Displaying publications 1 - 20 of 52 in total

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  1. Yan Hung SK, Hiew FL, Viswanathan S
    Ann Indian Acad Neurol, 2019 1 30;22(1):102-103.
    PMID: 30692769 DOI: 10.4103/aian.AIAN_232_18
    Multiple co-infections can predispose a patient to autoimmune encephalitis. Out of thirty cases of N-methyl-D-aspartate receptor (NMDAR) encephalitis seen at a single tertiary referral center, only two cases of co-infection with NMDAR encephalitis were identified. One of these cases was highly interesting due to the presence of more than one co-infections along with the presence of cortical dysfunction, seizures, and orofacial dyskinesias at the onset in a male in the absence of tumors, which was refractory to initial treatment.
  2. Gopalai AA, Lim SY, Aziz ZA, Lim SK, Tan LP, Chong YB, et al.
    Ann Acad Med Singap, 2013 May;42(5):237-40.
    PMID: 23771111
    INTRODUCTION: The G2385R and R1628P LRRK2 gene variants have been associated with an increased risk of Parkinson's disease (PD) in the Asian population. Recently, a new LRRK2 gene variant, A419V, was reported to be a third risk variant for PD in Asian patients. Our objective was to investigate this finding in our cohort of Asian subjects.

    MATERIALS AND METHODS: Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine.

    RESULTS: The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624).

    CONCLUSION: A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.

  3. Chee KY, Ong KY, Mak CY, Yacob S, Yeo SC, Thrichelam N, et al.
    Asia Pac Psychiatry, 2017 Dec;9(4).
    PMID: 28326670 DOI: 10.1111/appy.12278
    INTRODUCTION: The objective of this study was to establish the psychometric properties of the AD8 Dementia Screening Interview in patients with Parkinson disease (PD) with or without cognitive impairment using the Montreal Cognitive Assessment Tool (MoCA) for comparison.

    METHODS: The AD8 was translated into Malay for Malay-speaking participants. A correlation analysis and a receiver operator characteristic curve were generated to establish the psychometric properties of the AD8 in relation to the MoCA.

    RESULTS: One hundred fifty patients and their caretakers completed the AD8 and MoCA. Using a cutoff score of 1/8, the AD8 had 81% sensitivity and 59% specificity for the detection of cognitive impairment in PD. With a cutoff score of 2/8, the AD8 had 83% specificity and 64% sensitivity. The area under the receiver operator characteristic curve was 80%, indicating good-to-excellent discriminative ability.

    DISCUSSION: These findings suggest that the AD8 can reliably differentiate between cognitively impaired and cognitively normal patients with PD and is a useful caregiver screening tool for PD.

  4. Ching YM, Viswanathan S, Mohamed Nor N, Shuib S, Kamarudin B, Mansor S, et al.
    Auto- immunity highlights, 2019 Dec;10(1):13.
    PMID: 32257069 DOI: 10.1186/s13317-019-0123-7
    Background: Multiple sclerosis is an immune mediated disease targeting the central nervous system. Association of non-human leukocyte antigen gene, CD58, with multiple sclerosis has been reported in several populations but is unclear among Southeast Asians. This pilot study was conducted to explore the association between CD58 polymorphism and multiple sclerosis among the Malay population in Malaysia.

    Methods: Blood samples were collected from 27 multiple sclerosis patients, and compared with 58 age- and gender matched healthy individuals. All patients were tested negative for anti-aquaporin 4. DNA was extracted from the blood and genotyped for 3 single nucleotide polymorphisms rs12044852, rs2300747 and rs1335532 of gene CD58 by real-time PCR.

    Results: The majority of multiple sclerosis patients were female (85.2%). The general mean age of onset was 30.5 years. Genotyping results showed that frequencies of the alleles were between 40 and 50% for MS patients and healthy individuals. Association (allelic model) between multiple sclerosis and CD58 gene polymorphism alleles rs12044852 (p = 0.410), rs2300747 (p = 0.881) and rs1335532 (p = 0.407) were indistinct.

    Conclusions: The impact of the CD58 gene polymorphism was not prominent in this pilot study, implying that genetic composition contributing to multiple sclerosis may be different between different populations, thus results in a heterogeneity of disease manifestation and distribution.

