The Relation Between Injury of the Spinothalamocortical Tract and Central Pain in Chronic Patients With Mild Traumatic Brain Injury.

OBJECTIVES: Little is known about the pathogenetic etiology of central pain in patients with traumatic brain injury (TBI). We investigated the relation between injury of the spinothalamocortical tract (STT) and chronic central pain in patients with mild TBI. DESIGN: Retrospective survey. PARTICIPANTS: We recruited 40 consecutive chronic patients with mild TBI and 21 normal control subjects: 8 patients were excluded by the inclusion criteria and the remaining 32 patients were finally recruited. The patients were classified according to 2 groups based on the presence of central pain: the pain group (22 patients) and the nonpain group (10 patients). METHODS: Diffusion tensor tractography for the STT was performed using the Functional Magnetic Resonance Imaging of the Brain Software Library. Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume of each STT were measured. RESULTS: Lower FA value and tract volume were observed in the pain group than in the nonpain group and the control group (P < .05). By contrast, higher MD value was observed in the pain group than in the nonpain group and the control group (P < .05). However, no significant differences in all diffusion tensor imaging parameters were observed between the nonpain group and the control group (P > .05). CONCLUSIONS: Decreased FA and tract volume and increased MD of the STTs in the pain group appeared to indicate injury of the STT. As a result, we found that injury of the STT is related to the occurrence of central pain in patients with mild TBI. We believe that injury of the STT is a pathogenetic etiology of central pain following mild TBI.

Relation between cingulum injury and cognition in chronic patients with traumatic brain injury; diffusion tensor tractography study.

OBJECTIVES: Many diffusion tensor imaging (DTI) studies have reported an association between cingulum injury and cognition in patients with traumatic brain injury (TBI) using DTI parameters. In this study, we attempted to investigate the relation between cingulum injury and cognition in chronic patients with TBI, using the integrity of the cingulum as well as DTI parameters. METHOD: Thirty five consecutive chronic patients with TBI were recruited. The intelligence quotient (IQ) of the Wechsler Intelligence Scale and Memory Assessment Scale (MAS) was used for assessment of cognition. The patients were classified into three groups, according to continuity to the lower portion of the genu of the corpus callosum: type A-both sides of the cingulum showed intact continuity, type B-either cingulum showed a discontinuation, and, type C-both cingulums showed discontinuation. We measured the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and voxel number of both cingulums. RESULTS: The IQ and MAS scores of type A and B were significantly higher than those of type C, respectively (p < 0.05), however, we did not observe a significant difference between type A and type B (p > 0.05). A positive correlation was observed between the FA value of the cingulum, and IQ and MAS, respectively (IQ r = 0.373, p < 0.05, MAS r = 0.357, p < 0.05), and between the voxel number and MAS (r = 0.500, p < 0.05). By contrast, we observed a negative correlation between the ADC value and IQ (r = -0.353, p < 0.05). CONCLUSION: In terms of integrity to the basal forebrain and DTI parameters of the injured cingulum, DTI findings showed a close association with whole cognition and memory in chronic patients with TBI.

Limb apraxia in a patient with cerebral infarct: diffusion tensor tractography study.

We report on a patient with ideomotor apraxia (IMA) and limb-kinetic apraxia (LKA) following cerebral infarct, which demonstrated neural tract injuries by diffusion tensor tractography (DTT). A 67-year-old male was diagnosed as cerebral infarct in the left frontal cortex (anterior portion of the precentral gyrus and prefrontal cortex) and centrum semiovale. The patient presented with severe paralysis of the right upper extremity and mild weakness of the right lower extremity at onset. At the time of DTT scanning (5 months after onset), the patient was able to move all joint muscles of the right upper extremity against gravity, except for the finger extensors, which he could extend partially against gravity. The patient showed intact ideational plan for motor performance; however, his movements were slow, clumsy, and mutilated when executing grasp-release movements of his affected hand. The patient's score on the ideomotor apraxia test was 20 (cut-off score < 32). DTTs for premotor cortex fibers, supplementary motor area fibers, and superior longitudinal fasciculus of the left hemisphere showed partial injuries, compared with those of the right side, and these injuries appeared to be responsible for IMA and LKA in this patient.

Classification of cause of motor weakness in traumatic brain injury using diffusion tensor imaging.

