Dong-Wha Kang

Significance of Acute Multiple Brain Infarction on Diffusion-Weighted Imaging

BACKGROUND AND PURPOSE Diffusion-weighted imaging (DWI) is superior to conventional MRI in identification of small new ischemic lesions and discrimination of recent infarcts from old ones. Thus, this technique is useful in the detection of acute multiple brain infarcts (AMBI). We sought to determine the frequency and the topographical and etiologic patterns of AMBI detected on DWI. METHODS We studied 329 consecutive ischemic stroke patients who underwent DWI and MRI/MR angiography within 4 days of stroke onset. AMBI was defined as noncontiguous high signal intensities on DWI in >1 vascular territory. Stroke mechanism was determined according to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). RESULTS We detected AMBI in 95 patients (28.9%). AMBI in anterior circulation was found in 62 cases: in 1 hemisphere in 42 (group A) and in bilateral hemispheres in 20 (group B). Twenty-two patients had AMBI in the posterior circulation (group C) and 11 in both anterior and posterior circulations (group D). The most frequent cause of stroke was large-artery atherosclerosis in groups A (33/42), B (9/20), and C (15/22) (P=0.02) and cardioembolism in group D (6/11) (P=0.02). Elevated fibrinogen or hematocrit was significantly associated with group B (P=0.01). In 9 patients in groups B and D, anatomic variations of anterior or posterior cerebral arteries or patent posterior communicating artery contributed to AMBI. CONCLUSIONS Different topographical patterns of AMBI are associated with different vascular pathologies and stroke mechanisms. Hemorheologic abnormality or vascular anatomic variations may be contributing factors in the pathogenesis of AMBI in bilateral cerebral hemispheres or in both anterior and posterior circulations.

Fluoxetine Treatment in Poststroke Depression, Emotional Incontinence, and Anger Proneness A Double-Blind, Placebo-Controlled Study

Background and Purpose— The efficacy and safety of the selective serotonin reuptake inhibitor fluoxetine have rarely been studied in the treatment of poststroke emotional disturbances. Methods— Stroke patients (152) who had poststroke depression (PSD), emotional incontinence (PSEI), or anger proneness (PSAP) were studied. PSD was evaluated by Beck Depression Inventory and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, PSEI by Kim’s criteria, and PSAP was assessed by Spielberger Trait Anger Scale. Subjects were randomly given either fluoxetine 20 mg/day (n=76) or placebo (n=76) for 3 months. Follow-up evaluations were done 1, 3, and 6 months after the beginning of the treatment. The primary outcome measurement was the scores of emotional disturbances at each follow-up assessment. The secondary outcome measurements were the percentage changes of the scores and the subjective responses of the patients. Results— Although patients in the fluoxetine group more often dropped out because of adverse effects, fluoxetine administration was generally safe. Fluoxetine significantly improved PSEI and PSAP, whereas no definitive improvement of PSD was found. Improvement of PSAP was noted even at 3 months after the discontinuation of the treatment. Conclusions— Fluoxetine is efficacious in the treatment of PSEI and PSAP. Its effect on PSD is not solidly confirmed.

Diffusion-weighted imaging in Wallerian degeneration

We report two patients displaying hyperintensities on diffusion-weighted imaging (DWI) in the area of Wallerian degeneration (WD) at 12 days after stroke. High signal intensities were more conspicuous on DWI than on T2-weighted images. Both patients showed decreased diffusion anisotropy resulting in elevated apparent diffusion coefficient in the area of WD. These patients illustrate that DWI may be useful in the detection of the early stage of WD.

Neuroprotective effect of low dose riluzole in gerbil model of transient global ischemia

Riluzole is a neuroprotective agent the efficacy of which was proven in amyotrophic lateral sclerosis in human and in animal models of cerebral ischemia. However, the dosage used in animal experiments was much higher than that in human. We investigated the efficacy of low dose riluzole, which was similar to the dose used in human trials, in animal model of global ischemia. Global ischemia was induced in male Mongolian gerbils for 5min under monitoring of rectal temperature. Riluzole (0.8 mg/kg) were injected intraperitoneally 30min before ischemia. Seven days after ischemia, animals were decapitated and surviving nerve cells in hippocampal CA1 area were quantified. The number of surviving cells was compared between in riluzole-treated and control groups and the former showed statistically significant better survivals than the latter (P<0.001).

Interpretation of Wada memory test for lateralization of seizure focus by use of 99mTechnetium-HMPAO SPECT

Summary: Purpose: Although the intracarotid amobarbital procedure (IAP) or Wada test is useful in lateralizing seizure focus in patients with temporal lobe epilepsy (TLE), the results of the IAP memory test are frequently nonlateralizing. An insufficient suppression of the medial temporal region contralateral to the seizure focus may contribute to the failure of lateralization. We tried to correlate IAP memory results with the functional changes in the contralateral medial temporal region as measured by single photon emission computed tomography. (SPECT) during IAP.

Interpretation of increased anterior cerebral artery flow velocity on transcranial Doppler ultrasound.

Transcranial Doppler ultrasound (TCD) is well known as the method of evaluating cerebral hemodynamics and detecting stenoocclusion of the intracranial basal arteries. To enable the identification of each vessel under investigation means that considerations regarding vascular anatomy and collateral flows should be incorporated when the findings are interpreted. Anatomic variations of the anterior cerebral artery (ACA) make it difficult to interpret the TCD findings of the ACA. Therefore, we tried to establish how accurately it allows the prediction of ACA status. Consecutive 2,027 patients underwent TCD examination in our laboratory between May 1997 and April 2000. Patients with arteriovenous malformation or fistula, moyamoya disease, intracranial hemorrhage, internal carotid artery stenosis with moderate to severe degrees (150%) and poor temporal windows were excluded from this study. In addition, results involving time intervals between TCD and transfemoral cerebral angiography (TFCA) of in excess of 1 month were also discarded. Among the 1,165 patients who met the above conditions, only 50 patients underwent TFCA and were recruited for this analysis. The mean time interval between TFCA and TCD was 4.9 days. The degree of stenosis was determined by measuring the vessel concerned at its points of maximal narrowing and comparing this with the angiographically normal vessel section adjacent to the stenosis. The diameter below which a vessel could be called ‘hypoplastic’ has not been defined clearly. We used the term ‘hypoplastic A1’ to describe a vessel with a whole segment diameter of less than half of the contralateral ACA diameter. The TCD was performed with a Trans-Scan machine (EME, Überlingen, Germany) using a 2-Hz pulse wave probe through transtemporal windows, according to published standards [1, 2]. The mean flow velocity (MFV) and asymmetry index (AI) of the A1 segment on TCD were calculated. The AI was defined as follows: AI = AMV1 – MV2 A W200/(MV1 + MV2), where MV1 and MV2 represent the MFV of homologous arteries [3]. An MFV 670 cm/s was interpreted as ‘abnormally increased’ MFV. This value was the upper limit of the confidence interval (5%) in our laboratory. Flow patterns of A1 on TCD were divided into three categories (table 1). In 50 subjects, normal MFVs of both ACAs were identified in 23 patients and bilaterally increased MFVs in 3. Twen-