Displaying publications 1 - 20 of 27 in total

  1. Viswanathan S
    Mult. Scler., 2015 Apr;21(4):488-91.
    PMID: 24948685 DOI: 10.1177/1352458514537698
    We report two cases of neuromyelitis optica spectrum disorder with hypoglossal nerve involvement resulting in a wasted tongue associated with other brainstem symptoms of hypogeusia, hypersalivation, hiccough, increased sweating, hyperemesis and myelitis (in the second patient). This occurred due to involvement of the hypoglossal, tractus solitarius and dorsal vagal nuclei. Though the myelitis and other brainstem signs recovered the hypoglossal nerve involvement resulting in a unilateral wasted tongue did not. It is important to consider neuromyelitis optica and its spectrum disorders in the differential diagnosis of a wasted tongue though its occurrence is rare.
  2. Schee JP, Viswanathan S
    Mult. Scler., 2018 May 01.
    PMID: 29771191 DOI: 10.1177/1352458518775912
    We identified five female patients retrospectively with relapsing short-segment partial myelitis whose clinical and paraclinical features were suggestive of cord involvement of multiple sclerosis (MS)-type albeit not rigidly fulfilling the 2017 McDonald criteria. Notably, these patients had not developed any typical MS-like brain lesions despite repeated neuroimaging assessments over years. Comprehensive work-up for differential diagnoses of MS and other causes of transverse myelitis particularly neuromyelitis optica spectrum disorders had been consistently negative on longitudinal follow-up. Thus, we postulate a possible entity of pure spinal MS which may represent a novel forme fruste within the MS disease spectrum.
  3. Viswanathan S, Wah LM
    Mult. Scler., 2018 Aug 16.
    PMID: 30113245 DOI: 10.1177/1352458518792430
    OBJECTIVES: This study looked at observed crude prevalence/incidence of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) in Malaysia and identified any inter-ethnic differences for MS/NMOSD.

    METHODS: This was a nationwide tertiary hospital-based retrospective cross-sectional study using the capture-recapture method. It looked at the estimated crude prevalence of confirmed MS and NMOSD and annual incidence on 29 December 2017. Recapture of data was done between February and March 2018 on 1 March 2018. Public and referring private institutions were accessed.

    RESULTS: The survey identified 767 MS and 545 NMOSD subjects, with crude prevalence rates of 2.73 per 100,000 (95% confidence interval (CI): 2.53; 2.92 per 100,000 population) and 1.94 per 100,000 (95% CI: 1.77; 2.10 per 100,000 population) with observed crude annual incidence of 0.55 (95% CI: 0.43; 0.58) for MS and 0.39 per 100,000 (95% CI: 0.35; 0.47) for NMOSD. The MS:NMOSD ratios were 1.4:1.0. The capture-recapture method revealed 913 MS (95% CI: 910; 915.9) and 580 (95% CI: 578.8; 581.2) NMOSD with prevalence per 100,000 of 3.26 (95% CI: 3.05; 3.47) and 2.07 (95% CI: 1.90; 2.24), respectively. In the MS group, 59.4% were Malay, 16.6% Chinese, 20.5% Indian, and 3.5% were from indigenous groups. In the NMOSD group, 47.3% were Malay, 46.9% Chinese, 3.5% Indian, and 2.3% were from other indigenous groups. The ratio of NMOSD to MS among the Chinese was 2:1, but the ratio of MS to NMOSD among the Malays was 1.8:1, and that in Indians was 8.3:1.

    CONCLUSION: There is a modest increase in the prevalence of MS and NMOSD in Malaysia with inter-ethnic differences for MS/NMOSD.

  4. Viswanathan S, Botross N, Rusli BN, Riad A
    Mult Scler Relat Disord, 2016 Nov;10:112-115.
    PMID: 27919476 DOI: 10.1016/j.msard.2016.10.001
    Acute disseminated encephalomyelitis (ADEM) complicating dengue infection is still exceedingly rare even in endemic countries such as Malaysia. Here we report two such cases, the first in an elderly female patient and the second in a young man. Both presented with encephalopathy, brainstem involvement and worsening upper and lower limb weakness. Initial magnetic resonance imaging (MRI) of the brain was normal in the first case. Serum for dengue Ig M and NS-1 was positive in both cases. Cerebrospinal fluid (CSF) showed pleocytosis in both with Dengue IgM and NS-1 positive in the second case but not done in the first. MRI brain showed changes of perpendicular subcortical palisading white matter, callosal and brainstem disease mimicking multiple sclerosis (MS) in both patients though in the former case there was a lag between the onset of clinical symptoms and MRI changes which was only clarified on reimaging. The temporal evolution and duration of the clinical symptoms, CSF changes and neuroimaging were more suggestive of Dengue ADEM rather than an encephalitis though initially the first case began as dengue encephalitis. Furthermore in dengue encephalitis neuroimaging is usually normal or rarely edema, haemorrhage, brainstem, thalamic or focal lesions are seen. Therefore, early recognition of ADEM as a sequelae of dengue infection with neuroimaging mimicking MS and repeat imaging helped in identifying these two cases. Treatment with intravenous steroids followed by maintenance oral steroids produced good outcome in both patients.
  5. 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.
  6. 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).
  7. 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.
  8. 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.

