Evaluation of post-stroke rehabilitation using neuromuscular electrical stimulation and gait training in a rat model of focal cerebral ischemia

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Evaluation of post-stroke rehabilitation using neuromuscular electrical stimulation and gait training in a rat model of focal cerebral ischemia

 

Author: Leung, Lai-yee
Title: Evaluation of post-stroke rehabilitation using neuromuscular electrical stimulation and gait training in a rat model of focal cerebral ischemia
Degree: M.Phil.
Year: 2006
Subject: Hong Kong Polytechnic University -- Dissertations.
Cerebrovascular disease -- Patients -- Rehabilitation.
Cerebral ischemia.
Neural stimulation.
Electric stimulation.
Transcutaneous electrical nerve stimulation.
Department: Dept. of Health Technology and Informatics
Pages: xvii, 139 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2059312
URI: http://theses.lib.polyu.edu.hk/handle/200/1578
Abstract: Treadmill exercise and neuromuscular electrical stimulation (NMES) were commonly used as strategies in stroke rehabilitation. Clinical studies have revealed the functional and physiological benefits of treadmill exercise in people after stroke. Recent animal studies showed that early rehabilitation (24hours after stroke) reduced brain damage in rat after stroke, but some studies showed exacerbation of infarction. The beneficial effects of early intervention of exercise on stroke are still controversial. Many studies have demonstrated that NMES improved muscle strength and gait. Functional brain imaging studies showed activation of cerebral cortex when NMES was applied in healthy subjects. The in vivo effects of NMES has not been well studied. The objective of this research was to investigate the neurological, functional and physiological effects of treadmill training and NMES in rehabilitation of ischemic stroke using a rat model. In this study, focal cerebral ischemia was induced by occluding middle cerebral artery using intraluminal suture technique in rats. A total of 55 rats were included in the study and they were assigned into sham-operated group (Sham), control group (Control), Exercise group (EX) and electrical stimulation group (ES). Two-week treadmill exercise and NMES were prescribed 24 hours after stroke to EX group and ES group respectively. Sham (without stroke) and Control groups (with stroke, but no intervention) were remained in cages for two weeks. Body weight was measured daily as an indicator of general physiological status of the rats after stroke. Postural reflexes and limb placing tests, which were used to detect the improvement in neurological deficits caused by stroke, were performed daily. Brain weight, infarction volume, brain edema index were measured to evaluate the brain damage or recovery after interventions. Wet weight of affected tibialis anterior was used to indicate muscle atrophy or growth. In the microdialysis study, cerebral spinal fluid from right hippocampus of the rats was collected in vivo before, during and after interventions on day 1, 2, 4, 7 and 14 after stroke. Concentration of aspartate, glutamate, taurine and gamma-aminobutyric acid (GABA) were obtained by high performance liquid chromatography (HPLC) with fluorescence detection. These are common excitatory (aspartate and glutamate) and inhibitory (taurine and GABA) neurotransmitters in mammalian central nervous system and they involved in many mechanisms such as cerebral ischemia and physical activities. Firstly, the results showed that treadmill exercise might facilitate functional recovery. Secondly, NMES might reduce brain damage and atrophy on ipsilesional hemisphere of the brain. It also showed significant increase in the wet weight of the stimulated muscles. Thirdly, there were increases in hippocampal glutamate and aspartate levels during interventions in Ex group, as shown by other studies. However the increases did not persist with days. Only small increases in these two neurotransmitters were observed during the first week in EX and ES groups. The increased levels were lower than the excitotoxic levels, which might not be enough to exacerbate brain damage after ischemic insults. Finally, the levels of taurine and GABA were suppressed by both interventions. In conclusion, treadmill exercise facilitated functional recovery, whereas NMES increased muscle mass on the affected side and reduce brain damage and atrophy after stroke. Moreover, natural recovery in Control group might be triggered by ischemic injury. This ischemia-induced recovery might be dominant during the 1st week after ischemic insults in all groups. In addition, temporary and small increase in glutamate and aspartate might not worsen the brain damage. Finally, taurine might play an important role in natural recovery, but not in recovery triggered by the interventions. The findings of this study contribute to further investigations on effects of different strategies of rehabilitation on ischemic injured brain and also provide scientific basis for the underlying mechanisms of motor recovery after ischemic stroke.

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