Displaying publications 21 - 40 of 100 in total

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  1. Fong SL, Wong KT, Tan CT
    Brain, 2024 Mar 01;147(3):830-838.
    PMID: 38079534 DOI: 10.1093/brain/awad415
    Dengue virus is a flavivirus transmitted by the mosquitoes, Aedes aegypti and Aedes albopictus. Dengue infection by all four serotypes (DEN 1 to 4) is endemic globally in regions with tropical and subtropical climates, with an estimated 100-400 million infections annually. Among those hospitalized, the mortality is about 1%. Neurological involvement has been reported to be about 5%. The spectrum of neurological manifestations spans both the peripheral and central nervous systems. These manifestations could possibly be categorized into those directly related to dengue infection, i.e. acute and chronic encephalitis, indirect complications leading to dengue encephalopathy, and post-infectious syndrome due to immune-mediated reactions, and manifestations with uncertain mechanisms, such as acute transverse myelitis, acute cerebellitis and myositis. The rising trend in global dengue incidence calls for attention to a more explicit definition of each neurological manifestation for more accurate epidemiological data. The actual global burden of dengue infection with neurological manifestation is essential for future planning and execution of strategies, especially in the development of effective antivirals and vaccines against the dengue virus. In this article, we discuss the recent findings of different spectrums of neurological manifestations in dengue infection and provide an update on antiviral and vaccine development and their challenges.
  2. Lim KS, Choo WY, Wu C, Tan CT
    Epilepsy Behav, 2013 Nov;29(2):395-9.
    PMID: 24090773 DOI: 10.1016/j.yebeh.2013.08.027
    INTRODUCTION: None of the quantitative scales for public attitudes toward epilepsy had been translated to Malay language. This study aimed to translate and test the validity and reliability of a Malay version of the Public Attitudes Toward Epilepsy (PATE) scale.
    METHOD: The translation was performed according to standard principles and tested in 140 Malay-speaking adults aged more than 18 years for psychometric validation.
    RESULTS: The items in each domain had similar standard deviations (equal item variance), ranging from 0.90 to 1.00 in the personal domain and from 0.87 to 1.23 in the general domain. The correlation between an item and its domain was 0.4 and above for all items and was higher than the correlation with the other domain. Multitrait analysis showed that the Malay PATE had a similar variance, floor and ceiling effects, and relative relationship between the domains as the original PATE. The Malay PATE scale showed a similar correlation with almost all demographic variables except age. Item means were generally clustered in the factor analysis as the hypothesized domains, except those for items 1 and 2. The Cronbach's α values were within acceptable range (0.757 and 0.716 for the general and personal domains, respectively).
    CONCLUSION: The Malay PATE scale is a validated and reliable translated version for measuring public attitudes toward epilepsy.
  3. Tai ML, Jivanadham JS, Tan CT, Sharma VK
    J Headache Pain, 2012 Jun;13(4):291-7.
    PMID: 22422347 DOI: 10.1007/s10194-012-0434-9
    Headache aetiology and presentation are considerably different in elderly individuals. However, literature on headache characteristics among Asians is limited. The objective of this study was to evaluate the headache characteristics among elderly in an outpatient clinic setting in Malaysia, a South-East Asian country with diverse ethnicity. In this prospective cross-sectional study, patients presenting with headache to Neurology and Primary Care Clinics of University Malaya Medical Centre between February 2010 and July 2010 were included. Data for consecutive eligible adult patients were entered in a prospective headache registry. International Headache Criteria II (ICHD-II) were used to classify various headache subtypes. Patients with headache due to intracranial space occupying lesions were excluded. Patient were divided into two age groups-elderly (55 years and above) and younger (less than 55 years of age). Of the 175 screened patients, 165 were included in the study-70 in elderly age group and 95 in younger group. Tension-type headache was the commonest subtype (45.7 %) among the elderly while Migraine without aura (54.7 %) was more common in young adults. More elderly patients suffered from chronic daily headache as compared to younger patients (47.1 vs. 28.4 %; p = 0.015). Headache subtypes and frequency differ considerably among elderly South East Asian patients.
  4. Lim KS, Wu C, Choo WY, Tan CT
    Epilepsy Behav, 2012 Jun;24(2):207-12.
    PMID: 22564888 DOI: 10.1016/j.yebeh.2012.03.038
    A quantitative scale of public attitudes toward epilepsy is essential to determine the magnitude of social stigma against epilepsy. This study aims to develop and validate a cross-culturally applicable scale of public attitudes toward epilepsy.
  5. Thumboo J, Seah A, Tan CT, Singhal BS, Ong B
    Ann Acad Med Singap, 2011 Feb;40(2):67-73.
    PMID: 21468459
    INTRODUCTION: The Multiple Sclerosis International Quality of Life questionnaire (MusiQoL) is a self-administered, multi-dimensional, patient-based health-related quality of life (HRQoL) instrument. With increasing prevalence of multiple sclerosis (MS) in Asian countries, a valid tool to assess HRQoL in those patients is needed. The aim of this study was to evaluate patient acceptability, content validity and psychometric properties of an Asian version of the English MusiQoL in Singapore, Malaysia and India.

