Su Min Son

Comparison of TMS and DTT for predicting motor outcome in intracerebral hemorrhage

BACKGROUND TMS (transcranial magnetic stimulation) and DTT (diffusion tensor tractography) have different advantages in evaluating stroke patients. TMS has good clinical accessibility and economical benefit. On the contrary, DTT has a unique advantage to visualize neural tracts three-dimensionally although it requires an expensive and large MRI machine. Many studies have demonstrated that TMS and DTT have predictive values for motor outcome in stroke patients. However, there has been no study on the comparison of these two evaluation tools. In the current study, we compared the abilities of TMS and DTT to predict upper motor outcome in patients with ICH (intracerebral hemorrhage). METHODS Fifty-three consecutive patients with severe motor weakness were evaluated by TMS and DTT at the early stage (7-28 days) of ICH. Modified Brunnstrom classification (MBC) and the motricity index of upper extremity (UMI) were evaluated at onset and 6 months after onset. RESULTS Patients with the presence of a motor evoked potential (MEP) in TMS or a preserved corticospinal tract (CST) in DTT showed better motor outcomes than those without (p=0.000). TMS showed higher positive predictive value than DTT. In contrast, DTT showed higher negative predictive value than TMS. CONCLUSIONS TMS and DTT had different advantages in predicting motor outcome, and this result could be a reference to predict final neurological deficit at the early stage of ICH.

Motor outcome prediction using diffusion tensor tractography in pontine infarct

We investigated whether the integrity of the corticospinal tract classified by diffusion tensor tractography (DTT) can predict the motor outcome in 25 patients with pontine infarct. DTTs were obtained in the early stage of stroke (5–30 days) and were classified into two groups (type A: the integrity of corticospinal tract was preserved around the infarct; type B: corticospinal tract was interrupted). DTT type A patients showed better motor function than the type B patients at 6 months after onset. DTT obtained at the early stage of pontine infarct appears to have predictive value for motor outcome in patients with pontine infarct. Ann Neurol 2008

Diffusion tensor imaging findings in neurologically asymptomatic patients with end stage renal disease.

Various neurological problems of the brain are known to occur in patients with end stage renal disease (ESRD). However, little is known about diffusion tensor imaging (DTI) findings in patients with ESRD. Using DTI, we attempted to investigate DTI findings in patients with ESRD who showed no specific lesions on conventional brain MRI. We recruited 10 consecutive patients with ESRD for whom at least 3 years had passed since the start of peritoneal dialysis and who showed no neurological abnormality on neurologic examination. We excluded 6 patients who showed cerebral infarct (4 patients) and diabetes mellitus with peripheral neuropathy (2 patients); finally, 4 patients (39.75 ± 9.84 years) were included in this study. We evaluated hand motor function and cognition. DTI data were acquired using a 1.5-T Philips Gyroscan Intera system and diffusion tensor tractographies (DTTs) for five neural tracts (corticospinal tract, fornix, superior longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus) were evaluated. With the exception of 1 patient who revealed a mild abnormality at a higher cognitive function, no abnormalities in motor and cognitive function were observed. Among the 10 DTTs, except for those of the corticospinal tract, all 4 patients had more than one lesion. Patients with ESRD showed abnormalities on DTTs that were associated with cognition; however, they did not show significant cognitive abnormalities.

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.

The clinical application of the arcuate fasciculus for stroke patients with aphasia: A diffusion tensor tractography study

Little is known about the clinical usefulness of diffusion tensor tractography (DTT) for the arcuate fasciculus (AF) in stroke patients with aphasia. Using DTT, we attempted to investigate the clinical usefulness of the AF in patients with aphasia. Five stroke patients and 7 age- and sex-matched normal subjects were recruited for this study. We recruited stroke patients with language dysfunction who had lesions in the left corona radiata and basal ganglia level. DTT for the AF was reconstructed using DTI-studio software. Korean-Western Aphasia Battery (K-WAB) was used for measurement of language function. Patient 1, who showed mild dysarthria, revealed a normal left AF in terms of integrity and DTT parameters. In patient 2, with conduction aphasia, the left AF showed partial injury; however, the integrity of the left AF was spared. Patients 3 and 4, who had no brain lesions at Brocas area on conventional brain MRI, showed disruptions of the left AF over the stroke lesions after originating from Wernickes area and they presented with Brocas aphasia. Patient 5 revealed global aphasia on K-WAB and the left AF was not reconstructed due to severe injury and Wallerian degeneration. We found that DTT for the AF could provide useful information on the presence or severity of injury of the AF, which could not be detected on conventional brain MRI in stoke patients. In addition, it could be helpful in classification of the aphasia type of stroke patients.

The relation between motor function of stroke patients and diffusion tensor imaging findings for the corticospinal tract

Although the corticospinal tract (CST) is a major neural tract for motor function, the detailed role of the CST has not been clearly elucidated. We investigated relations between motor function of patients with chronic hemiparetic stroke and diffusion tensor imaging (DTI) findings for the CST. We recruited 82 consecutive chronic stroke patients. Medical Research Council, Modified Brunnstrom Classification, and Functional Ambulatory Category were used in measurement of the affected side. All motor functions showed positive correlations with fractional anisotropy (FA) and fiber number (FN) ratios (p<0.05). With regard to Medical Research Council, shoulder abductor (r=0.70, 0.68), elbow flexor (r=0.75, 0.72), finger flexor (r=0.73, 0.74), and finger extensor (r=0.69, 0.77) showed strong correlations with FA and FN ratios. Modified Brunnstrom Classification (r=0.70, 0.73) also showed strong correlation. According to our findings, it appears that the CST is related to motor function of upper and lower extremities, with particular relation to motor function of upper extremities, including the hand, compared with other motor functions.

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.

Diffusion tensor imaging demonstrated radiologic differences between diplegic and quadriplegic cerebral palsy.

Little information is available on the use of imaging for the classification of cerebral palsy patients. The present study examined the radiological differences between quadriplegic cerebral palsy patients (QCP), diplegic cerebral palsy patients (DCP) and normal control subjects (NC) by performing diffusion tensor imaging (DTI) of the corticospinal tract (CST) of upper and lower extremities. Twenty-three cerebral palsy patients (11 QCP, 12 DCP) and 12 NC were enrolled. DTI were scanned using a 1.5 T and the CST images were analyzed using FMRIB software. We measured the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the CST. Compared to DCP and NC, QCP had decreased mean FA and increased mean ADC values of the CSTs of upper and lower extremities. The mean FA values of the lower extremities in DCP were significantly decreased, compared to NC; however this was not observed for the mean FA value of the upper extremities. The DTI results of the CST in QCP and DCP significantly corresponded with their typical clinical manifestation. DTI may thus be a very powerful modality to assess the state of CST in cerebral palsy patients.

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.

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.