Individuals With Multiple Sclerosis Exhibit More Regular Center of Mass Accelerations After Physical Therapy.

Objective: The purpose of this investigation was to explore if a physical therapy program involving strength, flexibility, balance, and walking can improve the uncharacteristic gait variability and overall mobility of persons living with multiple sclerosis (pwMS). Design: Pre-post design to evaluate the mobility improvements after undergoing 6 weeks of a gait and balance physical therapy intervention. Setting: The initial 2 weeks were conducted at a medical center under close supervision of a physical therapist. The remaining 4 weeks were performed by the patient at their home and monitored via teleconferences. Participants: Fifteen pwMS with relapsing-remitting (N=11) or secondary progressive multiple sclerosis (N=4) were enrolled in this study (7 women; mean age: 54.8±9 years; Kurtzke Expanded Disability Status Score range: 3.0-6.5). A group of healthy age-matched controls (N=15) were used for comparisons. Interventions: The 6-week physical therapy intervention included exercises that targeted strength, flexibility, balance, and walking. The initial 2 weeks of the intervention were performed on-site with the remaining 4 weeks home-based. The therapy was performed twice-a-day for 5 consecutive days each week. Each session was 45 minutes in length. Main Outcome Measures: Preferred walking speed, spatiotemporal gait kinematics, and a 6-minute walk test were completed before and after therapy. The standard deviation (SD) and sample entropy were used to evaluate the amount of variability and the regularity of the time-dependent variations in the center of mass (COM) accelerations during the 6-minute walk test. Results: Before the intervention, the SD of the COM was reduced, and the time-dependent variations were less regular in the pwMS than the control group. After therapy, the SD was 12% larger, and the time-dependent variations were more 7% regular in the pwMS. The effect size for these changes were large (0.91 and 0.94, respectively), suggesting these changes were meaningful. The changes in the regularity of the COM were related to the mobility improvements in the preferred walking velocity and 6-minute walk test. Conclusions: The results suggest that pwMS have altered COM variability during gait, which can be improved with a similar physical therapy program. These changes appear to be linked with the extent of the mobility improvements.

Disruption of Sensorimotor Cortical Oscillations by Visual Interference Predicts the Altered Motor Performance of Persons with Cerebral Palsy.

Emerging evidence indicates that aberrations in sensorimotor cortical oscillations likely play a key role in uncharacteristic motor actions seen in cerebral palsy. This interpretation is largely centered on the assumption that the aberrant cortical oscillations primarily reflect the motor aspects, with less consideration of possible higher-order cognitive connections. To directly probe this view, we examined the impact of cognitive interference on the sensorimotor cortical oscillations seen in persons with cerebral palsy using magnetoencephalography. Persons with cerebral palsy (N = 26, 9-47 years old) and controls (N = 46, 11-49 years) underwent magnetoencephalographic imaging while completing an arrow-based version of the Eriksen flanker task. Structural equation modeling was used to evaluate the relationship between the extent of interference generated by the flanker task and the strength of the sensorimotor cortical oscillations and motor performance. Our results indicated that the impact of cognitive interference on beta and gamma oscillations moderated the interference effect on reaction times in persons with cerebral palsy, above and beyond that seen in controls. Overall, these findings suggest that alterations in sensorimotor oscillatory activity in those with cerebral palsy at least partly reflects top-down control influences on the motor system. Thus, suppression of distracting stimuli should be a consideration when evaluating altered motor actions in cerebral palsy.

Maximal daily stepping cadence partially explains functional capacity of individuals with end-stage knee osteoarthritis.