    MATERIALS AND METHODS: English speaking patients older than 18 years of age with a defi nite diagnosis of MS were included. The self-administered survey material included the adapted HRQoL questionnaire, a validated generic HRQoL questionnaire: the short-form 36 (SF-36), as well as a checklist of 14 symptoms. We assessed the internal and external validity of the adapted MusiQoL.

    RESULTS: A total of 81 patients with MS were included in the study. The questionnaire was generally well accepted. In the samples from Malaysia and Singapore, all scales exhibited good internal consistency (Cronbach's alpha >0.70). Correlation to SF-36 was generally good, demonstrating high construct validity (P <0.001) in some aspects of the MusiQoL.

    CONCLUSION: The Asian adaptation of the English version of the MusiQoL in evaluating HRQoL seems to be a valid, reliable tool with adequate patient acceptability and internal consistency.

  6. Tai ML, Lim SY, Tan CT
    J Clin Neurosci, 2010 Aug;17(8):1089-90.
    PMID: 20542699 DOI: 10.1016/j.jocn.2009.11.034
    Paroxysmal kinesigenic dyskinesia is a rare disorder, and there are few reports of Asian patients with this condition. We reviewed the clinical features of all patients with idiopathic paroxysmal kinesigenic dyskinesia (PKD) seen at a major neurological centre in Malaysia. The charts of 11 patients with idiopathic PKD seen between 1995 and 2008 were reviewed retrospectively. The male:female ratio was 9:2. Ten patients were of Chinese ethnicity, and one was Malay. Three patients (from two families) had a family history of PKD. The involuntary movement was dystonia in 73% of patients. In one patient, attacks were precipitated by vestibular stimulation. One patient had generalized epilepsy. Another patient who did not have epilepsy demonstrated epileptiform discharges. Only slightly over one-quarter of patients had a positive family history. Males, and people of Chinese ancestry, seem to be affected more frequently by PKD in certain Asian populations.
  7. Lim KS, Wo SW, Wong MH, Tan CT
    Epilepsy Behav, 2013 Apr;27(1):130-4.
    PMID: 23416283 DOI: 10.1016/j.yebeh.2012.12.034
    Studies on the impact of epilepsy on employment have been extensively performed in European and some Asian countries but not in Southeast Asia such as Malaysia, a country with a robust economy, low unemployment rate, and minimal social security benefits for the unemployed. This study aims to determine the impact of epilepsy on employment in Malaysia.
  8. Wo MC, Lim KS, Choo WY, Tan CT
    Epilepsy Behav, 2015 Apr;45:21-30.
    PMID: 25794681 DOI: 10.1016/j.yebeh.2015.02.016
    This study aimed to explore positive and negative factors affecting the employability in patients with uncontrolled seizures.
  9. Wo MC, Lim KS, Choo WY, Tan CT
    Epilepsy Res, 2015 Oct;116:67-78.
    PMID: 26354169 DOI: 10.1016/j.eplepsyres.2015.06.016
    People with epilepsy were (PWE) reported to have poorer employment rate. However, the methodologies used differ greatly from one study to another, making global comparison difficult. We aimed to determine the employment rate of PWE globally using a unified definition of employment rate and to summarize the reported positive and negative factors affecting employability in PWE, using a systematic review.
  10. Wo MC, Lim KS, Choo WY, Tan CT
    Epilepsy Res, 2016 Dec;128:6-11.
    PMID: 27792885 DOI: 10.1016/j.eplepsyres.2016.10.003
    PURPOSE: People with epilepsy (PWE) are negatively prejudiced in their ability to work. This study aimed to examine demographic, clinical and psychological factors associated with employability in PWE.

    METHODS: This study recruited epilepsy patients from a neurology clinic in Malaysia. Employability was measured using employment ratio, with a ratio ≥90% (ER90) classified as high employability. Basic demographic data such as age, gender, marital status, religion, education level and household income was collected. Clinical measures consisted of age of seizure onset, seizure frequency, type of epilepsy, aura, polytherapy, nocturnal seizures and seizure control. Psychological measures included Work Self-Determination Index (WSDI), Rosenberg Self-Esteem Scale (SES), and Multidimensional Scale of Perceived Social Support (MSPSS).

