Cortical electrical stimulation combined with rehabilitative training: enhanced functional recovery and dendritic plasticity following focal cortical ischemia in rats

This study assessed the behavioral and dendritic structural effects of combining subdural motor cortical electrical stimulation with motor skills training following unilateral sensorimotor cortex lesions in adult male rats. Rats were pre-operatively trained on a skilled forelimb reaching task, the Montoya staircase test, and then received endothelin-1 induced ischemic lesions of the sensorimotor cortex. Ten to 14 days later, electrodes were implanted over the peri-lesion cortical surface. Rats subsequently began 10 days of rehabilitative training on the reaching task in 1 of 3 conditions: 1. 50 Hz stimulation during training, 2. 250 Hz stimulation during training or 3. no stimulation. No significant difference in performance was found between the 250 Hz and no stimulation groups. The 50 Hz stimulation group had significantly greater rates of improvement with the impaired forelimb in comparison to 250 Hz and no stimulation groups combined. Fifty Hz stimulated animals also had a significant increase in the surface density of dendritic processes immunoreactive for the cytoskeletal protein, microtubule-associated protein 2, in the peri-lesion cortex compared to the other groups. These results support the efficacy of combining rehabilitative training with cortical electrical stimulation to improve functional outcome and cortical neuronal structural plasticity following sensorimotor cortical damage.     

Dual extradural cortical stimulation in chronic stroke patients with large infarcts: technical case report

Abstract

Objective and importance: Recent works on extradural cortical stimulation have been successful in improving neurological recovery in chronic stroke patients. On the other hand, single perirolandic stimulations are often associated with disappointing results.

Clinical presentation: We report two cases of chronic stroke in which the magnitude of infarct was too large to be improved with single perirolandic stimulation. Patient 1 had severe hemiplegia associated with large cortical infarct in the right frontoparietal area. The patient could neither stand independently or walk. Patient 2 had hemiplegia and aphasia due to cortical infarct in the left middle cerebral artery territory. Both patients had intensive rehabilitative training for more than 6 months with no beneficial results.

Intervention: Two paddle electrodes covering frontal and parietal area were implanted, followed by dual cortical stimulation with concurrent rehabilitative training in patient 1. After 6 months of stimulation, the patient could walk with a good posture. Two paddle electrodes were implanted to cover pre-motor and motor cortex in patient 2. After similar treatment, the motor function was markedly improved.

Conclusion: Dual cortex stimulation, which acts on more diffuse areas or functionally related areas, is beneficial to promote the motor recovery in chronic stroke patients with large infarcts.     

Cortical stimulation improves skilled forelimb use following a focal ischemic infarct in the rat

Abstract

Improving functional recovery following cerebral strokes in humans will likely involve augmenting brain plasticity. This study examined skilled forelimb behavior, neocortical evoked potentials, and movement thresholds to assess cortical electrical stimulation concurrent with rehabilitative forelimb usage following a focal ischemic insult. Adult rats were trained on a task that required skilled usage of both forelimbs. They then underwent an acute focal ischemic insult to the caudal forelimb area of sensorimotor cortex contralateral to their preferred forelimb. During the same procedure, they also received a stimulation electrode over the infarct area and two depth electrodes anterior to the lesion to record evoked potentials. One week following the surgery, rats received cortical stimulation during performance of the skilled task. Evoked potentials and movement thresholds were also determined. Functional assessment revealed that cortical stimulation resulted in superior performance compared to the no stimulation group, and this was initially due to a shift in forelimb preference. Cortical stimulation also resulted in enhanced evoked potentials and a reduction in the amount of current required to elicit a movement, in a stimulation frequency dependent manner. This study suggests that cortical stimulation, concurrent with rehabilitative training, results in better forelimb usage that may be due to augmented synaptic plasticity.     

The effect of locomotor training combined with functional electrical stimulation in chronic spinal cord injured subjects: walking and reflex studies

With the new developments in traumatology medicine, the majority of spinal cord injuries sustained are clinically incomplete and the proportion is likely to continue to rise. Thus, it is necessary to continue to develop new treatment and rehabilitation strategies and understand the factors that can enhance recovery of walking following spinal cord injury (SCI). One new development is the use of functional electrical stimulation (FES) device to assist locomotion. The objective of this review is to present findings from some recent studies on the effect of long-term locomotor training with FES in subjects with SCI. Promising results are shown in all outcome measures of walking, such as functional mobility, speed, spatio–temporal parameters, and the physiological cost of walking. Furthermore, the change in the walking behavior could be associated with plasticity in the CNS organization, as seen by the modification of the stretch reflex and changes in the corticospinal projection to muscles of the lower leg. In conclusion, recovery of walking is an increasing possibility for a large number of people with SCI. New modalities of treatment have become available for this population but most still need to be evaluated for their efficacy. This review has focused on FES assisted walking as a therapeutic modality in subjects with chronic SCI, but it is envisaged that the care and recovery of SCI in the early phase of recovery could also be improved.