  5. Krishnan D, Viswanathan S, Rose N, Benjamin HSN, Ong AM, Hiew FL
    BMC Neurol, 2021 Sep 21;21(1):366.
    PMID: 34548039 DOI: 10.1186/s12883-021-02394-3
    BACKGROUND: Spinal AVF (SAVF), a potentially treatable cause of myelopathy, remains a challenging diagnosis. Its rarity and non-specific imaging findings often result in misdiagnosis despite a high index of clinical suspicion. The classically described high T2 signal in the spinal cord or prominent vascular flow voids in the intradural space were not infrequently missed on initial imaging, only to be picked up at follow-up imaging after progression of symptoms. Additionally, small sized fistulas(
  6. Gopalai AA, Lim SY, Chua JY, Tey S, Lim TT, Mohamed Ibrahim N, et al.
    Biomed Res Int, 2014;2014:867321.
    PMID: 25243190 DOI: 10.1155/2014/867321
    The LRRK2 gene has been associated with both familial and sporadic forms of Parkinson's disease (PD). The G2019S variant is commonly found in North African Arab and Caucasian PD patients, but this locus is monomorphic in Asians. The G2385R and R1628P variants are associated with a higher risk of developing PD in certain Asian populations but have not been studied in the Malaysian population. Therefore, we screened the G2385R and R1628P variants in 1,202 Malaysian subjects consisting of 695 cases and 507 controls. The G2385R and R1628P variants were associated with a 2.2-fold (P = 0.019) and 1.2-fold (P = 0.054) increased risk of PD, respectively. Our data concur with other reported findings in Chinese, Taiwanese, Singaporean, and Korean studies.
  7. Fu Liong H, Abdul Wahab SA, Yakob Y, Lock Hock N, Thong WK, Viswanathan S
    Case Rep Neurol Med, 2014;2014:926510.
    PMID: 25093132 DOI: 10.1155/2014/926510
    Pompe's disease (acid maltase deficiency, glycogen storage disease type II) is an autosomal recessive disorder caused by a deficiency of lysosomal acid α-1,4-glucosidase, resulting in excessive accumulation of glycogen in the lysosomes and cytoplasm of all tissues, most notably in skeletal muscles. We present a case of adult-onset Pompe's disease with progressive proximal muscles weakness over 5 years and respiratory failure on admission, requiring prolonged mechanical ventilation. Electromyography showed evidence of myopathic process with small amplitudes, polyphasic motor unit action potentials, and presence of pseudomyotonic discharges. Muscle biopsy showed glycogen-containing vacuoles in the muscle fibers consistent with glycogen storage disease. Genetic analysis revealed two compound heterozygous mutations at c.444C>G (p.Tyr148∗) in exon 2 and c.2238G>C (p.Trp746Cys) in exon 16, with the former being a novel mutation. This mutation has not been reported before, to our knowledge. The patient was treated with high protein diet during the admission and subsequently showed good clinical response to enzyme replacement therapy with survival now to the eighth year. Conclusion. In patients with late-onset adult Pompe's disease, careful evaluation and early identification of the disease and its treatment with high protein diet and enzyme replacement therapy improve muscle function and have beneficial impact on long term survival.
  8. Ahuja A, Tyagi PK, Kumar M, Sharma N, Prakash S, Radha, et al.
    Cells, 2022 Sep 07;11(18).
    PMID: 36139367 DOI: 10.3390/cells11182792
    Stem cells are a well-known autologous pluripotent cell source, having excellent potential to develop into specialized cells, such as brain, skin, and bone marrow cells. The oral cavity is reported to be a rich source of multiple types of oral stem cells, including the dental pulp, mucosal soft tissues, periodontal ligament, and apical papilla. Oral stem cells were useful for both the regeneration of soft tissue components in the dental pulp and mineralized structure regeneration, such as bone or dentin, and can be a viable substitute for traditionally used bone marrow stem cells. In recent years, several studies have reported that plant extracts or compounds promoted the proliferation, differentiation, and survival of different oral stem cells. This review is carried out by following the PRISMA guidelines and focusing mainly on the effects of bioactive compounds on oral stem cell-mediated dental, bone, and neural regeneration. It is observed that in recent years studies were mainly focused on the utilization of oral stem cell-mediated regeneration of bone or dental mesenchymal cells, however, the utility of bioactive compounds on oral stem cell-mediated regeneration requires additional assessment beyond in vitro and in vivo studies, and requires more randomized clinical trials and case studies.
  9. Hiew FL, Ramlan R, Viswanathan S, Puvanarajah S
    Clin Neurol Neurosurg, 2017 Jul;158:114-118.
    PMID: 28514704 DOI: 10.1016/j.clineuro.2017.05.006
    OBJECTIVES: This study aimed to evaluate the clinical and electrophysiological characteristics of various distinctive classical and localised Guillain-Barré syndrome (GBS) subtypes.

