Bart Nienhuis

Posturographic assessment of sitting balance recovery in the subacute phase of stroke

Although early sitting balance is a well-known predictor of functional outcome after stroke, it is still unknown which aspects of normal upright sitting balance are most sensitive to subsequent recovery. This study used an adjustable chair mounted on a force platform to assess the recovery of quiet-sitting balance in 16 patients with a first supratentorial stroke during their inpatient rehabilitation. The patients underwent three posturographic assessments at 6-week intervals from the moment of their admission, on average 5.6 weeks after stroke. Each quiet-sitting balance assessment consisted of two series of four 30-s test conditions: sitting with eyes open and closed, on both a stable and unstable (air cushion) surface. The RMS of the center-of-pressure (COP) velocities was used as the primary measure of lateral and anteroposterior balance control. It was found that, compared to 10 healthy elderly, lateral balance was more affected by stroke than balance in the anteroposterior direction, especially during visual deprivation, and most sensitive to subsequent functional changes induced by spontaneous recovery or rehabilitation. Furthermore, lateral balance control showed the strongest association with the Berg Balance Scale as a clinical measure of balance capacity. Hence, (lateral) trunk control seems to be a primary target for rehabilitation. Since an unstable support was necessary to obtain significant effects of stroke, recovery and visual deprivation, it may be important to use an unstable support during sitting balance training as well.

Clinical gait analysis in a rehabilitation context: some controversial issues

Objective: To determine the focus of clinical gait analysis in order to explain the observed mismatch between the available technology for movement analysis and the aims of clinical rehabilitation medicine. Design: Literature search using two different interactive computerized search systems. Outcome measures: The selected studies on clinical gait analysis were screened on the type of tasks they employed in the assessment of gait. The tasks were divided into impairment-orientated and disability-orientated. Results: The results indicated a dominance of simple motor tasks focusing at the level of impairments. In only 15 out of the 96 reviewed articles were tasks used that were aimed at the level of disabilities. Conclusions: A gap exists between the conceptual frameworks used in clinical rehabilitation medicine and those used in clinical movement analysis.

Dual-tasking interferes with obstacle avoidance reactions in healthy seniors.

Dual-tasking can lead to falls, as does a deterioration of obstacle avoidance (OA) skills. Hence, it is expected that a combination of both would be even more detrimental, especially when OA is time-critical. Previous studies confirmed this expectation, however, due to several limitations in their design it is yet too early to draw any definitive conclusions on the allocation of attentional resources in OA under dual-task conditions. Therefore, attentionally demanding primary and secondary tasks were used with the instruction to perform as well as possible on both tasks. Nineteen healthy senior individuals (60±4.7 years, 8 females) performed an OA task on a treadmill while walking at 3 km/h as a single task and combined with an auditory Stroop task. Biceps femoris (BF) muscle response times, OA failure rates and composite scores were used to evaluate the data. Increased OA failure rates (3%, p=0.03) and delayed BF response times (21 ms, p<0.001) were found under dual-task conditions. Composite scores were reduced during (p<0.001) and just after obstacle crossing (p=0.003). In conclusion, dual-tasking during time-critical OA affects the motor as well as the cognitive task when subjects are instructed to keep up performance on both tasks. This adds to the evidence indicating an increased risk of tripping or falling when attention is divided during walking in the presence of unexpected obstacles.

Evidence for bilaterally delayed and decreased obstacle avoidance responses while walking with a lower limb prosthesis

OBJECTIVE To examine whether the increased failure rates in obstacle avoidance of patients with lower limb amputation can be understood on the basis of increased delay and/or decreased amplitudes of obstacle avoidance responses. METHODS Subjects performed obstacle avoidance on a treadmill while EMG recordings were made of several major muscles of the leg. RESULTS It was found that subjects with a lower limb amputation have delayed responses (e.g. delays of 20 ms for the Biceps Femoris) and have decreased response amplitudes (36-41% smaller). Furthermore, such changes were observed not only on the prosthetic side, but also on the sound side. The decreased amplitudes were associated with increased failure rates in the obstacle avoidance task. CONCLUSIONS It is concluded that the bilaterally delayed and reduced responses in persons with a lower limb prosthesis reflect a basic reorganization within the central nervous system aimed at providing synchronized activity in both lower limbs, even though the peripheral deficit involves only one limb. SIGNIFICANCE The present results on obstacle avoidance responses can be used to evaluate future prosthetic training involving obstacle crossings for amputee rehabilitation.

