Changes of the corticospinal tract in the unaffected hemisphere in stroke patients: A diffusion tensor imaging study.

We investigated changes of the corticospinal tract (CST) in the unaffected hemisphere according to severity of the CST injury, using diffusion tensor imaging (DTI). According to the severity of the CST injury in the affected hemisphere, the stroke patients showed different aspects of fiber volume increment of the CST in the unaffected hemisphere; the fiber volume was increased in the early phase in patients with mild injury of CST and later phase in patients with severe injury of CST.

Characteristics of injury of the corticospinal tract and corticoreticular pathway in hemiparetic patients with putaminal hemorrhage.

BACKGROUND: No study on the characteristics of injury of the corticospinal tract (CST) or corticoreticular pathway (CRP) in patients with putaminal hemorrhage has been reported. In this study, using diffusion tensor tractography, we attempted to investigate the characteristics of injury of the CST and CRP in hemiparetic patients with putaminal hemorrhage. METHOD: Fifty seven consecutive patients with putaminal hemorrhage and 57 healthy control subjects were recruited for this study. Diffusion tensor imaging was performed during the early period (8 ~ 30 days) after onset. We defined injury of the CST or CRP in terms of the configuration (discontinuation of a neural tract) or abnormal DTT parameters (the fractional anisotrophy value or fiber number was more than two standard deviations lower than that of normal control subjects). The Motricity Index, the modified Brunnstrom Classification, and the Functional Ambulation Categories were used for evaluation of motor function. RESULTS: Among 57 patients, injury of the CST was found in 41 patients (71.9%) and injury of the CRP was found in 50 patients (87.8%), respectively, and 37 patients (64.9%) had injury of both the CST and CRP. All three motor functions of patients with injury of both the CST and CRP were significantly lower than those of patients with injury of either the CST or CRP (p < 0.05). CONCLUSION: Our results indicate that the putaminal hemorrhage frequently accompanies injury of both the CST and CRP, and the CRP appears to be more vulnerable to putaminal hemorrhage than the CST. These findings suggest the necessity for evaluation of both the CRP and the CST in patients with putaminal hemorrhage.

Diffusion tensor imaging findings of optic radiation in patients with putaminal hemorrhage.

OBJECTIVES: Little is known about optic radiation (OR) injury in intracerebral hemorrhage (ICH). We attempted to investigate OR injury in patients with ICH by diffusion tensor imaging (DTI). METHODS: Forty-three consecutive patients with putaminal hemorrhage and 40 normal healthy control subjects were recruited. DTI data were acquired at the beginning of rehabilitation (average 34 days after onset). DTI-Studio software was used to reconstruct the OR. Fractional anisotropies (FA) and fiber numbers of the ORs were measured. FA values and fiber numbers of affected ORs were described as abnormal when they were more than 2.5 SD lower than those of normal controls. RESULTS: Thirty (70%) of the 43 patients showed an OR abnormality in the affected hemisphere. In 13 (30%) patients, the affected OR was disrupted or nonreconstructable. On the other hand, of the 20 patients with preserved OR integrity, 14 (33%) had a low FA value and 3 (7%) a low FA and fiber number. The other 13 (30%) of the 43 patients had no abnormal OR findings. CONCLUSION: Seventy percent of patients showed any abnormality of OR in the affected hemisphere on DTI. This result suggests that patients with putaminal hemorrhage are at high risk of OR injury.

Prediction of motor outcome based on diffusion tensor tractography findings in thalamic hemorrhage.

OBJECTIVES: Little is known about the usefulness of diffusion tensor tractography (DTT) findings of the corticospinal tract (CST) in terms of predicting motor outcome after thalamic hemorrhage. We investigated the predictive value of DTT for motor outcome in patients with thalamic hemorrhage. METHODS: Twenty-one patients were recruited; DTTs were obtained within 7-30 d of thalamic hemorrhage. We determined fractional anisotropies (FAs), tract numbers, and tract lengths of CSTs and calculated affected CST versus unaffected CST ratios for each value. In addition, patients were classified into two groups; a DTT type A group, in which the CST was preserved around the hematoma, and a DTT type B group, in which the CST was interrupted. Six months after thalamic hemorrhage, motor functions of affected sides were evaluated using upper Motricity Index (MI), lower MI, total MI, the modified Brunnstrom classification (MBC) and functional ambulation category (FAC). RESULTS: DTT parameters of CSTs, that is, FA ratios, tract number ratios and tract length ratios of affected/unaffected CSTs were found to be positively correlated with 6-month upper MIs, lower MIs, total MIs, MBCs and FACs. In addition, all motor function scores at 6 months after onset were higher in the DTT type A group than in the DTT type B group. CONCLUSIONS: Early DTT evaluation of CSTs appears to be useful for predicting motor outcomes of affected extremities at chronic stage in patients with thalamic hemorrhage.

