Abstract: The ipsilateral motor pathway is a normal motor control pathway and is accepted as one of the recovery mechanisms after stroke. Among the motor recovery mechanisms following stroke, the ipsilateral motor pathway from the unaffected motor cortex to the affected extremities has been the most actively researched. This mechanism is important clinically because it contributes to motor recovery in the early stages after the onset of stroke, and is related to poor motor outcome. In addition, the ipsilateral motor pathway can be manipulated by various rehabilitative interventions. We have reviewed the literature on the ipsilateral motor pathway in stroke patients…in relation to the methods of evaluation, previous studies, the underlying pathophysiologic mechanism, clinical characteristics, and rehabilitative aspects.
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Keywords: Stroke, motor recovery, brain plasticity, hemiplegia, brain
Abstract: The corticospinal tract (CST) is the major neuronal pathway that mediates voluntary movements. The preservation or recovery of the CST is mandatory for good recovery of impaired motor function in patients with a stroke. However, the role of the CST in motor recovery in stroke patients is not well-elucidated. In the current study, we reviewed the literature related to the role of the CST in motor recovery in stroke patients with respect to the following: recovery of a damaged CST, peri-lesional reorganization at the subcortical level, peri-lesional reorganization at the level of the cortex, the ipsilateral motor pathway from the…affected hemisphere to the affected extremities, and locomotor recovery.
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Keywords: Corticospinal tract, stroke, motor recovery, hemiplegia
Abstract: Detailed information about motor recovery is essential for brain rehabilitation because it enables us to establish scientific rehabilitative strategies and predict motor outcome. For this review, we summarized the literature on motor recovery of patients with traumatic brain injury (TBI) in relation to the following: epidemiology of motor weakness, mechanisms of injury that cause motor weakness, course of motor recovery, and mechanisms underlying motor recovery. The motor weakness in patients with TBI is characterized by a low incidence, decreased severity, long recovery time, and good motor outcome when comparing with cognitive or behavior problems following TBI or the motor weakness…affecting stroke patients. However, there are few studies describing the course of motor recovery and the underlying mechanisms of motor recovery. Knowledge in the course of recovery and the mechanisms of recovery can alert clinicians to obtain the salient information about the critical period for rehabilitation and the rehabilitative strategies respectively. Therefore, we suggest that further research should focus on these topics.
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Keywords: Brain injury, motor recovery, rehabilitation, hemiparesis
Abstract: The corticospinal tract (CST) is the most important motor pathway in the human brain, therefore, the accurate estimation of the CST state following brain injury would enable us to predict the motor outcome or enable accurate surgical planning. The corona radiata (CR) and the posterior limb of the internal capsule (PL) are important locations because they are related to poor motor outcome. In this study, we reviewed the available literature regarding the location of the CST at the CR and PL in the human brain. The results of this review indicate that the CST is located in the posterior portion…of the CR and PL. However, a direct comparison of the results of previous studies would be impossible because many of the previous studies did not define the exact boundary or analytic standards used to locate the CR or PL. Therefore, further complementary studies that define these in detail are warranted.
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Keywords: Corticospinal tract, motor function, diffusion tensor imaging
Abstract: The corticospinal tract (CST) is the most important neural tract for motor function in the human brain. Therefore, clarification of CST injury would be an important topic in traumatic brain injury (TBI) rehabilitation. In this review, I reviewed diffusion tensor imaging (DTI) studies on CST injuries in terms of etiology and recovery in patients with TBI. Although DTI has several unique advantages for research on CST injury in TBI, only a dozen DTI studies on this topic have been reported: etiology of CST injury (9 studies), recovery of CST injury (3 studies). As for the etiology of CST injury in…TBI, the previous studies have demonstrated the usefulness of DTI in diagnosis of CST injury in cases of diffuse axonal injury, transtentorial herniation, cerebral hemorrhage, and cortical contusion; moreover, according to the severity of TBI. The three studies on recovery of CST injury focused on recovery of a CST injured by diffuse axonal injury. In the future, we suggest an increase in the total number of DTI studies on this topic. In particular, research on recovery of CST injury should be encouraged. Moreover, studies of the various recovery mechanisms related to the CST are necessary.
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Abstract: Elucidation of the motor recovery mechanisms in stroke patients is important because such information could provide the scientific basis for stroke rehabilitation. The motor recovery mechanism after stroke, however, has not yet been clearly elucidated, but several suggested mechanisms have been proposed. These include the ipsilateral motor pathway from the unaffected motor cortex to the affected hand, peri-lesional reorganization, the recovery of a damaged lateral corticospinal tract, and contribution of the secondary motor area. Additionally, little is known about the motor recovery mechanism for patients with intracerebral hemorrhage, for locomotor recovery, and for damage at the subcortical level. Therefore, we…suggest that further research should be focused on the elucidation of motor recovery mechanisms in relation to the above topics. In the current study, we tried to review the literatures about the motor recovery mechanisms of the patients with stroke.
