Pei K Loh

National University Health System, Singapore

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Publications (7)24.79 Total impact

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    ABSTRACT: Recanalization of occluded intracranial arteries remains the aim of intravenous (IV) tissue plasminogen activator (tPA) therapy in acute ischemic stroke (AIS). To examine the timing and impact of recanalization on functional outcomes in AIS. A longitudinal cohort of consecutive IV tPA–treated patients with AIS from January 2007 through December 2010. Data were collected for demography, risk factors, stroke subtypes, blood pressure, and National Institutes of Health Stroke Scale scores. Early recanalization (ER) was identified by transcranial Doppler monitoring during the first 2 hours of treatment. Recanalization was reevaluated at 24 hours by computed tomographic angiography (CTA). Patients with ER and patent index artery at 24 hours on CTA were labeled as having persistent recanalization (PR). Recanalization at 24 hours on CTA regardless of transcranial Doppler status was labeled as CTR. Favorable outcome was defined as a modified Rankin Scale score of 0 to 1 at 3 months. University hospital stroke center. A total of 240 patients with AIS who underwent IV tPA treatment. Of 2238 patients with AIS, 240 (11%) received IV tPA. The median age was 65 years (range, 19-92 years) and 44% of the study group was male. The median National Institutes of Health Stroke Scale score was 17 (range, 3-35) and the median onset-to-treatment time was 149 minutes (range, 46-270 minutes). Of the 240 patients, 122 (50.8%) achieved favorable outcomes at 3 months. Data for ER, PR, and CTR were analyzed for 160 patients. Early recanalization was seen in 82 patients (51.3%); 67 cases (81.7%) had PR and 84 cases (52.5%) had CTR. National Institutes of Health Stroke Scale score at onset (odds ratio per 1-point increase, 0.938; 95% CI, 0.888-0.991), ER (odds ratio, 3.048; 95% CI, 1.537-6.046), PR (odds ratio, 5.449; 95% CI, 2.382-12.464), and CTR (odds ratio, 4.329; 95% CI, 2.131-8.794) were independent predictors of favorable outcomes. Intravenous tPA–induced arterial recanalization within the first 24 hours in AIS is a strong predictor of favorable outcomes at 3 months.
    JAMA Neurol. 03/2013; 70(3):353-8.
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    ABSTRACT: BACKGROUND Recanalization of occluded intracranial arteries remains the aim of intravenous (IV) tissue plasminogen activator (tPA) therapy in acute ischemic stroke (AIS). OBJECTIVE To examine the timing and impact of recanalization on functional outcomes in AIS. DESIGN A longitudinal cohort of consecutive IV tPA-treated patients with AIS from January 2007 through December 2010. Data were collected for demography, risk factors, stroke subtypes, blood pressure, and National Institutes of Health Stroke Scale scores. Early recanalization (ER) was identified by transcranial Doppler monitoring during the first 2 hours of treatment. Recanalization was reevaluated at 24 hours by computed tomographic angiography (CTA). Patients with ER and patent index artery at 24 hours on CTA were labeled as having persistent recanalization (PR). Recanalization at 24 hours on CTA regardless of transcranial Doppler status was labeled as CTR. Favorable outcome was defined as a modified Rankin Scale score of 0 to 1 at 3 months. SETTING University hospital stroke center. PATIENTS A total of 240 patients with AIS who underwent IV tPA treatment. RESULTS Of 2238 patients with AIS, 240 (11%) received IV tPA. The median age was 65 years (range, 19-92 years) and 44% of the study group was male. The median National Institutes of Health Stroke Scale score was 17 (range, 3-35) and the median onset-to-treatment time was 149 minutes (range, 46-270 minutes). Of the 240 patients, 122 (50.8%) achieved favorable outcomes at 3 months. Data for ER, PR, and CTR were analyzed for 160 patients. Early recanalization was seen in 82 patients (51.3%); 67 cases (81.7%) had PR and 84 cases (52.5%) had CTR. National Institutes of Health Stroke Scale score at onset (odds ratio per 1-point increase, 0.938; 95% CI, 0.888-0.991), ER (odds ratio, 3.048; 95% CI, 1.537-6.046), PR (odds ratio, 5.449; 95% CI, 2.382-12.464), and CTR (odds ratio, 4.329; 95% CI, 2.131-8.794) were independent predictors of favorable outcomes. CONCLUSIONS Intravenous tPA-induced arterial recanalization within the first 24 hours in AIS is a strong predictor of favorable outcomes at 3 months.
    Archives of neurology 12/2012; · 7.58 Impact Factor
