Tania Lam

A systematic review of functional ambulation outcome measures in spinal cord injury

Study design:Systematic review.Objectives:To systematically review the psychometric properties of outcome measures used to assess ambulation in people with spinal cord injury (SCI).Setting:Vancouver, BC, Canada.Methods:A keyword literature search of original articles that evaluated the psychometric properties of ambulation outcome measures in the SCI population was conducted using multiple databases. Multidimensional scales of function were included if specific data were available on ambulation-related subscales. Reliability, validity and responsiveness values were extracted and conclusions drawn about the psychometric quality of each measure.Results:Seven outcome measures were identified and were broadly categorized into timed and categorical measures of ambulation. Timed measures included timed walking tests that showed excellent reliability, construct validity and responsiveness to change. The psychometric properties of the categorical scales were more variable, but those that were developed specifically for the SCI population had excellent reliability and validity. Categorical scales also exhibited some floor or ceiling effects.Conclusion:Excellent tools are available for measuring functional ambulation capacity. Further work is required to develop and evaluate outcome measures to include environmental factors that contribute to the ability to achieve safe, functional ambulation in everyday settings.Sponsorship:Rick Hansen Man-in-Motion Foundation and Ontario Neurotrauma Fund.

A Systematic Review of the Effects of Pharmacological Agents on Walking Function in People with Spinal Cord Injury

Studies of spinalized animals indicate that some pharmacological agents may act on receptors in the spinal cord, helping to produce coordinated locomotor movement. Other drugs may help to ameliorate the neuropathological changes resulting from spinal cord injury (SCI), such as spasticity or demyelination, to improve walking. The purpose of this study was to systematically review the effects of pharmacological agents on gait in people with SCI. A keyword literature search of articles that evaluated the effects of drugs on walking after SCI was performed using the databases MEDLINE/PubMed, CINAHL, EMBASE, PsycINFO, and hand searching. Two reviewers independently evaluated each study, using the Physiotherapy Evidence Database (PEDro) tool for randomized clinical trials (RCTs), and the modified Downs & Black scale for all other studies. Results were tabulated and levels of evidence were assigned. Eleven studies met the inclusion criteria. One RCT provided Level 1 evidence that GM-1 ganglioside in combination with physical therapy improved motor scores, walking velocity, and distance better than placebo and physical therapy in persons with incomplete SCI. Multiple studies (levels of evidence 1-5) showed that clonidine and cyproheptadine may improve locomotor function and walking speed in severely impaired individuals with incomplete SCI. Gains in walking speed associated with GM-1, cyproheptadine, and clonidine are low compared to those seen with locomotor training. There was also Level 1 evidence that 4-aminopyridine and L-dopa were no better than placebo in helping to improve gait. Two Level 5 studies showed that baclofen had little to no effect on improving walking in persons with incomplete SCI. There is limited evidence that pharmacological agents tested so far would facilitate the recovery of walking after SCI. More studies are needed to better understand the effects of drugs combined with gait training on walking outcomes in people with SCI.

Locomotor adaptations and aftereffects to resistance during walking in individuals with spinal cord injury.

Muscle activity during the swing phase of walking is influenced by proprioceptive feedback pathways. Previous studies have shown that feedback and anticipatory motor commands contribute to locomotor adaptive strategies to prolonged exposure to a resistance against leg movements during walking. The purpose of this study was to determine whether people with motor-incomplete spinal cord injuries (SCI) modulate flexor muscle activity in response to different levels of resistance in a similar way as uninjured controls. A second purpose was to determine whether people with motor-incomplete SCI have the capacity to form anticipatory motor commands following exposure to resistance. Subjects walked on a treadmill with the Lokomat robotic gait orthosis. The Lokomat applied different levels of a velocity-dependent resistance, normalized to each subjects maximum voluntary contraction of the hip flexors. Each condition consisted of 20 steps against resistance followed by 20 steps without. Electromyography and kinematics of the lower limb were recorded. Although both groups responded to the resistance with an overall increase in rectus femoris activity during swing, the SCI group showed weak modulation of muscle activity to different levels of resistance. Following removal of the resistance, both groups showed aftereffects, but they were manifested differently. Controls responded to the removal of resistance with a high step, whereas the SCI subjects exhibited increased step length. The size of the aftereffect was related to the amount of added resistance. In addition, the SCI group showed a negative relationship between the size of the aftereffect and locomotor function.

