Displaying publications 1 - 20 of 152 in total

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  1. Abdullah S, Fadzli F, Ramli N, Tan CT
    Mult Scler Relat Disord, 2017 Feb;12:34-38.
    PMID: 28283103 DOI: 10.1016/j.msard.2016.12.011
    BACKGROUND AND OBJECTIVE: The recently introduced International Consensus diagnostic criteria for diagnosis of neuromyelitis spectrum disorder include patients who are seronegative for AQP4 antibody. The criteria are dependent on typical MRI changes in the spinal cord, optic nerve and brain. This study aims to determine whether there are significant differences in the MRI brain images between AQP4 positive and negative patients with IIDDs.

    METHOD: MRI brain of patients with a diagnosis of IIDDs presented to the Hospital from 2010 to 2015 was analysed. The MRI was assessed by 2 radiologists blinded to the AQP4 status, on features said to be typical of NMOSD and MS.

    RESULTS: Thirty nine patients fulfilled the criteria and were included in the study. They consisted of 19 AQP4 seropositive and 20 AQP4 seronegative patients. The mean age was older (37.0 vs. 28.8 years) among the AQP4 positive group. The majority of the patients were ethnic Chinese (72%), followed by the Malays and Indians. Those with AQP4 seropositive status generally has less brain lesions, and significantly less fulfilling the McDonald DIS criteria as compared to those with AQP4 seronegative status (15.8% vs. 60.0%, p=0.005). None of the seven cerebral MRI features highlighted in NMOSD 2015 diagnostic criteria, said to be characteristic of NMOSD was more common among the AQP4 positive patients. These features were in fact seen less frequently among the AQP4 seropositive patients. An example was the extensive hemispheric lesion seen in 10.5% of AQP4 seropositive patients vs. 45% of that AQP4 seronegative group.

    CONCLUSION: There was no characteristic MRI brain features in the Malaysian AQP4 seropositive IIDD patients versus those who are seronegative. This could be a reflection of ethnical difference.