BACKGROUND: Many studies have attempted to elucidate the causes of motor weakness in patients with traumatic brain injury (TBI). Most of these studies have focused on the specific cause of motor weakness. However, little is known about the classification and elucidation of the causes of motor weakness in consecutive patients with TBI. OBJECTIVE: To attempt to classify with diffusion tensor imaging the causes of motor weakness in patients with TBI by conducting an analysis of the injury mechanism of the corticospinal tract (CST). DESIGN: Retrospective study. SETTING: Rehabilitation department of a university hospital. Patients  We recruited 41 consecutive patients who showed motor weakness among patients with TBI admitted for rehabilitation. MAIN OUTCOME MEASURES: We classified the causes of weakness according to the injury mechanism of the CST on diffusion tensor imaging. RESULTS: Injury mechanisms of the CST were classified as follows, in order: diffuse axonal injury, 24 patients (58.5%); traumatic intracerebral hemorrhage, 9 patients (21.9%); transtentorial herniation, 6 patients (14.6%); and focal cortical contusion, 4 patients (9.8%). In patients with diffuse axonal injury, the mean number of lesions composing CST injury was 3.6 (range, 2-6) and CST injury locations were as follows: the pons (61%), the cerebral peduncle (50%), the medulla (40%), the posterior limb of the internal capsule (17%), and the corona radiata (13%). CONCLUSION: We found that diffusion tensor imaging was useful in elucidation and classification of the causes of motor weakness resulting from CST injury in patients with TBI.

Prognostic factors for motor outcome in patients with compressed corticospinal tract by intracerebral hematoma.

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.

The cortical activation effect of phonation on a motor task: a functional MRI study.

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.

Cortical reorganization of sensori-motor function in a patient with cortical infarct.

PURPOSE: We describe a patient with cortical infarct, whose sensori-motor function for the hand seemed to be reorganized into the lateral area, as demonstrated by functional MRI (fMRI). METHODS: A 59-year-old male patient presented with severe sensori-motor dysfunction of the left hand, which first occurred at the onset of an infarct in the right primary sensori-motor cortex (SM1) centered on the precentral knob. The sensori-motor function of the affected hand recovered to a normal state at 6 months from onset. fMRI was performed using the blood oxygen level-dependent technique at 1.5T with a standard head coil (at 6 months from onset). The active and passive movements were performed at the metacarpophalangeal joint using a specially equipped apparatus, and touch stimulation was applied on the dorsum of the hand using a rubber brush. RESULTS: The contralateral SM1 centered on the precentral knob was found to be activated during the active movements, passive movements, and touch of the unaffected (right) hand movements. By contrast, the lateral area of the infarcted SM1 of the right hemisphere was activated during the three kinds of stimulation of the affected hand. CONCLUSIONS: We conclude that the sensori-motor function of the affected hand seemed to have been reorganized into the lateral area of the infarcted SM1.

Motor function reorganization in a patient with a brainstem lesion: DTT, fMRI and TMS study.

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.

Cortical activation pattern of compensatory movement in stroke patients.

OBJECTIVE: Little is known about the cortical activation pattern of compensatory movement (CM) in stroke patients. We attempted to investigate the cortical activation pattern of compensatory movement in stroke patients, using functional MRI (fMRI). METHODS: Eight hemiparetic stroke patients were recruited for this study. We measured the shoulder abduction angle when each subject was simulating eating in a sitting position, which was considered as the degree of CM. The fMRI was performed at 1.5T using an elbow motor task at a frequency of 0.5 Hz. RESULTS: There was an inverse correlation between the shoulder abduction angle of the affected side and the LI (Laterality Index) (r=-0.745; p< 0.05). The shoulder abduction angle of the affected side was significantly related to the sum of activated voxels in all regions of interest (r=0.776; p< 0.05) and the activated voxels of the supplementary motor area (r=951; p< 0.05). However, we did not find any correlation between the shoulder abduction angle and the activated voxels of other brain areas. CONCLUSIONS: We demonstrated that a greater shoulder abduction angle on the affected side requires more cortical activation. Therefore, CM appears to be related to the change of the cortical motor control toward greater recruitment of cortical neurons.

Transcallosal fibers from corticospinal tract in patients with cerebral infarct.

Diffusion tensor image tractography (DTT) can visualize white matter tracts and provide a powerful vehicle with which to investigate the neural pathway at the subcortical level. We attempted to demonstrate the clinical significance of transcallosal fibers (TCF) originating from the corticospinal tract in patients with corona radiata infarct located below the corpus callosum, using diffusion tensor image tractography (DTT). Forty patients with corona radiata infarct located below the corpus callosum and 26 control subjects were enrolled in this study. We classified the DTT findings as follows: no transcallosal fiber from the CST (type A), transcallosal fiber ended in the corpus callosum or connected to the cortex of the opposite hemisphere (type B), and transcallosal fiber that descended toward the lesion after passing through the corpus callosum (type C). Type C indicated that the presence of transcallosal fibers starting from the CST of the unaffected hemisphere was significantly more prevalent in the patients, and these patients showed the poorest motor function. It seems that transcallosal fibers originated from the CST of the unaffected hemisphere, and fibers descending toward the lesion in patients with corona radiata infarct may act to compensate for motor deficits.

