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Accidental falls, especially those occurring in the elderly, are a major health and research topic nowadays. Besides environmental hazards and the physiological changes associated with aging, medication use (e.g. benzodiazepines, vasodilators and antidepressants) and polypharmacy are significant risk factors for falling as well. Exposure to NSAIDs has been associated with accidental falls too, although information on this area is less consistent. Therefore, the main goal of this review is to provide an updated overview of all the evidence published on the risk of falling due to NSAID use thus far. A systematic literature search for material published between 1966 and March 2008 in PubMed, EMBASE, the Cochrane Database of Systematic Reviews, Exerpta Medica, Current Contents and Science Citation Index was combined with a check of the reference lists of all the retrieved articles. Validity and data extraction of the eligible articles was assessed by adapted criteria, based on checklists that were originally developed to assess case-control or cohort studies. From the 16 selected articles, two studies were rejected because of clustering of data and one article was excluded because it contained the same data as that in one of the included articles. None of the articles retrieved included a randomized controlled trial. The remaining 13 studies all showed some lack in completeness of their statistical methods, and much variation in reporting of effects. The overall mean age was high in the study populations, leaving the results to be poorly generalizable to a larger population and other age categories. Despite these imperfections, all studies showed an increased risk of falling due to NSAID use (four significant, nine non-significant), and a tendency towards an increased fall risk with NSAID exposure could be noted. The results shown in the present review suggest that an increased risk for accidental falls is probable when elderly individuals are exposed to NSAIDs. The studies with the highest quality show that the community-dwelling elderly in particular appear to be at higher risk. This review can serve as a comprehensive overview of the published evidence on fall risk of elderly individuals attributable to the use of NSAIDs, and as an inducement for future research.

van den Hurk P, Mars RB, van Elswijk G, Hegeman J, Pasman JW, Bloem BR, Toni I. Online maintenance of sensory and motor representations: effects on corticospinal excitability. J Neurophysiol 97: [1642][1643][1644][1645][1646][1647][1648] 2007. First published November 29, 2006; doi:10.1152/jn.01005.2006. Flexible behavior requires the ability to delay a response until it is appropriate. This can be achieved by holding either a sensory or a motor representation online. Here we assess whether maintenance of sensory or motor material drives the motor system to different functional states, as indexed by alterations of corticospinal excitability. We used singlepulse TMS to measure corticospinal excitability evoked during the delay period of a novel paradigm in which task contingencies, rather than explicit verbal instructions, induced participants to use either sensory or motor codes to solve a delay-nonmatch-to-sample (DNMS) task. This approach allowed us to probe the state of the motor system while the participants were retaining either sensory or motor codes to cross the delay period, rather than the control of short-term storage driven by verbal instructions. When participants could prepare the movement in advance (preparation trials), the excitability of the motor cortex contralateral to the moving hand increased, whereas the excitability of the ipsilateral motor cortex decreased. The increase in excitability was confined to the prime mover, whereas the decrease in excitability extended to cortical territories controlling muscles unrelated to the response. Crucially, these changes in excitability were evoked only during preparation trials and not during trials in which subjects needed to maintain sensory items online (memory trials). We infer that short-term storage of sensory information and preparation of motor responses have differential and specific access to the output stage of the motor system. I N T R O D U C T I O NWe can cross time intervals interposed between stimuli and responses either by remembering events or by anticipating them (Rainer et al. 1999). Both strategies require the maintenance of task-relevant information in the brain, although the type of information maintained online might be different. When identification of a sensory stimulus and action selection are separated in time, a sensory representation of the stimuli needs to be held online (working memory; Goldman-Rakic 1987;Miyake and Shah 1999). Conversely, when action selection and movement execution are separated in time, subjects can prepare a specific response in advance (motor preparation;Tanji and Evarts 1976). Recent studies suggest that short-term storage of sensory information and movement preparation can be seen as conceptually and neuronally distinct phenomena (Curtis et al. 2004; Di Pellegrino and Wise 1996;Fuster 2000;Mars et al. 2005;Rowe et al. 2000). However, this issue remains controversial because other authors have argued that the same physiological mechanisms might support both motor preparation and working memory (C...

