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OBJECTIVE: To investigate relationship between the diffusion indexes of corticospinal tract (CST) and the neurological motor outcomes in chronic pontine stroke patients. METHODS: Diffusion tensor imaging (DTI) is performed in 27 patients with chronic pontine stroke. Fractional anisotropy (FA) values along the CST area, the track number, and the CST length are measured. Neurological and motor outcomes are evaluated based on Fugl-meyer (FM), National Institutes of Health Stroke Scale (NIHSS), Barthel index (BI), and modified Rankin scale (mRS) scores. The relationships between FA ratios (rFAs) in the CST of stroke subjects and their clinical motor scores are analyzed through Spearman's correlation analysis. Then, diffusion tensor tractography (DTT) is performed to show the injury degree of CST. RESULTS: First, FA values are decreased in the infarct area, cerebral peduncle, posterior limb of the internal capsule, and precentral gyrus compared with those in the contralateral side. The number of CST is decreased in the ipsilateral side of the infarct. Second, rFAs in the cerebral peduncle, posterior limb of the internal capsule, and CST rnum correlate positively with FM scores (r = 0.824, 0.672, 0.651, p < 0.001) and negatively with mRS scores (r = –0.835, –0.604, –0.645, p≤0.001). Third, the injury degree of CST correlates negatively with FM scores (r = –0.627, p < 0.001). CONCLUSIONS: The study demonstrates that rFAs in the cerebral peduncle, posterior limb of the internal capsule, and CST rnum associate with motor outcome, suggesting that DTI may be applicable for outcome evaluation. [ABSTRACT FROM AUTHOR]

Purpose: Diffusion tensor imaging (DTI) studies indicate the structural integrity of the ipsilesional corticospinal tract (CST) and the transcallosal motor tract, which are closely linked to stroke recovery. However, the individual contribution of these 2 fibers on different levels of outcomes remains unclear. Here, we used DTI tractography to investigate whether structural changes of the ipsilesional CST and the transcallosal motor tracts associate with motor and functional recovery after stroke rehabilitation. Methods: Ten participants with post-acute stroke underwent the Fugl-Meyer Assessment (FMA), theWolf Motor Function Test (WMFT), the Functional Independence Measure (FIM), and DTI before and after bilateral robotic training. Results: All participants had marked improvements in motor performance, functional use of the affected arm, and independence in daily activities. Increased fractional anisotropy (FA) in the ipsilesional CST and the transcallosal motor tracts was noted from pre-treatment to the end of treatment. Participants with higher pre-to-post differences in FA values of the transcallosal motor tracts had greater gains in the WMFT and the FIM scores. A greater improvement on the FMA was coupled with increased FA changes along the ipsilesional CST. Conclusions: These findings suggest 2 different structural indicators for post-stroke recovery separately at the impairment-based and function-based levels. [ABSTRACT FROM AUTHOR]

Background: Huntington's disease (HD) is an autosominal dominant neurodegenerative condition that leads to progressive loss of motor and cognitive functions. Early symptoms in HD include subtle executive dysfunction related to white and grey matter loss in cortico-striatal-thalamic loops. There is no cure for HD and hence a significant need for early intervention with the potential to delay the clinical onset of the disease. Objective: The objective of the present pilot study was to devise a novel behavioural intervention involving drumming and rhythm exercises that targets early dysexecutive problems, such as difficulties in sequence and reversal learning, response speed, timing, and dual tasking. Method: One preclinical person and nine people with early to advanced stages of HD were recruited of whom five completed the two months intervention. The effects of rhythm exercise on executive function, basal ganglia volume, and white matter microstructure in the anterior corpus callosum, the anterior thalamic radiation, and the cortico-spinal tract were assessed post- relative to pre-training. Results: After two months training, improvements in executive function and changes in white matter microstructure, notably in the genu of the corpus callosum that connects prefrontal cortices of both hemispheres, were observed. No changes in basal ganglia volume were present. Conclusion: This pilot study provides novel preliminary evidence that carefully targeted behavioural stimulation in HD can result in cognitive enhancement and improvements in callosal white matter microstructure. [ABSTRACT FROM AUTHOR]