  9. 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.
  10. 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.
  11. Botross NP, Riad AA, Viswanathan S, Nordin RB, Lock HN
    Scott Med J, 2014 May;59(2):e1-6.
    PMID: 24671628 DOI: 10.1177/0036933014529868
    Gaucher's disease is a lysosomal storage disorder caused by the deficiency of glucocerebrosidase. Gaucher's disease has three clinical types: non-neuronopathic (Type 1), Acute Neuropathic (Type 2) and chronic neuronopathic (Type 3). The chronic neuronopathic (Type 3) is characterised by a variety of disease variants with onset in childhood with hepatomegaly, skeletal lesions and later slow horizontal saccades, treatment-resistant generalised tonic-clonic and myoclonic seizures, dementia, progressive spasticity, cognitive deterioration, ataxia and death in the second or third decade of life.
  12. Viswanathan S, Rose N, Masita A, Dhaliwal JS, Puvanarajah SD, Rafia MH, et al.
    Mult Scler Int, 2013;2013:614716.
    PMID: 24455266 DOI: 10.1155/2013/614716
    Background. Multiple sclerosis (MS) is an uncommon disease in multiracial Malaysia. Diagnosing patients with idiopathic inflammatory demyelinating diseases has been greatly aided by the evolution in diagnostic criterion, the identification of new biomarkers, and improved accessibility to neuroimaging in the country. Objectives. To investigate the spectrum of multiple sclerosis in Malaysia. Methods. Retrospective analysis with longitudinal follow-up of patients referred to a single tertiary medical center with neurology services in Malaysia. Results. Out of 245 patients with idiopathic inflammatory demyelinating disease, 104 patients had multiple sclerosis. Female to male ratio was 5 : 1. Mean age at onset was 28.6 ± 9.9 years. The Malays were the predominant racial group affected followed by the Chinese, Indians, and other indigenous groups. Subgroup analysis revealed more Chinese having neuromyelitis optica and its spectrum disorders rather than multiple sclerosis. Positive family history was reported in 5%. Optic neuritis and myelitis were the commonest presentations at onset of disease, and relapsing remitting course was the commonest disease pattern observed. Oligoclonal band positivity was 57.6%. At disease onset, 61.5% and 66.4% fulfilled the 2005 and 2010 McDonald's criteria for dissemination in space. Mean cord lesion length was 1.86 ± 1.65 vertebral segments in the relapsing remitting group as opposed to 6.25 ± 5.18 vertebral segments in patients with neuromyelitis optica and its spectrum disorders. Conclusion. The spectrum of multiple sclerosis in Malaysia has changed over the years. Further advancement in diagnostic criteria will no doubt continue to contribute to the evolution of this disease here.
  13. Sobri Muda A, Kwah YG, Al-Edrus SA, Wong SL, Norzaini MZ, Viswanathan S
    Neuroradiol J, 2010 Nov;23(4):443-6.
    PMID: 24148636
    We describe a rare case of multiple dilated Virchow-Robin spaces in the brainstem in a patient presenting initially with blepharospasm with subsequent spread to involve the face and neck. On magnetic resonance imaging (MRI), these lesions demonstrated an isointense signal to cerebrospinal fluid on all sequences with no mass effect or enhancement. Although rare, this condition should be considered part of the differential diagnosis when evaluating cystic abnormalities in the brainstem. This is the first reported case of blepharospasm with subsequent orofacial and neck dystonia caused by dilated Virchow-Robin spaces. The imaging findings and differential diagnoses are discussed.
  14. Viswanathan S, Rose N, Arip M, Chai CH, Law WC, Sim R, et al.
    Mult Scler Relat Disord, 2018 Oct;25:300-308.
    PMID: 30172173 DOI: 10.1016/j.msard.2018.07.003
