Neurorehabilitation and Neural Repair current issue

ASNR/WFNR News

2008-07-28

Augmenting Clinical Evaluation of Hemiparetic Arm Movement With a Laboratory-Based Quantitative Measurement of Kinematics as a Function of Limb Loading

Ellis, M. D., Sukal, T., DeMott, T., Dewald, J. P. A. — 2008-07-28

Background. Kinematic and kinetic measurements used in laboratory settings can quantify upper extremity movement impairment following stroke, but their relationship to clinical methods of evaluating movement impairment is unclear. Objective. To test whether the Arm Coordination Training 3D device (ACT^3D) could provide a repeatable quantitative measurement of range of motion during upper extremity reaching along a range of functional levels of loads on the arm and correlate with clinical assessments of arm impairment. Methods . Work area during reaching along clockwise and counterclockwise hand paths was measured under 9 limb-loading conditions ranging from no load to twice the weight of the upper extremity in 11 individuals with chronic hemiparetic stroke on 2 separate occasions. Participants were given a battery of clinical assessments that included the Fugl-Meyer Motor Assessment, Chedoke McMaster Stroke Assessment, Reaching Performance Scale, Modified Ashworth Scale, and the Stroke Impact Scale, by a physical therapist who did not know the results of the kinematic studies. Results. A reproducible testretest reduction in work area was found when participants were required to support up to and beyond the weight of their limb. Work area was correlated with most upper extremity clinical assessments, suggesting criterion validity. Conclusions . Reaching work area during various loading conditions is a robust measurement that quantifies the effect of abnormal joint torque coupling and provides useful data that can be applied in the clinical setting.

Clinical Assessment of Motor Imagery After Stroke

Malouin, F., Richards, C. L., Durand, A., Doyon, J. — 2008-07-28

Objective. The aim of this study was to investigate: (1) the effects of a stroke on motor imagery vividness as measured by the Kinesthetic and Visual Imagery Questionnaire (KVIQ-20); (2) the influence of the lesion side; and (3) the symmetry of motor imagery. Methods. Thirty-two persons who had sustained a stroke, in the right (n = 19) or left (n = 13) cerebral hemisphere, and 32 age-matched healthy persons participated. The KVIQ-20 assesses on a 5-point ordinal scale the clarity of the image (visual scale) and the intensity of the sensations (kinesthetic scale) that the subjects are able to imagine from the first-person perspective. Results. In both groups, the visual scores were higher (P = .0001) than the kinesthetic scores and there was no group difference. Likewise, visual scores remained higher than kinesthetic scores irrespective of the lesion side. The visual scores poststroke were higher (P = .001) when imagining upper limb movements on the unaffected side than those on the affected side. When focusing on the lower limb only, however, the kinesthetic scores were higher (P = .001) when imagining movements of the unaffected compared to those on the affected side. Conclusions. The vividness of motor imagery poststroke remains similar to that of age-matched healthy persons and is not affected by the side of the lesion. However, after stroke motor imagery is not symmetrical and motor imagery vividness is better when imagining movements on the unaffected than on the affected side, indicating an overestimation possibly related to a hemispheric imbalance or a recalibration of motor imagery perception.

Prevalence of Sleep Disturbance in Closed Head Injury Patients in a Rehabilitation Unit

2008-07-28

Traumatic brain injury (TBI) is a leading cause of disability in young people in the United States. Disorders of arousal and attention are common in closed head injury (CHI). Daytime drowsiness impairs participation in rehabilitation, whereas nighttime wakefulness leads to falls and behavioral disturbances. Sleep disturbances in TBI reported in the literature have included excessive daytime somnolence, sleep phase cycle disturbance, narcolepsy, and sleep apnea. Although well known to the clinician treating these patients, the extent and prevalence of disrupted sleep in patients in an acute inpatient rehabilitation unit has not been described. Objective. To determine the prevalence of sleep wake cycle disturbance (SWCD) in patients with CHI in a TBI rehabilitation unit. Design. Prospective observational. Setting. Inpatient specialized brain injury rehabilitation unit. Patients. Thirty-one consecutive admissions to a brain injury rehabilitation unit with the diagnosis of CHI. Results. Twenty-one patients (68%) had aberrations of nighttime sleep. There was no significant difference in Glasgow Coma Score on admission to trauma nor was there any significant difference in age between the affected and unaffected groups. Patients with SWCD had longer stays in both the trauma center (P < .003) and the rehabilitation center (P < .03). Conclusions. There is a high prevalence of SWCD in CHI patients admitted to a brain injury rehabilitation unit. Patients with SWCD have longer stays in both acute and rehabilitation settings and may be a marker for more severe injury.