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The aim of the studies reported here was to quantify changes in balance control for stance and gait tasks with age and to pinpoint possible advantages and difficulties in using these tasks and measures derived from them to identify pathological balance control in patients. Some 470 normal subjects in the age range 6 to 82 were examined for a battery of 14 stance and gait tasks. During the tasks, angular velocity transducers mounted at lumbar 1–3 measured pitch and roll angular velocities of the body. A combination of outcome measures from several tasks was used to create an overall balance control index. Three types of sensory analyses on pitch angle and velocity amplitudes for stance trials were used to quantify possible changes in the contributions of visual, somatosensory and vestibular inputs to balance control with age for 2-legged stance tasks. Correlation analysis on task variables was used to determine the relationship of subjects' age and height on outcome measures. Outcome measures showed a characteristic "L" or "U" shaped profile with a rapid decrease in values between 7 and 25 years of age, a plateau until 55 then a gradual increase with age after 55 years of age for most stance and gait tasks. The sensory analysis technique using differences between stance tests indicated that visual contributions to balance control continuously increased with age between the ages of 15 and 80, and vestibular and lower leg somatosensory contributions remain relatively constant with age. Sensory analysis calculated as commonly-used quotients of outcome measures revealed large variance across all ages, asymmetric distributions, and no clear trends in sensory contributions to stance with age. A third technique based on a discriminant function analysis using measures from model patient populations indicated that proprioceptive but not vestibular contributions first increased with age and then decreased after 55 years of age. Correlations of outcome measures with age and height indicated that both contributed equally to changes in outcome measures between the ages of 7 and 25, otherwise height had no effect. We conclude that both stance and gait tasks should be selected for identifying changes in balance control from that of healthy persons with a preference for gait tasks as these show less variation with age. Because of the large increases in variance in the elderly and those younger than 20 years, appropriate age-matched reference values should be employed to ascertain if trunk sway is out of normal ranges.

Knee rigidity due to aging or disease is associated with falls. A causal relationship between instability and knee rigidity has not been established. Here, we examined whether insufficient knee movement due to knee rigidity could underlie poor balance control in patients. We addressed this by examining the effect of artificially "locking" the knees on balance control in 18 healthy subjects, tested with and without individually fitted knee casts on both legs. Subjects were exposed to sudden rotations of a support surface in six different directions. The primary outcome measure was body centre of mass (COM) movement, and secondary outcome measures included biomechanical responses of the legs, pelvis and trunk. Knee casts caused increased backward COM movement for backward perturbations and decreased vertical COM movement for forward perturbations, and caused little change in lateral COM movement. At the ankles, dorsiflexion was reduced for backward perturbations. With knee casts, there was less uphill hip flexion and more downhill hip flexion. A major difference with knee casts was a reversed pelvis pitch movement and an increased forward trunk motion. These alterations in pitch movement strategies and COM displacements were similar to those we have observed previously in patients with knee rigidity, specifically those with spinocerebellar ataxia (SCA). Pelvis roll and uphill arm abduction were also increased with the casts. This roll movement strategy and minor changes in lateral COM movement were not similar to observations in patients. We conclude that artificial knee rigidity increases instability, as reflected by greater posterior COM displacement following support surface tilts. Healthy controls with knee casts used a pitch movement strategy similar to that of SCA patients to offset their lack of knee movement in regaining balance following multidirectional perturbations. This similarity suggests that reduced knee movements due to knee rigidity may contribute to sagittal plane postural instability in SCA patients and possibly in other patient groups. However in the roll plane, healthy controls rapidly compensate by adjusting arm movements and hip flexion to offset the effects of knee rigidity.