    PATIENTS AND METHODS: Clinical characteristics and electrophysiological data of sixty-one consecutive patients admitted between 2012 and 2015 were systematically analysed and reclassified according to the new GBS clinical classification. Neurophysiology was evaluated with Hadden et al.'s vs recently proposed Rajabally et al.'s criteria. Functional severity and clinical outcome of various GBS subtypes were ascertained.

    RESULTS: All patients initially identified as GBS or related disorders can be sub-classified into having classical GBS (41, 67%), classic Miller-Fisher Syndrome (MFS) (6, 10%), Pharyngeal-cervical-brachial (PCB) (3, 5%), paraparetic GBS (4, 7%), bifacial weakness with paresthesia (3, 5%), acute ophthalmoparesis (AO) (1, 2%) and overlap syndrome (3, 5%): one (2%) with GBS/Bickerstaff brainstem encephalitis overlap and 2 (3%) with GBS/MFS overlap. Greater proportion of axonal classical GBS (67% vs 55%, p=0.372) seen with Rajabally et al.'s criteria and a predominantly axonal form of paraparetic variant (75%) independent of electrodiagnostic criteria were more representative of Asian GBS cohort. Classical GBS patients had lowest admission and discharge Medical Research Council Sum Score (MRCSS), greater functional disability and longest length of in-patient stay. Twenty (20/21, 95%) patients who needed mechanical ventilation had classical GBS. Patients required repeated dose of intravenous immunoglobulin (5/6, 3%) or plasma exchange (4/4, 100%) more frequently had axonal form of classical GBS.

    CONCLUSION: Phenotype recognition based on new GBS clinical classification, supported by electrodiagnostic study permits more precise clinical subtypes determination and outcome prognostication.