OBJECTIVES: The lateral corticospinal tract (CST) is one of the most important neuronal pathways that mediate voluntary movements in the human brain. However, little is known about the role of the lateral CST on the gait. We attempted to investigate differences in gait pattern using a motion analysis system according to the integrity of the contralateral CST, which was classified using diffusion tensor tractography (DTT) in chronic hemiparetic stroke patients. METHODS: We recruited 16 chronic hemiparetic stroke patients and 12 normal subjects for this study. DTT findings of the CST for patients were classified into two groups: group A (eight patients); the integrity of the CST was preserved, group B (eight patients) - the CST was discontinued at or below the stroke lesion. We compared variables of gait between group A, group B, and normal controls using the motion analysis system. RESULTS: Group A and the control group showed a significantly higher peak angle for ankle dorsiflexion, knee internal rotation, and hip flexion, compared with group B (p < 0.05). On the other hand, the peak angle for ankle plantarflexion/external rotation, knee flexion/abduction, and hip extension of group A and group B were significantly lower than those of the control group (p < 0.05). CONCLUSION: We found that severe injury of the contralateral CST caused decreased movement of ankle dorsiflexion, knee internal rotation, and hip flexion in chronic hemiparetic stroke patients. As a result, the circumduction and abduction gait pattern in stroke patients is closely associated with severe injury of the contralateral CST. [ABSTRACT FROM AUTHOR]

BACKGROUND: Good motor outcome after stroke has been found to correlate with increased activity in a dorsal premotor (PMd) brain circuit, suggesting that therapeutic strategies targeting this circuit might have a favorable, causal influence on motor status. OBJECTIVE: This study addressed the hypothesis that a Premotor Therapy that exercises normal PMd functions would provide greater behavioral gains than would standard Motor Therapy; and that Premotor Therapy benefits would be greatest in patients with greater preservation of PMd circuit elements. METHODS: Patients with chronic hemiparetic stroke (n = 15) were randomized to 2-weeks of Premotor Therapy or Motor Therapy, implemented through a robotic device. RESULTS: Overall, gains were modest but significant (change in FM score, 2.1 ± 2.8 points, p < 0.02) and did not differ by treatment assignment. However, a difference between Therapies was apparent when injury to the PMd circuit was considered, as the interaction between treatment assignment and degree of corticospinal tract injury was significantly related to the change in FM score (p = 0.018): the more the corticospinal tract was spared, the greater the gains provided by Premotor Therapy. Similar results were obtained when looking at the interaction between treatment assignment and PMd function (p = 0.03). CONCLUSIONS: Targeted engagement of a brain circuit is a feasible strategy for stroke rehabilitation. This approach has maximum impact when there is less stroke injury to key elements of the targeted circuit. [ABSTRACT FROM AUTHOR]

Purpose: To test whether diffusion tensor imaging could evaluate potential motor capability of patients with chronic cerebral infarction. Methods: We used constraint-induced movement therapy (CIMT) as a rehabilitation, which reveals potential motor capability. We also investigated the relationship between the outcome of CIMT and the ratio between fractional anisotropy values (rFA) in affected and unaffected sites of the corticospinal tract before CIMT. Imaging was performed in cerebral infarction patients (n = 14) and the rFA of the posterior limb of internal capsule (PLIC) was measured before CIMT. Patients were evaluated before and after CIMT using the Fugl-Meyer (F-M) assessment, Wolf Motor Function Test, Action Research Arm Test, and Motor Activity Log and association between PLIC- rFA and these scores was determined. Results: All patients showed an improvement in mobility following the 10-day CIMT session. Strong positive correlation was found only between F-M after CIMT and PLIC-rFA (r = 0.8098, p = 0.0004). A strong linear relationship was observed after CIMT. Conclusion: These data support PLIC-rFA as a new marker of the CIMT-induced improvement in motor function (F-M). [ABSTRACT FROM AUTHOR]