BACKGROUND: Individuals with end-stage knee osteoarthritis (OA) walk at a lower intensity (ie, slower step cadence) contributing to worse physical function. Previous literature reports daily step counts and sedentary time, with little information regarding stepping bouts or cadence. Determining relationships between daily higher stepping cadence duration and clinical outcomes can move the field toward optimal daily stepping prescription. OBJECTIVE: To quantify daily physical activity patterns of individuals with end-stage knee OA and determine the contribution of high stepping cadence to explain functional capacity variability. DESIGN: Cross-sectional analysis. SETTING: Veterans Administration medical center. PARTICIPANTS: U.S. military veterans (n = 104; age: 67.1 years [7.2]; mean [SD]; male [89.3%]) with end-stage knee OA were enrolled. INTERVENTION: Not applicable. MAIN OUTCOME MEASURE: Functional capacity (6-Minute Walk Test [6MWT]). Physical activity (activPAL wearable sensor; cadence and time sitting, standing, and stepping), pain (Western Ontario and McMaster Universities Osteoarthritis Index-pain subscale) sociodemographic variables, and comorbidities (body mass index and Functional Comorbidity Index) are the main explanatory variables. RESULTS: Participants' wake time was mainly sitting (11.0 h/day) in ≥60-minute bouts (29.7% ± 12.7 of sitting time). Standing (3.4 hours/day) and stepping (1.4 h/day) primarily occurred in 0-5 minute bouts (standing: 87.7% ± 14.4 of standing time, stepping: 98.7% ± 12.7 of stepping time) and stepping cadence was predominantly incidental (1-19 spm; 52.9% ± 9.6 of total stepping time). Backward elimination model results indicated shorter medium-to-brisk cadence bout duration, older age, and higher pain significantly explained shorter 6MWT distance (Adj R2 =0.24, p < .01). CONCLUSIONS: Individuals with knee OA spend most of their waking hours sitting, while standing and stepping occurs in short bouts at very low stepping cadence. Decreased time in high stepping cadence is associated with lower functional capacity. Future studies should explore if increasing the daily time spent in higher step cadence can improve functional capacity in this population.

Spinal cord microstructural changes are connected with the aberrant sensorimotor cortical oscillatory activity in adults with cerebral palsy.

Previous animal models have illustrated that reduced cortical activity in the developing brain has cascading activity-dependent effects on the microstructural organization of the spinal cord. A limited number of studies have attempted to translate these findings to humans with cerebral palsy (CP). Essentially, the aberrations in sensorimotor cortical activity in those with CP could have an adverse effect on the spinal cord microstructure. To investigate this knowledge gap, we utilized magnetoencephalographic (MEG) brain imaging to quantify motor-related oscillatory activity in fourteen adults with CP and sixteen neurotypical (NT) controls. A subset of these participants also underwent cervical-thoracic spinal cord MRI. Our results showed that the strength of the peri-movement beta desynchronization and the post-movement beta rebound were each weaker in the adults with CP relative to the controls, and these weakened responses were associated with poorer task performance. Additionally, our results showed that the strength of the peri-movement beta response was associated with the total cross-sectional area of the spinal cord and the white matter cross-sectional area. Altogether these results suggest that the altered sensorimotor cortical activity seen in CP may result in activity-dependent plastic changes within the spinal cord microstructure, which could ultimately contribute to the sensorimotor deficits seen in this population.

Postamputation Cognitive Impairment Is Related to Worse Perceived Physical Function Among Middle-Aged and Older Prosthesis Users.

OBJECTIVE: To compare characteristics between middle-aged and older prosthesis users with and without cognitive impairment and determine whether cognitive impairment contributes to variability in perceived physical function. DESIGN: Cross-sectional, observational study SETTING: General community. PARTICIPANTS: Adults 45 years or older, at least 1-year post lower limb amputation (LLA) who were walking independently with a prosthesis (N=119). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: We identified cognitive impairment using an education-adjusted Telephone Interview for Cognitive Status-modified score. Perceived physical function was measured using the Prosthesis Mobility Questionnaire. RESULTS: Of 119 participants (mean age, 62.6±8.2 years; male: 89.1%; vascular etiology: 82.4%; years since amputation: 4.9±4.7 years), 28 (23.5%) had cognitive impairment. Compared with participants without cognitive impairment, those with cognitive impairment were more likely to use an assistive device (60.7% vs 25.3%, P=.002); were older (66.3±7.3 vs 61.5±8.1 years, P=.006) and had more chronic conditions (7.1±3.4 vs 5.4±2.5, P=.004), more depressive symptoms (6.6±5.1 vs 4.2±3.8, P=.008), and worse perceived physical function (2.0±0.6 vs 2.6±0.7, P<.001). Using backward stepwise linear regression, we found that participants with cognitive impairment had worse perceived physical function (standardized parameter estimate [ß]=-0.15, P=.02), even after adjusting for depressive symptoms (ß=-0.31, P<.001), prosthesis satisfaction (ß=0.34, P<.001), number of chronic conditions (ß=-0.19, P=.006), and assistive device use (ßcane=0.01, P=.93; ßother=-0.20, P=.003). Together, these variables explained 59% of perceived physical function variability. CONCLUSIONS: Cognitive impairment is common and associated with worse perceived physical function post LLA, even after controlling for physical and mental health differences. Tailored rehabilitation interventions may be needed to improve perceived physical function in prosthesis users with cognitive impairment.