  2. Abdullah S, Lim KS, Wong WF, Tan HJ, Tan CT
    Neurology Asia, 2015;20(2):167-175.
    MyJurnal
    Background& Objective: Investigation modalities, such as MRI and CSF examination, are neither sensitive nor specific in the early phase of anti-NMDAR encephalitis. Nuclear imaging may be useful to monitor the response to treatment but limited by the availability.We aimed to determine the role of EEG as a tool for early diagnosis as well as a tool to assess disease progression and response to treatment. Methods: A total of 99 EEGsdone in 16 patients diagnosed with anti-NMDAR encephalitis throughout the course of illness, were reviewed retrospectively. The EEG changes were correlated with the clinical presentations and response to treatment. Sixteen EEGs of patients with schizophrenia and mood disorder, and 10 EEGs of patients with infective encephalitis were included as control. Results: EEGs performed during the psychiatric and cognitive dysfunctionphase in patient with anti-NMDAR encephalitis, showed diffuse background slowing in the delta-theta range in all the patients. Serial EEGs showed that the dominant background frequency improved with improvement in cognitive status. Nine patients had complete recovery with normalisation of the EEG abnormalities. Eight patients had their typical clinical seizure recorded during EEG monitoring, but only 2 (25.0%) with EEG correlation. Ten patients had status epilepticus (62.5%), 5 had EEG recorded during their status epilepticus, of which only one with EEG correlation (20.0%). Eleven patients had asymmetric background (68.8%), but only 1 has correlation with focal changes in the MRI brain (9.1%). Even though the EEGs of patients with infective encephalitis also showed background slowing, their CSF analysis was supportive of an infective cause. EEGs of patients with established psychiatric disorder were within normal limits.
    Conclusion: EEG abnormality has a good correlation with the degree of psychiatric and cognitive dysfunction in patient with anti-NMDAR encephalitis, and is useful in early diagnosis, monitoring the progress and the response to treatment. However, it has poor correlation with clinical seizures.
  3. Abdullah S, Wong WF, Tan CT
    Mult Scler Int, 2017;2017:1359761.
    PMID: 28203460 DOI: 10.1155/2017/1359761
    Background. There have been inconsistent reports on the prevalence and pathogenicity of anti-Aquaporin 4 (AQP4) in patients presented with idiopathic inflammatory demyelinating diseases (IIDDs). Objective. To estimate the prevalence of anti-AQP4 antibody in patients with IIDDs presented to University Malaya Medical Centre in terms of patients' clinical and radiological presentations and prognoses. Methods. Retrospective data review of IIDDs patients presented from 2005 to 2015. Patients were classified into classical multiple sclerosis (CMS), opticospinal (OS) presentation, optic neuritis (ON), transverse myelitis (TM), brainstem syndrome (BS), and tumefactive MS. Anti-Aquaporin 4 antibody was tested using the Indirect Immunofluorescence Test (IIFT) cell-based assay. Statistical analysis was done using the SPSS version 20. Results. Anti-AQP4 antibody was detected in 53% of patients presented with IIDDs. CMS was more common in the seronegative group, 27/47 (57.45%; p < 0.001). Conversely, OS involvement was more common in the seropositive group, 26/53 (49.06%; p < 0.001). Longitudinally extensive spinal cord lesions (LESCLs) on MRI were also more common in the seropositive group, 29/40 (72.50%; p = 0.004). Only 2/40 (5.00%) had MRI evidence of patchy or multiple short-segment spinal cord lesions in the AQP4-positive group (p = 0.003). The relapse rate and Expanded Disability Status Scale (EDSS) were also higher in the seropositive group (5.43 versus 3.17, p = 0.005; 4.07 versus 2.51, p = 0.006, resp.). Typical clinical presentations that defined NMO were also seen in the seronegative patients, but in a lower frequency. Conclusion. Our cohort of patients had a higher prevalence of seropositivity of anti-AQP4 antibody as compared to those in Western countries. This was also associated with a more typical presentation of opticospinal involvement with LESCLs on MRI, a higher rate of relapse, and EDSS.
  4. Abubakar S, Teoh BT, Sam SS, Chang LY, Johari J, Hooi PS, et al.
    Emerg Infect Dis, 2013 Dec;19(12):1989-91.
    PMID: 24274071 DOI: 10.3201/eid1912.120530
    An outbreak of fever associated with myalgia and myositis occurred in 2012 among 89 of 92 college students and teachers who visited Pangkor Island, Malaysia. The Sarcocystis nesbitti 18S rRNA gene and sarcocysts were obtained from muscle tissues of 2 students. Our findings indicate emergence of S. nesbitti infections in humans in Malaysia.
  5. Alders EE, Hentzen A, Tan CT
    Headache, 1996 Jun;36(6):379-84.
    PMID: 8707557 DOI: 10.1046/j.1526-4610.1996.3606379.x
    This community study on headache in Malaysia was based on IHS diagnostic criteria and showed the last-year prevalence of migraine was 9.0%. Migraine with aura accounted for only 10.6% of the migrainous population. The last-year prevalence of tension headache was 26.5% (94.4% episodic, 5.6% chronic) and 28.2% for other types of headache. No case of cluster headache was found. Almost two thirds of the migraine subjects graded their headaches as severe, while almost 60% of the tension headache subjects and almost 70% of the other headache subjects graded their headaches as mild. Overall, there was higher prevalence in females for migraine and tension headache, and in males for the other types of headache. The prevalence of headache was lower among those younger than 15 and older than 65 years of age. No significant differences were found in the prevalence of headache among the different racial groups nor among the urban versus the rural population. All the headache types shared the same triggering factors suggesting that different physiological characteristics are responsible for the type of pain suffered. In the location of this community with its tropical climate, headache was attributed to sun exposure in 51.9% of the migraine subjects, 55.7% of the tension headache subjects, and 36.6% of the group with other headaches.
  6. Amudha K, Chee KH, Tan KS, Tan CT, Lang CC
    Int J Clin Pract, 2003 Jun;57(5):369-72.
    PMID: 12846339
    Atherosclerosis is a progressive, disseminated condition that affects all the vascular beds. Peripheral arterial disease (PAD), a manifestation of atherosclerosis, measured non-invasively in the legs by ankle-brachial index (ABI) is associated with increased cardiovascular morbidity and mortality. Though several studies in the western industrialised countries have shown that PAD is widely prevalent in the general older population at risk, not much data are available in the South East Asian developing countries. We have conducted an epidemiological survey on the prevalence of PAD in high-risk patients at an urban hospital in Malaysia. A total of 301 consecutive patients aged 32-90 years were recruited during their follow-up clinic visits for established cardiovascular disease, ischaemic stroke or diabetes mellitus > or = 5 years. All participants underwent ABI measurement and were subjected to the Edinburgh claudication questionnaire to assess leg symptoms. The prevalence of PAD in our high-risk population was 23%, of which only 27% were symptomatic with the classical intermittent claudication. All the patients with PAD were diagnosed at the time of the study. PAD was found in 33% of patients with pre-existent cardiovascular disease, 28% in patients with ischaemic stroke and 24% in diabetic patients. PAD was also highly prevalent among the younger patients. Our study has shown that PAD is highly prevalent among high-risk Malaysian patients and is not necessarily a disease of older age. Only 27% of these patients were symptomatic. All the subjects with PAD were diagnosed at the time of the study, which would suggest it is an unrecognised and underdiagnosed condition, even in patients with atherosclerotic risk factors.
  7. Audrey C, Lim KS, Ahmad Zaki R, Fong SL, Chan CY, Sathis Kumar T, et al.
    Epilepsy Res, 2022 Nov;187:107033.
    PMID: 36274423 DOI: 10.1016/j.eplepsyres.2022.107033
    OBJECTIVES: Prevalence of seizures in brain tumors vary substantially between studies even with similar histopathological types. We aimed to identify the seizure prevalence of the commonest types of brain tumors.

