Search

The objective of this paper is to (1) identify from the literature a potential critical period for the maturation of the corticospinal tract (CST) and (2) report pilot data on an intensive, activity-based therapy applied during this period, in children with lesions to the CST. The best estimate of the CST critical period for the legs is when the child is younger than 2 years of age. Previous interventions for walking in children with CST damage were mainly applied after this age. Our preliminary results with training children younger than 2 years showed improvements in walking that exceeded all previous reports. Further, we refined techniques for measuring motor and sensory pathways to and from the legs, so that changes can be measured at this young age. Previous activity-based therapies may have been applied too late in development. A randomized controlled trial is now underway to determine if intensive leg therapy improves the outcome of children with early stroke. [Copyright &y& Elsevier]

Abstract: Objective: Short-interval intracortical inhibition (SICI) in leg and hand muscles was characterized in individuals with incomplete spinal cord injury (SCI) to understand how such inhibition limits corticospinal drive after spinal insult. Methods: We compared SICI during a voluntary contraction in 16 SCI and 14 control subjects, the latter group tested over a larger range of conditioning and test stimulus (CS and TS) intensities to best match the SCI data. Results: The average peak SICI in the tibialis anterior muscle was typically 3–4 times lower in the SCI subjects compared to controls. When matched for absolute TS intensity, in terms of maximum stimulator output, both U-shaped SICI recruitment curves were produced by similar CS intensities. SICI in the first dorsal interosseous muscle of the hand tended to be larger than in the ankle flexor. Conclusions: Incomplete SCI reduces SICI compared to controls, but the absolute CS intensities that produce the U-shaped SICI recruitment curves are unchanged. Significance: These findings suggest that although the relative excitability profile of cortical SICI networks is unchanged after SCI, the effective inhibition of corticospinal tract output by these neurons is reduced. [Copyright &y& Elsevier]

Abstract: Objective: Spasticity is a common complication with neurological diseases and CNS lesions. Instrumented systems to evaluate spasticity often cannot provide an immediate result, thus limiting their clinical usefulness. In this study we investigated the accuracy and reliability of the portable Neurokinetics RA1 Ridgidity Analyzer to measure stiffness of the ankle joint in 46 controls, 14 spinal cord injured (SCI) and 23 multiple sclerosis (MS) participants. Methods: Ankle stiffness measures were made twice by two raters, at speeds above and below the expected stretch reflex threshold. Ankle torque was measured with the portable device and a stationary torque motor. Inter- and intra-rater reliability was assessed with the intra-class correlation coefficient (ICC). Results: Stiffness measures with the portable and stationary devices were significantly correlated for controls and MS participants (p <0.01). Intra-rater reliability for the portable device ranged from 0.60–0.89 (SCI) and 0.63–0.67 (control) and inter-rater reliability ranged from 0.70–0.73 (SCI) and 0.61–0.77 (control). Ankle stiffness measures in SCI and MS participants were significantly larger than in controls for both slow (p <0.05) and fast movements (p <0.01), with stiffness being larger for fast compared to slow movements in SCI and MS participants (p <0.05), but not in controls (p =0.5). Conclusion: The portable device correlated well with measures obtained by a torque motor in both controls and MS participants, showed high intra- and inter-rater reliability for the SCI participants, and could easily distinguish between stiff and control ankle joints. However, the device, in its current form, may be less accurate during rapid movements when inertia contributes to stiffness and the shape of the air-filled pads did not provide a good interface with the foot. Significance: This study demonstrates that a portable device can potentially be a useful diagnostic tool to obtain reliable information of stiffness for the ankle joint. [Copyright &y& Elsevier]