1.Ischaemic stroke in young adults: A comparative study between Malaysia and Australia
Kay Sin Tan ; Chong Tin Tan ; Leonid Churilov ; Mark Mackay ; Geoffrey A Donnan
Neurology Asia 2010;15(1):1-9
Background and Objectives: There is a paucity of comparative studies on young strokes between
populations of different ethnicities and geographical regions. The purpose of this study was to compare
the patterns, risk factors and etiologies of ischaemic stroke in younger patients between stroke registries
in Malaysia and Australia. Methods: From January 2007 to March 2008, all consecutive ischaemic
stroke patients from the age of 18 to 49 were studied. Results: There were 67 patients for Malaysia
and 61 for Australia, with 4 deaths in the Malaysian series (case-fatality of 6%), and no deaths for
Australia. The mean age was 41.5±8.8 yrs for Malaysia and 40.1±8.8 years for Australia. The ethnic
origin was Malays, Chinese and Indian for Malaysia, and Caucasians (85%) for Australia. The sex
ratio was M : F = 1.4 : 1 for Malaysia and 1.54 :1 for Australia. The differences in risk factors for
Malaysia versus Australia were: Diabetes (OR 7.25; 95% CI 2.78-19.45), hypertension (OR 6.42;
95% CI 2.75-15.22) and chronic renal disease (OR 5.2; 95% CI 1.02-35.87). Conversely, smoking
was a signifi cant risk factor for Australia (OR 2.75; 95% CI 1.2-6.37). The Malaysian patients have
signifi cantly higher proportions of large vessel atherosclerosis and small vessel occlusion by TOAST
classifi cation, accounting for 60% of patients, while the Australian series had greater proportions of
cardioembolism and patients in the determined aetiologies category, specifi cally vascular dissection.
Conclusion: There were signifi cantly more large vessel atherosclerosis and small vessel occlusion
among young Malaysians with ischaemic stroke as compared to Australia.
2.Mitochondrial neurogastrointestinal encephalomyo pathy (MNGIE) in a Malaysian patient with a novel mutation in thymidine phosphorylase gene: A case report
Kay Sin Tan ; Heng Gee Lee ; Lay Hoong Lian ; Ying Shean Lu ; Bee Chin Chen ; Chee Woon Wang ; Jayaram Menon
Neurology Asia 2012;17(2):163-168
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare neurodegenerative
multisystem disorder inherited in an autosomal recessive manner and characterized clinically by
gastrointestinal dysmotility, cachexia, ophthalmoparesis and/or ptosis, peripheral neuropathy and
leukoencephalopathy. Heterogenous causative mutations in the thymidine phosphorylase (TP) gene
located on chromosome 22q13 have been identifi ed. This is the fi rst reported case of a 25-year-old
Malaysian patient, of indigenous Bajau ethnicity who presented with recurrent abdominal pain before
developing other clinical features of classical MNGIE. Biochemical correlates include elevated plasma
levels of thymidine, deoxyuridine and lactate. The brain MRI showed diffuse leucoencephalopathy
while nerve conduction studies were consistent with demyelinating polyneuropathy. Direct DNA
sequencing of the nine coding exons of the TP gene showed both a novel and a previously described
mutation. The former is a point mutation in exon 5 (NG_011860.1:g.7387C>T) at amino acid position
179, resulting in a stop codon and premature truncation of thymidine phosphorylase(TP) protein
while the latter mutation occurred at exon 10 (NG_011860.1:g.9279C>T) resulting in a missense
homozygous mutation at amino acid position 471. Defi nite diagnosis was based on clinical features,
plasma and urinary nucleosides and the identifi cation of mutations in the TP gene. This case report
adds to the knowledge of genotype-phenotype relationship of TP mutations and its occurrence among
ethnic groups worldwide.
3.TT genotype of the methylenetetrahydrofolate reductase C677T polymorphism is an important determinant for homocysteine levels in multi-ethnic Malaysian ischaemic stroke patients.