OBJECTIVES: Motor control of musculature of proximal and distal joints has been suggested to differ. However, no study comparing patterns of activation between movements of proximal and distal joints has been conducted. In this study, using functional near infrared spectroscopy (fNIRS), we attempted to compare patterns of cortical activation generated during movements of shoulder and hand. METHODS: Nine normal subjects were recruited. fNIRS was performed using a fNIRS system with 49 channels. Flexion-extension movements of the right shoulder or hand were performed. We measured values of oxy-hemoglobin (HbO) and total-hemoglobin (HbT) in three regions of interest: the primary sensory-motor cortex (SM1), the premotor cortex (PMC), and the prefrontal cortex (PFC). The relative activation ratio of HbO and HbT was estimated for comparison of the relative activity of the left PMC or PFC to the left SM1. RESULTS: Mean values of HbO and HbT of the left SM1, PMC, and PFC were higher during movements of the right shoulder, compared with movements of the left hand. Relative activation ratios for movements of the right shoulder (HbO: PMC-104.5%, PFC-110.9%; HbT: PMC-136.3%, PFC-200.1%) were greater than 100%, and, by contrast, less than 100% (HbO: PMC-57.5%, PFC-84.8%; HbT: PMC-88.9%, PFC-70.3%) for movements of the right hand. CONCLUSIONS: Our results appear to indicate that movements of the shoulder require greater neural recruitment than movements of the hand. In addition, the PMC and PFC appeared to have greater involvement than the SM1 in movements of the shoulder; by contrast, the SM1 appears to have greater involvement than the PMC and PFC in movements of the hand. [ABSTRACT FROM AUTHOR]

BACKGROUND: Middle cerebral artery (MCA) territory infarct is the most common type of cerebral vascular territory infarct. Accurate prediction of motor outcome is important for stroke rehabilitation. OBJECTIVES: We conducted an investigation of prognostic factors of motor outcome in patients with a large MCAterritory infarction, using diffusion tensor tractography (DTT) of the corticospinal tract (CST). METHODS: A total of 37 consecutive hemiparetic patients with a large MCA territory infarct were recruited for this study; DTT was performed within 5-30 days after onset. Patients were classified into three groups according to DTT findings: in group A - CST integrity was preserved around infarct regions, in group B - CSTs were discontinuous, and, in group C - the upper ends of CSTs did not reach infarcted regions. Fractional anisotropy (FA) ratio of the affected CST (versus the unaffected ipsilateral CST) was calculated, and evaluation of motor function was performed using the Motricity Index (MI), modified Brunnstrom classification (MBC) score, and the functional ambulation category (FAC) score at onset and at six months after onset. RESULTS: Significantly greater changes in motor function (MI, MBC, and FAC) were observed between onset and six months post-onset in group A, compared with groups B and C (p < 0.05). However, no significant difference was observed between groups B and C (p > 0.05). FA ratios showed positive correlation with six-month MIs, and scores for MBC and FAC (p < 0.05). CONCLUSIONS: Results of this study demonstrate the usefulness of early DTT findings of CSTs for prediction of motor outcome in patients with a large MCA territory infarct. [ABSTRACT FROM AUTHOR]

BACKGROUND: The corticoreticular pathway (CRP) innervates the proximal muscles of extremities and axial muscles; therefore, it is involved in postural control and gait. We report on a patient who exhibited proximal weakness due to a CRP injury, which was evaluated using diffusion tensor tractography (DTT). METHODS: A 62-year-old male patient who had been injured in a traffic accident underwent conservative management for a contusional hemorrhage in the right frontotemporal lobes, and a subdural and epidural hematoma in the right temporoparietal lobes. The patient exhibited right proximal weakness (shoulder: 3+, hip: 3+) at two weeks after onset. Findings on brain MRI revealed encephalomalactic lesions in both frontal lobes. RESULTS: Findings on DTT of the left CRP showed discontinuation at the midbrain level; in contrast, the integrities of the corticospinal tract in both hemispheres were maintained from the cerebral cortex to the medulla along the known pathway of the corticospinal tract. CONCLUSION: The proximal weakness of the right shoulder and hip observed in this patient appeared to be attributed to injury of the left CRP. [ABSTRACT FROM AUTHOR]