Arm movements can increase leg muscle activity during submaximal recumbent stepping in neurologically intact individuals

Facilitation of leg muscle activity by active arm movements during locomotor tasks could be beneficial during gait rehabilitation after spinal cord injury. The present study explored the effects of arm movements on leg muscle activity during submaximal recumbent stepping. Healthy subjects exercised on a recumbent stepping machine both with and without arm movements. Activity of five leg muscles was recorded and compared for stepping with and without arm movements. To determine which arm movements are optimal for leg muscle facilitation, subjects were instructed to step with 1) mechanically coupled vs. decoupled arm and leg movements, 2) synchronous vs. asynchronous arm movements, and 3) at 50 vs. 70 RPM. Leg muscle activity was increased by active arm movements in all muscles, except the vastus lateralis muscle. Activity of other extensors (soleus, medial gastrocnemius, and biceps femoris) was primarily increased during the extension phase, whereas activity of flexors (tibialis anterior) was also increased during the flexion phase. Facilitation was more or less consistent for both frequencies and for synchronous and asynchronous movements. For coupled arm movements, facilitation tended to be diminished or absent. The observed facilitation in the present study is probably of neuromuscular rather than biomechanical origin, since the arms are probably hardly involved in postural control or weight-bearing during recumbent stepping. Further studies in patients should explore the possibility to integrate neuromuscular facilitation in rehabilitation programs.

The assessment of motor recovery: A new look at an old problem

After nervous system damage, functional recovery usually occurs. It is of great clinical importance to follow the course of recovery and, when possible, predict the extent. This measurement and prediction of recovery is one of the main challenges facing clinicians today. The majority of assessment procedures currently employed, however, are impairment-oriented; that is, these procedures are oriented primarily at the disease or organ level. Until now, few procedures have been available that focus at the disability or behavioural level. This lack of disability-oriented assessment procedures hinders the development and evaluation of rehabilitation programmes, as impairment-oriented assessment scores have little relevance for the prediction of daily functioning. In this paper, a preliminary task-set is presented that may function as an impetus for the development of novel disability-oriented assessment procedures in neurological rehabilitation. Motor behaviour is not assessed in vacuo, rather as the end result of a continuous interaction between motor, sensory and cognitive processes. With this task set, it is possible to evaluate the changing influence of sensory and cognitive factors on the quality of motor performance over time. These changes, it is argued, are a crucial component of functional recovery.

Plantar pressure with and without custom insoles in patients with common foot complaints.

Background: Although many patients with foot complaints receive customized insoles, the choice for an insole design can vary largely among foot experts. To investigate the variety of insole designs used in daily practice, the insole design and its effect on plantar pressure distribution were investigated in a large group of patients. Materials and Methods: Mean, peak, and pressure-time-integral per sensor for 204 subjects with common foot complaints for walking with and without insoles was measured with the footscan® insole system (RSscan International). Each insole was scanned twice (precision3D), after which the insole height along the longitudinal and transversal cross section was calculated. Subjects were assigned to subgroups based on complaint and medial arch height. Data were analyzed for the total group and for the separate subgroups (forefoot or heel pain group and flat, normal or high medial arch group). Results: The mean pressure significantly decreased under the metatarsal heads II-V and the calcaneus and significantly increased under the metatarsal bones and the lateral foot (p < 0.0045) due to the insoles. However, similar redistribution patterns were found for the different foot complaints and arch heights. There was a slight difference in insole design between the subgroups; the heel cup was significantly higher and the midfoot support lower for the heel pain group compared to the forefoot pain group. The midfoot support was lowest in the flat arch group compared to the high and normal arch group (p < 0.05). Conclusion: Although the insole shape was specific for the kind of foot complaint and arch height, the differences in shape were very small and the plantar pressure redistribution was similar for all groups. Clinical Relevance: This study indicates that it might be sufficient to create basic insoles for particular patient groups.