BackgroundAlcohol is a commonly used social drug and driving under influence is a well-established risk factor for traffic accidents[1]. To improve road safety, legal limits are set for blood alcohol concentration (BAC) and driving, usually at 0.05% (most European countries) or 0.08% (most US states, Canada and UK). In contrast, for walking there are no legal limits, yet there are numerous accounts of people stumbling and falling after drinking. Alcohol, even at these low concentrations, affects brain function and increases fall risk. An increased fall risk has been associated with impaired obstacle avoidance skills. Low level BACs are likely to affect obstacle avoidance reactions during gait, since the brain areas that are presumably involved in these reactions have been shown to be influenced by alcohol. Therefore we investigated the effect of low to moderate alcohol consumption on such reactions.Thirteen healthy senior individuals (mean(SD) age: 61.5(4.4) years, 9 male) were subjected to an obstacle avoidance task on a treadmill after low alcohol consumption. Fast stepping adjustments were required to successfully avoid suddenly appearing obstacles. Response times and amplitudes of the m. biceps femoris, a prime mover, as well as avoidance failure rates were assessed.FindingsAfter the first alcoholic drink, 12 of the 13 participants already had slower responses. Without exception, all participants' biceps femoris response times were delayed after the final alcoholic drink (avg ± sd:180 ± 20 ms; p < 0.001) compared to when participants were sober (156 ± 16 ms). Biceps femoris response times were significantly delayed from BACs of 0.035% onwards and were strongly associated with increasing levels of BAC (r = 0.6; p < 0.001). These delays had important behavioural consequences. Chances of hitting the obstacle were doubled with increased BACs.ConclusionsThe present results clearly show that even with BACs considered to be safe for driving, obstacle avoidance reactions are inadequate, late, and too small. This is likely to contribute to an increased fall risk. Therefore we suggest that many of the alcohol-related falls are the result of the disruptive effects of alcohol on the online corrections of the ongoing gait pattern when walking under challenging conditions.

Objective: We investigated whether long-term bilateral vestibular loss subjects could combine auditory biofeedback of trunk sway with their remaining natural sensory inputs on balance to provide an improved control of trunk sway. A successful integration of natural and artificial signals would provide a basis for a balance prosthesis. Methods: Trunk sway of 6 bilateral peripheral vestibular loss subjects (BVL) was recorded using either angular position- or velocity-based auditory feedback or no feedback during stance and gait tasks. Roll and pitch trunk movements were recorded with angular velocity transducers mounted just above the waist and feedback without a delay to 4 loudspeakers placed at the left, right, front and rear borders of the 5 m long by 4 m wide test environment. The two types of auditory feedback or no feedback were provided to the subjects in random order. In the feedback modes, sway greater than a preset angle (ca. 0.5 deg) or velocity (ca. 3 deg/s) thresholds caused a tone to be emitted from the speaker towards which the subject moved. The tone volume increased with increasing angle or angular velocity amplitude. Results: For all stance tasks BVL subjects without auditory feedback had a significantly different balance control with respect to that of normal controls. BVL sway values eyes open on a normal surface were reduced with auditory feedback with the greatest reductions in the roll plane. Specifically for the task of standing on 1 leg eyes open with position-auditory- feedback, amplitudes of pitch and roll angles and angular velocities were indistinguishable from those of normal controls. Sway during stance tasks on foam with eyes closed showed no improvement with feedback, remaining greater than normal. For some gait tasks there was a decrease in trunk sway with velocity feedback. Conclusions: These initial results indicate that subjects with vestibular loss could incorporate the auditory prosthetic sensory information into their balance commands, particularly in the roll plane if the balance task is performed with eyes open. Position information appears more useful than velocity information in reducing trunk sway during stance tasks. Future work will need to determine the effect of a training time on the improvement in balance control using such a prosthetic device and the ideal position and velocity auditory feedback combination.