The main function of the corticospinal tract (CST) is control of the distal musculature used for fine movements, in contrast, the corticoreticular pathway (CRP) innervates the proximal and axial musculature. We report on a patient with an intracerebral hemorrhage (ICH) who showed recovery of an injured CST and an injured CRP by diffusion tensor tractography (DTT). The patient, a 38-year-old man, presented with severe paralysis of the right upper and lower extremities due to a spontaneous ICH in the left corona radiata and basal ganglia. When he started rehabilitation at 3 weeks after onset, he showed more severe weakness in the proximal joints (shoulder and hip joints) than distal joints (hand and ankle joints). This proximal weakness improved rapidly in parallel with distal weakness over 3 weeks of rehabilitation. DTT performed at 3 and 6 weeks post-ICH revealed that a thin left CST observed at 3 weeks thickened at 6 weeks, and that a discontinuation of the left CRP at the midbrain level at 3 weeks was restored at 6 weeks. In addition, the track volumes of the left CST and CRP increased from 221 and 244 at 3 weeks to 725 and 625 at 6 weeks. In conclusion, we demonstrated the recovery of an injured CST and an injured CRP in a patient with ICH. [ABSTRACT FROM AUTHOR]

Most of the motor recovery in stroke occurs within 3 months after stroke onset and this period has been regarded as critical for motor recovery. Little is known about the motor recovery process during the critical period of stroke. We report on a patient with intracerebral hemorrhage (ICH) who showed recovery of an injured corticospinal tract (CST) during the critical period for motor recovery. A 43-year-old woman underwent conservative management for a spontaneous ICH in the right corona radiata and basal ganglia. She presented with complete left hemiplegia at the onset of ICH. She showed continuous and slow recovery, and consequently, she was able to flex her left fingers without gravity at 6 weeks after onset and extend the left fingers without gravity at 12 weeks. The 3- and 6-week DTTs showed that the right CST was discontinued around the hematoma. However, the 12-week DTT revealed that the right CST was originated from the right primary motor cortex and descended along the CST pathway. No motor evoked potential (MEP) was evoked from the right hemisphere on the 3- and 6-week TMS study. However, on the 12-week TMS study, an MEP which had the characteristics of the CST was evoked from the right hemisphere to the left abductor pollicis brevis muscle. Our results indicate that the injured right CST had been recovered between 6 weeks and 12 weeks after ICH onset. Consequently, we believe that this case demonstrated the recovery process of a severely injured CST during the critical period for motor recovery after ICH. [ABSTRACT FROM AUTHOR]

The corticospinal tract (CST) is the most important motor tract in the human brain. The authors compared CST fibers of the fingers and toes using diffusion tensor imaging. Eleven normal healthy subjects were recruited for this study. Functional MRI stimulation was performed using finger grasp-release movements and toe flexion-extension movements (1 Hz). CST fibers of the fingers and toes were determined by selecting fibers passing through seed (the CST portion in the pons) and target regions of interest (the activation areas of the cerebral cortex during active finger and toe movements, respectively). No significant differences were observed between CST fibers of the fingers and toes in terms of fractional anisotropy, mean diffusivity, or tract volume (P> 0.05), and no differences were observed between the connectivities of CST fibers of the fingers and toes and the dorsal premotor cortex or the supplementary motor area (P>0.05). However, the connectivities between CST fibers of legs and the contralateral primary motor cortex were greater than those of CST fibers of the fingers (P< 0.05). It was found that somatotopic CST fibers of the fingers and toes did not differ in terms of diffusion tensor imaging characteristics, but that transcallosal fibers to the contralateral motor cortex were more frequent for CST fibers of the toes than for CST fibers of the fingers. [ABSTRACT FROM AUTHOR]