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Keywords: Stroke, motor recovery, functional MRI, magnetic stimulation, diffusion tensor image
Abstract: We reviewed relevant diffusion tensor imaging (DTI) studies on prediction of motor outcome in hemiparetic stroke patients in order to evaluate the following objectives: characteristics of DTI for prediction of motor outcome in stroke patients, previous DTI studies, and future direction. DTI offers the unique advantage of visualization and estimation of the corticospinal tract, which is the most important neural tract for motor function. Although prediction of motor outcome is a very important topic for clinicians, only about a dozen DTI studies have been reported on this topic. These studies can be classified into two groups: 1) studies for adoption…of DTI parameters as a potential marker for prediction of motor outcome in stroke patients, and 2) studies for analysis of the integrity of the corticospinal tract in prediction of motor outcome. In order to increase the predictability of motor outcome, studies according to the somatotopy and studies combined with transcranial magnetic stimulation are necessary. Other additional studies on optimal DTI scanning time for motor prediction will also be required.
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Keywords: Stroke, motor function, diffusion tensor imaging, hemiparesis
Abstract: Characteristics of motor recovery mechanisms are known to be linked with motor outcome in stroke. Detailed knowledge of motor outcome and recovery mechanisms in stroke allow for prediction of prognosis and provide the basis for establishment of scientific rehabilitation strategies. Thirteen previous studies with regard to motor outcome (8 studies) and the motor recovery mechanisms (5 studies) in pontine infarct were reviewed. Several motor recovery mechanisms have been reported in pontine infarct: peri-lesional reorganization, and other possible recovery mechanisms (aberrant pyramidal tract, ipsilateral motor pathway, and motor recovery via spared corticospinal tract). Previous studies on motor outcome in pontine infarct…have reported generally good outcome. This good motor outcome appears to be related to the characteristics of the motor recovery mechanisms recovered by the lateral corticospinal tract. We think that further studies on motor outcome and recovery mechanisms should be performed for clarification of various motor tracts including non-corticospinal tract, which can affect the motor outcome and recovery mechanisms in pontine infarct. In addition, the effect of rehabilitation on these topics should also be elucidated.
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Abstract: Objectives: We report on a chronic stroke patient who showed motor recovery by improvement of limb-kinetic apraxia (LKA) after undergoing intensive rehabilitation for a period of one month, which was demonstrated by diffusion tensor tractography (DTT) and transcranial magnetic stimulation (TMS). Methods: A 50-year-old male patient presented with severe paralysis of the left extremities at the onset of thalamic hemorrhage. At thirty months after onset, the patient exhibited moderate weakness of his left upper and lower extremities. In addition, he exhibited a slow, clumsy, and mutilated movement pattern during grasp-release movements of his left hand. During a one-month period of…intensive rehabilitation, which was started at thrity months after onset, the patient showed 22% motor recovery of the left extremities. The slow, clumsy, and mutilated movement pattern of the left hand almost disappeared. Results: DTTs of the corticospinal tract (CST) in both hemispheres originated from the cerebral cortex, including the primary motor cortex, and passed along the known CST pathway. The DTT of the right CST was located anterior to the old hemorrhagic lesion. TMS study performed at thirty and thirty-one months after onset showed normal and similar findings for motor evoked potential in terms of latency and amplitude of the left hand muscle. Conclusions: We think that the motor weakness of the left extremities in this patient was mainly ascribed to LKA and that most of the motor recovery during a one-month period of rehabilitation was attributed to improvement of LKA.
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Keywords: Motor recovery, stroke, diffusion tensor tractography, transcranial magnetic stimulation, apraxia, limb-kinetic apraxia
Abstract: Brain plasticity can be classified as adaptive and maladaptive. Maladaptive plasticity indicates hindered functional recovery or the development of an unwanted symptom. Although a considerable amount is known about adaptive plasticity in stroke, relatively little is known of maladaptive plasticity. In the current study, previous studies on motor function-related maladaptive plasticity in stroke are reviewed in terms of compensatory movement pattern (CMP), delayed-onset involuntary abnormal movements (IAMs), and the ipsilateral motor pathway as a motor recovery mechanism. For successful stroke rehabilitation, it is important that the characteristics of maladaptive plasticity are accurately recognized. However, there is a lack of definitive…evidence regarding the recognition of motor function-related maladaptive plasticity, although it seems that each of the three above-mentioned topics are involved. As for CMP, patients with a good neurological state as much as having a normal movement pattern, should be considered to have maladaptive plasticity, and in terms of the ipsilateral motor pathway, patients with bilateral innervations can be considered to have maladaptive plasticity. On the other hand, IAMs due to delayed neuronal degeneration should be ruled out in patients with delayed-onset IAMs. Therefore, for the accurate recognition of motor function-related maladaptive plasticity in stroke, a thorough evaluation of neurological state using brain mapping techniques is necessary, and subsequently, the prevention or intensive management of maladaptive plasticity is needed.
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Keywords: Plasticity, maladaption, adaption, stroke, compensation, motor recovery