    METHODS: Systematic computerized search of PubMed, Embase, and Web of Science were performed. The meta-analysis of pooled prevalence and 95 % confidence interval (CI) for tumor-related seizures were calculated by using a random effect model. Based on the 2014 epilepsy definition, a mean seizure prevalence of 60 % is used to indicate high seizure prevalence in this study.

    RESULTS: 74 studies that reported seizure prevalence with 23,116 patients were included in this meta-analysis. These tumors has higher seizure incidence rate (at least 60 %) with pooled prevalence of 63 % for adult with low-grade astrocytoma (95 % CI: 57-68 %), 65 % for oligodendroglioma (95% CI: 57-72 %), 72 % for oligoastrocytoma (95 % CI: 67-77 %), 81 % for ganglioglioma (95 % CI: 66-97 %) and 94 % for DNET (94 % CI: 83-100 %).

    CONCLUSION: This study highlights the type of brain tumors that carry a high seizure prevalence. Screening for subtle seizures and early management of seizures may be beneficial in patients with low-grade astrocytoma (adult), oligodendroglioma, oligoastrocytoma, ganglioglioma or DNET brain tumor.

  8. Aye SM, Lim KS, Ramli NM, Tan CT
    Lupus, 2013 Apr;22(5):510-4.
    PMID: 23358870 DOI: 10.1177/0961203312474705
    This is a case report on an uncommon correlation between periodic lateralized epileptiform discharges (PLEDs) and white-matter lesions in cerebral lupus, and with a reduced cerebral blood flow (CBF) in single-photon emission computed tomography (SPECT). A 47-year-old woman with a long-term history of systemic lupus erythematosus (SLE) presented with a seizure followed by frontal lobe dysfunction clinically. An electroencephalogram (EEG) showed bilateral independent PLEDs in the frontal region. A magnetic resonance image of the brain showed white-matter changes in the frontal periventricular region. Cerebral angiogram did not reveal any evidence of vasculitis. A cerebral SPECT with tracer injected during the EEG showing PLEDs showed a reduction in CBF in the frontal regions. Clinical recovery was observed with intravenous immunoglobulin. This case shows that PLEDs can be seen with white-matter changes in SLE.
  9. Carrizosa Moog J, Kakooza-Mwesige A, Tan CT
    Seizure, 2017 Jan;44:108-112.
    PMID: 27986419 DOI: 10.1016/j.seizure.2016.11.032
    Epilepsy is considered by the World Health Organization a public health priority with more than 50 million human beings affected by the disease. More than 80% of persons with epilepsy live in low and middle income countries and most of them in tropical areas. Several emerging, re-emerging and neglected diseases are symptomatic etiologies that jointly contribute to the enormous global burden of epilepsy. Besides the clinical strengths to reduce diagnostic and treatment gaps, other strategies in social, economic, cultural, educational and health policies are needed to prevent and treat appropriately vulnerable and affected persons with epilepsy. From the public health point of view, several of those strategies could be more effective in reducing the incidence and burden of the disease than the clinical approach of diagnosis and treatment. Special attention has to be given to stigma reduction and promotion of human rights. Several aspects mentioned in this abstract slip away the scope of the article, but it is a remainder to approach epilepsy in an inter- and transdisciplinary manner, an integral and pertinent approach needed and requested in tropical counties. The article focuses only on emergent and re-emergent etiologies of epilepsy in the tropics like malaria, HIV, neurocysticercosis, viral encephalitis and traumatic brain injury.
  10. Chan CK, Low JS, Lim KS, Low SK, Tan CT, Ng CC
    Neurol Sci, 2020 Mar;41(3):591-598.
    PMID: 31720899 DOI: 10.1007/s10072-019-04122-9
    INTRODUCTION: Genetic (idiopathic) generalized epilepsy (GGE) is a common form of epilepsy characterized by unknown aetiology and a presence of genetic component in its predisposition.