    RESULTS: Of 146 PWE, 64.4% had high employability. The participants were predominantly female (52%), Chinese (50.7%), single (50%), having tertiary education (55.5%) and focal epilepsy (72.6%). Clinically, only type of epilepsy was significantly correlated to employability of PWE. Employability of PWE was associated with ability to work (indicated by education level, work performance affected by seizures, ability to travel independently and ability to cope with stress at work) and family overprotection. The high employability group was found to have lower self-perceived stigma (ESS), higher self-determined motivation (WSDI), self-esteem (SES) and perceived social support (MSPSS), than the low employability group. Logistic regression analysis showed that tertiary education level (AOR 3.42, CI: 1.46-8.00), higher self-determination (WSDI, AOR 1.09, CI: 1.012-1.17), lower family overprotection (AOR 0.76, CI: 0.61-0.95), and generalised epilepsy (AOR 4.17, CI: 1.37-12.70) were significant predictors for higher employability in PWE.

    CONCLUSION: Ability to work (education level), clinical factor (type of epilepsy) and psychological factor (self-determined motivation and family overprotection) were important factors affecting employability in PWE.

    Study site: neurology clinic Universiti Malaya Medical Centre (UMMC)
  11. Idris MI, Tai SML, Tan CT, Tan KS
    Case Rep Neurol, 2020 12 14;12(Suppl 1):106-109.
    PMID: 33505281 DOI: 10.1159/000500950
    Streptococcus pneumoniae are Gram-positive bacteria that are responsible for many types of illnesses including pneumonia, sinus infections, and community-acquired meningitis. One important complication of bacterial meningitis is intracranial vasculopathy. Possible etiologies include vasculitis, vasospasm, endocarditis, or intra-arterial thrombosis. We present a case report of S. pneumoniae meningitis treated with antibiotics in which clinical improvement correlated with serial transcranial Doppler ultrasonography (TCD) improvement, suggesting vasospasm or vasculitis as a possible mechanism for intracranial vasculopathy.
  12. Toh, Tsun-Haw, Lim, Kheng-Seang, Ng, Ching-Ching, Imran Idris, Sherrini Bazir Ahmad, Lim, Thien-Thien, et al.
    MyJurnal
    Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease of small cerebral arteries. This case series aims to describe the mutations in NOTCH3and their phenotypes in Malaysia. We includedpatients who were genetically confirmed to have CADASIL, diagnosed at the University of Malaya Medical Centre, Malaysia. Family members who fulfilled clinical or imaging criteria, and patients from two previous published Malaysian families were also included. Six families (eleven cases) were included in this series. Genetic testing revealed NOTCH3 mutations in c.328C>T (p.Arg110Cys, R110C), c.553T>G (p.Cys185Gly, C185G), c.1630C>T (p.Arg544Cys, R544C) and c.160C>T (p.Arg54Cys, R54C). Two out of four Chinese families had R544C mutation in exon 11, with a later age of onset, absence of migraine and lack of anterior temporal pole involvement on MRI. One family with mixed Indian and Chinese ancestry had a mutation in exon 3 with R110C and another Indian family exon 4 with C185G mutation. This case series highlights the genotypic and phenotypic variability of CADASIL in a multi-ethniccountry. The finding of p.Arg544Cys mutation among the older Chinese families, similar to those reported in Jeju Island and Taiwan, suggest the need to screen the older Chinese stroke patients with typical MRI changes.
  13. 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.
  14. 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.

  15. Tai, Sharon Mei-Ling, Tan, Hong-Yien, Yong, Yean-Kong, Esaki M. Shankar, Yap, Jun-Fai, Tan, Chong Tin, et al.
    Neurology Asia, 2017;22(3):209-220.
    MyJurnal
    Background: Tuberculous meningitis is a life-threatening manifestation resulting from infection
    by Mycobacterium tuberculosis, especially in the developing countries. The molecular aspects of
    pathogenesis of tuberculous meningitis remain poorly understood. We evaluated the correlation of
    cerebrospinal fluid (CSF) and serum cytokine levels with the clinical outcome of 15 HIV-negative
    patients with tuberculous meningitis. We also assessed the association of CSF and serum cytokines
    with neuroimaging of brain findings in the patients.