  10. Hiew FL, Thit WM, Alexander M, Thirugnanam U, Siritho S, Tan K, et al.
    J Cent Nerv Syst Dis, 2021;13:11795735211057314.
    PMID: 35173510 DOI: 10.1177/11795735211057314
    Therapeutic plasma exchange (TPE) is an effective and affordable treatment option in most parts of Southeast Asia (SEA). In 2018, the SEA TPE Consortium (SEATPEC) was established, consisting of regional neurologists working to improve outcome of various autoimmune neurological diseases. We proposed an immunotherapeutic guideline prioritizing TPE for this region. We reviewed disease burden, evidence-based treatment options, and major guidelines for common autoimmune neurological disorders seen in SEA. A modified treatment algorithm based on consensus agreement by key-opinion leaders was proposed. Autoimmune antibody diagnostic testing through collaboration with accredited laboratories was established. Choice of first-line immunotherapies (IVIg/corticosteroid/TPE) is based on available evidence, clinicians' experience, contraindications, local availability, and affordability. TPE could be chosen as first-line therapy for GBS, CIDP, MG (acute/short term), IgG, A paraproteinemic neuropathy, and NMDAR encephalitis. Treatment is stopped for acute monophasic conditions such as GBS and ADEM following satisfactory outcome. For chronic immune disorders, a therapy taper or long-term maintenance therapy is recommended depending on the defined clinical state. TPE as second-line treatment is indicated for IVIg or corticosteroids refractory cases of ADEM, NMOSD (acute), MG, and NMDAR/LGI1/CASPR2/Hashimoto's encephalitis. With better diagnosis, treatment initiation with TPE is a sustainable and effective immunotherapy for autoimmune neurological diseases in SEA.
  11. Viswanathan S, Hung SKY, Goyal V, Apiwattanakul M, Thirugnanam UN, Abdullah S, et al.
    J Clin Apher, 2018 Oct;33(5):559-568.
    PMID: 29626354 DOI: 10.1002/jca.21630
    In December 2017, 79 delegates attended the 2nd regional plasmapheresis conference and workshop for Southeast Asia (SEA) on the immunomodulatory role of plasma exchange in central and peripheral nervous system disorders in Kuala Lumpur, Malaysia. This meeting featured 6 plenary lectures, interactive sessions dedicated for experience sharing, case presentations, and a practical session for paramedics. Clinical experts and researchers from 7 SEA countries and India shared experience and challenges in treating autoimmune neurological disorders. While the spectrum of diseases and neurology practice remained largely similar, there was great disparities in accessibility of therapeutic plasma exchange (TPE) within SEA countries and between urban or rural settings. Costs, human resources, and healthcare policies are common challenges in providing sustainable TPE services. Novel techniques and innovative ideas in performing TPE were explored. A working consortium comprising of key opinion leaders was proposed to improve standards of TPE and enhance future research.
  12. Viswanathan S, Hiew FL
    J Clin Apher, 2019 Aug;34(4):434-444.
    PMID: 30829434 DOI: 10.1002/jca.21696
    There has been an increase in the use of therapeutic plasma exchange (TPE) in immune-mediated neurological disorders in recent years. However, accessibility and availability of TPE remains low and costly, especially for a country with limited healthcare funding like Malaysia. With expanding clinical indications in neurological disorders, and increasingly expensive conventional immunomodulatory treatment such as intravenous immunoglobulin and monoclonal antibodies, TPE remains an effective part of first or second-line treatment. In this article, we detailed the historical aspects of the use of TPE in neurological disorders in Malaysia over the last four decades and discussed the challenges behind the establishment of the first in-house neurology-driven TPE service in the country. Local TPE database from a national neurology centre in Kuala Lumpur over the past 20 years was analyzed. We observed a remarkable three folds increase in the use of TPE at our center over the past 10 years (total 131 TPE treatments) compared to a decade prior, with expanding clinical indications predominantly for central nervous system demyelinating disorders. Besides using membrane filtration method, centrifugal technique was adopted, providing new opportunities for other clinical beneficiaries such as a neurologist driven "in-house TPE unit". However, there were real world challenges, especially having to provide services with limited funding, human resources, and space. In addition, much has to be done to improve accessibility, availability, and sustainability of TPE services at our center and nationwide. Nevertheless, even with limited resources and support, it is possible with concerted efforts to work within the confines of these limitations to establish a safe, successful, and sustainable TPE service.
  13. Viswanathan S, Hiew FL, Siritho S, Apiwattanakul M, Tan K, Quek AML, et al.
    J Clin Apher, 2021 Dec;36(6):849-863.
    PMID: 34694652 DOI: 10.1002/jca.21937
    INTRODUCTION: Therapeutic plasma exchange (TPE) for neuroimmunological disorders has played an increasingly important role within the Southeast Asian (SEA) region. The South East Asian Therapeutic Plasma exchange Consortium (SEATPEC) was formed in 2018 to promote education and research on TPE within the region. The advent of the Covid-19 pandemic has produced challenges for the development and expansion of this service.

    METHODOLOGY: A qualitative and semi-quantitative questionnaire-based survey was conducted by SEATPEC member countries from January to June 2020 (Phase 1) and then from July 2020 to January 2021 in (Phase 2) to assess the impact of Covid-19 on regional TPE.

    OBJECTIVES: The study's main objectives were to explore the challenges experienced and adaptations/adjustments taken by SEATPEC countries in order to continue safe and efficient TPE during the Covid-19 pandemic.