The effects of hydrocephalus on the periventricular white matter in intracerebral hemorrhage: a diffuser tensor imaging study.

OBJECTIVES: Many diffusion tensor imaging (DTI) studies have described the effects of hydrocephalus on periventricular white matter in patients with normal pressure hydrocephalus. However, little is known about hydrocephalus following stroke. We investigated the effect of hydrocephalus on periventricular white matter in patients with hydrocephalus after an intracerebral hemorrhage (ICH) using DTI. METHODS: Fourteen patients with ICH and hydrocephalus, and 17 age- and sex-matched normal control subjects were recruited. DTI parameters were estimated in six regions of interest (ROIs) in periventricular white matter: the anterior corona radiata, the posterior corona radiata, the genu of the corpus callosum, the splenium of corpus callosum, the anterior limb of the internal capsule, and the posterior limb of the internal capsule. RESULTS: Mean fractional anisotropy of the anterior corona radiata in patients was significantly higher than in controls (p < 0.05), but apparent diffusion coefficient (ADC) was not different in the two groups (p > 0.05). No significant differences between fractional anisotropies and ADCs were observed in the other five ROIs (p > 0.05). CONCLUSIONS: The anterior corona radiata was found to be more compressed by hydrocephalus than the other five regions of periventricular white matter examined in patients with hydrocephalus following ICH. It is believed that the results of the present study will be useful for the diagnosis and management of hydrocephalus following stroke.

Evidence of corticospinal tract injury at midbrain in patients with subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Clear elucidation of the exact pathophysiological mechanisms of motor weakness in patients with subarachnoid hemorrhage has not yet been achieved. We attempted to investigate injury to the corticospinal tract in patients with subarachnoid hemorrhage using diffusion tensor imaging. METHODS: Twenty-two patients with subarachnoid hemorrhage and 24 control subjects were recruited for this study. DTI-Studio software was used for reconstruction of the corticospinal tract. We measured fractional anisotropy and apparent diffusion coefficient values at 5 regions of interest along the corticospinal tract pathway including: the corona radiata, the posterior limb of the internal capsule, the upper midbrain, the midpons, and the upper medulla. RESULTS: Fractional anisotropy value for the midbrain region of interest was lower in the patient group compared with the control group without change of apparent diffusion coefficient value (P<0.05). By contrast, fractional anisotropy and apparent diffusion coefficient values of the other 4 regions of interest were not different between the patient and control groups. CONCLUSIONS: Injury of the corticospinal tract at the midbrain was observed in patients with subarachnoid hemorrhage. Injury of the corticospinal tract at the midbrain appears to be one of the various pathophysiological mechanisms for motor weakness after subarachnoid hemorrhage.

Neural connectivity of the pedunculopontine nucleus in relation to walking ability in chronic patients with intracerebral hemorrhage.

OBJECTIVES: As the mesencephalic locomotor center, the pedunculopontine nucleus (PPN) is known to be involved in control of locomotor function. We investigated neural connectivity of the PPN in relation to walking ability in chronic patients with spontaneous intracerebral hemorrhage. METHODS: Forty-three consecutive chronic patients with subcortical hemorrhage and 20 healthy control subjects were recruited. A seed region of interest was manually drawn on the PPN and connectivity of the PPN was measured. RESULTS: In the affected hemisphere, connectivity with the ipsilesional cerebellar locomotor center and connectivity with the contralesional pontine locomotor center were decreased in patients who could not walk, compared with patients who could walk and normal controls (p < 0.05). CONCLUSIONS: Connectivity between the PPN and ipsi-lesional cerebellum locomotor center and contralesional pontine locomotor center in the affected hemisphere appears to be related to walking ability.

Injury of fornix in patients with intracerebral hemorrhage.