Clarification of the clinical characteristics of motor function in stroke patients with complete corticospinal tract (CST) injury would be of importance in stroke rehabilitation. However, this topic has not been clearly elucidated. We conducted an investigation of the clinical characteristics of motor function in chronic hemiparetic stroke patients with complete CST injury, as confirmed by transcranial magnetic stimulation and diffusion tensor imaging. Forty-one consecutive chronic hemiparetic stroke patients who showed an absence of motor evoked potential in muscles of the upper and lower extremities upon transcranial magnetic stimulation and in whom the integrity of the CST discontinued around stroke lesion on diffusion tensor imaging tractography were recruited. Mean Medical Research Council scores for distal musculature were lower than those for proximal musculature (P< 0.001). Mean Medical Research Council scores for upper extremity muscles were lower than those for lower extremity muscles (P< 0.001). The mean Motricity Index score for muscles of the upper extremities was lower than that for muscles of the lower extremities (P< 0.001). None of the patients had a functional hand; in contrast, 56% of patients were able to walk independently. We found that motor weaknesses of distal joint musculature and upper extremities were more severe than those of proximal joint musculature and lower extremities following complete injury of the CST in stroke, respectively. As a result, despite the absence of a functional hand in all patients, more than half were able to walk independently. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Little is known about recovery of the corticospinal tract (CST) after injury by transtentorial herniation (TH). We present with a patient who showed recovery of the CST after injury by TH, using diffusion tensor tractography (DTT) and transcranial magnetic stimulation (TMS). A 69-year-old female underwent craniotomy and drainage of an intracerebral hemorrhage in the left corona radiata and basal ganglia. Brain CT showed left TH and brain MRI revealed a leukomalactic lesion at the left cerebral peduncle. The patient presented with complete paralysis of the right extremities at ICH onset, but slowly recovered some function to the point of being able to move the affected extremities against gravity at about 6 months after onset. Three-week DTT showed disruption of the left CST below the cerebral peduncle; however, this disruption was recovered on 1-year DTT. Three-week TMS showed no motor evoked potential for the affected hemisphere; in contrast, motor evoked potentials that were compatible with regenerated CST were obtained from the affected hand muscle at 6 months. Using DTT and TMS in a patient with ICH, we demonstrated recovery of the CST after injury by TH. [ABSTRACT FROM AUTHOR]

Little is known about prognostic factors associated with motor outcome when the corticospinal tract (CST) was compressed by hematoma. Using diffusion tensor tractography (DTT), we attempted to investigate prognostic factors for motor outcome in patients whose affected CST was compressed by hematoma. The study included 51 consecutive severe hemiparetic patients with a hematoma involving the corona radiata and basal ganglia. Integrities of the affected CSTs were preserved to the cerebral cortex and were found to be compressed by a hematoma on DTT. Patients were classified into four groups according to the region which the CST was originated from the precentral gyrus (type A), postcentral gyrus (type B), posterior parietal cortex (type C), and premotor cortex (type D). We measured the ratios of DTT parameters between affected/unaffected hemispheres.The motor function of the affected extremities at 6-month after onset was better with the following order: DTT type A, type B, type C, and type D patients. The 6-month motor function for DTT type A patients was higher than that of DTT type D patients (p=0.008). The fractional anisotropy ratio between the affected and unaffected CST was positively correlated with the 6-month motor function of the affected extremities (Pearson's correlation coefficient, p=0.025, r=0.313). We found that motor outcome differed according to the originated area of the affected CST and the degree of injury of the affected CST in patients whose affected CST was compressed by hematoma. [ABSTRACT FROM AUTHOR]

