Byung Yeon Choi

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.