    We performed a retrospective observational analytical study looking at the frequencies and characteristics of multiple sclerosis(MS) and neuromyelitis optica spectrum disorders(NMOSD) in consecutive patients with idiopathic inflammatory demyelinating disease (IIDDs) attending three centers (2009-2017). Of 523 patients with IIDDs, there were 173 patients with NMOSD and 230 patients with MS. The percentage of NMOSD: IIDDs was 33%. The percentage of NMOSD:Total MS and NMOSD cohort was 43%. Of 141 seropositive NMOSD patients, 134(95%) were from the three main ethnic groups. The percentage of seropositive NMOSD to IIDDs and to combined MS and NMOSD was 26.9% and 35% respectively. Ratios of MS to NMOSD were nearly equal at 1.3 to 1.0, reinforcing the high ratio of NMOSD to MS in Asia. Nearly half of the Chinese cohort were seropositive ie; 71/141 (50%) with the remainder being Malays; 56/141 (39.7%) and Indians; 7/141 (5%). Amongst the other indigenous groups seropositivity was seen in 2 each of Iban, Bajau, Kadazan descent as well as one of Bidayuh origin. Comparatively, seropositivity in NMOSD is commoner amongst the Chinese compared to the Malays (p ≤ 0.005) and Indians, p ≤ 0.05 with ratios as high as 10:1. In the MS group of 230 subjects, 123(53.5%) were Malays (ratio of MS:NMOSD of 2:1), 41(17.8%) were Chinese, (ratio of MS:NMOSD of 0.5:1.0) and 54 (23.5%)were Indians (ratios of MS:NMOSD of 5:1 amongst the Indians). The remainder from East Malaysia were made up of 2 each of Kadazans, Ibans and Bajaus including 3 each of Bidayuh and Eurasian descent. Comparatively, in the NMOSD and MS cohorts a female preponderance was noted more so amongst Chinese NMOSD patients, with rare familial occurrence in both but more in Malay MS/NMOSD patients. This study also highlighted some of the inter-ethnic differences in presentation of MS and NMOSD amongst the 3 main ethnic races in Malaysia and confirms indigenous races having MS/NMOSD which needs further research. It also reviewed current literature on similar inter-ethnic differences world wide. To conclude, MS and NMOSD are the commonest demyelinating diseases seen in Malaysia with interesting inter-ethnic differences and similarities.
  15. Kaliyappan R, Viswanathan S, Suthanthiram B, Subbaraya U, Marimuthu Somasundram S, Muthu M
    PLoS ONE, 2016;11(9):e0162013.
    PMID: 27603787 DOI: 10.1371/journal.pone.0162013
    The WRKY family of transcription factors orchestrate the reprogrammed expression of the complex network of defense genes at various biotic and abiotic stresses. Within the last 96 million years, three rounds of Musa polyploidization events had occurred from selective pressure causing duplication of MusaWRKYs with new activities. Here, we identified a total of 153 WRKY transcription factors available from the DH Pahang genome. Based on their phylogenetic relationship, the MusaWRKYs available with complete gene sequence were classified into the seven common WRKY sub-groups. Synteny analyses data revealed paralogous relationships, with 17 MusaWRKY gene pairs originating from the duplication events that had occurred within the Musa lineage. We also found 15 other MusaWRKY gene pairs originating from much older duplication events that had occurred along Arecales and Poales lineage of commelinids. Based on the synonymous and nonsynonymous substitution rates, the fate of duplicated MusaWRKY genes was predicted to have undergone sub-functionalization in which the duplicated gene copies retain a subset of the ancestral gene function. Also, to understand the regulatory roles of MusaWRKY during a biotic stress, Illumina sequencing was performed on resistant and susceptible cultivars during the infection of root lesion nematode, Pratylenchus coffeae. The differential WRKY gene expression analysis in nematode resistant and susceptible cultivars during challenged and unchallenged conditions had distinguished: 1) MusaWRKYs participating in general banana defense mechanism against P.coffeae common to both susceptible and resistant cultivars, 2) MusaWRKYs that may aid in the pathogen survival as suppressors of plant triggered immunity, 3) MusaWRKYs that may aid in the host defense as activators of plant triggered immunity and 4) cultivar specific MusaWRKY regulation. Mainly, MusaWRKY52, -69 and -92 are found to be P.coffeae specific and can act as activators or repressors in a defense pathway. Overall, this preliminary study in Musa provides the basis for understanding the evolution and regulatory mechanism of MusaWRKY during nematode stress.
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