    METHODS: To understand the genetic factor in a family with GGE, we performed whole exome sequencing (WES) on a trio of a juvenile myoclonic epilepsy/febrile seizure (JME/FS) proband with JME/FS mother and healthy father. Sanger sequencing was carried out for validation of WES results and variant detection in other family members.

    RESULTS: Predictably damaging variant found in affected proband and mother but absent in healthy father in SCN1A gene was found to be associated with generalized epilepsy and febrile seizure. The novel non-synonymous substitution (c.5753C>T, p.S1918F) in SCN1A was found in all family members with GGE, of which 4/8 were JME subtypes, and/or febrile seizure, while 3 healthy family member controls did not have the mutation. This mutation was also absent in 41 GGE patients and 414 healthy Malaysian Chinese controls.

    CONCLUSION: The mutation is likely to affect interaction between the sodium channel and calmodulin and subsequently interrupt calmodulin-dependent modulation of the channel.

  11. Chan CK, Lim KS, Low SK, Tan CT, Ng CC
    Epilepsy Res, 2023 Jan;189:107070.
    PMID: 36584483 DOI: 10.1016/j.eplepsyres.2022.107070
    Epilepsy is a complex neurological disease that can be caused by both genetic and environmental factors. Many studies have been conducted to investigate the genetic risk variants and molecular mechanisms of epilepsy. Disruption of excitation-inhibition balance (E/I balance) is one of the widely accepted disease mechanisms of epilepsy. The maintenance of E/I balance is an intricate process that is governed by multiple proteins. Using whole exome sequencing (WES), we identified a novel GABRA1 c.448G>A (p.E150K) variant and ERBB4 c.1972A>T (p.I658F, rs190654033) variant in a Malaysian Chinese family with genetic generalized epilepsy (GGE). The GGE may be triggered by dysregulation of E/I balance mechanism. Segregation of the variants in the family was verified by Sanger sequencing. All family members with GGE inherited both variants. However, family members who carried only one of the variants did not show any symptoms of GGE. Both the GABRA1 and ERBB4 variants were predicted damaging by MutationTaster and CADD, and protein structure analysis showed that the variants had resulted in the formation of additional hydrogen bonds in the mutant proteins. GABRA1 variant could reduce the efficiency of GABAA receptors, and constitutively active ERBB4 receptors caused by the ERBB4 variant promote internalization of GABAA receptors. The interaction between the two variants may cause a greater disruption in E/I balance, which is more likely to induce a seizure. Nevertheless, this disease model was derived from a single small family, further studies are still needed to confirm the verifiability of the purported disease model.
  12. Chee CP, Tan CT, Nuruddin R
    Br J Neurosurg, 1990;4(6):529-33.
    PMID: 2076215
    An unusual case of syringomyelia secondary to a cauda equina meningioma involving the conus medullaris is described. The tumour was totally removed with decompression of an adjacent cyst and syrinx resulting in resolution of the symptoms and radiological appearance.
  13. Chew NK, Tan CT, Goh KJ
    J Clin Neurosci, 2002 Sep;9(5):604-5.
    PMID: 12383430
    A 24-year-old woman presented with a 3.5-year history of paroxysmal dystonia that was precipitated by sudden movement, especially when she started to walk. It was characterised by shrugging of shoulders, flexion of the neck and thoracic spine, and stiffness of the right leg followed by falls. Each attack lasted for less than 5min. Inadequate sleep and stress were exacerbating factors. There was no similar family history. Physical examination and investigations were normal. The following manoeuvres that caused vestibular stimulation precipitated attacks: turning her head from side to side while standing still, sitting still on a rotating chair and an ice-water caloric test. She had partial responses to phenytoin and levodopa, and a good response to haloperidol. Vestibular stimulation as a precipitating factor in paroxysmal kinesigenic choreoathetosis has not been reported previously.
  14. Chew NK, Sim BF, Tan CT, Goh KJ, Ramli N, Umapathi P
    Neurology, 2001 Aug 14;57(3):529-31.
    PMID: 11502928
    In a hospital series of 70 patients on follow-up after radiotherapy for nasopharyngeal carcinoma, 14 patients (20%) developed delayed post-irradiation bulbar palsy 1 to 18 years after radiotherapy (mean 5.5 years). Functional disability was moderate to severe. Three patients had aspiration pneumonia with one mortality. Post-irradiation bulbar palsy was a common complication and probably resulted from direct neuronal damage.
  15. Chia ZJ, Lim KS, Fong SL, Sim RS, Rajahram GS, Narayanan V, et al.
    Epilepsy Behav, 2020 09;110:107158.
    PMID: 32512367 DOI: 10.1016/j.yebeh.2020.107158
    BACKGROUND: Epilepsy stigma is an important issue affecting people with epilepsy (PWE) in various social aspects of life. Most studies on stigma were among the metropolitan population but rarely on indigenous people. Hence, this study aimed to understand the attitudes toward epilepsy of the East Malaysians, comparing with the West Malaysians previously reported.

