Young-Min Shon

Impaired kidney function and cerebral microbleeds in patients with acute ischemic stroke

Background: We investigated the association between the presence of cerebral microbleeds and poor kidney function in patients with acute ischemic stroke. Methods: We retrospectively examined consecutive acute ischemic stroke patients who underwent gradient echo MRI. The presence of cerebral microbleeds on gradient echo MRI was independently interpreted. The number and location of microbleeds were assessed. Demographics including age, sex, risk factors, and stroke subtype were obtained. Kidney function was estimated by measuring glomerular filtration rate (GFR) with the modification of diet in renal disease method. Results: Of the 152 patients included, 45 (29.6%) patients had cerebral microbleeds on gradient echo MRI. The cerebral microbleeds were most commonly located in deep or infratentorial location (27/45 [60%]). Hypertension, presence of leukoaraiosis, old age, and low GFR were associated with the presence of cerebral microbleeds (p = 0.064, <0.001, 0.014, and <0.001). The mean GFR levels were lower in patients with cerebral microbleeds (65.15 ± 22.54 vs 78.82 ± 19.11 mL/min/1.73 m2). After the adjustment of risk factors, age, and sex, low GFR levels were associated with the presence of cerebral microbleeds (odds ratio, 3.85; 95% confidence interval, 1.52 to 9.76, p = 0.004). Conclusion: Impaired kidney function is associated with the presence of cerebral microbleeds in acute ischemic stroke.

Cognitive improvement after long-term electrical stimulation of bilateral anterior thalamic nucleus in refractory epilepsy patients

INTRODUCTION The cognitive and behavioral effect of deep brain stimulation (DBS) administered to the deep cerebral nuclei for epilepsy treatment is unknown. We investigated the cognitive outcomes at least 12 months after DBS to the bilateral anterior thalamic nucleus (ATN) for controlling intractable epilepsy. METHODS Nine patients with intractable epilepsy who were not candidates for resective surgery, but who were treated by bilateral ATN DBS underwent cognitive and behavioral assessments before implantation and more than 1 year after DBS surgery. Postoperative cognitive assessments were carried out under a continuous stimulation mode. RESULTS The mean seizure-reduction rate of these patients after ATN DBS was 57.9% (35.6-90.4%). Cognitive testing showed favorable results for verbal fluency tasks (letter and category, p<0.05), and a significant improvement in delayed verbal memory was observed (p=0.017). However, we did not observe any significant changes in general abilities (IQ, MMSE), information processing (digit forward and backward, Trail A, and Digit Symbol), or executive function (Trail B and WCST). Interestingly, we did not observe any significant cognitive decline approximately 1 year (mean, 15.9 months) after ATN DBS surgery. CONCLUSIONS We showed that ATN DBS not only resulted in promising clinical effects but was also associated with improvements in both verbal recall and oral information processing, which may be related to the bilateral activation of the fronto-limbic circuit following DBS surgery. Further controlled, long-term studies with larger populations are warranted for elucidating the clinical effects of ATN DBS.

Difference of the hippocampal and white matter microalterations in MCI patients according to the severity of subcortical vascular changes: neuropsychological correlates of diffusion tensor imaging.

OBJECTIVES Most imaging studies of mild cognitive impairment (MCI) have focused on gray matter alterations, although many MCI patients demonstrate subcortical vascular changes. We investigated the changes of the hippocampal area and various white matter areas in MCI patients with using diffusion tensor imaging (DTI), according to the severity of subcortical vascular changes, and we then correlated the DTI findings with the neuropsychological results. PATIENTS AND METHODS Among the 40 MCI patients, the 21 non-vascular MCI (nvMCI) and 19 vascular MCI (vMCI) patients were subdivided according to Erkinjunttis imaging criteria. The mean diffusivity (MD) and fractional anisotropy (FA) were compared in the bilateral temporal, frontal, parietal and occipital white matter regions, as well as in the bilateral hippocampi, centrum semiovale, and the midline genu and splenum of the corpus callosum among the nvMCI and vMCI patients and the 17 controls. The neuropsychological findings were also compared between the subgroups. RESULTS All the MCI patients showed decreased FA and increased MD in all the regions except the occipital areas. In the parietal regions and centrum semiovale, the vMCI patients had a greater FA decrease than the nvMCI patients and controls. In the hippocampi, the FA was lowest in the nvMCI patients. The memory function in the nvMCI patients was more impaired than that in the vMCI patients. The vMCI patients showed impairment of the visuospatial and frontal executive functions. CONCLUSION We were able to correlate the microstructural alterations with the neuropsychological findings in the MCI subgroups.