OBJECTIVES: Many diffusion tensor tractography (DTT) studies have reported on fornix injury in various diseases. However, there has been no DTT study on fornix injury by intracerebral hemorrhage (ICH). We attempted to investigate fornix body injury in patients with ICH, using DTT. METHODS: We identified 58 consecutive stroke patients using the following criteria: (1) first-ever stroke, (2) age: 45-65 years, (3) hemorrhage confined within the corona radiata and basal ganglion level, (4) an available DTT scan performed during the early stage of ICH (1-5 weeks after onset). Among 58 consecutive patients, we identified six patients who showed disruption at the fornix body. RESULTS: Following ICH, 10.7% of patients revealed complete disruption of the fornix body on DTT. Results from DTT of the fornix showed disruption in anterior and posterior portions of the fornix body in three patients, in the anterior portion of the fornix body in two patient, and in the posterior portion of the fornix body in one patient. CONCLUSIONS: We report on six patients who showed complete disruption of the fornix body following ICH. It is our belief that the fornix of patients with ICH could be evaluated using DTT.

Contribution of the pedunculopontine nucleus on walking in stroke patients.

OBJECTIVES: We attempted to investigate changes of the pedunculopontine nucleus (PPN) according to walking ability in chronic stroke patients, using diffusion tensor imaging (DTI). METHODS: 55 consecutive chronic stroke patients who were not able to walk due to injury of the corticospinal tract (CST) at stroke onset and 22 age-matched normal control subjects were recruited. We measured the values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the PPN and assessed the walking ability of each patient. RESULTS: In patients who were able to walk independently, the FA value of the PPN in the affected hemisphere was increased without change of the ADC value (p < 0.05). Increase of the FA value was positively correlated with the degree of walking ability (p < 0.05). In contrast, the ADC value was increased in the affected hemisphere of patients who could not walk, without change of the FA value (p < 0.05). This increase of the ADC value was negatively correlated with the degree of walking ability (p < 0.05). CONCLUSION: We found that the neuronal activity of the PPN in the affected hemisphere was increased in stroke patients who were able to walk independently. Therefore, we think that the PPN in the affected hemisphere contributed to walking ability in stroke patients with CST injury.

Periventricular white matter injury by primary intraventricular hemorrhage: a diffusion tensor imaging study.

OBJECTIVES: Intraventricular hemorrhage (IVH) in adult stroke patients is known to be an independent risk factor for poor functional outcome. Using diffusion tensor imaging (DTI), we attempted to investigate the effect of IVH on the white matter. METHODS: We recruited 10 consecutive patients with IVH and 18 age- and sex-matched control subjects. Using a 1.5-T Philips Gyroscan Intera system, DTI data was acquired at an average of 84 days (range: 38-149) after IVH onset. We measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values at the fornix, corpus callosum (CC), corona radiata (CR), and posterior limb of the internal capsule (PL). In addition, integrity and fiber number were measured for the fornix. RESULTS: DTI revealed disruption of the fornix in all patients. FA values showed a decrease in the fornix, CC, and CR; in contrast, the ADC value showed an increase in the CC, without changes in the fornix or CR. Fiber number of the fornix also decreased. However, no change was observed in the PL. CONCLUSIONS: We found periventricular white matter (fornix, CC, and CR) injury following IVH. We think that this result would be helpful in the establishment of management strategies for patients with IVH.

Transpontine connection fibers between corticospinal tracts in hemiparetic patients with intracerebral hemorrhage.

OBJECTIVES: A connection of fibers between corticospinal tracts (CSTs) at the pons, originating from the CST of the affected hemisphere, has been observed in hemiparetic patients with stroke. The authors investigated the incidence and the clinical significance of transpontine connection of fibers (TCFs) in hemiparetic patients with intracerebral hemorrhage (ICH), using diffusion tensor tractography (DTT). SUBJECTS AND METHODS: Forty-two patients with ICH with weakness of the affected extremities at the time of DTI scanning and 41 age-matched control subjects were recruited. TCFs were classified into three types according to severity: type A - no TCF extending to the opposite hemisphere, type B - a TCF crossing to the opposite hemisphere and ending at the subcortical level, and type C - a TCF crossing the pons and ascending to the cortex of the opposite hemisphere. RESULTS: TCFs originating from the CST in affected and unaffected hemispheres were significantly more prevalent among patients than controls (both p < 0.05). In addition, TCF severity was found to be closely related to motor function reduction in affected extremities (p < 0.05) and to extent of CST injury in affected hemispheres (p < 0.05). CONCLUSIONS: TCF appears to represent a compensatory mechanism associated with motor weakness or CST injury in patients with ICH.

Corticospinal tract change in the unaffected hemisphere at the early stage of intracerebral hemorrhage: a diffusion tensor tractography study.