    RESULTS: The pandemic was found to disrupt the delivery of TPE services in all SEATPEC countries. Contributing factors were multifactorial due to overstretched medical services, staff shortages, quarantines and redeployments, fear of acquiring Covid-19, movement restriction orders, and patient's psychological fear of attending hospitals/testing for Covid-19. All SEATPEC countries practiced careful stratification of cases for TPE (electives vs emergencies, Covid-19 vs non-Covid-19 cases). SEATPEC countries had to modify TPE treatment protocols to include careful preprocedure screening of patient's for Covid-19, use of personal protective equipment (PPE) and post-TPE sanitization of machines and TPE suites.

    CONCLUSION: Based on the responses of the survey, SEATPEC countries produced a consensus statement with five recommendations for safe and effective TPE within the region.

  14. Rattanathamsakul N, Siritho S, Viswanathan S, Hiew FL, Apiwattanakul M, Tan K, et al.
    J Clin Apher, 2023 Aug;38(4):437-446.
    PMID: 36896493 DOI: 10.1002/jca.22047
    INTRODUCTION: Therapeutic plasma exchange (TPE) for neuroimmunological disorders has played an important role in the Southeast Asian region. This study investigates the challenges of performing TPE within the region.

    METHOD: A questionnaire-based survey was conducted and launched to 15 South East Asian Therapeutic Plasma Exchange Consortium (SEATPEC) members from seven countries in January 2021. It included demographics, TPE techniques, indications, challenges, timing, outcome measurement, and access to laboratory testing in each local center.

    RESULTS: A total of 15 neurologists from 12 participating centers were included. They usually perform five sessions of TPE (100.0%), with 1 to 1.5 plasma volume (93.3%), and exchanges via the central catheter (100.0%). Acute relapses of neuromyelitis optica spectrum disorder and myasthenia gravis are the most common indications. They used a combination of normal saline and 5% albumin (60.0%) as replacement fluid. Most (66.7%) used TPE as an add-on treatment in steroid-refractory cases or as first-line treatment for severe attacks. They suggested assessing the TPE efficacy of TPE by the interval to the next attack, post-TPE relapse rates, and TPE-related complications. The major challenges within our region are expense, reimbursibility, and access to TPE.

    CONCLUSION: Although countrywise differences exist, all share similarities regarding methods, indications, timing, obstacles, and challenges of TPE for neuroimmunological conditions. Regional collaboration will be essential to identify strategies to reduce these barriers to access to TPE in the future.

  15. Hiew FL, Ong JJ, Viswanathan S, Puvanarajah S
    J Clin Neurosci, 2018 Apr;50:203-207.
    PMID: 29398193 DOI: 10.1016/j.jocn.2018.01.018
    Long-term outcome in Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is very limited, especially from Asian countries. We aimed to determine the outcome of our cohort of CIDP patients and to define the relevant clinical, electrophysiological and laboratory determinants of disease activity, progression and treatment response. We retrospectively reviewed records of 23 CIDP patients attending our Neurology service at Kuala Lumpur Hospital, Malaysia between January 2000 and December 2016. We analysed data on neurological deficits, electrophysiological and laboratory parameters to determine diagnostic characteristics, correlation with disease activity and clinical outcomes following treatment. Included were 15 (65%) males and 8 (35%) females with a mean age of 42.7 years (SD 14.4). Mean duration of follow-up visit was 66 months (range 6-134 months). The cohort consists of 19 classical (sensory-motor) CIDP and 4 MADSAM. Large majority of patients (66%) had either stable active disease (CDAS 3, 44%) or were in remission (CDAS class 2, 22%) following treatment with standard immunotherapies (Intravenous Immunoglobulins, steroids or immunosuppressants). The proportion of CIDP patients in each CDAS class was comparable to published cohorts from North America and Europe. Medical Research Council (MRC) sum score was the only clinical score that differed across CDAS classes (p = .010) with significant inverse correlation (Spearman's rho -0.664, p = .001). In conclusion, treatment outcomes of our CIDP cohort was comparable to those of published series. Further studies with larger cohort of patients from other parts of Asia are important to determine the long-term outcome of this heterogenous disease in this region.
  16. Viswanathan S, Wong AH, Quek AM, Yuki N
    J Neuroimmunol, 2015 May 15;282:92-6.
    PMID: 25903734 DOI: 10.1016/j.jneuroim.2015.03.021
    To evaluate the use of intravenous immunoglobulin (IVIG) in preventing relapses in patients with neuromyelitis optica (NMO) and its spectrum disorders (NMOSDs).
  17. Whittam DH, Karthikeayan V, Gibbons E, Kneen R, Chandratre S, Ciccarelli O, et al.
    J Neurol, 2020 Dec;267(12):3565-3577.
    PMID: 32623595 DOI: 10.1007/s00415-020-10026-y
    INTRODUCTION: While monophasic and relapsing forms of myelin oligodendrocyte glycoprotein antibody associated disorders (MOGAD) are increasingly diagnosed world-wide, consensus on management is yet to be developed.