It is well-known that sound production can affect the motor system. We investigated whether a short, loud phonation affected cortical activation caused by a motor task using functional MRI. Fifteen right-handed healthy subjects were recruited for this study. We compared the cortical activation caused by the performance of a motor task (right hand grasp-release movements) to that caused by the performance of the motor task with phonation("ah" sound). We found that performance of the motor task with phonation resulted in less activation in the primary sensori-motor cortex than did the performance of the motor task alone. It seemed that phonation during the motor task enhanced the efficiency of cortical activation compared to that caused by the motor task alone. [ABSTRACT FROM AUTHOR]

Objective: We report on a hemiparetic patient who showed a new motor pathway posterior to the lesion in the midbrain and upper pons, demonstrated by three combined method of diffusion tensor tractography(DTT)/functional MRI(fMRI)/transcranial magnetic stimulation(TMS). Methods: A 21-year-old left hemiparetic male who suffered from tuberous meningitis at the age of 12 months after birth. The evaluations were performed at 20 years after onset. Brain MRI showed focal encephalomalatic lesions~due to infarcts in right anterior thalamus, midbrain and upper pons. DTT, fMRI and TMS were performed simultaneously. Results: The contralateral primary sensori-motor cortex was activated during either affected or unaffected hand movements. DTT showed that the motor tracts descended along the known pathway of the CST, with the exception of the motor tract of the affected hemisphere, which descended along the posterior portion to the lesion in the right midbrain and the pons, and then rejoined the CST in the mid-pons. The TMS results suggested that the motor tract of the affected hemisphere had the characteristics of a CST. Conclusion: We believe that the motor function of the affected hand in this patient had been recovered through the pathway posterior to the lesion in the midbrain and upper pons. [ABSTRACT FROM AUTHOR]

Diffusion tensor imaging (DTI) can be useful in detecting corticospinal tract (CST) injury at the subcortical white matter level. In the current study, we attempted to investigate the incidence and distribution of CST injury in patients with diffuse axonal injury (DAI), using DTI. Fourteen patients who showed motor weakness without any specific lesion along the CST pathway on conventional brain MRI, and twelve age-matched, normal healthy control subjects were recruited. DTI was performed using 1.5 T with a synergy-L Sensitivity Encoding (SENSE) head coil. Fractional anisotropy was measured using the region of interest method. A CST injury was defined as the FA value of a certain area being decreased two standard deviations below that of normal controls. All 14 patients had more than one lesion at the CST injury, and the mean number of CST injuries was 3.6 (range: 2–7). The CSTs were involved at the following locations: the pons (61%), the cerebral peduncle (39%), the corona radiata (21%), the medulla (14%), and the posterior limb (11%). The pons was the most prevalent area of CST injury in patients with weakness caused by DAI at the subcortical level. We found that DTI is a useful technique for detecting a DAI of the CST at the subcortical level. [ABSTRACT FROM AUTHOR]

There have been no studies on motor recovery in severe quadriplegic patients with traumatic brain injury (TBI) resulting from combined causes of weakness; this type of patient is often seen in rehabilitation clinics. We report on a quadriplegic patient who showed long-term motor recovery from severe weakness caused by a diffuse axonal injury (DAI) on the brainstem and a traumatic intracerebral hemorrhage (ICH) on left cerebral peduncle, as evaluated by diffuse tensor imaging (DTI) and functional MRI (fMRI). A 17-year-old male patient presented with quadriparesis at the onset of TBI. Over the 28-month period following the onset of the injury, the motor function of the four extremities slowly recovered to a range that was nearly normal. Two longitudinal DTIs (at 11 and 28~months from onset) and fMRI (at 28~months) were performed. Fractional anisotropy and an apparent diffusion coefficient were measured using the region of interest method, and diffusion tensor tractography was conducted using a DTI/fMRI combination. Fractional anisotrophy values in the brainstem, which were markedly decreased on the 11-month DTI, were increased on the 28-month DTI. On the fMRI performed at 28 months, the contralateral primary sensori-motor cortex was activated by the movement of either the right or left hand. Diffusion tensor tractography showed that fiber tracts originating from the motor-sensory cortex passed through the known corticospinal tract pathway to the pons. It seems that the weakness of this patient recovered due to the recovery of the damaged corticospinal tracts. [ABSTRACT FROM AUTHOR]