Elsa Haniffah Mejia MOHAMED ; Kay Sin TAN ; Johari Mohd ALI ; Zahurin MOHAMED
Annals of the Academy of Medicine, Singapore 2011;40(4):186-191
INTRODUCTIONThe functional point mutation C677T in the methylenetetrahydrofolate reductase (MTHFR) gene, has been reported to contribute to hyperhomocysteinaemia which is a risk factor for atherothrombotic ischaemic strokes. This study evaluated the prevalence of the C677T polymorphism of the gene in Malaysian ischaemic stroke subjects of Malay, Chinese and Indian ethnicities, and its association with homocysteine levels (tHcy).
MATERIALS AND METHODSA total of 292 subjects were recruited, comprising 150 ischaemic stroke patients and 142 control subjects who were age and sex matched. Plasma homocysteine, serum folate and vitamin B12 were measured in all subjects. Genotyping was carried out using PCR-RFLP.
RESULTSThe homocysteine levels were significantly higher (P = 0.001) in the stroke group (11.35 ± 2.75 μmol/L) compared to the control group (10.38 ± 2.79 μmol/L). The MTHFR C677T genotype distribution for the stroke group was 46%, 40% and 14%, respectively for CC, CT and TT genotypes and 59.9%, 33.8% and 6.3%, respectively for the control group. The genotype and allelic frequencies were significantly different between the 2 groups, with P = 0.02 and P = 0.004 respectively. No significant difference was seen in the genotype distribution inter-ethnically. An increasing tHcy was seen with every additional T allele, and the differences in the tHcy for the different genotypes were significant in both the control (P <0.001) and stroke groups (P <0.001).
CONCLUSIONThis study shows that TT genotype of the methylenetetrahydrofolate reductase C677T polymorphic gene is an important determinant for homocysteine levels in Malaysian ischaemic stroke patients.
China ; ethnology ; Ethnic Groups ; genetics ; Female ; Folic Acid ; blood ; Gene Frequency ; Genotype ; Homocysteine ; blood ; genetics ; Humans ; Hyperhomocysteinemia ; complications ; India ; ethnology ; Malaysia ; Methylenetetrahydrofolate Reductase (NADPH2) ; genetics ; Middle Aged ; Point Mutation ; Polymorphism, Genetic ; Stroke ; blood ; genetics ; Vitamin B 12 ; blood
4.A Rare but Disabling Stroke.
Kar Foo LAU ; Kay Sin TAN ; Khean Jin GOH ; Norlisah RAMLI ; Sharon Ml TAI
Annals of the Academy of Medicine, Singapore 2019;48(3):109-111
5.Cerebral venous thrombosis in multi-ethnic patients from Malaysia
Mei-Ling Sharon TAI ; Khairul Azmi Abdul KADIR ; Chong Tin TAN ; Kay Sin TAN
Neurology Asia 2020;25(2):127-138
Background & Objectives: The literature on cerebral venous thrombosis (CVT) in South East Asia is
limited. The objectives were to evaluate the clinical profile, predisposing factors and clinical outcome
of the CVT patients in Malaysia. Methods: We conducted a retrospective descriptive study of the CVT
patients admitted to the neurology ward. The clinical presentation, predisposing factors, radiological
findings, treatment and prognostic characteristics were evaluated from the charts. Clinical outcome
on discharge and six months was measured by Modified Rankin Scale (mRS) scores. Poor outcome
and good outcome was defined as Modified Rankin Scale (mRS) scores of 3-6 and 0-2 respectively.
Results: Forty nine CVT patients who presented between 2007 and 2017 were recruited. The mean age
was 43.51±16.52. The patients consisted of 39 Malaysians (13 Indians, 12 Malays, 12 Chinese, one
Iban, one Eurasian descent), and ten non-Malaysians. Thirty (61.2%) patients were women. The most
common presenting complaint was headache (75.5%). Six percent had multiple risk factors, whereas
51% had idiopathic CVT. The most common predisposing factors were oral contraceptive pill use
(18.4%), followed by infection (12.2%), especially central nervous system (CNS) infection (6.1%);
11.8% had prothrombotic disorder. The most common location for CVT was superior sagittal sinus
(83.7%). On neuroimaging, 77.6% had parenchymal lesions, 53.1% had venous infarcts and 38.8% had intracerebral haemorrhage, one patient had CVT complicated by rare venous collateral channels. Poor outcome on discharge and at six months was 38.8% and 33.3% respectively. On univariate analysis, female gender (p=0.002), seizures (p=0.037) and cerebral oedema (p=0.018) were associated with poor functional outcome. On binary logistic regression, female gender (OR=14.50, 95% CI 2.10-99.94,p=0.003) and seizures (OR=6.54, 95% CI 1.33-32.07, p=0.017) were associated with poor outcome.