Continuous Amplitude-Integrated Electroencephalographic Monitoring is a Useful Prognostic Tool for Hypothermia-Treated Cardiac Arrest Patients

Background— Modern treatments have improved the survival rate following cardiac arrest, but prognostication remains a challenge. We examined the prognostic value of continuous electroencephalography according to time by performing amplitude-integrated electroencephalography on patients with cardiac arrest receiving therapeutic hypothermia. Methods and Results— We prospectively studied 130 comatose patients treated with hypothermia from September 2010 to April 2013. We evaluated the time to normal trace (TTNT) as a neurological outcome predictor and determined the prognostic value of burst suppression and status epilepticus, with a particular focus on their time of occurrence. Fifty-five patients exhibited a cerebral performance category score of 1 to 2. The area under the curve for TTNT was 0.97 (95% confidence interval, 0.92–0.99), and the sensitivity and specificity of TTNT<24 hours after resuscitation as a threshold for predicting good neurological outcome were 94.6% (95% confidence interval, 84.9%–98.9%) and 90.7% (95% confidence interval, 81.7%–96.2%), respectively. The threshold displaying 100% specificity for predicting poor neurological outcome was TTNT>36 hours. Burst suppression and status epilepticus predicted poor neurological outcome (positive predictive value of 98.3% and 96.4%, respectively). The combination of these factors predicted a negative outcome at a median of 6.2 hours after resuscitation (sensitivity and specificity of 92.0% and 96.4%, respectively). Conclusions— A TTNT<24 hours was associated with good neurological outcome. The lack of normal trace development within 36 hours, status epilepticus, and burst suppression were predictors of poor outcome. The combination of these negative predictors may improve their prognostic performance at an earlier stage.

Effect of Chronic Deep Brain Stimulation of the Subthalamic Nucleus for Frontal Lobe Epilepsy: Subtraction SPECT Analysis

Objectives: Experimental data and case reports of patients with intractable epilepsy treated with deep brain stimulation (DBS) of the subthalamic nucleus (STN) suggest a considerable anticonvulsant effect. However, no satisfactory mechanisms of action have yet been elucidated. We investigated the putative therapeutic mechanisms of DBS from cerebral perfusion changes as measured by subtracting the SPECT image of the pre-DBS period from that of the chronic post-DBS state. Methods: Two patients who had previous resective surgery on their right frontal cortices with or without anterior callosotomy were selected for DBS of the STN. Both of them showed frequent bilateral asymmetric tonic seizures (left > right) with rare drop attacks, and 1 patient’s seizure frequency was more than 15/month during the pre-DBS period. They had both taken more than four antiepileptic agents for more than 10 years. After video-EEG monitoring, the irritative zones of the brain were delineated. The regional cerebral blood flow (rCBF) changes between the two SPECT images (pre-DBS and post-DBS after at least 6 months) were analyzed by SPECT subtraction with the volumetric MRI coregistration method using Analyze 5.0 software. Results: After chronic STN DBS (18 months, case 1; 6 months, case 2), both patients experienced markedly reduced seizure frequencies (86.7% reduction in patient 1, 88.6% in patient 2). In patient 1, the increased rCBF was observed in the right frontal areas (dorsolateral and inferior frontal area), which corresponded to the irritative zones as confirmed by previous EEG recording. Unexpectedly, there was definite hyperperfusion in the right superior and inferior temporal areas as well as rCBF increase in the right superior frontal area (SMA) in patient 2. Conclusions: We demonstrated that the cerebral perfusion increase in the irritative zones of epilepsy patients is associated with favorable seizure reduction after STN DBS in 2 cases of frontal lobe epilepsy. Although the exact mechanism remains unknown, our findings suggest that the perfusion changes after STN DBS in frontal lobe epilepsy patients are quite different from those in subjects with Parkinson’s disease. Our preliminary data suggest the clinical relevance of subtraction SPECT imaging in assessing the postprocedural outcome as well as the characteristics of SPECT perfusion patterns in other epilepsy syndromes.

Group-specific regional white matter abnormality revealed in diffusion tensor imaging of medial temporal lobe epilepsy without hippocampal sclerosis

Purpose:  In comparison to temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (TLE‐HS), TLE patients without HS (TLE‐NH) have a similar clinical course but may result in worse surgical outcome. We investigated whether the clinical features related to the lack of HS in TLE patients (TLE‐NH) can be explained by water diffusion abnormalities throughout diffusion tensor imaging (DTI) by voxel‐based analysis.