Altered Somatosensory Cortical Activity Is Associated with Cortical Thickness in Adults with Cerebral Palsy: Multimodal Evidence from MEG/sMRI.

Somatosensory cortical activity is altered in individuals with cerebral palsy (CP). However, previous studies have focused on the lower extremities in children with CP and have given less attention to structural changes that may contribute to these alterations. We used a multimodal neuroimaging approach to investigate the relationship between somatosensory cortical activity and cortical thickness in 17 adults with CP (age = 32.8 ± 9.3 years) and 18 healthy adult controls (age = 30.7 ± 9.8 years). Participants performed a median nerve paired-pulse stimulation paradigm while undergoing magnetoencephalography (MEG) to investigate somatosensory cortical activity and sensory gating. Participants also underwent magnetic resonance imaging to evaluate cortical thickness within the area of the somatosensory cortex that generated the MEG response. We found that the somatosensory responses were attenuated in the adults with CP (P = 0.004). The adults with CP also hypergated the second stimulation (P = 0.030) and had decreased cortical thickness in the somatosensory cortex (P = 0.015). Finally, the strength of the somatosensory response was significantly correlated with the cortical thickness (P = 0.023). These findings demonstrate that the aberrant somatosensory cortical activity in adults with CP extends to the upper extremities and appears to be related to cortical thickness.

Cortical oscillations that underlie visual selective attention are abnormal in adolescents with cerebral palsy.

Adolescence is a critical period for the development and refinement of several higher-level cognitive functions, including visual selective attention. Clinically, it has been noted that adolescents with cerebral palsy (CP) may have deficits in selectively attending to objects within their visual field. This study aimed to evaluate the neural oscillatory activity in the ventral attention network while adolescents with CP performed a visual selective attention task. Adolescents with CP (N = 14; Age = 15.7 ± 4 years; MACS I-III; GMFCS I-IV) and neurotypical (NT) adolescents (N = 21; Age = 14.3 ± 2 years) performed the Eriksen flanker task while undergoing magnetoencephalographic (MEG) brain imaging. The participants reported the direction of a target arrow that was surrounded by congruent or incongruent flanking arrows. Compared with NT adolescents, adolescents with CP had slower responses and made more errors regarding the direction of the target arrow. The MEG results revealed that adolescents with CP had stronger alpha oscillations in the left insula when the flanking arrows were incongruent. Furthermore, participants that had more errors also tended to have stronger alpha oscillatory activity in this brain region. Altogether these results indicate that the aberrant activity seen in the left insula is associated with diminished visual selective attention function in adolescents with CP.

Cortical oscillations that underlie working memory are altered in adults with cerebral palsy.