Conclusion: The CVT patients in this study had a higher proportion of CNS infections. Poor outcome
was independently associated with female gender and seizures.
7.Clinical profile, risk factors and aetiology of young ischaemic stroke patients in Asia: A prospective, multicentre, observational, hospital-based study in eight cities
Kay Sin Tan ; Jose C Navarro ; Ka Sing Wong ; Yi Ning Huang ; Hou Chang Chiu ; Niphon Poungvarin ; Shan Jin Ryu ; Ester Bitanga ; Nijasri Suwanwela ; Sardar Mohd Alam ; Woo Yoon
Neurology Asia 2014;19(2):117-127
Background and Objective: There is a lack of international collaborative studies on young adults with ischaemic stroke in Asia. The aim of this study was to investigate risk factors, aetiology and outcome at hospital discharge of these patients across 8 participating countries in Asia. Methods: This was a prospective, observational, multicentre, hospital based cohort study. Consecutive young stroke patients with confirmed cerebral infarction between the ages of 18-49 were recruited from December 2011 to May 2012. Data was collected for patient demography, risk factors, investigations, clinical profile and TOAST classification. Outcome measures were death and independence (modified Rankin score≤ 2) at hospital discharge. Results: Two hundred and eighteen patients with the mean age was 40.8±6.7 years were recruited. There was a larger proportion of male patients with a ratio of 1.9:1. Traditional risk factors observed were hypertension (n=103; 47.3%), dyslipidaemia (n=93; 42.4%), smoking (n=85; 38.8%), diabetes (n=53; 24.3%), alcohol use (n=33; 15.0%), a previous history of stroke and transient ischaemic attacks (6.4%), family history (n=12; 5.5%), migraine (n=6;2.8%), pregnancy related (n=5; 2.3%) and numerous cardiac risk factors (0.9-5.5%). The majority suffered arterial infarction; n=216 (99.4%) while n=2 (0.6%) had venous strokes. The predominant stroke subtypes were large artery atherosclerosis (LAA); 29.8% and small vessel occlusion (SVO); 20.2%. LAA and SVO accounted for 37.5% of all stroke subtypes in the ≤36 year age-group. Cardioembolism (15.1%) and stroke of determined aetiology (14.7%) contributed to the other categories of identified stroke subtypes. Mortality on hospital discharge was 3.1% while 65.1% of patients were independent on discharge. Conclusion: This study demonstrated the substantial presence of premature atherosclerosis and conventional risk factors in young ischaemic stroke patients from 8 Asian cities. Venous infarction from cerebral venous thrombosis was rare in this study. Outcome on hospital discharge was poorer compared to Western studies. Detection of vascular risk factors and primary prevention measures should be initiated during late adolescence or early adulthood in urban Asia.
8.Complication of acute stroke: A study in ten Asian countries
Jose C Navarro ; Ester Bitanga ; Nijasri Suwanwela ; Hui Meng Chang ; Shan Jin Ryu ; Yi Ning Huang ; Lawrence Wong ; Deepak Arjundas ; Bhim Sen Singhal ; Sang Bok Lee ; Byung Woo Yoon ; N Venketasubramanian ; Hou Chang Chiu ; Niphon Poungvarin ; Kay Sin Tan ; Sardar Mohd Alam ; Duc Hinh Le
Neurology Asia 2008;13(1):33-39
Background and Objective: There is a paucity of studies looking into the frequency of complications
after stroke among Asians. We sought to determine the frequency and rate of complications among
Asians after acute stroke. Methods: Consecutive patients with acute stroke among 10 participating Asian
countries were included in the study. The frequency and timing of pre-determined complications, and
their relation to area of admission were noted. Results: Of the 1,153 patients included in the study, 423
(41.9%) developed complications within the first 2 weeks of stroke. Recurrent stroke, chest infections
and urinary tract infections were most commonly encountered, and were most frequent within the
first week of stroke onset. A lower rate of complications was noted among patients admitted at an
organized stroke unit.