Treadmill-based locomotor training with leg weights to enhance functional ambulation in people with chronic stroke: a pilot study.

Background and Purpose: Novel locomotor training strategies for individuals with disorders of the central nervous system have been associated with improved locomotor function. The purpose of this study was to investigate the effects of treadmill-based locomotor training combined with leg weights on functional ambulation in individuals with chronic stroke. We assessed functional ambulation and muscle activity in ambulatory individuals with chronic stroke. Methods: We used a pre/posttest design. Six individuals with chronic stroke who were community ambulators were recruited. Participants underwent a 30-minute treadmill-based locomotor training sessions three times per week for four to 12 weeks. The training program involved treadmill walking for 30 minutes with partial body weight support as needed. Leg weights, equivalent to 5% of body weight, were affixed around the paretic leg. Outcome measures consisted of the 10-m walk test, the modified Emory Functional Ambulation Profile, and temporal gait parameters. Results: Improvements were observed in functional ambulation measures, particularly the stairs subscore of the modified Emory Functional Ambulation Profile. Participants also exhibited an increase in the proportion of time the paretic leg spent in swing. No significant improvements were observed in the 10-m walk test. Conclusions: This pilot study demonstrates that the combination of leg weights and treadmill training is a feasible approach, that is well tolerated by participants. This approach may have the potential to improve some aspects of functional ambulation and the performance of activities requiring hip and knee flexion.

Using Robot-Applied Resistance to Augment Body-Weight–Supported Treadmill Training in an Individual With Incomplete Spinal Cord Injury

Background and Purpose The efficacy of task-specific gait training for people with spinal cord injury (SCI) is premised on evidence that the provision of gait-related afferent feedback is key for the recovery of stepping movements. Recent findings have shown that sensory feedback from flexor muscle afferents can facilitate flexor muscle activity during the swing phase of walking. This case report was undertaken to determine the feasibility of using robot-applied forces to resist leg movements during body-weight–supported treadmill training (BWSTT) and to measure its effect on gait and other health-related outcomes. Case Description The patient described in this case report was a 43-year-old man with a T11 incomplete chronic SCI. He underwent 36 sessions of BWSTT using a robotic gait orthosis to provide forces that resist hip and knee flexion. Outcomes Tolerance to the training program was monitored using the Borg CR10 scale and heart rate and blood pressure changes during each training session. Outcome measures (ie, 10-Meter Walk Test, Six-Minute Walk Test, modified Emory Functional Ambulation Profile [mEFAP], Activities-specific Balance Confidence Scale, and Canadian Occupational Performance Measure) were completed and kinematic parameters of gait, lower-extremity muscle strength (force-generating capacity), lower-limb girth, and tolerance to orthostatic stress were measured before and after the training program. Discussion The patient could tolerate the training. Overground walking speed, endurance, and performance on all subtasks of the mEFAP improved and were accompanied by increased lower-limb joint flexion and toe clearance during gait. The patients ambulatory self-confidence and self-perceived performance in walking also improved. These findings suggest that this new approach to BWSTT is a feasible and potentially effective therapy for improving skilled overground walking performance.

Turning capacity in ambulatory individuals poststroke.

