height and arch flattening were not found to be significantly related. However, the initial medial force peak in the low arch group occurred significantly later than in the normal and high arch groups, and the anterior force peak in the low flattening group was lower compared with the medium and high flattening groups (P < 0.05). Both arch measurements were ineffective in accounting for the observed variability in the ground reaction forces in running. Specifically, the impact forces did not differ for the different arch height and arch lowering groups.

Effects of arch height of the foot on angular motion of the lower extremities in running.

It has been suggested that a relationship exists between the height of the medial longitudinal arch of the foot and athletic injuries to the lower extremities. However, the functional significance of arch height in relation to injury is not well understood. The purpose of this study was to determine the influence of arch height on kinematic variables of the lower extremities that have been associated with the incidence of injury in running in an attempt to gain some insight into a functional relationship between arch height and injury. The three-dimensional kinematics of the lower extremities were measured during running for 30 subjects using high-speed video cameras. A joint coordinate system was used to calculate the three-dimensional orientation of the ankle joint complex for a single stance phase. Simple, linear regression analyses showed that arch height does not influence either maximal eversion movement or maximal internal leg rotation during running stance. However, assuming that knee pain in running can result from the transfer of foot eversion to internal rotation of the tibia, a functional relationship between arch height and injury may exist in that the transfer of foot eversion to internal leg rotation was found to increase significantly with increasing arch height. A substantial (27%), yet incomplete, amount of the variation in the transfer of movement between subjects was explained by arch height, indicating that there must be factors other than arch height that influence the kinematic coupling at the ankle joint complex. Additionally, the transfer of movement is only one factor of many associated with the etiology of knee pain in running.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer simulation of landing movement in downhill skiing: anterior cruciate ligament injuries.

Anterior cruciate ligament (ACL) injuries typically occur in high-speed downhill skiing during the landing phase following a jump. A direct dynamics simulation model was developed which allows investigation of possible ACL injury mechanisms without the need to use actual skiers in a potentially dangerous environment. The model included multibody dynamics, muscle dynamics and a model for ski-snow interaction. The model's ability to reproduce an actual landing movement was investigated by minimizing the differences between measured and stimulated landing movements as a function of constant muscle stimulation levels. The remaining difference was mainly due to noise in the measurements. A small balance disturbance was induced to simulate an injury condition. This disturbance caused the modeled skier to fall slightly backwards. A recovery attempt was made by maximal activation of the quadriceps and iliopsoas muscles. Peak resultant shear force at the knee joint in ACL direction was substantially higher in the injury simulation (1001 N) when compared to the simulated normal landing movement (589 N). Taking into account quadriceps contraction and orientation of the ACL with respect to tibial plateau, peak ACL force during the injury simulation was estimated to be 1350 N, which is within the range of failure loads for this ligament. The external forces were mainly (75%) responsible for this loading. The contribution of the fully activated quadriceps muscles was only 25%. It was concluded that the model could reproduce a typical landing movement and is therefore considered to be sufficiently realistic. Second, the simulation results suggest that external forces are the main cause for ACL injuries during landing movements in downhill skiing.

[Effect of ski tapering on turning radius and stress]. / Einfluss der Skitaillierung auf Schwungradius und Belastung.

The first part of this paper deals with the influence of the side cut on the turn radius, which was examined by measuring the turn radius of a self-running sledge-like construction and by comparing it to Howe's prediction. The turn radius at the beginning of the turn has proved to be between 65 and 85% of the theoretically expected result. In the second part a carvers turn radius was determined and the reaction force acting on the skier was calculated. The result shows a strong reduction of the turn radius along the path which increases the load on the skier. The effect of side cut and velocity on the load was examined. Using carver skis even small changes in velocity resulted in considerable load changes.

The effect of knee brace and knee sleeve on the proprioception of the knee in young non-professional healthy sportsmen.

BACKGROUND: Proprioception has been defined as the capacity to feel the position of a joint in space as sensed by the central nervous system. Prophylactic knee braces are supposed to help in knee injury prevention not just with a mechanical support of the joint but also improving proprioception. The main aim of this study was to determine the effects of a knee brace and a knee sleeve on knee proprioception. The secondary aim was to determine if different starting angles of the knee and different movement directions influence knee proprioception. METHODS: We tested a group of twenty healthy male sport students without knee injuries. They were tested with the brace, with the sleeve and without support. The threshold of detection of passive knee movement with a starting knee angle of 30° and 60°, both in flexion and extension was determined. RESULTS: We did not find any statistically significant change in the threshold of detection of passive knee movement wearing the brace or the sleeve compared to the unsupported condition (p=0.462, α=0.05). We found a significantly lower proprioceptive sensitivity starting at the more flexed knee angle (p=0.005, α=0.05) and moving in extension than in the other test situations (p=0.001, α=0.05). CONCLUSION: Movement direction and starting position appear to influence the threshold of detection of passive knee movement. The results of this study also suggest that knee supports do not influence either positively or negatively knee proprioception of uninjured active subjects.

[Mean speed of winter sport participants depending on various factors]. / Durchschnittsgeschwindigkeit von Wintersportlern in Abhängigkeit verschiedener Einflussfaktoren.

Objective of this study was to evaluate speeds on ski slopes depending on various factors as gender, age, height, weight, and nationality, helmet use, used type of gear, skiing ability, risk taking behaviour and weather conditions. The average speed measured with a radar speed gun was 44 km/h for all observations. A multivariate logistic regression model revealed five independent factors for higher speeds on slopes: younger age, male gender, skier, higher skill level, and riskier behaviour. Helmet use is not associated with higher speeds on slopes. Therefore, ski helmets have been recommended because helmet use is associated with a considerable reduction of head injury risk. In general, to avoid speed related injuries, preventive recommendations include skiing under speed control consistent with the individual skiing ability, and slope and weather conditions.

[Who is wearing a ski helmet? Helmet use on Austrian ski slopes depending on various factors]. / Wer trägt einen Skihelm? Helmtragequote auf österreichischen Skipisten in Abhängigkeit verschiedener Einflussfaktoren.

Objective of this study was to evaluate the actual helmet use on Austrian ski slopes depending on various factors as gender, age, and nationality, used type of gear, skiing ability and risk taking behaviour on slopes. In total, 63% of all observed subjects used ski helmets. However, significant differences have been found with regard to age, nationality, and skiing ability. While 78% of participants younger than 20 years used helmets, only 53% of those over 60 years were wearing ski helmets. Helmet use was significantly higher in locals compared to foreigners (75 vs. 52%) and in more skilled skiers compared to less skilled skiers (67 vs. 47%). No significant differences have been found with regard to gender, used type of gear, and risk taking behaviour. Thus, future helmet campaigns should also be aimed at older people, ski guest from other nations, and less skilled skiers.