The Recovery Mechanism Of Lower Limb’s Motor Dysfunction And Dysphagia In Brain Injury Patients

Brain injury often causes a variety of functional defects, such as hemiplegia and dysphagia and aphasia and cognitive impairments, producing a significant socio-economic burden. Clinical studies showed that rehabilitation therapy was one of the most effective treatments for these functional defects. However, there still exist many non-standard methods, which was mainly due to our little knowledge for the recovery mechanism of neurological functions after brain injury. Therefore, in the study, we mainly used bold oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) and clinical comparison study to explore the recovery mechanism of lower limb’s motor dysfunction and dysphagia in brain injury patients, which mainly consisted of five parts:1) the neural mechanism of motor imagery facilitating the lower limb’s motor function;2) the recovery mechanism of lower limb’s motor dysfunction in brain injury patients;3) the recovery characteristics of lower limb’s motor dysfunction in patients with unilateral medial prefrontal lobe lesions;4) the neural mechanism of opercular syndrome;5) the neural mechanism of the oral phase of swallowing. By these studies, we want to provide some theoretic basis for novel therapeutic methods of lower limb’s motor dysfunction and dysphagia in brain injury patients.Charpter one:the recovery mechanism of lower limb’s motor dysfunction in brain injury patients.Part one:A fMRI study of healthy volunteer executing and imagining unilateral knee flexion-extension[abstract] Objective To explore the neural substrate of executing and imagining unilateral knee flexion-extension, and to provide a theoretic basis for the motor imgery of hemiplegic lower extremity in brain injury patients. Methods To investigate the activation pattern of cortex while eight healthy volunteers executing or imagining unilateral sequential knee flexion-extension by BOLD-fMRI, and image data were analysed by microsoft SPM5. Results When subjects are executing unilateral knee flexion-extension, contralateral paracentral lobe and contralateral premotor area and right temperal gyrus and two sides of inferior parietal lobes are significantly acitvated. When subjects are imagining unilateral knee flexion-extension, significant activations are observed in contralateral premotor area and contralateral inferior parietal lobe. Paracentral lobe is not activated during imagining unilateral knee flexion-extension. Basal ganglia is not activated while executing or imagining unilateral knee flexion-extension. Conclusions Contralateral inferior parietal lobe and contralateral supplementary motor area might be the common components of the neural network of executing and imagining unilateral knee flexion-extension, imaging kneee flexion-extension can activate the neural network of executing sequential knee flexion-extension.Part two:The fMRI study of executing hemiplegic knee extension-flexion in poststroke patients.[Abstract] Objective To investigate the mechanism of hemiplegic lower extremity motor recovery in poststroke patients. Methods the difference of activation pattern between7post stroke patients and8healthy controls when executing unilateral knee sequential extension-flexion is studied by BOLD-fMRI, all image dataes were analysed by microsoft SPM5. Results When8healthy controls were executing unilateral knee flexion-extension, contralateral paracentral lobe and contralateral supplementarty motor area and right temperal gyrus and both sides of inferior parietal lobes are significantly acitvated. Ipsilateral parietal lobe BA7and BA5are significantly activated in six of seven stroke patients when excuting paretic knee flexion-extension. Conclusions nonaffected hemisphere’s compensation is a main mechanism of paretic lower extremity motor recovery in stroke patients, executing hemiplagic knee extension-flexion probably depend on the activation of BA7and BA5in nonaffected hemisphere directly.Part three:The recovery characteristics of walking and lower extremity volitional actions in patients with unilateral medial prefrontal lobe lesions[Abstract] Aim:To explore the recovery characteristics of walking and lower extremity volitional actions in patients with unilateral medial prefrontal lobe (MPFL) lesions, and determine the implications of these characteristics in order to optimize rehabilitation therapy and improve prognostic prediction. Method:We prospectively identified8patients with unilateral MPFL lesions as the medial prefrontal lobe group (MPFL group), and10patients with basal ganglia lesions as the control group, known as the basal ganglia group (BG group). All patients presented with complete contralateral hemiplegia when