    OBJECTIVE: To survey the current global clinical practice of clinicians treating MOGAD.

    METHOD: Neurologists worldwide with expertise in treating MOGAD participated in an online survey (February-April 2019).

    RESULTS: Fifty-two responses were received (response rate 60.5%) from 86 invited experts, comprising adult (78.8%, 41/52) and paediatric (21.2%, 11/52) neurologists in 22 countries. All treat acute attacks with high dose corticosteroids. If recovery is incomplete, 71.2% (37/52) proceed next to plasma exchange (PE). 45.5% (5/11) of paediatric neurologists use IV immunoglobulin (IVIg) in preference to PE. Following an acute attack, 55.8% (29/52) of respondents typically continue corticosteroids for ≥ 3 months; though less commonly when treating children. After an index event, 60% (31/51) usually start steroid-sparing maintenance therapy (MT); after ≥ 2 attacks 92.3% (48/52) would start MT. Repeat MOG antibody status is used by 52.9% (27/51) to help decide on MT initiation. Commonly used first line MTs in adults are azathioprine (30.8%, 16/52), mycophenolate mofetil (25.0%, 13/52) and rituximab (17.3%, 9/52). In children, IVIg is the preferred first line MT (54.5%; 6/11). Treatment response is monitored by MRI (53.8%; 28/52), optical coherence tomography (23.1%; 12/52) and MOG antibody titres (36.5%; 19/52). Regardless of monitoring results, 25.0% (13/52) would not stop MT.

    CONCLUSION: Current treatment of MOGAD is highly variable, indicating a need for consensus-based treatment guidelines, while awaiting definitive clinical trials.

  18. Hung SKY, Hiew FL, Viswanathan S, Puvanarajah S
    J Peripher Nerv Syst, 2018 Sep;23(3):183-189.
    PMID: 30027593 DOI: 10.1111/jns.12282
    Intravenous immunoglobulin (IVIG), corticosteroids and therapeutic plasma exchange (TPE) are evidence-based conventional treatments for chronic inflammatory demyelinating polyneuropathy (CIDP). In many centres, unconventional treatments are frequently used as alternatives. We evaluated the outcome of conventional and unconventional therapies in 31 CIDP patients. Overall response rate with conventional first-line immunotherapies was 77% (20/26), comparable between IVIG and corticosteroids (80% vs 70%). Use of TPE was limited. Treatment response among typical and atypical CIDP were comparable (76 vs 80%). Non-responders were patients with progressive form of typical CIDP and DADS. Majority (21/26, 81%) of patients with persistent neurological deficits received maintenance therapy. Two subgroups of patients frequently treated with maintenance immunosuppressants were those with improving or stable disease following first-line treatment (12, 57%) and those with progressive form of CIDP (2, 10%). Primary indications for immunosuppressant use were corticosteroids-sparing and additional immunosuppression effects. Nine (64%) patients with improving or stable disease given azathioprine were taken off corticosteroids after a median duration of 14 months (range 12-108). Two (14%) eventually achieved cure or clinical remission without treatment. Maintenance IVIg was given to 6 (29%) relapsing CIDP patients; none of achieved cure or remission after similar median duration of treatment. Less potent immunosuppressant drugs (azathioprine, mycophenolate mofetil, and methotrexate) were frequently used, with moderate adverse effect profiles. In resource limited setting, unconventional treatments were commonly used among CIDP patients with different clinical course of progression. In most cases, careful risk-benefit re-assessment is required to justify its further use.
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