Lam T, Luttmann K: Turning capacity in ambulatory individuals poststroke. Am J Phys Med Rehabil 2009;88:873–886. Objective: To compare turning capacity in ambulatory individuals poststroke with controls and to determine the relationship between turning capacity, functional ambulation, motor recovery, and gait asymmetry. Design: This was a cross-sectional experimental study using community-dwelling, ambulatory chronic stroke survivors (n = 13) and age-matched able-bodied controls (n = 10). Neural impairment resulting from stroke was assessed by the Chedoke-McMaster Stroke Assessment for the leg and foot. Turning capacity was measured by the number of steps and time required to complete 45-, 90-, and 180-degree turns. Functional ambulation and balance were assessed by the 10-m walk test, Timed Up and Go test, Emory Functional Ambulation Profile, and the Berg Balance Scale. Gait asymmetry was measured by single-support gait asymmetry. Results: Participants with stroke required a significantly greater number of steps and longer time to complete the 45-, 90-, and 180-degree turns compared with controls. The average number of steps or time required to turn 45, 90, or 180 degrees was not different whether the turns were made to the paretic side or to the nonparetic side in the participants with stroke or whether turns were made toward the dominant or nondominant side in the controls. In the participants with stroke, turning capacity for 180-degree turns to both the paretic and nonparetic side was significantly correlated to the 10-m walk test, Timed Up and Go test, Emory Functional Ambulation Profile, and Berg Balance Scale. Single-support gait asymmetry was also significantly correlated to 180-degree turning capacity. Conclusions: The results of this study demonstrate that turning capacity poststroke is compromised, as exemplified by the greater number of steps and time required to complete turns at each angle tested. Turning capacity was related to the degree of gait asymmetry and the level of functional ambulation. Further work is needed to elucidate the contribution of biomechanical and neurologic parameters of hemiplegic gait impairments to turning capacity.

Reliability and validity of using the Lokomat to assess lower limb joint position sense in people with incomplete spinal cord injury

BackgroundProprioceptive sense (knowing where the limbs are in space) is critical for motor control during posture and walking, and is often compromised after spinal cord injury (SCI). The purpose of this study was to assess the reliability and validity of using the Lokomat, a robotic exoskeleton used for gait rehabilitation, to quantitatively measure static position sense of the legs in persons with incomplete SCI.MethodsWe used the Lokomat and custom software to assess static position sense in 23 able-bodied (AB) subjects and 23 persons with incomplete SCI (American Spinal Injury Association Impairment Scale level B, C or D). The subject’s leg was placed into a target position (joint angle) at either the hip or knee and asked to memorize that position. The Lokomat then moved the test joint to a “distractor” position. The subject then used a joystick controller to bring the joint back into the memorized target position. The final joint angle was compared to the target angle and the absolute difference was recorded as an error. All movements were passive. Known-groups validity was determined by the ability of the measure to discriminate between able-bodied and SCI subjects. To evaluate test-retest reliability, subjects were tested twice and intra-class correlation coefficients comparing errors from the two sessions were calculated. We also performed a traditional clinical test of proprioception in subjects with SCI and compared these scores to the robotic assessment.ResultsThe robot-based assessment test was reliable at the hip and knee in persons with SCI (P ≤ 0.001). Hip and knee angle errors in subjects with SCI were significantly greater (P ≤ 0.001) and more variable (P < 0.0001) than in AB subjects. Error scores were significantly correlated to clinical measure of joint position sense (r ≥ 0.507, P ≤ 0.013).ConclusionsThis study shows that the Lokomat may be used as a reliable and valid clinical measurement tool for assessing joint position sense in persons with incomplete SCI. Quantitative assessments of proprioceptive deficits after neurological injury will help in understanding its role in the recovery of skilled walking and in the development of interventions to aid in the return to safe community ambulation.

Short-term Cortical Plasticity Associated With Feedback-Error Learning After Locomotor Training in a Patient With Incomplete Spinal Cord Injury