OBJECTIVE: This investigation used magnetoencephalography (MEG) to identify the neurophysiological mechanisms contributing to the altered cognition seen in adults with cerebral palsy (CP). METHODS: Adults with CP (GMFCS levels I-IV) and demographically-matched controls completed a Sternberg-type working memory task during MEG. Secondarily, they completed the National Institutes of Health (NIH) cognitive toolbox. Beamforming was used to image the significant MEG oscillatory responses and the resulting images were examined using statistical parametric mapping to identify cortical activity that differed between groups. RESULTS: Both groups had a left-lateralized decrease in alpha-beta (11-16 Hz) power across the occipital, temporal, and prefrontal cortices during encoding, as well as an increase in alpha (9-13 Hz) power across the occipital cortices during maintenance. The strength of alpha-beta oscillations in the prefrontal cortices were weaker in those with CP during encoding. Weaker alpha-beta oscillation within the prefrontal cortex was associated with poorer performance on the NIH toolbox and a higher GMFCS level. CONCLUSIONS: Alpha-beta aberrations may impact the basic encoding of information in adults with CP, which impacts their overall cognition. Altered alpha-beta oscillation might be connected with gross motor function. SIGNIFICANCE: This experimental work highlights the aberrant alpha-beta during encoding as possible neurophysiological mechanism of the cognitive deficiencies.

Cognitive-Motor Interference Heightens the Prefrontal Cortical Activation and Deteriorates the Task Performance in Children With Hemiplegic Cerebral Palsy.

OBJECTIVE: To compare the prefrontal cortex (PFC) activation and task performance during single- and dual-task conditions between typically developing (TD) children and children with hemiplegic cerebral palsy (HCP). DESIGN: A prospective, comparative design. SETTING: Research laboratory. PARTICIPANTS: Participants (N=21) included 12 TD children (age, 6.0±1.1y) and 9 children with HCP (age, 7.2±3.1). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: PFC activation was assessed by measuring the concentration of oxygenated hemoglobin while the children performed a shape-matching task with their more affected arm while sitting on a stable (single task) vs dynamic surface (dual task). The task performance was assessed with the total number of shapes matched, dual-task cost, and reaction time (RT). RESULTS: For both conditions, the children with HCP exhibited greater PFC activation, matched a fewer shapes, and had slower RT than the TD children. These differences were accentuated during the dual-task condition and the dual-task cost was greater. An increase in the PFC activation during the dual-task condition was tightly correlated with a higher dual-task cost in children with HCP (r=0.77, P=.01). CONCLUSIONS: Children with HCP appear to have a heightened amount of PFC activity while performing a dual task. The greater cortical activity may be a result of the finite attentional resources that are shared between both the motor as well as cognitive demands of the task. The cognitive-motor interference is likely exacerbated in children with HCP because of the structural and functional brain changes as a result of an insult to the developing brain.

Beyond the eye: Cortical differences in primary visual processing in children with cerebral palsy.

Despite the growing clinical recognition of visual impairments among people with cerebral palsy (CP), very few studies have evaluated the neurophysiology of the visual circuitry. To this end, the primary aim of this investigation was to use magnetoencephalography and beamforming methods to image the relative change in the alpha-beta and gamma occipital cortical oscillations induced by a spatial grating stimulus (e.g., visual contrast) that was viewed by a cohort of children with CP and typically-developing (TD) children. Our results showed that the high-contrast, visual gratings stimuli induced a decrease in alpha-beta (10 - 20 Hz) activity, and an increase in both low (40 - 56 Hz) and high (60 - 72 Hz) gamma oscillations in the occipital cortices. Compared with the TD children, the strength of the frequency specific cortical oscillations were significantly weaker in the children with CP, suggesting that they had deficient processing of the contrast stimulus. Although CP is largely perceived as a musculoskeletal centric disorder, our results fuel the growing impression that there may also be prominent visual processing deficiencies. These visual processing deficits likely impact the ability to perceive visual changes in the environment.

Hand Motor Actions of Children With Cerebral Palsy Are Associated With Abnormal Sensorimotor Cortical Oscillations.