    METHOD: This study was performed among the indigenous people in Kuching and Sibu (Sarawak) and Kota Kinabalu (Sabah) using the Public Attitudes Toward Epilepsy (PATE) scale. A higher score indicates poorer attitude.

    RESULT: A total of 360 respondents (41.7% Kadazan-Dusun, 30.6% Bidayuh, and 24.7% Iban) aged 34.6 ± 12.6 years completed the questionnaire. They were predominantly females and had lower education level and income compared with the West Malaysians. The Sabah population had significantly lower mean scores (better attitudes) than those in Sarawak, in both personal and general domains (p 

  16. Chia ZJ, Lim KS, Lee SR, Lai WW, Chan PQ, Ng SJ, et al.
    Epilepsy Behav, 2021 Apr;117:107798.
    PMID: 33582391 DOI: 10.1016/j.yebeh.2021.107798
    BACKGROUND: In epilepsy stigma, certain perceptions are culturally dependent and greatly influence a person's attitudes. Hence, we aimed to explore the perceptions associated with attitudes toward epilepsy in various urban subpopulations.

    METHOD: This is a mixed-method study employing the Public Attitude Toward Epilepsy (PATE) scale as the quantitative measure, followed by a semi-structured interview. The qualitative data were then counted and analyzed concurrently with the quantitative data.

    RESULT: A total of 410 respondents (104 people with epilepsy [PWE]; 104 family members [FM]; 100 medical students [MS]; 102 public [Pb]) aged 37 years (IQR 23-55) were recruited. They were mostly female (57.3%), Chinese (52.0%), and highly educated (63.7%). The attitudes toward epilepsy among medical students are the best, followed by the PWE and their family members, and the worst among the public. The qualitative results revealed 4 main themes, which were "general social values", "epilepsy severity and control", "PWE's abilities", and "harms and burdens to the respondents and others". A two-dimensional perception model was constructed based on these themes, which consisted of general-personal and universal-specific dimensions. Generally, the PWE/FM subgroup focused more on PWE's abilities, whereas the MS/Pb subgroup more on general social values, and harms and burden. In the education aspect, most attitudes were related to the epilepsy severity and PWE's abilities, whereas in employment, the main consideration was the PWE's abilities. Burden to life and concern about inheritance were major considerations in the marital relationship. Those with positive attitudes tend to highlight the importance of general social values, while negative attitudes associated more with epilepsy severity. In general domain, general social values were the main considering factor but in personal domain, most participants will consider epilepsy severity and control, harms and burden to themselves.