Diffusion tensor tractography (DTT) is useful for elucidating the status of the corticospinal tract (CST). The purpose of this study was to investigate the usefulness of DTT for determining the causes of motor weakness in patients with traumatic brain injury (TBI). Five patients with TBI were recruited for this study. DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding (SENSE) head coil. DTT was obtained with termination criteria of FA < 0.2 and an angle change > 45°. On the DTT of patient 1, who had diffuse axonal injury, the focal lesion was detected in the left pons, and was not detected on routine brain images. In patients with deep cerebral hemorrhage, the integrity of the CST of patient 3 was preserved, although the lesion was more extensive than that of patient 2, who showed severe degeneration with the disruption of the CST at the lesion site. In patient 4, the integrity of the left CST was disrupted by a left transtentorial herniation. Although the CST of the affected hemisphere was connected at the cortex level in patient 5, who had a cortical contusional hemorrhage, the motor function of the lower extremity was worse than that of the upper extremity according to the involvement of the somatotopic area of the primary motor cortex. DTT would be useful in elucidating the causes of motor weakness in patients with TBI at the subcortical level, including conditions such as diffuse axonal injury, deep intracerebral hemorrhage, and transtentorial herniation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The diffusion tensor tractography (DTT) allows the corticospinal tract(CST) to be visualized at the subcortical level and functional MRI (fMRI) is capable of precisely identifying activation sites at the cortex. Therefore, it seems that combined DTT/fMRI would allow more accurate evaluation of the state of the CST. We have attempted to demonstrate cortical reorganization in a patient with cortical hemorrhage using DTT analyzed by fMRI activations. Six normal subjects and a 12-year-old female patient with a hemorrhage in the left fronto-parietal cortex were recruited. fMRI was performed at 1.5-T with timed hand grasp-release movements, and DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding head coil. Three-dimensional reconstructions of the fiber tracts were obtained using the fMRI activation as the seed region of interest and the CST area of the anterior pons as the target region of interest. The tract of the affected hemisphere originated from the lateral area of the injured precentral knob and descended along the known corticospinal tract pathway. It seems that the motor function of the affected hand was reorganized into the lateral area of the injured precentral knob. Therefore, these combined modalities would be helpful in elucidating the state of the CST. [ABSTRACT FROM AUTHOR]

Objectives: Diffusion tensor image tractography (DTT) could be useful for exploring the state of the corticospinal tract (CST) at the level of the subcortical white matter. The purpose of this study was to demonstrate the speed of degeneration of the CST in patients with cerebral infarct, using DTT. Design: Two patients with middle cerebral artery territory infarct were recruited for this study. DTT was performed 5 times with an interval of 7 days, starting at 2 days after onset, using a 1.5-T system with a synergy-L Sensitivity Encoding head coil. The termination criteria used were fractional anisotrophy < 0.3, 0.2, 0.1, respectively, and an angle change > 45°. Results: Detection of CST degeneration began at the 9 day DTT in both patients. The most rapid CST degeneration was noted for 7 days at 16 days from onset. We did not detect any tract in the affected hemisphere of both patients at the 23-day DTT. Conclusions: We demonstrated that CST degeneration begins before 9 days from onset and progresses rapidly in patients with middle cerebral artery territory infarct. It seems that the CST degeneration began earlier than expected. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study is to identity the recovery process of the corticospinal tract with diffuse axonal injury (DAI) using diffusion tensor imaging (DTI). Design: A 47-year-old female patient and six age-matched control subjects were evaluated. The patient presented with quadriparesis (more severe in the right extremities than the left ones) due to DAI at the onset of traumatic brain injury. Over the 24-month period following the onset of the injury, motor function of the four extremities slowly recovered to range which was close to normal. Two longitudinal DTIs were acquired from the patient (at 10 weeks and 24 months from onset) and from the control subjects. Fractional anisotropy (FA) and an apparent diffusion coefficient were measured using the region of interest (ROI) method. Results: On the 10-week DTI, FAs of ROIs of the brainstem in both hemispheres of the patient were significantly lower than those of the control subjects. Compared to normal controls, the patient showed significantly increased FA in both sides of the brainstem at 24 months after the onset, which occurred in parallel with the improvement in motor function. Conclusions: Recovery in this patient could be attributed to the recovery of the corticospinal tract with diffuse axonal injury. [ABSTRACT FROM AUTHOR]