OBJECTIVES: Contribution by the unaffected hemisphere is one of the motor recovery mechanisms following stroke. We attempted to investigate changes in the corticospinal tract (CST) in the unaffected hemisphere at the early stage in patients with intracerebral hemorrhage (ICH), using diffusion tensor tractography (DTT). SUBJECTS AND METHODS: Fifty-three consecutive hemiparetic patients and 40 age- and sex-matched control subjects were enrolled. DTT was performed using a 1.5-tesla system at the early stage of ICH (7-28 days after onset). We measured the fiber number, fractional anisotropy and apparent diffusion coefficient of CST tractography in the unaffected hemisphere, and assessed the motor function of the affected extremities. RESULTS: The fiber number of the CST in the unaffected hemisphere of the patient group was higher than that of the control group (p = 0.000). In contrast, the fractional anisotropy value was lower than that of the control group (p = 0.018). However, there were no significant differences in the apparent diffusion coefficient values between the 2 groups (p = 0.654). CONCLUSIONS: We demonstrated that the CST in the unaffected hemisphere was changed at the early stage in patients with ICH, using DTT.

Difference of recovery course of motor weakness according to state of corticospinal tract in putaminal hemorrhage.

OBJECTIVES: We investigated differences in recovery course of motor weakness according to the state of the corticospinal tract (CST) in putaminal hemorrhage, using diffusion tensor tractography (DTT). METHODS: We recruited 36 patients with complete weakness of the affected extremities at onset. The patients were classified into two groups according to the findings of DTT for the CST at chronic stage: group A- preserved integrity of the CST around the lesion, and group B- discontinued integrity of the CST. Motor function of the affected extremities was measured over a six month period using the Motricity Index (MI). RESULTS: The MI scores differed significantly each month, except at the onset, between group A and group B (p<0.05). In both groups, we observed significant increases between onset and one month, between one month and two months, between two month and three months, and between three months and four months (p<0.05). However, there were no significant increases after four months (p>0.05). The degree of difference between months was as follows: onset ∼1 month, 1 month ∼2months, 2 months ∼3months, and 3 months ∼4months. CONCLUSIONS: Patients with preserved integrity of the CST showed better motor function than patients with discontinued integrity of the CST. In both groups, significant motor recovery was achieved during the first four months after onset. In addition, the most rapid motor recovery occurred during the first month and then decreased gradually with the passage of time.

Injury of the corticoreticular pathway in subarachnoid haemorrhage after rupture of a cerebral artery aneurysm.

OBJECTIVE: Several studies have reported on injury of the corticoreticular pathway in patients with stroke and traumatic brain injury. However, little is known about injury of the corticoreticular pathway in patients with subarachnoid haemorrhage. The aim of the current study was to investigate corticoreticular pathway injury in patients with subarachnoid haemorrhage. DESIGN: Comparative study. SUBJECTS: Among 137 patients with subarachnoid haemorrhage, 17 patients with motor weakness who showed intact integrity of the corticospinal tract were recruited. METHODS: Motricity Index was used for measurement of motor function. The fractional anisotropy value, apparent diffusion coefficient value, fibre volume, and integrity of the corticoreticular pathway were used for the diffusion tensor imaging parameters. RESULTS: Twelve (70.6%) of 17 patients and 18 (52.9%) of 34 hemispheres showed a discontinuation of the corticoreticular pathway at the midbrain level. The contralateral shoulder, hip, and lower extremity of the discontinued corticoreticular pathway showed lower motor functions, in comparison with those of the contralateral side of the intact corticoreticular pathway (p < 0.05). By contrast, the Motricity Index for distal joint, upper and total Motricity Index were not different irrespective of the state of the corticoreticular pathway (p > 0.05). CONCLUSION: Corticoreticular pathway injury is common in patients with motor weakness after subarachnoid haemorrhage, and it appears to be related to weakness in the contralateral shoulder, hip and lower extremity.

Injury of the mammillothalamic tract in patients with subarachnoid haemorrhage: a retrospective diffusion tensor imaging study.