An Accelerometry-Based Comparison of 2 Robotic Assistive Devices for Treadmill Training of Gait

Regnaux, J.-P., Saremi, K., Marehbian, J., Bussel, B., Dobkin, B. H. — 2008-07-28

Objective. Two commercial robotic devices, the Gait Trainer (GT) and the Lokomat (LOKO), assist task-oriented practice of walking. The gait patterns induced by these motor-driven devices have not been characterized and compared. Methods. A healthy participant chose the most comfortable gait pattern on each device and for treadmill (TM) walking at 1, 2 (maximum for the GT), and 3 km/h and over ground at similar speeds. A system of accelerometers on the thighs and feet allowed the calculation of spatiotemporal features and accelerations during the gait cycle. Results . At the 1 and 2 km/h speed settings, single-limb stance times were prolonged on the devices compared with overground walking. Differences on the LOKO were decreased by adjusting the hip and knee angles and step length. At the 3 km/h setting, the LOKO approximated the participant's overground parameters. Irregular accelerations and decelerations from toe-off to heel contact were induced by the devices, especially at slower speeds. Conclusions. The LOKO and GT impose mechanical constraints that may alter leg accelerations–decelerations during stance and swing phases, as well as stance duration, especially at their slower speed settings, that are not found during TM and overground walking. The potential impact of these perturbations on training to improve gait needs further study.

Endurance and Resistance Exercise Training Programs Elicit Specific Effects on Sciatic Nerve Regeneration After Experimental Traumatic Lesion in Rats

2008-07-28

Objective. To evaluate the effects of endurance, resistance, and a combination of both types of exercise training on hindlimb motor function recovery and nerve regeneration after experimental sciatic nerve lesion in rats. Methods. Sciatic nerve crush was performed on adult male rats, and after 2 weeks of the nerve lesion, the animals were submitted to endurance, resistance, and a combination of endurance-resistance training programs for 5 weeks. Over the training period, functional recovery was monitored weekly using the Sciatic Functional Index (SFI) and histological and morphometric nerve analyses were used to assess the nerve regeneration at the end of the trainings. Results. The SFI values of the endurance-trained group reached the control values from the first posttraining week and were significantly better than both the resistance-trained group at the first, second, and third posttraining weeks and the concurrent training group at the first posttraining week. At the distal portion of the regenerating sciatic nerve, the endurance-trained group showed a greater degree of the myelinated fiber maturation than the sedentary, resistance-trained, and concurrent training groups. Furthermore, the endurance-trained group showed a smaller percentage area of endoneurial connective tissue and a greater percentage area of myelinated fibers than the sedentary group. Conclusion . These data provide evidence that endurance training improves sciatic nerve regeneration after an experimental traumatic injury and that resistance training or the combination of 2 strategies may delay functional recovery and do not alter sciatic nerve fiber regeneration.

Effects of Electrical Stimulation at Different Frequencies on Regeneration of Transected Peripheral Nerve

2008-07-28

Background. Electrical stimulation of damaged peripheral nerve may aid regeneration. Objective. The purpose of this study was to determine whether 1 mA of percutaneous electrical stimulation at 1, 2, 20, or 200 Hz augments regeneration between the proximal and distal nerve stumps. Methods. A10-mm gap was made in rat sciatic nerve by suturing the stumps into silicone rubber tubes. A control group received no stimulation. Starting 1 week after transection, electrical stimulation was applied between the cathode placed at the distal stump and the anode at the proximal stump every other day for 6 weeks. Results. Higher frequency stimulation led to less regeneration compared to lower frequencies. Quantitative histology of the successfully regenerated nerves revealed that the groups receiving electrical treatment, especially at 2 Hz, had a more mature structure with a smaller cross-sectional area, more myelinated fibers, higher axon density, and higher ratio of blood vessel to total nerve area compared with the controls. Electrophysiology showed significantly shorter latency, longer duration, and faster conduction velocity. Conclusion. Electrical stimulation can have either a positive or negative impact on peripheral nerve regeneration. Clinical trials that combine stimulation with rehabilitation must determine the parameters that are most likely to be safe and effective.