Conclusion: There is a similar rate of frequency and timing of complications after acute stroke among
Asians as compared with other populations.
9.Moyamoya disease in a young woman with intraand extracranial vessels involvement on vessel wall imaging
TOH Tsun-Haw ; Kay-Sin TAN ; Norlisah RAMLI ; Kartini RAHMAT ; Chong-Tin TAN ; Kar-Foo LAU ; Mei-Ling Sharon TAI
Neurology Asia 2019;24(3):281-285
Moyamoya disease (MMD) was first described
in 1957 as “bilateral hypoplasia of internal
carotid arteries (ICAs)”.1
Aside from involving the intracranial arteries, MMD can also affect
extracranial ICAs and external carotid arteries
(ECAs).2-4 High resolution magnetic resonance
(MR) vessel wall imaging (VWI) is increasingly
being used to help with the diagnosis and
characterization of the condition focusing mainly
on intracranial vessels and extracranial ICAs.5-9
We present a case of a young woman with MMD,
demonstrating vessel wall enhancement of nonstenotic maxillary branches of bilateral ECAs.
10.Percutaneous transcatheter aortic valve implantation for degenerated surgical bioprostheses: the first case series in Asia with one-year follow-up.
Paul Toon-Lim CHIAM ; See-Hooi EWE ; Jia-Lin SOON ; Kay-Woon HO ; Yong-Koong SIN ; Swee-Yaw TAN ; Soo-Teik LIM ; Tian-Hai KOH ; Yeow-Leng CHUA
Singapore medical journal 2016;57(7):401-405
INTRODUCTIONPercutaneous transcatheter aortic valve implantation (TAVI) has become an established therapy for inoperable and high-surgical-risk patients with severe aortic stenosis. Although TAVI in patients with degenerated surgical aortic bioprostheses (i.e. valve-in-valve TAVI) is increasingly reported in Western studies, such data is lacking in Asian patients. We describe the initial experience of valve-in-valve TAVI in Asia.
METHODSEight patients who underwent valve-in-valve TAVI due to degenerated aortic bioprostheses were enrolled. The mechanism of bioprosthetic valve failure was stenotic, regurgitation or mixed. All procedures were performed via transfemoral arterial access, using the self-expanding CoreValve prosthesis or balloon-expandable SAPIEN XT prosthesis.
RESULTSThe mean age of the patients was 71.6 ± 13.2 years and five were male. Mean duration to surgical bioprosthesis degeneration was 10.2 ± 4.1 years. Valve-in-valve TAVI was successfully performed in all patients. CoreValve and SAPIEN XT prostheses were used in six and two patients, respectively. There were no deaths, strokes or permanent pacemaker requirement at 30 days, with one noncardiac mortality at one year. All patients experienced New York Heart Association functional class improvement. Post-procedure mean pressure gradients were 20 ± 11 mmHg and 22 ± 8 mmHg at 30 days and one year, respectively. Residual aortic regurgitation (AR) of more than mild severity occurred in one patient at 30 days. At one year, only one patient had mild residual AR.
CONCLUSIONIn our experience of valve-in-valve TAVI, procedural success was achieved in all patients without adverse events at 30 days. Good clinical and haemodynamic outcomes were sustained at one year.
Aged ; Aged, 80 and over ; Aortic Valve ; surgery ; Aortic Valve Insufficiency ; surgery ; Aortic Valve Stenosis ; surgery ; Arteries ; Bioprosthesis ; Cardiac Catheterization ; methods ; Female ; Fluoroscopy ; Follow-Up Studies ; Heart Valve Prosthesis ; Heart Valve Prosthesis Implantation ; Hemodynamics ; Humans ; Male ; Middle Aged ; Pacemaker, Artificial ; Prosthesis Failure ; Severity of Illness Index ; Transcatheter Aortic Valve Replacement