they were admitted to our ward. We checked their ability to walk daily. After a period of rehabilitation therapy, and when each of the two groups began to walk independently, their motor functions were assessed by hip bending and knee extension, the Fugl-Meyer scale (FM), the10-meter walk test (10MWT) and the Mini Mental State Examination (MMSE) for a total of seven times, or once every two weeks for twelve weeks.Results:After a period of rehabilitation therapy, seven patients in the MPFL group could slightly bend their affected-side hip, but could not extend their affected-side knees as instructed after regaining the ability to walking independently. In the following twelve weeks, these seven patients remained the same in terms of bending their affected-side hip and extending their affected-side knee as instructed. However, ten patients in BG group first recovered the ability to bend their affected-side hip and extend their affected-side knees as instructed, then recovered the ability to walk. Conclusion:Most patients with unilateral MPFL lesions have a dissociation between the recovery of walking and instructed actions of the lower extremities, which might be related to the neural mechanism of the rhythmic movement pattern of walking, the impairment of the planning and initiation of instructed actions by MPFL lesions, and/or MPFL lesions sparing the sensorimotor area (SMA). The neural basis of this phenomenon merits further investigation.Charpter two:The recovery mechanism of dysphagia in brain injury patients.Part one:A fMRI study of the neural mechanism of opercular syndromeObjectives:This study explored cortical lesions that may be responsible for OS with functional MRI (fMRI), and to elucidate the central neural mechanism of dysphagia in brain injury patients. Methods:fMRI was performed on8healthy volunteers, to compare the cortical activation patterns elicited by two characteristically affected motor dysfunctions in OS, namely, tapping the teeth and moving the tongue tip backwards along the palate. The activated areas common to the two tasks in the healthy volunteers as captured in fMRI images were compared with the sites of cerebral lesions in the OS patient seen on CT; fMRI images were analyzed using Statistical Parametric Mapping software.Results:The activated areas common to the two tasks were located at the bilateral rolandic opercula (ROs), and the partial precentral gyri (PCGs) adjacent to the bilateral ROs, which approximated the areas of the visible brain lesions of the patient. Conclusions:Damage to the bilateral PCGs adjacent to the ROs, or to the unilateral RO and contralateral precentral gyrus adjacent to the RO, might lead to OS.Part two:A fMRI study of the oral phase of swallowing in healthy volunteersAbstract:Objective To explore the neurophysiology mechanism of the oral phase of swallowing in healthy humans. Methods Eight healthy volunteers knocking the tooth and moving tongue tip backwards along the palate, the activation pattern of cortex was showed with functional fMRI. Image data were analysed by microsoft SPM5. Results When subjects were knocking the tooth, bilateral precentral gyruses, adjacent rolandic operculums (ROs) and supplementary motor areas (SMAs) are significantly activated. When subjects were moving tongue tip backwards along the palate, significant activations were observed in bilateral precentral gyruses, adjacent ROs, and SMAs, cerebellum tuber and cerebellum Inferior Semi-Lunar Lobule. The common activated areas during knocking the tooth and moving tongue tip backwards are located at bilateral precentral gyruses, ROs and SMAs. Conclusions Bilateral precentral gyruses and adjacent ROs and SMAs are parts of the neural network of swallowing.In conclusion, a series of experiments were conducted by fMRI and clinical comparison study in the thesis. First, we obtained three results as followed:1) imagining unilateral knee flexion-extension could activate the partial neural network of executing knee flexion-extension;2) the non-affected hemisphere is activated during moving paretic lower extremity in stroke patients; and3) most patients with unilateral MPFL lesions have a dissociation between the recovery of walking and instructed actions of the lower extremities. These results not only will be potentially helpful for developing new therapy techniques, but also help us better understanding the recovery mechanism of lower limb’s motor dysfunction in brain injury patients. Secondly, we founded that Bilateral precentral gyruses and adjacent ROs and SMAs are parts of the neural network of swallowing, and explore the neural mechanism of opercular syndrome, which provide a theoretical basis for the rehabilitational assessment and therapy of dysphagia in brain injury patients.