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    ABSTRACT: The rates and extent of recovery in acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (IV-tPA) remain highly variable. Hyperdense middle cerebral artery sign (HMCAS) on pretreatment unenhanced computerized tomography (CT) of the brain represents the presence of thrombus, often associated with severe neurological deficits and poor clinical outcome at 3 months. However, HMCAS is reliable only in AIS patients managed conservatively. In patients treated with systemic thrombolysis, HMCAS may disappear (representing clot dissolution) or persist (persisting clot) on the follow-up CT scan of the brain. We aimed at evaluating whether disappearance or the persistence of HMCAS on follow-up CT scan of the brain can predict the final outcome at 3 months. Data from consecutive AIS patients treated with IV-tPA, in a standardized protocol, from January 2007 to March 2010 were included in the prospective thrombolysis registry at our tertiary care center. For this evaluation, posterior circulation stroke was excluded. HMCAS was assessed on admission as well as follow-up CT by 2 independent stroke neurologists, blinded to the patient data or outcomes. Functional outcomes assessed by the modified Rankin Scale (mRS) at 3 months were dichotomized as good (mRS score 0-1) and poor (mRS score 2-6). The data were analyzed for the early predictors of poor functional outcome with SPSS version 19 for Windows. Of the total of 2,238 patients admitted during the study period, 226 (11%) with anterior circulation AIS treated with intravenous thrombolysis were included. Median age of the patients was 65 years (range 19-92), 63% were males and they had a median National Institutes of Health Stroke Scale (NIHSS) score of 16 points (range 4-32). HMCAS was observed on admission CT scan in 109 (48.2%) patients and persisted on follow-up CT in 52 (47.7%) of them. Overall, 108 (47.8%) patients achieved poor functional outcome at 3 months. Admission NIHSS score (OR per 1-point increase = 1.241; 95% CI = 1.151-1.337, p < 0.0005), lesser change in NIHSS score at 24 h (OR per 1-point reduction = 0.730; 95% CI = 0.666-0.800, p < 0.0005) and persistence of HMCAS on follow-up CT scan (OR = 3.352; 95% CI = 1.991-11.333, p = 0.039) were associated with poor outcome at 3 months. Persistence of HMCAS on the follow-up CT scan of the brain in acute ischemic stroke patients treated with IV-tPA can be used as an early predictor of poor functional outcome.
    Cerebrovascular Diseases 03/2012; 33(5):446-52. · 2.81 Impact Factor
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    ABSTRACT: BACKGROUND AND AIMS: Acute ischemic stroke (AIS) due to basilar artery thrombosis (BAT) causes high mortality and severe disability. Early neurological assessment and timely thrombolysis might improve outcome. BAT is difficult to diagnose due to wide spectrum of presentation and decreased conscious level. Emergency physicians often intubate BAT patients with airway compromise before arrival of stroke neurologist. We evaluated role of computerized tomography (CT) angiography (CTA) of brain and cervical arteries in early diagnosis of acute BAT in intubated patients and facilitating decision for thrombolysis. METHODS: Consecutive AIS patients presenting between 2007 and 2009 within 6 hours of symptom onset, with sudden deterioration in conscious level and intubation before assessment by neurologist, were included. All patients underwent brain CT and CTA. Outcomes were assessed at 3 months. RESULTS: Thrombolytic therapy, mainly intravenous tissue plasminogen activator (IV-TPA), was administered to 161 (8.4%) of 1,917 AIS patients during the study period. Acute BAT contributed 10.9% of our cohort. CTA was performed in 152 (94.4%) patients and the rest were excluded due to their impaired renal functions. Five patients (3 males, mean age 72 years) presenting with acute obtundation and airway compromise were intubated, sedated, and paralyzed before assessment by neurologist. CTA showed BAT in all. IV-TPA was initiated at 213 ± 59 minutes in 4 patients while 1 received intraarterial thrombolysis at 13 hours. There was no intracranial hemorrhage. Mean length of hospital stay was 11.8 days. Despite severe stroke at presentation, good functional recovery at 3 months (modified Rankin scale [mRS] 1) occurred in 2 patients; mRS 4 in 1, and 2 died. CONCLUSION: In patients with BAT, intubated before assessment by neurologist, CTA might help in confirming the diagnosis and facilitating therapeutic decision making for initiating thrombolysis. J Neuroimaging 2012;XX:1-4.
    Journal of neuroimaging: official journal of the American Society of Neuroimaging 02/2012; · 3.36 Impact Factor
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    ABSTRACT: Our knowledge about various inherited and acquired causes of thrombophilic disorders has increased significantly during the past decade. Technology for various diagnostic tests for these rare disorders has matched the rapid advances in our understanding about the thrombophilic disorders. Inherited thrombophilic disorders predispose young patients for various venous or arterial thrombotic and thromboembolic episodes. Our understanding has also improved about various gene-gene and gene-environment interactions and their impact on the resultant heterogenous clinical manifestations. We describe various thrombophilic disorders, their diagnostic tests, pathogenic potential in isolation or with other concurrent inherited/acquired defects and possible therapeutic and prophylactic strategies. Better understanding, optimal diagnostic and screening protocols are expected to improve the diagnostic yield and help to reduce morbidity, disability, and mortality in relatively younger patients harbouring these inherited and acquired thrombophilic disorders.
    Stroke research and treatment. 01/2011; 2011:670138.
  • Pei Kee Loh, Vijay K Sharma
    Stroke 03/2010; 41(3):e164; author reply 165. · 6.16 Impact Factor
  • Pei Kee Loh, Vijay K Sharma
    Journal of neurology, neurosurgery, and psychiatry 02/2010; 81(2):203. · 4.87 Impact Factor