Preserved and Impaired Aspects of Feed-Forward Grip Force Control After Chronic Somatosensory Deafferentation

Hermsdorfer, J., Elias, Z., Cole, J. D., Quaney, B. M., Nowak, D. A. — 2008-07-28

Background. Although feed-forward mechanisms of grip force control are a prerequisite for skilled object manipulation, somatosensory feedback is essential to acquire, maintain, and adapt these mechanisms. Objective. Individuals with complete peripheral deafferentation provide the unique opportunity to study the function of the motor system deprived of somatosensory feedback. Methods. Two individuals (GL and IW) with complete chronic deafferentation of the trunk and limbs were tested during cyclic vertical movements of a hand-held object. Such movements induce oscillating loads that are typically anticipated by parallel modulations of the grip force. Load magnitude was altered by varying either the movement frequency or object weight. Results. GL and IW employed excessive grip forces probably reflecting a compensatory mechanism. Despite this overall force increase, both deafferented participants adjusted their grip force level according to the load magnitude, indicating preserved scaling of the background grip force to physical demands. The dynamic modulation of the grip force with the load force was largely absent in GL, whereas in IW only slower movements were clearly affected. Conclusions. The authors hypothesize that the deafferented patients may have utilized visual and vestibular cues and/or an efferent copy of the motor command of the arm movement to scale the grip force level. Severely impaired grip force-load coupling in GL suggests that sensory information is important for maintaining a precise internal model of dynamic grip force control. However, comparably better performance in IW argues for the possibility that alternative cues can be used to trigger a residual internal model.

Determining the Optimal Challenge Point for Motor Skill Learning in Adults With Moderately Severe Parkinson's Disease

Onla-or, S., Winstein, C. J. — 2008-07-28

Objective. To test the predictions of the Challenge Point Framework (CPF) for motor learning in individuals with Parkinson's disease (PD) by manipulating nominal task difficulty and conditions of practice. Methods. Twenty adults with PD and 20 nondisabled controls practiced 3 variations of a laboratory-based goal-directed arm movement over 2 days. A between-group (PD, nondisabled) 2-factor design compared 2 levels of nominal task difficulty (low, high) and 2 levels of practice condition (low, high demand). Learning was assessed with a no-feedback recall test 1 day after practice. Performance was quantified using a root mean square error difference between the goal and participant-generated movement. Results. All participants improved with practice. Under the low-demand practice condition, adults with PD demonstrated comparable learning to that of controls when nominal task difficulty was low but not high. In contrast, under the high-demand practice condition, adults with PD demonstrated preserved motor learning for both levels of task difficulty, but only if recall was tested under the same context as that used during practice. Conclusions. In general, the predictions of CPF were supported. Together, the level of nominal task difficulty and the inherent demand of the practice condition played a critical role in determining the optimal challenge point for motor learning in individuals with PD. More important, and in contrast to the predictions of CPF, a high-demand practice condition appeared to have a facilitative effect on motor learning. However, this benefit revealed the context specificity of motor learning in adults with PD.

Motor Cortical Disinhibition During Early and Late Recovery After Stroke

Manganotti, P., Acler, M., Zanette, G. P., Smania, N., Fiaschi, A. — 2008-07-28

Background. Functional neuroimaging studies show adaptive changes in areas adjacent and distant from the stroke. This longitudinal study assessed whether changes in cortical excitability in affected and unaffected motor areas after acute stroke correlates with functional and motor recovery. Methods. We studied 13 patients with moderate to severe hemiparesis 5 to 7 days (T1), 30 days (T2), and 90 days (T3) after acute unilateral stroke, as well as 10 healthy controls. We used paired-pulse transcranial magnetic stimulation to study intracortical inhibition and facilitation, recording from the bilateral thenar eminences. F waves were also recorded. Results. At T1, all patients showed significantly reduced intracortical inhibition in the unaffected hemisphere. At T2, in patients whose motor function recovered, intracortical inhibition in the unaffected hemisphere returned to normal. In patients with poor clinical motor recovery, abnormal disinhibition persisted in both hemispheres. At T3, in patients whose motor function progressively recovered, the abnormal disinhibition in the unaffected hemisphere decreased further, whereas in patients whose motor function remained poor, abnormal inhibition in the unaffected hemisphere persisted. No modification of F-wave latency and amplitude were found in patients and controls. Conclusions. During early days after stroke, motor cortical disinhibition involves both cerebral hemispheres. Longitudinal changes in motor disinhibition of the unaffected hemisphere may reflect the degree of clinical motor recovery.