Are older adults more dependent on visual information in regulating self-motion than younger adults?

Older adults look at the ground more while they are walking than younger adults do. In the present study, the effect of blocking that exproprioceptive visual information on the walking pattern of older adults was investigated. The first 0.75 m of the floor in front of healthy young adults (n = 10, mean age = 26.0 years) and 2 groups of older adults (n = 10, mean age 65.7 years; and n = 9, mean age = 75.9 years) was occluded. The dependent variables were step velocity, step length, and step frequency. The effect of the manipulation on those kinematic variables increased with age. The older adults had a significant increase in velocity and step length. The possible use of optic flow information from the ground to regulate the velocity of self-motion is discussed.

Sensitivity of the OLGA and VCM models to erroneous marker placement: Effects on 3D-gait kinematics

Gait data need to be reliable to be valuable for clinical decision-making. To reduce the impact of marker placement errors, the Optimized Lower Limb Gait Analysis (OLGA) model was developed. The purpose of this study was to assess the sensitivity of the kinematic gait data to a standard marker displacement of the OLGA model compared with the standard Vicon Clinical Manager (VCM) model and to determine whether OLGA reduces the errors due to the most critical marker displacements. Healthy adults performed six gait sessions. The first session was a standard gait session. For the following sessions, 10mm marker displacements were applied. Kinematic data were collected for both models. The root mean squares of the differences (RMS) were calculated for the kinematics of the displacement sessions with respect to the first session. The results showed that the RMS values were generally larger than the stride-to-stride variation except for the pelvic kinematics. For the ankle, knee and hip kinematics, OLGA significantly reduced the averaged RMS values for most planes. The shank, knee and thigh anterior-posterior marker displacements resulted in RMS values exceeding 10°. OLGA reduced the errors due to the knee and thigh marker displacements, but not the errors due to the ankle marker displacements. In conclusion, OLGA reduces the effect of erroneous marker placement, but does not fully compensate all effects, indicating that accurate marker placement remains of crucial importance for adequate 3D-gait analysis and subsequent clinical decision-making.

The effect of a non-steroidal anti-inflammatory drug on two important predictors for accidental falls: Postural balance and manual reaction time. A randomized, controlled pilot study

Accidental falls in older individuals are a major health and research topic. Increased reaction time and impaired postural balance have been determined as reliable predictors for those at risk of falling and are important functions of the central nervous system (CNS). An essential risk factor for falls is medication exposure. Amongst the medications related to accidental falls are the non-steroidal anti-inflammatory drugs (NSAIDs). About 1-10% of all users experience CNS side effects. These side effects, such as dizziness, headaches, drowsiness, mood alteration, and confusion, seem to be more common during treatment with indomethacin. Hence, it is possible that maintenance of (static) postural balance and swift reactions to stimuli are affected by exposure to NSAIDs, indomethacin in particular, consequently putting older individuals at a greater risk for accidental falls. The present study investigated the effect of a high indomethacin dose in healthy middle-aged individuals on two important predictors of falls: postural balance and reaction time. Twenty-two healthy middle-aged individuals (59.5 ± 4.7 years) participated in this double-blind, placebo-controlled, randomized crossover trial. Three measurements were conducted with a week interval each. A measurement consisted of postural balance as a single task and while concurrently performing a secondary cognitive task and reaction time tasks. For the first measurement indomethacin 75 mg (slow-release) or a visually identical placebo was randomly assigned. In total, five capsules were taken orally in the 2.5 days preceding assessment. The second measurement was without intervention, for the final one the first placebo group got indomethacin and vice versa. Repeated measures GLM revealed no significant differences between indomethacin, placebo, and baseline in any of the balance tasks. No differences in postural balance were found between the single and dual task conditions, or on the performance of the dual task itself. Similarly, no differences were found on the manual reaction time tasks. The present study showed that a high indomethacin dose does not negatively affect postural balance and manual reaction time in this healthy middle-aged population. Although the relatively small and young sample limits the direct ability to generalize the results to a population at risk of falling, the results indicate that indomethacin alone is not likely to increase fall risk, as far as this risk is related to above mentioned important functions of the CNS, and not affected by comorbidities.