Background. The neuroimaging literature on cerebral palsy (CP) has predominantly focused on identifying the structural aberrations (eg, fiber track integrity), with very few studies examining neural activity within the key networks that serve the production of hand movements. Objective. We aimed to start to fill this knowledge gap by using magnetoencephalographic brain imaging to quantify the temporal dynamics of the sensorimotor oscillations during a hand motor action. Methods: Children with CP (n = 12; MACS [Manual Abilities Classification System] levels I-III) and typically developing (TD) children (n = 26) performed an arrow-based version of the Eriksen flanker task where a button press was performed with either the second or third digit of the right hand depending on the arrow's direction. Results: Overall, the children with CP were less accurate and had slower reaction times compared with the TD children. These behavioral differences were closely linked with aberrant sensorimotor cortical oscillations seen in the children with CP. Compared with the TD children, the children with CP had a weaker gamma (68-82 Hz) response during motor execution and a weaker post-movement beta rebound (PMBR; 14-26 Hz) response on movement termination. Moreover, we observed a significant correlation between the amplitude of the gamma and PMBR with reaction time, with weaker gamma and PMBR responses being linked with slower reaction times. Conclusions: Overall, these results suggest that aberrations in motor-related gamma and beta cortical oscillations are associated with the impaired hand motor actions seen in children with CP.

Impaired anticipatory vision and visuomotor coordination affects action planning and execution in children with hemiplegic cerebral palsy.

BACKGROUND: Action-planning and execution deficits in children with hemiplegic cerebral palsy (HCP) are potentially due to deficits in the integration of sensory information, such as vision, with motor output. AIMS: To determine differences in anticipatory visual patterns in children with HCP compared to typically developing (TD) children, and to assess visuomotor coordination in children with HCP. METHODS AND PROCEDURES: We included 13 children with HCP (Age = 6.8 + 2.9 yrs) and 15 TD children (Age = 5.8 + 1.1 yrs). The experimental task used in this study is a valid action-planning task, which consisted of initially reaching and grasping an object placed at a fixed position, followed by placing the object in a random target position. Visual patterns were recorded using a head-mounted eye-tracker system and arm movements were recorded using motion capture (120 Hz). OUTCOMES AND RESULTS: Children with HCP had delayed anticipatory gaze time and longer latency than TD children during the planning and execution phases. Children with HCP also had a higher frequency of gaze shifts, longer reaction times (RT) and movement times (MT) than TD children. CONCLUSIONS AND IMPLICATIONS: Children with HCP may have deficits in anticipatory vision, which potentially affected planning and executing a goal-directed action. Therapeutic interventions focusing on improving visuomotor coordination may improve the motor performance in children with HCP.

Neural activation within the prefrontal cortices during the goal-directed motor actions of children with hemiplegic cerebral palsy.

The primary aim of the study was to explore the prefrontal cortical (PFC) activation while performing a shape-matching motor task in children with hemiplegic cerebral palsy (HCP) as compared with typically developing (TD) children. Fifteen TD children ([Formula: see text]) and 12 children with HCP ([Formula: see text]) were included. We assessed the PFC activation while performing an ecologically valid upper extremity shape-matching task of different complexities by measuring the concentration of oxygenated hemoglobin (HbO) using functional near-infrared spectroscopy. The motor task performance was assessed by quantifying the average number of shapes matched, reaction time (RT), task errors, nine-hole peg test (NHPT), and the box and block test (BBT). Overall, there was a systematic increase in the HbO in the PFC across the shape-matching complexity conditions. Our results also revealed that the children with HCP had an increased amount of PFC activation while performing all of the shape-matching tasks. The increased PFC activation paralleled the differences in the number of shapes matched, RT, task errors, NHPT, and BBT. The atypical motor actions seen in children with HCP may be partially related to the greater cognitive demands placed on the PFC.

Hand-Arm Bimanual Intensive Therapy Improves Prefrontal Cortex Activation in Children With Hemiplegic Cerebral Palsy.

