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.

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.

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.

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.

Effects of short-term acclimatization to altitude (3200 m) on aerobic and anaerobic exercise performance

Aerobic exercise performance decreases upon ascent to altitude whereas anaerobic performance remains unchanged. Although the effects of 1 - 3 wk of altitude acclimatization on both aerobic and anaerobic exercise performance have been well studied, the effects of short-term altitude acclimatization (i.e., 45 h) on these parameters have not been well defined. Therefore, both aerobic and anaerobic exercise performance was evaluated in five healthy men (51.4 +/- 7.7 years, 175 +/- 4.2 cm, and 73.8 +/- 6.1 kg) at low altitude (LA, 600 m), upon acute exposure (approximately 1 - 3 h) to 3200 m (HA1) and on the third day of altitude exposure (HA3, 3200 m). Subjects performed three consecutive exercise tests, separated by approximately 1 - 3 h of rest, of various durations (i.e., 30 s, 5 min, and 50 min) on a cycle ergometer in each environmental condition. Anaerobic cycling performance (i. e., 30 s) was the same at LA, HA1, and HA3. Aerobic cycling performance (i. e., 5 min and 50 min) was reduced by 12.0 and 11.3 %, respectively, upon acute exposure to altitude. There was no change in the 5-min cycling performance but the 50-min cycling performance improved by 5.7 % from HA1 to HA3 which implies a 50 % recovery of the initial loss. These findings are important for individuals going to high altitude for work, for athletic competition, or recreation.

Effects of aspirin during exercise on the incidence of high-altitude headache: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the efficacy of aspirin for headache when exercising during acute high-altitude exposure.

BACKGROUND

Aspirin effectively prevents headache when mostly resting during acute high-altitude exposure. However, the majority of individuals exposed to high altitude perform mountaineering activities, which might trigger headache.

DESIGN

Randomized, double-blind, placebo-controlled trial.

METHODS

Thirty-one healthy volunteers (20 men, 11 women; aged 22 to 59 years) were transported to an altitude of about 3000 meters and climbed up to 3800 meters. They then descended to a mountain hut at 3480 meters and spent 2 nights there. Tablets (placebo or 320 mg aspirin) were administered three times at 4-hour intervals, beginning 2 hours before arrival at high altitude. Headache scoring and measurements of heart rate, blood pressure, and arterial oxygen saturation were performed.

RESULTS

Ninety-three percent (14 of 15) of the placebo group and 56% (9 of 16) of the aspirin group developed headache when mountaineering activities were performed during acute exposure to high altitude (P<.05). Five hours after arrival at high altitude, mean resting oxygen saturation was 86.1% +/- 2.1% with aspirin and 85.7 % +/- 2.8% with placebo (P =.66). However, subjects in the aspirin group developed headache at saturation values less than or equal to 86%, while those in the placebo group developed headache at saturation values less than 90%.

CONCLUSIONS

Although the prophylactic intake of about 1 gram of aspirin reduced the headache incidence when exercising during acute high-altitude exposure, the incidence of headache was higher than previously shown for resting conditions. Aspirin resulted in tolerance to lower arterial oxygen saturation without development of headache; exercise had the opposite effect.

Cardiopulmonary and metabolic responses in healthy elderly humans during a 1-week hiking programme at high altitude

Worldwide there are approximately 100 million visitors to high altitude annually and about 15% of those are elderly. Nevertheless, basic information on the cardiopulmonary and metabolic responses to physical activity at high altitude in the elderly is scarce. Therefore, we studied 20 voluntary healthy elderly subjects (55-77 years) who were randomly assigned to a low- (600 m) or a high altitude (2,000 m) group. Both groups increased the duration of their daily hiking from 2.5 to 5 h during a period of 1 week. Pre- and post-hiking cardiopulmonary variables at rest were measured daily. Exercise tests (3 min step test) were performed on days 1, 4 and 7. Of the morning values at rest, only arterial oxygen saturation (SaO2) had decreased after the 1st night at high altitude. After hiking however, SaO2 was diminished on all days at high altitude. Post-hiking heart rates increased from baseline on days 1 and 2 in the low- and on days 1-5 in the high-altitude group. Exercising SaO2 (%) in the three tests was decreased [84.9 (SD 2.8), 88.1 (SD 2.1), 87.2 (SD 2.3)] compared to baseline [93.2 (SD 2.0); P < 0.05] and blood lactate concentrations were increased [3.1 (SD 0.7), 3.4 (SD 0.3), 3.3 (SD 0.2)] compared to baseline [2.7 (SD 0.6); P < 0.05] in all tests at high altitude. The 1-week hiking programme was well tolerated by the healthy elderly at both low and high altitudes. Ventilatory adaptation to high altitude in the elderly seemed to have been completed within the first 2 days during the measurements at rest. However, cardiopulmonary and metabolic responses to exercise were increased and recovery from exercise was delayed during the 1-week hiking programme at high altitude. Heart rate and SaO2 measurements are considered to be highly sensitive in estimating the state of acclimatisation and for monitoring exercise intensity and duration at high altitude.