Recovery From Amnesic Confabulatory Syndrome After Right Fornix Lesion

Ruggeri, M., Sabatini, U. — 2008-07-28

Background. Reports of amnesia due to bilateral fornix lesions are rare. A unilateral right fornix lesion is not known to cause an amnestic confabulatory syndrome. Objective. To investigate the role of right fornix lesion in amnesia, the association of confabulation with executive disorders, and to evaluate the long-term recovery of memory and executive functions after surgical removal of a pilocytic astrocytoma in the right orbitofrontal region extending to the right fornix. Methods. Neuropsychological testing was performed 3 and 17 months after surgery. Results. Severe anterograde global amnesia, mild retrograde amnesia, momentary and spontaneous confabulation, and mild executive deficits were found initially and mostly recovered by 17 months. Conclusions. The authors hypothesize that the lesion of the right fornix was sufficient to cause amnesia by disconnecting the hippocampal formations from the anterior thalamic nuclei and mammillary bodies and interrupting the cholinergic efferents to the hippocampus from the medial septum, according to the extended hippocampal system framework. Sparing of the left fornix may be sufficient to ensure a good recovery of memory. Confabulation is strongly associated with the improvement of executive functions, specifically the ability to suppress irrelevant memory traces.

Reinvestment and Falls in Community-Dwelling Older Adults

Wong, W. L., Masters, R. S. W., Maxwell, J. P., Abernethy, A. B. — 2008-07-28

Background. Falls are common in older adults and have many adverse consequences. In an attempt to prevent further incidents, elder fallers may consciously monitor and control their movements. Ironically, conscious movement control may be one factor that contributes to disruption of automaticity of walking, increasing the likelihood of subsequent falls. Objective. The Movement Specific Reinvestment Scale (MSRS), which aims to measure the propensity for movement-related self-consciousness and for conscious processing of movement, was used to try to discriminate elder fallers from non-fallers. Methods. Fifty-two volunteer older adults, aged 65 or above, participated. In addition to the 10-item MSRS, participants completed the Mini-Mental State Examination questionnaire, Timed "Up & Go" test, and Four Word Short-Term Memory test. Demographics including age, gender, and history of falling were collected. Results. Elder fallers scored significantly higher than non-fallers on both the movement self-consciousness and conscious motor processing components of the MSRS. Logistic regression revealed a significant association between the MSRS (conscious motor processing component) and "faller or non-faller" status. Conclusions. Elder fallers may have a higher propensity to consciously control their movements. The MSRS shows potential as a clinical tool with which to predict falls in the elderly, as well as to gain insight into the perception of safety during walking in any impaired patient.

Outcomes With Stroke and Lateropulsion: A Case-Matched Controlled Study

Babyar, S. R., White, H., Shafi, N., Reding, M. — 2008-07-28

Background and Objective . Lateropulsion after stroke has not been tracked using a case-matched controlled study and a standardized lateropulsion scale. Matched pairs of patients with stroke, with and without lateropulsion, were compared for functional outcomes and discharge destination following inpatient rehabilitation. Methods. A retrospective chart review of patients with ischemic stroke at an inpatient rehabilitation hospital matched 36 pairs of patients with versus without lateropulsion. Scores of 2 or greater on the Burke Lateropulsion Scale identified lateropulsion. Matching criteria were side of stroke, sex, age, admission motor Functional Independence Measure (FIM), and interval poststroke. FIM efficiency (change in total FIM/length of stay) and discharge destination were analyzed with Wilcoxon signed-ranks tests. Results. FIM efficiency and discharge FIM scores were lower in the lateropulsion group. Groups had similar mean lengths of stay. Post-hoc analyses showed that only patients with lateropulsion and right brain damage had significantly different FIM efficiency and discharge FIM scores. Lower extremity weakness was greater in the lateropulsion group at discharge; patients with right brain damage accounted for this difference. Patients with lateropulsion required more dependent living situations at discharge, especially if they had right brain damage. Conclusions. Patients with lateropulsion following stroke have a lower FIM efficiency and more dependency at discharge when compared with matched controls with equal functional limitations. Secondary analyses show worse outcomes for the subgroup of patients with right hemisphere stroke; lateropulsion and greater leg weakness may account for differences. Patients with lateropulsion may require longer rehabilitation to reach outcome goals.