Brain activation pattern according to exercise complexity: a functional MRI study.

The aim of this study was to compare the areas of brain activation between complex and simple exercises in a unimanual hand and to assess the possibility of an exercise task for paretic hands following stroke. The subjects included 11 healthy right-handed volunteers. The complex exercise was a wooden ball rotation task with the unimanual hand and the simple exercise was a hand grasp task performed during a functional MRI scan. Stronger activation of the left primary sensorimotor cortex, the left premotor area, and the ipsilateral cerebellum emerged when the complex movement was performed. Ipsilateral activity was located in the primary sensory cortex and premotor area, and contralateral activity was shown in the left cerebellum. These results suggest that a unimanual ball rotation task may be appropriate for rehabilitation of a movable paretic hand in an early stage of stroke recovery, which should provide motor and sensory input using external stimuli, while the simple motor task may appropriate in a compensatory stage, and should inhibit the ipsilateral activity due to maladaptive plasticity.

Degeneration speed of corticospinal tract in patients with cerebral infarct.

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 degrees . 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.

Focal lesions of the corticospinal tract demonstrated by diffusion tensor imaging in patients with diffuse axonal injury.

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 degrees 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.

Medial reorganization of motor function demonstrated by functional MRI and diffusion tensor tractography.

PURPOSE: Peri-lesional reorganization is a motor recovery mechanism after brain injury. The object of this study was to demonstrate the peri-lesional reorganization, using functional MRI (fMRI) and diffusion tensor tractography (DTT). METHODS: Six control subjects and a 53 year-old woman with left primary sensori-motor cortex (SM1) and underlying deep white matter injury were evaluated. The patient presented with complete paralysis of the right hand after the resection of a meningioma on the left SM1. The motor function of the affected hand had recovered slowly the extent of her being able to overcome some resistance for 6 months. At 2 years after the operation, fMRI was performed at 1.5 T in parallel with timed finger flexion-extension movements in all subjects and DTT was performed only in the patient. RESULTS: The contralateral SM1 centered on the precentral knob was activated during hand movements of unaffected (left) side or control subjects. However, the medial area of the injured SM1 was activated during affected (right) hand movements. DTT of the affected (left) hemisphere originated from the medial area of the injured SM1 and descended along the medial side of injured deep white matter. CONCLUSIONS: It seems that the motor function of the affected hand was reorganized into the medial area of the injured SM1 and deep white matter in this patient.

mRNA expression of cytokines and chemokines in herniated lumbar intervertebral discs.

STUDY DESIGN: The mRNA expressions of cytokines and chemokines were assessed in herniated lumbar disc specimens. OBJECTIVES: To investigate whether the mRNAs of interleukin (IL)-1alpha, tumor necrosis factor (TNF)-alpha, RANTES, IL-8, IL-10, and transforming growth factor (TGF)-beta are expressed in surgically obtained herniated disc specimens; and to discover which of them are the predominant cytokines associated with the clinical symptoms and signs, and whether any differences in the mRNA expression exist depending on the different types of disc herniations. SUMMARY OF BACKGROUND DATA: It has been postulated that cytokines are involved in causing radicular leg pain in lumbar disc herniations. Although a few studies have been done on lumbar disc herniations concerning IL-1alpha and TNF-alpha, almost none has been carried out in the cases of the other of cytokines and chemokines. METHODS: Using a reverse transcription-polymerase chain reaction, mRNA expressions of cytokines and chemokines were investigated in herniated disc specimens. The straight leg raising test, development of radicular pain by back extension, symptom duration, pain intensity using a visual analogue scale, and herniation types were described. RESULTS: The mRNAs of IL-8, TNF-alpha, IL-1alpha, RANTES, and IL-10 were expressed in 16 (70%), 15 (65%), 9 (39%), 4 (17%), and 2 (9%) of the 23 herniated disc specimens, respectively. The mRNA of TGF-beta was expressed in 5 of 10 specimens (50%). IL-8 mRNA expression was associated with the development of radicular pain by back extension and short symptom duration (average 3.8 weeks). The mRNAs of IL-1alpha were expressed more frequently in transligamentous extensions than in subligamentous extensions, but the expression was weak. CONCLUSION: Interleukin-8 appears to be associated with development of radicular pain by back extension and to be activated on acute or subacute disc herniations. IL-8 seems to participate in the pathomechanism of nerve root inflammation in lumbar disc herniations, which implies that it may be considered a target for therapeutic intervention.