[Effect of ski tapering on turning radius and stress]

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.

Benefits of training at moderate altitude versus sea level training in amateur runners

After more than 25 years of research of altitude training (AT) there is no consensus regarding either the training programme at altitude or the effects of AT on performance at sea level. Based on a review of the research work on AT, we investigated combined base training and interval training at moderate altitude and compared immediate and delayed effects on sea level performance with those following similar sea level training (SLT). The altitude group (AG, 10 male amateur runners) trained at 2315 m (natural altitude) and the sea level group (SLG, 12 male amateur runners) at 187 m. Both groups performed 7 days of base training (running on a trail) lasting between 60 and 90 min a day and 5 days of interval training (speed and hill runs) for between 10 and 45 min a day. Incremental exercise tests were performed 1 week before (t1), 3 days after (t2) and 16 days after (t3) the 12-day main training period. Within AG, exercise performance improved from t1 to t2 by 8% (P < 0.05) and from t2 to t3 by 8% (P < 0.05). Maximum oxygen uptake (VO2max) increased from t2 to t3 by 10% (P < 0.05). Within SLG exercise performance increased from t2 to t3 by 8% (P < 0.05). At t3, relative and absolute VO2max in AG were significantly higher in comparison with SLG (P = 0.005 and P = 0.046 respectively). The improved performance 3 days after AT may be explained in part by an increased oxygen uptake at submaximal exercise intensities without a change in VO2max. Further enhancement in performance 2 weeks after AT, however, seems to have been due to the clearly enhanced VO2max. Progressive cardiovascular adjustments might have contributed primarily to the time-dependent improvements observed after AT, possibly by an enhanced stroke volume overcompensating the reduced heart rates during submaximal exercise. In conclusion, our findings would suggest that training at a moderate natural altitude improves performance at sea level more than SLT. Combining base and interval training with regulation of intensity by training at constant heart rates during acclimatization at altitude would seem to be a successful training regimen for amateur runners. Most beneficial effects became apparent during the subsequent SLT around 2 weeks after return from altitude. Therefore, we are convinced that AT should be reconsidered as a potent tool for enhancing aerobic capacity, at least in non-elite athletes.

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.

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)

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.

Footprint parameters as a measure of arch height

The human foot has frequently been categorized into arch height groups based upon analysis of footprint parameters. This study investigates the relationship between directly measured arch height and many of the footprint parameters that have been assumed to represent arch height. A total of 115 male subjects were measured and footprint parameters were calculated from digitized outlines. Correlation and regression analyses were used to determine the relationship between footprint measures and arch height. It may be concluded from the results that footprint parameters proposed in the literature (arch angle, footprint index, and arch index) and two further parameters suggested in this study (arch length index and truncated arch index) are invalid as a basis for prediction or categorization of arch height. The categorization of the human foot according to the footprint measures evaluated in this paper represent no more than indices and angles of the plantar surface of the foot itself.

Consequences of 6 weeks of strength training on red cell O2 transport and iron status

Effects of endurance training on O2 transport and on iron status are well documented in the literature. Only a few data are available concerning the consequences of strenuous anaerobic muscular exercise on red cell function. This study was performed to test the influence of strength training alone on parameters of red cell O2 transport and iron status. Twelve healthy untrained males participated in a strength-training programme of 2-h sessions four times a week lasting 6 weeks. After 6 weeks a small but significant reduction of haemoglobin (Hb; -5.4 g.l-1) was found (p less than 0.05). Mean red cell volume did not change, but a pronounced decrease of mean cell Hb concentration (from 329.2 g.l-1, SE 2.5 to 309.8 g.l-1, SE 1.2; p less than 0.001) and mean corpuscular Hb (from 29.6 pg, SE 0.4 to 27.7 pg, SE 0.3; p less than 0.01) was observed. Serum ferritin decreased significantly by 35% (p less than 0.01); transferrin, serum iron and iron saturation of transferrin were unaltered. Serum haptoglobin concentration was diminished significantly by 30.5% (p less than 0.01). The reticulocyte count had already increased after 3 weeks of training (p less than 0.05) and remained elevated during the following weeks. Strength training had no significant influence on the O2 partial pressure at which Hb under standard conditions was 50% saturated, red cell 2,3-diphosphoglycerate and ATP concentration as well as on erythrocytic glutamate-oxalacetate transaminase activity. The data demonstrate that mechanical stress of red cells due to the activation of large muscle masses led to increased intravascular haemolysis, accompanied by a slightly elevated erythropoiesis, which had no detectable influence on Hb-O2 affinity. Training caused an initial depletion of body iron stores (prelatent iron deficiency). Although Hb had decreased by the end of the training phase a true "sports anaemia" could not be detected.