OBJECTIVE: Few studies have reported on injury of the mammillothalamic tract (MTT) in patients with stroke. However, no study in patients with subarachnoid haemorrhage (SAH) has been reported. Using diffusion tensor tractography, we attempted to investigate injury of the MTT in patients with SAH. METHODS: We recruited 16 patients with SAH and 15 control participants. DTI was obtained at 5.7±1.5 weeks after onset and reconstruction of the MTT was performed using the probabilistic tractography method. The fractional anisotropy (FA) value and tract number of the MTT and the Mini-Mental State Examination (MMSE) score were determined. Values of FA and tract volume showing a decrement of more than two SDs that of normal control were defined as abnormal. RESULTS: The FA value and tract volume in the patient group were significantly lower than those in the control group (p<0.05). In addition, MMSE showed strong (r=0.67, p=0.005) positive correlation with tract volume without correlation with FA. In the individual analysis, 16 MTTs of 32 MTTs in 16 patients showed abnormalities of the MTT in terms of the FA value, the tract volume or the presence of a reconstructed MTT. As a result, 10 (62.5%) of 16 patients showed abnormality of the MTT in at least one hemisphere. CONCLUSIONS: We found that patients with SAH showed injury of the MTT and this injury showed correlation with cognitive dysfunction.

Injury of the cingulum in patients with putaminal hemorrhage: a diffusion tensor tractography study.

OBJECTIVES: Little is known about the pathophysiological mechanisms of cognitive impairment in patients with putaminal hemorrhage (PH). Using diffusion tensor tractography, we investigated injury of the cingulum in patients with PH. METHODS: We recruited 63 patients with PH, who were classified according to three groups, based on integrity of the cingulum to the lower portion of the genu of the corpus callosum: group A; preserved integrity, group B; discontinuation of integrity in the affected hemisphere, and group C; discontinuation of integrity in both hemispheres. RESULTS: Thirty four patients (54.0%) belonged to group A, 16 patients (25.4%) to group B, and the remaining 13 patients (20.6%) to group C. Regarding the Mini-Mental State Examination, significant differences were observed between group A and group C, and between group B and group C without significant difference between group A and group B (p < 0.05). In terms of the volume of hematoma, significant differences were observed among the three groups (p < 0.05). Regarding the most anterior point of the hematoma, significant differences were observed between group A and groups B and C (p < 0.05); in contrast, regarding the most point of hematoma, significant differences were observed between group C and groups A and B, respectively (p < 0.05). CONCLUSION: We found that the anterior cingulum is vulnerable to PH. Therefore, our results suggest the necessity for evaluation of the cingulum in patients with PH particularly if the hematoma is large or close to the anterior margin or midline of the brain.

Recovery of an injured corticospinal tract during a critical period in a patient with intracerebral hemorrhage.

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.

Injuries of the cingulum and fornix after rupture of an anterior communicating artery aneurysm: a diffusion tensor tractography study.

BACKGROUND: After rupture of an anterior communicating artery (ACoA) aneurysm, the anterior cingulum and the fornix can be vulnerable to injury. However, very little is known about this topic. OBJECTIVE: To investigate injuries of the cingulum and fornix in patients with an ACoA aneurysm rupture with diffusion tensor tractography. METHODS: Eleven consecutive patients with an ACoA aneurysm rupture and 11 age- and sex-matched normal control subjects were recruited. Diffusion tensor imaging was scanned at an average of 54.1 days (range, 29-97 days) after onset of ACoA aneurysm rupture. RESULTS: We found that 6 (54.5%) and 7 (63.6%) of 11 patients revealed no trajectory of the anterior cingulum and the fornical body on diffusion tensor tractography, respectively. In terms of diffusion tensor imaging parameters, we found that the fractional anisotropy value and tract volume of the cingulum and fornix were decreased (P < .05) and that mean diffusivity values were increased (P < .05), except for those of the left fornix, which showed no difference (P > .05). CONCLUSION: We found injuries of the cingulum and fornix in patients with an ACoA aneurysm rupture. It is our belief that sustained memory impairment of patients with an ACoA aneurysm rupture might be related to injury of the cingulum and fornix. Therefore, we recommend evaluation of the cingulum and fornix with diffusion tensor tractography for patients with an ACoA aneurysm rupture.

The clinical characteristics of motor function in chronic hemiparetic stroke patients with complete corticospinal tract injury.

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.

Simultaneous fabrication of line defects-embedded periodic lattice by topographically assisted holographic lithography.

We have demonstrated simultaneous fabrication of designed defects within a periodic structure. For rapid fabrication of periodic structures incorporating nanoscale line-defects at large area, topographically assisted holographic lithography (TAHL) technique, combining the strength of hologram lithography and phase-shift interference, was proposed. Hot-embossing method generated the photoresist patterns with vertical side walls which enabled phase-shift mask effect at the edge of patterns. Embossing temperature and relief height were crucial parameters for the successful TAHL process. Periodic holes with a diameter of 600 nm at a 1 µm-pitch incorporating 250 nm wide line-defects were obtained simultaneously.