Effects of an Articulated Ankle Foot Orthosis on Gait Biomechanics in Adolescents with Traumatic Brain Injury: A Case-Series Report.

PURPOSE: To quantify the effects of an articulated ankle foot orthosis on genu recurvatum gait in adolescents with traumatic brain injury (TBI). METHODS: Gait analysis was conducted in 2 individuals with TBI during over ground ambulation with (braced condition) and without (barefoot condition) the AAFO. For each participant, stride-by-stride gait data were compared to assess differences between barefoot and braced walking conditions. RESULTS: During the braced versus barefoot condition, both participants demonstrated reduced plantar flexion at initial contact, increased knee flexion at initial contact, reduced peak knee extension during stance, and reduced peak and integral of internal knee flexor moment during stance. CONCLUSIONS: The data suggest that the AAFO reduced plantar flexion during stance, therefore attenuating the anterior displacement of the ground reaction force vector (GRFV) relative to the ankle and knee joint axes, and leading to a reduction in knee hyperextension and the internal knee flexor moment during stance. We posit that the reduction in internal knee flexor moment may lead to a more sustainable gait pattern with less potential for mechanical stress on the posterior knee joint capsule.

Myelin status is associated with change in functional mobility following slope walking in people with multiple sclerosis.

BACKGROUND: The level of myelin disruption in multiple sclerosis patients may impact the capacity for training-induced neuroplasticity and the magnitude of therapeutic response to rehabilitation interventions. Downslope walking has been shown to increase functional mobility in individuals with multiple sclerosis, but it is unclear if myelin status influences therapeutic response. OBJECTIVE: The current study aimed to examine the relationship between baseline myelin status and change in functional mobility after a walking intervention. METHODS: The Timed Up and Go test was used to measure functional mobility before and after completion of a repeated, six-session slope walking intervention in 16 participants with relapsing-remitting multiple sclerosis. Multi-component T2 relaxation imaging was used to index myelin water fraction of overall water content in brain tissue compartments. RESULTS: Results demonstrated that the ratio of the myelin water fraction in lesion to normal-appearing white matter (myelin water fraction ratio) significantly predicted 31% of the variance in change in Timed Up and Go score after the downslope walking intervention, where less myelin disruption was associated with greater intervention response. CONCLUSIONS: Myelin water content fraction ratio may offer a neural biomarker of myelin to identify potential responders to interventions targeting functional impairments in multiple sclerosis.

Establishing between-session reliability of TMS-conditioned soleus H-reflexes.

Transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) can be used to evaluate descending corticomotor influences on spinal reflex excitability through modulation of the Hoffman reflex (H-reflex). The purpose of this study was to characterize between-session reliability of cortical, spinal, and cortical-conditioned spinal excitability measures collected from the soleus muscle. Thirteen able-bodied young adult participants were tested over four sessions. Intraclass correlation coefficients were calculated to quantify between-session reliability of active motor threshold (AMT), unconditioned H-reflexes (expressed as a percentage of Mmax), and conditioned H-reflexes using short-latency facilitation (SLF) and long-latency facilitation (LLF). Pearson correlation coefficients were calculated to assess associations between H-reflex facilitation and unconditioned H-reflex amplitude. Between-session reliability for SLF (ICC=0.71) was higher than for LLF (ICC=0.45), was excellent for AMT (ICC=0.95), and was moderate for unconditioned H-reflexes (ICC=0.63). Our results suggest moderate-to-good reliability of SLF and LLF to evaluate cortical influences on spinal reflex excitability across multiple testing sessions in able-bodied individuals.

Changes in Post-Stroke Gait Biomechanics Induced by One Session of Gait Training.

The objective of this study was to determine whether one session of targeted locomotor training can induce measurable improvements in the post-stroke gait impairments. Thirteen individuals with chronic post-stroke hemiparesis participated in one locomotor training session combining fast treadmill training and functional electrical stimulation (FES) of ankle dorsi- and plantar-flexor muscles. Three dimensional gait analysis was performed to assess within-session changes (after versus before training) in gait biomechanics at the subject's self-selected speed without FES. Our results showed that one session of locomotor training resulted in significant improvements in peak anterior ground reaction force (AGRF) and AGRF integral for the paretic leg. Additionally, individual subject data showed that a majority of study participants demonstrated improvements in the primary outcome variables following the training session. This study demonstrates, for the first time, that a single session of intense, targeted post-stroke locomotor retraining can induce significant improvements in post-stroke gait biomechanics. We posit that the within-session changes induced by a single exposure to gait training can be used to predict whether an individual is responsive to a particular gait intervention, and aid with the development of individualized gait retraining strategies. Future studies are needed to determine whether these single-session improvements in biomechanics are accompanied by short-term changes in corticospinal excitability, and whether single-session responses can serve as predictors for the longer-term effects of the intervention with other targeted gait interventions.

Motor cortical functional geometry in cerebral palsy and its relationship to disability.

OBJECTIVE: To investigate motor cortical map patterns in children with diplegic and hemiplegic cerebral palsy (CP), and the relationships between motor cortical geometry and motor function in CP. METHODS: Transcranial magnetic stimulation (TMS) was used to map motor cortical representations of the first dorsal interosseus (FDI) and tibialis anterior (TA) muscles in 13 children with CP (age 9-16 years, 6 males.) The Gross Motor Function Measure (GMFM) and Melbourne upper extremity function were used to quantify motor ability. RESULTS: In the hemiplegic participants (N = 7), the affected (right) FDI cortical representation was mapped on the ipsilateral (N = 4), contralateral (N = 2), or bilateral (N = 1) cortex. Participants with diplegia (N = 6) showed either bilateral (N = 2) or contralateral (N = 4) cortical hand maps. The FDI and TA motor map center-of-gravity mediolateral location ranged from 2-8 cm and 3-6 cm from the midline, respectively. Among diplegics, more lateral FDI representation locations were associated with lower Melbourne scores, i.e. worse hand motor function (Spearman's rho = -0.841, p = 0.036). CONCLUSIONS: Abnormalities in TMS-derived motor maps cut across the clinical classifications of hemiplegic and diplegic CP. The lateralization of the upper and lower extremity motor representation demonstrates reorganization after insults to the affected hemispheres of both diplegic and hemiplegic children. SIGNIFICANCE: The current study is a step towards defining the relationship between changes in motor maps and functional impairments in CP. These results suggest the need for further work to develop improved classification schemes that integrate clinical, radiologic, and neurophysiologic measures in CP.