Background and Purpose For rehabilitation strategies to be effective, training should be based on principles of motor learning, such as feedback-error learning, that facilitate adaptive processes in the nervous system by inducing errors and recalibration of sensory and motor systems. This case report suggests that locomotor resistance training can enhance somatosensory and corticospinal excitability and modulate resting-state brain functional connectivity in a patient with motor-incomplete spinal cord injury (SCI). Case Description The short-term cortical plasticity of a 31-year-old man who had sustained an incomplete SCI 9.5 years previously was explored in response to body-weight–supported treadmill training with velocity-dependent resistance applied with a robotic gait orthosis. The following neurophysiological and neuroimaging measures were recorded before and after training. Sensory evoked potentials were elicited by electrical stimulation of the tibial nerve and recorded from the somatosensory cortex. Motor evoked potentials were generated with transcranial magnetic stimulation applied over the tibialis anterior muscle representation in the primary motor cortex. Resting-state functional magnetic resonance imaging was performed to evaluate short-term changes in patterns of brain activity associated with locomotor training. Outcomes Somatosensory excitability and corticospinal excitability were observed to increase after locomotor resistance training. Motor evoked potentials increased (particularly at higher stimulation intensities), and seed-based resting-state functional magnetic resonance imaging analyses revealed increased functional connectivity strength in the motor cortex associated with the less affected side after training. Discussion The observations suggest evidence of short-term cortical plasticity in 3 complementary neurophysiological measures after one session of locomotor resistance training. Future investigation in a sample of people with incomplete SCI will enhance the understanding of potential neural mechanisms underlying the behavioral response to locomotor resistance training.

Limited interlimb transfer of locomotor adaptations to a velocity-dependent force field during unipedal walking.

Several studies have demonstrated that motor adaptations to a novel task environment can be transferred between limbs. Such interlimb transfer of motor commands is consistent with the notion of centrally driven strategies that can be generalized across different frames of reference. So far, studies of interlimb transfer of locomotor adaptations have yielded disparate results. Here we sought to determine whether locomotor adaptations in one (trained) leg show transfer to the other (test) leg during a unipedal walking task. We hypothesized that adaptation in the test leg to a velocity-dependent force field previously experienced by the trained leg will be faster, as revealed by faster recovery of kinematic errors and earlier onset of aftereffects. Twenty able-bodied adults walked unipedally in the Lokomat robotic gait orthosis, which applied velocity-dependent resistance to the legs. The amount of resistance was scaled to 10% of each individuals maximum voluntary contraction of the hip flexors. Electromyography and kinematics of the lower limb were recorded. All subjects were right-leg dominant and were tested for transfer of motor adaptations from the right leg to the left leg. Catch trials, consisting of unexpected removal of resistance, were presented after the first step with resistance and after a period of adaptation to test for aftereffects. We found no significant differences in the sizes of the aftereffects between the two legs, except for peak hip flexion during swing, or in the rate at which peak hip flexion adapted during steps against resistance between the two legs. Our results indicate that interlimb transfer of these types of locomotor adaptation is not a robust phenomenon. These findings add to our current understanding of motor adaptations and provide further evidence that generalization of adaptations may be dependent on the movement task.

Quantification of Lower Extremity Kinesthesia Deficits Using a Robotic Exoskeleton in People With a Spinal Cord Injury

Background. Our ability to sense movement is essential for motor control; however, the impact of kinesthesia deficits on functional recovery is not well monitored in the spinal cord injury (SCI) population. One problem is the lack of accurate and reliable tools to measure kinesthesia. Objective. The purpose of this study was to establish the validity and reliability of a quantitative robotic assessment tool to measure lower limb kinesthesia in people with SCI. Methods. Seventeen individuals with an incomplete SCI and 17 age-matched controls completed 2 robotic-based assessments of lower limb kinesthesia sense, separated by at least 1 week. The Lokomat, a lower limb robotic exoskeleton, was used to quantify the movement detection score bilaterally for the hip and knee joints. Four passive movement speeds (0.5, 1.0, 2.0, and 4.0 deg/s) were applied in both flexion and extension directions. Participants responded via pressing a joystick button when movement was felt. Results. The movement detection score was significantly greater in people with SCI compared with the control group, particularly at the slowest movement speed. The difference between groups was more pronounced among those classified as ASIA (American Spinal Injury Association) Impairment Scale B. Our measure showed high test-retest reliability and good internal consistency for the hip and knee joints. Conclusions. Our findings demonstrated that lower limb kinesthesia deficits are common in the SCI population and highlighted the importance of valid and reliable tools to monitor sensory function. Future studies need to examine changes in sensory function in response to therapy.