    Methods: The prospective longitudinal study was
    conducted at the University Malaya Medical Centre between 2012 and 2014. Neuroimaging of the
    brain was performed and the findings of leptomeningeal enhancement, hydrocephalus, tuberculoma,
    infarcts and vasculopathy were recorded. The CSF and serum specimens were analyzed for IL-1ß,
    IL-8, IL-10, IL-18, IP-10, IFN-γ, MCP-1, TGF-ß, VEGF, TNF- α, IL-18BPa and MMP-9. The clinical
    outcome was graded at 3 months based on Modified Rankin scale (mRS).

    Results: On admission and
    at one month of anti-tuberculosis treatment, the CSF levels of IL-8, IL-1β, IP-10, IFN-γ and VEGF
    were elevated in all of the patients. Serum IP-10, MCP-1, IL-1β and IL-8 levels were increased on
    admission and at one month of anti-tuberculosis treatment. There were statistically significant differences
    between good and poor outcome (mRS at 3 months) for CSF IFN-γ (p=0.033), CSF IL-10 (p=0.033)
    and serum VEGF (p=0.033) at one month of treatment. None of the patients showed any association
    between CSF and serum cytokines on admission and at one month of anti-tuberculosis treatment with
    neuro-radiological findings.

    Conclusion: The CSF cytokine levels were not related to TBM disease severity on admission, and
    changes on MRI/CT scans. CSF levels of IFN-γ and IL-10 at one month of anti-tuberculosis treatment
    were associated with clinical outcome at 3 months. CSF cytokine levels on admission were not
    associated with the clinical outcome.
  16. Nadarajah S, Samsudin A, Ramli N, Tan CT, Mimiwati Z
    Optom Vis Sci, 2017 10;94(10):981-985.
    PMID: 28858045 DOI: 10.1097/OPX.0000000000001117
    SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between corneal hysteresis (CH) and obstructive sleep apnea syndrome (OSAS) severity has been reported. We provide evidence that CH is lower in OSAS and speculate on the possible causes.

    PURPOSE: The present study aims to look at the association between CH and severity of OSAS, and whether CH could be another link between OSAS and the development of glaucoma.

    METHODS: This was a cross-sectional, observational study at the University Malaya Medical Centre, Kuala Lumpur. Patients undergoing polysomnography for assessment of OSAS were recruited. We measured central corneal thickness (CCT) using optical biometry, and CH using ocular response analysis. Intraocular pressure (IOP) and Humphrey visual field (HVF) indices were also measured. The Apnea Hypopnea Index (AHI) divided patients into normal, mild, moderate, and severe OSAS categories. The normal and mild categories (47.9%) were then collectively called group 1, and the moderate and severe categories (52.1%) were called group 2. T tests, Pearson correlation tests, and general linear model analysis were performed, with P .05). CH correlated negatively with AHI (r = -0.229, P = .013) and positively with lowest oxygen saturation (r = 0.213, P = .022).

    CONCLUSIONS: CH is lower in moderate/severe OSAS than in normal/mild cases. This may be another link between OSAS and the development of glaucoma; further studies are indicated to determine the significance of this connection.

  17. Italiano CM, Wong KT, AbuBakar S, Lau YL, Ramli N, Syed Omar SF, et al.
    Clin Infect Dis, 2015 Apr 1;60(7):1134.
    PMID: 25537869 DOI: 10.1093/cid/ciu1163
  18. Yeap LL, Lim KS, Lo YL, Bakar MZ, Tan CT
    Epileptic Disord, 2014 Sep;16(3):375-9.
    PMID: 25167568 DOI: 10.1684/epd.2014.0671
    Hearing loss has been reported with valproic acid (VPA) use. However, this is the first case of VPA-induced hearing loss that was tested and confirmed with a VPA rechallenge, supported by serial audiometry and pharmacokinetic modelling. A 39-year-old truck driver with temporal lobe epilepsy was treated with VPA at 400 mg, twice daily, and developed hearing loss after each dose, but recovered within three hours. Hearing loss fully resolved after VPA discontinuation. Audiometry performed five hours after VPA rechallenge showed significant improvement in hearing thresholds. Pharmacokinetic modelling during the VPA rechallenge showed that hearing loss occurred at a level below the therapeutic range. Brainstem auditory evoked potential at three months after VPA discontinuation showed bilateral conduction defect between the cochlear and superior olivary nucleus, supporting a pre-existing auditory deficit. VPA may cause temporary hearing threshold shift. Pre-existing auditory defect may be a risk factor for VPA-induced hearing loss. Caution should be taken while prescribing VPA to patients with pre-existing auditory deficit.
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