Changes in glucose metabolism and metabolites during the epileptogenic process in the lithium-pilocarpine model of epilepsy

Purpose:  The metabolic and biochemical changes that occur during epileptogenesis remain to be determined. 18F‐Fluorodeoxyglucose positron emission tomography (FDG‐PET) and proton magnetic resonance spectroscopy (1H MRS) are noninvasive techniques that provide indirect information on ongoing pathologic changes. We, therefore, utilized these methods to assess changes in glucose metabolism and metabolites in the rat lithium‐pilocarpine model of epilepsy as markers of epileptogenesis from baseline to chronic spontaneous recurrent seizures (SRS).

Incidental Unruptured Intracranial Aneurysms in Patients with Acute Ischemic Stroke

Background: The management and clinical prognosis of incidental intracranial aneurysms in acute ischemic stroke patients have been understudied. We investigated the clinical outcome of acute ischemic stroke subjects with incidentally found intracranial aneurysms. Methods: We consecutively included acute ischemic stroke patients within 7 days of onset. Their demographics, risk factors, stroke subtypes, antithrombotics use and modified Rankin scale (mRS) at 3 months after stroke were obtained. CT or MR angiography was used to diagnose the intracranial aneurysms. The development of an aneurysmal rupture was checked during the following 3 months. Results: Incidental intracranial aneurysms were found in 17 (6.6%) of the 258 patients. The female sex and old age were associated with the presence of incidental intracranial aneurysms (p = 0.001, 0.032). The most common site of aneurysm was at the distal internal carotid artery (n = 9), followed by the middle cerebral artery (n = 6). The diameters of the aneurysms ranged from 2.09 to 8.06 mm. All the participants except 1 who had cancer were taking antiplatelet agents. No aneurysmal rupture or subarachnoid hemorrhage happened until 3 months after stroke.There was no significant difference in excellent outcome (3-month mRS = 0, 1) between the patients with an aneurysm and those without (28.6 vs. 53.4%, p = 0.097). Conclusion: There was no rupture of the incidentally found aneurysms in the patients with acute ischemic stroke during their first 3 months. The 3-month mRS was not affected by the presence of incidental intracranial aneurysm. A large cohort study and long-term follow-up are required.

Source Localization of Triphasic Waves: Implications for the Pathophysiological Mechanism

To investigate the current source location from the electroencephalograms (EEGs) of 12 patients who showed typical triphasic waves attributable to various causes, using the combination of a dipole source model and a distributed source model. The triphasic waves were explained by a single main dipole in 10 of the 12 patients, and 2 patients had two dipoles responsible for the triphasic waves. All the main dipoles had a radial orientation with respect to the frontal pole. The current density of the triphasic waves was distributed mainly in the bilateral medial frontal regions along the cingulate cortices. These findings suggest that current sources located in the medial frontal area are crucial for generating triphasic waves. The source localization may be useful for elucidating the pathophysiologic mechanism of generalized non-epileptic EEG activities, such as triphasic waves.

Coexisting Carotid Atherosclerosis in Patients with Intracranial Small- or Large-Vessel Disease

Background and Purpose The coexistence of carotid atherosclerosis in ischemic stroke patients with small-vessel disease (SVD) or intracranial large-vessel disease (ICLVD) was investigated using carotid duplex ultrasonography, and whether its coexistence affected the clinical prognosis was determined. Methods Ischemic stroke patients with SVD or ICLVD were enrolled (n=103). Risk factors, demographic data, and National Institutes of Health Stroke Scale (NIHSS) scores were obtained for all of the subjects. Early neurological progression was defined by an increase in NIHSS score during the first 7 days. Carotid ultrasonography was performed to measure the intima-media thickness (IMT) and carotid plaques. Results Among the 103 patients who were retrospectively enrolled in this study (56 with SVD and 47 with ICLVD), 66 (64.1%) had an atherosclerotic plaque and 23 (22.3%) had increased IMT. Increased IMT was observed more frequently in ICLVD than in SVD [15/47 (31.9%) vs. 8/56 (14.3%), p=0.032]. An atherosclerotic plaque was observed on subsequent carotid ultrasonographic examination in 28 (50%) of the 56 patients whose computed tomography angiography scans of the neck vessels were interpreted as normal. There was no association between presence of atherosclerotic change and early neurologic progression (p=0.94). Conclusions A coexisting atherosclerotic plaque or increased IMT was observed in 71.8% of patients with SVD or ICLVD. Whether the coexistence of carotid atherosclerotic change with either of these conditions affects the clinical prognosis remains to be elucidated.