[ARTICLE] Objective assessment of cortical activity changes in stroke patients before and after hand rehabilitation with and without botulinum toxin injection – Full Text

Abstract

Background Upper limb spasticity is a disabling condition and may result in severe functional limitation. The peripheral action of botulinum toxin (BTX) injection on spasticity is well known, but there are debates around its possible central action.
Aim The aim of this study was to assess the clinical, functional, and cortical activation outcome of two antispastic treatments for stroke of the hand and wrist. Thirty patients with upper limb poststroke spasticity were recruited in this study.
Patients and methods They were randomly allocated to two groups: group A and group B. Both groups received rehabilitation program, whereas group B received additional BTX injection. All patients were assessed at baseline and 8 weeks after treatment using the Modified Ashworth Scale, the Action Research Arm Test and Nine-Hole Peg Test, and somatosensory-evoked potential study of the median nerve.
Results Group B showed a higher percentage of change in Modified Ashworth Scale of the wrist flexors and long flexors of fingers and in Action Research Arm Test compared with group A.
Conclusion BTX injection in spastic muscles of the wrist and hand, followed by a rehabilitation program led to greater clinical and functional improvement compared with implementing the rehabilitation program alone.

Introduction

Upper limb spasticity can be disabling and can result in several functional limitations. Although some neural plasticity following stroke contributes to motor recovery, maladaptive plasticity can weaken motor function and limits the recovery. Spasticity represents an example of maladaptive plasticity [1].

Local injection of botulinum toxin-A (BTX) is the standard treatment for spasticity, particularly in poststroke patients. In addition to its peripheral action, evidence of its possible effects on central nervous systems has emerged [1].

Somatosensory-evoked potential (SEP) studies in patients with spasticity showed improvement in SEP following BTX injection, which may support the possible central action of BTX in the cerebral cortex [2],[3].[…]

Continue —> Objective assessment of cortical activity changes in stroke patients before and after hand rehabilitation with and without botulinum toxin injection Abu-Bakr OA, Nassar NM, Al-Ganzoury AM, Ahmed KA, Tawfik EA – Egypt Rheumatol Rehabil

[ARTICLE] Neural coupling of cooperative hand movements after stroke: role of ipsilateral afference – Full Text

Abstract

We investigated the role of ipsilateral ascending pathways in the neural coupling underlying cooperative hand movements of stroke subjects. Ipsi- and contralateral somatosensory evoked potentials (SSEP) were recorded following ulnar nerve stimulation during cooperative and non-cooperative hand movements. The amplitude ratio, that is, ipsilateral divided by contralateral amplitude, was highest during the cooperative task when the affected arm was stimulated, reflecting an enhanced afferent volley to the unaffected hemisphere. The presence of ipsilateral SSEP from the paretic arm was closely related with the patients’ hand function. This shows for the first time a laterality in ascending pathways after unilateral stroke and implies an involvement of the unaffected hemisphere in the control of paretic hand movements.

Introduction

Cooperative hand movements, defined as movements where the action of one hand is supported by counteraction of the other one (e.g., opening a bottle), are required in activities of daily living (ADL). These object-oriented movements are controlled by a task-specific neural coupling[1-3] which differs from that of neural networks underlying the control of non-cooperative bimanual tasks[4-11]. These bimanual separate hand movements, in contrast to cooperative hand movements studied here, do not use the neural coupling mechanism in movement control. The neural coupling is reflected in the appearance of electromyographic (EMG) reflex responses in activated forearm muscles of both sides following unilateral stimulation of ulnar nerve and activation of bilateral secondary somatosensory (S2) cortical areas in fMRI recordings[1]. These observations indicate that each hemisphere is task-specifically involved in the control of both hands during cooperative movements. The neural coupling underlying cooperative hand movements might be achieved by an involvement of ipsilateral pathways[2].

In stroke subjects, the neural coupling mechanism is preserved from the unaffected to the paretic side but defective from the affected side due to an impaired processing of afferent input[3]. For a better understanding of the compensatory role of the ipsilateral, unaffected hemisphere in movement control it is important to explore the function of ascending pathways in cooperative tasks. It is hypothesized that the strength of ipsilateral afference from the affected forearm to the unaffected hemisphere is reflected in ipsilateral somatosensory evoked potentials (SSEPs). This would indicate an involvement of the unaffected hemisphere in the control of the paretic arm/hand during cooperative movements and might determine outcome of hand function.

Continue —> Neural coupling of cooperative hand movements after stroke: role of ipsilateral afference – Schrafl-Altermatt – 2016 – Annals of Clinical and Translational Neurology – Wiley Online Library

Figure 1. Time-normalized EEG traces of post-stroke patients. Grand averages (N = 12) of the somatosensory evoked potentials (SSEPs) are shown. They were evoked during three different conditions, that is, resting (rest, A and D), non-cooperative bimanual movements (pro-sup, B and E) and cooperative hand movements (dyn-coop; C and F). Electrical stimulation of the ulnar nerve was applied at the affected (A–C) and the unaffected (D–F) arm of the stroke patients. Gray traces: contralateral potential; black traces: ipsilateral potentials.