Transcranial Electrical Stimulation (TES) is an important procedure in intraoperative motor monitoring. When neurosurgery is performed at certain difficult locations within the central nervous system (CNS), TES evaluates CNS functions during surgical manipulations to prevent post-operative complications. In TES, electrical stimulation is provided to the motor cortex through electrodes placed on the scalp, generating action potentials which travel through the nervous system. Despite widespread use, the sites of activation (AP generation) within the brain are not well understood. We have integrated computational and neurophysiologic models including a 3D volume conduction head model computed using the finite element method, a realistic corticospinal tract (CST) model, and a geometry-specific axon activation model for the CST to predict the sites of activation along the CST as a function of electrode placement and stimulation voltage, which have been verified by epidural recordings. We then develop a simple meshing and rendering algorithm to display the activating function along the CST. We have found that the AP generation appears closely linked to regions of high CST curvature. Our model and rendering algorithm provide a window to visualize the effects of TES in the brain. [ABSTRACT FROM AUTHOR]

Objectives: Diffusion tensor imaging (DTI) with fiber tractography (FT) could be useful for exploration of the state of the corticospinal tract (CST) at the subcortical white matter level. The purpose of this study was to demonstrate focal lesions of the CST in patients with diffuse axonal injury (DAI), using DTI with FT. Design: Two patients with DAI and six normal control subjects were recruited to this study. DTI was performed using 1.5-T with a synergy-L Sensitivity Encoding (SENSE) head coil. Fractional anisotropy (FA) and apparent diffusion coefficients (ADC) were measured using a region of interest (ROI) method. FTs were obtained with FA <0.3 and an angle change >45° as termination criteria. Results: On the DTI with FT, the focal lesions, which could not observed using routine brain MRI, were detected in the left brainstem of patient 1 and in the right pons and the left and right medulla of patient 2. The patients showed significantly decreased FA values in the focal lesions compared to normal controls. Conclusions: DTI with FT demonstrated focal lesions at the brainstem that had not been revealed by conventional brain MRI; these focal lesions explained the weaknesses of the patients. We conclude that DTI with FT may be a useful modality for use in investigating the status of CST in patients with DAI. [ABSTRACT FROM AUTHOR]

Purpose: We hypothesized that diffusion tensor imaging (DTI) could be useful for exploring corticospinal tract (CST) regeneration if longitudinal changes of diffusion anisotropy can be detected. In this study, we explored the recovery of a CST partially damaged by intracerebral hematoma in a patient by DTI. Methods: A 61-year-old female patient and six age-matched control subjects were evaluated. The patient presented with complete paralysis of the left extremities, which occurred at the onset of a spontaneous intracerebral hemorrhage (ICH) in the right corona radiata and internal capsule. Over the five-month period following onset, motor function of the affected extremities slowly recovered to the normal range. Two longitudinal DTIs were acquired from the patient (at 3 weeks and 5 months from onset) and one DTI from the control subjects. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured using a region of interest (ROI) method. Results: On the 3-week DTI, FA values of ROIs in the ICH regions in the affected hemisphere were significantly lower, and ADC values of ROIs in the same areas were significantly higher than those of the control subjects (p<0.002). However, both mean FA and ADC values of the affected hemisphere in the 5-month DTI showed no significant differences versus those of the control. [ABSTRACT FROM AUTHOR]