PURPOSE: To determine the changes in the prefrontal cortical (PFC) activation following hand-arm bimanual intensive therapy (HABIT) in children with hemiplegic cerebral palsy (HCP). METHODS: Nine children with HCP and 15 children who were developing typically participated in the study. Children with HCP received 50 hours of HABIT. We assessed pre- and post-HABIT PFC activation using functional near-infrared spectroscopy neuroimaging. Bimanual coordination and motor task performance were assessed using the Assisting Hand Assessment (AHA), the average number of shapes matched, the shape matching errors, the reaction time, the 9-hole peg test, and the box and blocks test. RESULTS: The PFC activation decreased following HABIT and became similar to what was seen in the children who were developing typically. Post-HABIT PFC activation improvements paralleled with the improvements seen in the AHA and the behavioral outcomes. CONCLUSION: HABIT potentially improves the PFC's involvement in the action planning of the upper extremity movements in children with HCP.

Changes in lower extremity strength may be related to the walking speed improvements in children with cerebral palsy after gait training.

BACKGROUND: Cerebral palsy (CP) has a high probability of resulting in lower extremity strength and walking deficits. Numerous studies have shown that gait training has the potential to improve the walking abilities of these children; however, the factors governing these improvements are unknown. AIMS: This study aimed to evaluate the relationship between change in lower extremity strength, walking speed and endurance of children with CP following gait training. METHODS AND PROCEDURES: Eleven children with CP (GMFCS levels=II-III) completed a gait training protocol three days a week for six weeks. Outcome measures included a 10m fast-as-possible walk test, 6min walking endurance test and lower extremity strength. OUTCOMES AND RESULTS: The group results indicated there were improvements in walking speed, walking endurance and lower extremity strength. In addition, there was a positive correlation between percent change in lower extremity strength and walking speed and a negative correlation between the percent change in lower extremity strength and the child's age. CONCLUSIONS: Our results imply that changes in lower extremity strength might be related to the degree of the walking speed changes seen after gait training. Younger children may be more likely to show improvements in lower extremity strength after gait training.

Errors in the ankle plantarflexor force production are related to the gait deficits of individuals with multiple sclerosis.

BACKGROUND: Individuals with multiple sclerosis (MS) often have limited mobility that is thought to be due to the neuromuscular impairments of the ankle. Greater isometric motor control of the ankle has been associated with better standing postural balance but its relationship to mobility is less understood. The objectives of this investigation were to quantify the motor control of the ankle plantarflexors of individuals with MS during a dynamic isometric motor task, and explore the relationship between the ankle force control and gait alterations. METHODS: Fifteen individuals with MS and 15 healthy adults participated in both a dynamic isometric ankle plantarflexion force matching task and a biomechanical gait analysis. FINDINGS: Our results displayed that the subjects with MS had a greater amount of error in their dynamic isometric force production, were weaker, walked with altered spatiotemporal kinematics, and had reduced maximal ankle moment at toe-off than the control group. The greater amount of error in the dynamic force production was related to the decreases in strength, step length, walking velocity, and maximal ankle moment during walking. INTERPRETATION: Altogether these results imply that errors in the ankle plantarflexion force production may be a limiting factor in the mobility of individuals with MS.

Individuals with multiple sclerosis redistribute positive mechanical work from the ankle to the hip during walking.

Individuals with multiple sclerosis (MS) typically walk slower, have reduced cadences and shorter step lengths. While these spatiotemporal gait alterations have been thought to be due to decreased power generation at the ankle, the distribution of mechanical work across the ankle, knee and hip joints during walking is not well understood. By quantifying the mechanical work at each joint, the compensatory mechanisms utilized by individuals with MS to maintain gait speed may be better understood. Fifteen subjects with MS (EDSS: 4.4±1.0) and fifteen healthy age-matched control subjects completed a three-dimensional gait analysis. The net mechanical work at the ankle, knee and hip joints was quantified for the stance phase of gait. Our results found that the less impaired leg of the subjects with MS generated a similar amount of mechanical work as the control group; however, the ankle joint produced less positive mechanical work, and the hip joint generated more positive mechanical work. Additionally, the less impaired leg of the subjects with MS and the leg of the control group generated more positive work than the more impaired leg of the subjects with MS. These outcomes suggest that individuals with MS may adopt a hip compensatory strategy with their less impaired leg during gait due to the limited amount of mechanical work generated at the ankle.