$414 Thursday, November 10, 2005 Poster Abstracts

Background: Hypointense susceptibility sign along the course of artery on T2*-weighted gradient-echo imaging (GRE) has been implicated as acute thromboembolic occlusion in patients with acute ischemic stroke. To evaluate clinical value of susceptibility sign by correlating presence and length of susceptibility sign with initial stroke severity. Methods: We analyzed MRI in 32 consecutive acute stroke patients with intracranial internal carotid artery (ICA) or proximal MCA occlusion on MR angiography. Neuroimaging was performed within 12 hours of symptom onset. Presence or absence of susceptibility sign on GRE was assessed and length of susceptibility sign was measured at hypointense segment along the course of MI trunk. Presence and length of susceptibility sign were correlated with National Institutes of Health Stroke Scale (NIHSS) score at admission, initial lesion volume on diffusion-weighted image (DWI). Results: Twenty patients (62.5%) had a positive susceptibility sign at occluded vessel confirmed by MRA. The sensitivity of susceptibility sign in intracranial ICA and MCA was 81.8% (9/11), and 52.4% (11/21), respectively. NIHSS score at admission (15.5 vs 8.5, P -- .001) and mean lesion volume on DWI (95.9 vs 30.3 cm 3, P -- .02) were higher in patients with susceptibility sign than those without. Tile length of susceptibility sign was positively correlated with initial lesion volmne on DWI (r - 0.481, P - .005) and NIHSS score at admission (r -- .457, P < .028). Age, sex, and risk factors were not different between patients with and without sign, but cardioembolism was more frequent in patients with susceptibility sign (80% vs 33.3%, P -- .021). Conclusion: Presence of T2*-weighted susceptibility sign on GRE in patients with acute MCA territory occlusion may be a useful indirect parameter to detect occluded segment and length of susceptibility sign have a positive correlation with initial stroke severity.

1231 Measurement of Cerebral Vasoinotor reactivity with Semi-Closed Rebreafldng Method: validation study and normal reference values

Jae-Hyeok Heo 1, Yong-Seok Lee 2. ZDepcrtment of Neurology, Seoul National University Boramae Hospital, Seoul, Korea; 2Seou[ National University, Seoul, Korea

Background: Cerebral vasomotor reactivity (VMR) is the capability of the arterioles to dilate and constrict. Transcratfial Doppler sonography (TCD) has been used to evaluate VMR with COo retention. However, previous methods (breath-holding or COo gas challenge) are incon- venient to apply, uncomfortable for the patients, and not reliable for adequate CO2 retention. We try to introduce a newly developed semi- closed rebreattfing method to evaluate VMR with validation. Methods: Consecutive subjects over 50 years old were included. Mirfimental status exanlination, MRI and MRA were performed in majority of subj cots. Patients with stroke, dementia, stenosis o f middle cerebral artery (MCA), or other intracranial diseases confirmed on MRI or M R A were excluded. CO2 retention was achieved by 5-minute rebreattfing in 6-liter reservoir bag with several punched-out pores, wlfich was continuously molfitored by capnometry. TCD measured tile change of mean flow velocity (MFV) of MCA before and after rebreathing, and VMR was calculated as percent change of MFV. Results: Thirty-seven subjects were included (26 men, mean age 63 d- 7 years old), and the rebreathing process was well tolerated by all subjects. Mean PCO2 level was 50 ± 4 nmlHg, and PCO2 over 45 mmHg had been aclfieved in 95% of the subjects. Mean V M R was 45.4 ± 23.1% on right and 48.9 d_ 27.6% on left MCA. V M R was increased as elevation of PCO2 level, and decreased as aging. Sex, diabetes, hypertension, hypercholesterolemia, or smoking did not show significfant relation with VMR. ContuSion: TCD measurenlent of VMR with semi-closed rebreattfing method is feasible and adequate CO2 retention may be achieved reliably. Practical application may be warranted and tile clinical significance reamins to be determined.

1232 Essential role of Endogenous Tissue Plasminogen Activator in Hemorrhage transformation after Ischemia/Reperthsion in Transient Focal Cerebral ISdlemia rats

I_i, y j1 , X/e, P], Zhao, LB 1, Mou, J], Li p1, Wang YL ]. 2Chongqing University of ivied~col Sciences, Chongqing, C/zinc

Background: Cerebral hemorrhage transformation is thought to be the most important pathophysiologic changes of ischemia/reperfusion. Recent study show that tissue plasnfinogen activator (tPA), a serine protease, may be associated with it through metalloproteinase 9 (MMP 9) induction. The aim of this study was to investigate whether endogenous tPA-induce M M P 9 upregnlarion play critical role in hemorrhage transformation after ischemia/reperfusion. Method: 40 Sprague Dawley rats were randomly divided into two groups. Transient cerebral ischemia was induced by a 3-h right middle cerebral artery suture occlusion (MCAO) followed by reperfusion for times from 3 h to 24h. The appearance of brain damage in rats was imaged and followed by means of magnetic resonance imaging (MRI). Neuroserpin, an inhibitor tPA, was administered intracerebrally immediately following MCA occlusion. Comparison of expression and activity profiling of endogenous tPA and MMP-9 between simple ischemia/reperfusion and neurosevpin-treated rats after reperfusion. Expression and activity profiling of endogenous tPA and MMP-9 were performed by im_munohistochemistry, in situ hybridization, immunocapture and Gelatin zymography asssays. Results: There is markedly cerebral hemorrhage in simple ischernia/ reperfusion rats but not in neuroserpin-treated rats at 24h after reperfusion. The endogenous tPA activity and its m R N A expression sigtfificantly increased at 6 and 12 hours within tile region of infarct after reperfusion in compare with neuroserpin treatment rats, (P < 0.01, respectively). We also observed an exacerbation of MMP-9 expression at the m R N A level in simple ischemia/reperfusion rats. Contusion: These results indicate that endogenous tPA increases expression of MMP-9 during reperfusion, which may be involved in the hemorrhage transformation of ischemia/reperfusion.

1233 An analysis on clinical manifestation of primary Subarachnoid Hemorrhage

Rui l i ang x, Yin Jiatmii 1. 2lnstitute of Neuroscience, the 2nd Affiliated Hospital of Guangzhou Medical College, Guangzhou, China

Background: Primary subarachnoid hemorrhage is a common neuro- logical emergency. Some non-special feature always causes misdiag- nosis and critical results. The sake was to investigate those non-special feature of subarachnoid hemorrhage and how to comfirm the diagnosis. Methods: We made a retrospective analysis on the in patients cases of subarachnoid hemorrhage from 1998 to 2003. All the clinical mani- festations and auxiliary examination were collected and analyzed. Results: We found that there were about 55.8% of the cases showed the typical mmfifestation, about 44.2% patients showed fever, dizzy, pain of neck, pain of lower limbs, lose strength in lower limbs and diarrhea as the first onset symptom. Only 75.6% cases has the positive sign of meningeal irritation sign. 86.7% cases whom received CT scan found positive results. There was a higher mortality rate of the patients with non-special feature than that of the patients with typical features. (X 2 - 5 . 6 2 6 P < 0.05) Contusion: The non-special feature of subarachnoid henlorrhage is the most common reason of misdiaguosis. It is strongly recommended that lumbar puncture should be done as early as possible when the probable cases were found, and CTA, MRA, DSA should be made for the pathogeny.

1234 Underlying Pathogenic medmtfisms detemfine the risk of subsequent Stroke in TranSient Isdleiidc Attack