    CONCLUSION: The perceptions underlying attitudes toward epilepsy were complex and varied between subpopulations, attitude levels, domains, and aspects of life. (304 words).

  17. Chia ZJ, Jehosua SY, Lim KS, Khosama H, Hamid DH, Fong SL, et al.
    Epilepsy Behav, 2020 02;103(Pt A):106833.
    PMID: 31839499 DOI: 10.1016/j.yebeh.2019.106833
    INTRODUCTION: Epilepsy stigma has been associated with poor quality of life among people with epilepsy (PWE). It is important to understand the variation and degree of epilepsy stigma in one of the most populous and culturally diverse nations in the world, Indonesia. Hence, this study aimed to test the validity and reliability of the Indonesian version of the Public Attitudes Toward Epilepsy (PATE) scale.

    METHOD: The translation was performed according to standard principles and tested in 200 native Indonesian speakers who were aged above 18-year-old for psychometric validation.

    RESULTS: The items in each domain had similar means and standard deviations (equal item variance), means ranging from 2.17 to 2.86 in general domain and 2.75 to 3.56 in personal domain and, standard deviations ranging from 0.87 to 1.05 and 0.88 to 1.01 in general and personal domain, respectively. Item-domain correlations were more than 0.5 for all items, and they correlate higher within their own domain compare with the other domain (convergent and divergent validity). Multitrait analysis showed similar variance, floor, and ceiling patterns to a great extent compared with the initial study. The Indonesian PATE scale also showed mostly similar correlation with demographic characteristics except monthly income. Principle axis analysis revealed strong factor loading (>0.3) in their hypothesized domain, except item 14. The Cronbach's α values for general and personal domains were 0.836 and 0.765, which were within the accepted range of 0.7 to 0.9.

    CONCLUSION: The Indonesian PATE scale is a validated and reliable translation for measuring public attitudes toward epilepsy.

  18. Chong HT, Tan CT
    Med J Malaysia, 2008 Dec;63(5):356-61.
    PMID: 19803290 MyJurnal
    Multiple sclerosis, although a rare disease in Asia, often presents significant diagnostic challenges to clinicians. There has been rapid advancement in the understanding of the underlying genetic influence, pathophysiology, investigation and treatment recently. This paper reviewed the latest development of various aspects of the disease and examined the differences between the manifestations of Asian and Western patients. The implications of these differences to investigation and treatment were also touched upon.
  19. Chong HT, Ramli N, Lee KH, Kim BJ, Ursekar M, Dayananda K, et al.
    Can J Neurol Sci, 2006 Feb;33(1):95-100.
    PMID: 16583730
    Magnetic resonance imaging (MRI) of the brain is the most important paraclinical diagnostic test in multiple sclerosis (MS). The appearance of MRI in Asians with MS is not well defined. We retrospectively surveyed the first brain and spinal cord MRI in patients diagnosed to have MS, according to Poser's criteria in seven regions throughout Asia to define the MRI changes among Asians with MS. There were 101 patients with first brain, and 86 with first spinal cord MRI, 66 of whom had both. The brain MRI showed a mean of 17 lesions per patient in T2 weighted images, mostly asymptomatic. Almost all the lesions were in the white matter, particularly in the juxtacortical, deep and periventricular white matter. A third of the lesions were greater than 5 mm, 14% enhanced with gadolinium. There were more supratentorial than infratentorial lesions at a ratio of 7.5: 1. Ninety five percent of the spinal cord lesions were in cervical and thoracic regions, 34% enhanced with gadolinium. The lesions extended over a mean of 3.6 +/- 3.3 vertebral bodies in length. Fifty (50%) of the brain and 54 (63%) of the spinal MRI patients had the optic-spinal form of MS. The MRI of the optic-spinal and classical groups of patients were similar in appearance and distribution, except that the optic-spinal MS patients have fewer brain but longer and more severe spinal cord lesions. In conclusion, the brain and spinal cord MRI of Asian patients with MS was similar to that of the West, although, in this study, Asian MS patients had larger spinal cord lesions.
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