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Fulltext Hypertensive brainstem encephalopathy: a diagnosis often overlooked

Tan YY, Tan K

Clin Med (Lond), 2019 Nov;19(6):511-513.
PMID: 31732595 DOI: 10.7861/clinmed.2019-0247

Hypertensive encephalopathy (HE) is a subset of posterior reversible encephalopathy syndrome. It typically involves the posterior supratentorial structures, but variations do occur. However, isolated brainstem involvement in HE is rare, with a few cases reported in the literature. Herein, we report a case of acute hypertensive brainstem encephalopathy in which the patient had mild symptoms with very high blood pressure and normal neurological examination. The computed tomography of the brain showed diffuse hypodensity at brainstem. The patient's symptoms improved drastically after hypertension had been controlled. Marked clinical-radiologic dissociation in this particular case was highly suggestive of hypertensive brainstem encephalopathy. Prompt recognition of the condition and aggressive treatment of hypertension in such patients is crucial to relieve oedema and to prevent life-threatening progression. Nevertheless, there is still a lack of awareness among physicians and radiologists regarding this rare clinical entity.
Fulltext An evaluation on pharmacokinetics parameters of phenytoin in adult epileptic patients: a single centre study from Malaysia

Tan, Kenny, Luen, Leong Wei, Ong, Yi Ping, Khai, H’ng Kee, Tan, Li May, Siti Nur Fatihah Abd Rahman, et al.

Malaysian Journal of Pharmaceutical Science, 2020;18(1):77-83.
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Phenytoin follows Michaelis-Menten, a non-linear pharmacokinetics that occurs when drug molecules saturates the enzymes ability to metabolise the drug. When this occurs, steady state phenytoin serum concentration increases in a disproportionate manner after a dosage increase. General population data are usually used for the phenytoin dose calculation. However, many studies show that population pharmacokinetic parameters of phenytoin have high variations. Thus, use of specific local pharmacokinetic parameters for each population group in estimating individualised phenytoin dose can reduce phenytoin toxicity cases. This prospective, observational study was conducted to estimate a local Vmax and Km of phenytoin for adult epileptic patients in neurological ward and clinic at Hospital Pulau Pinang, Malaysia. All therapeutic drug monitoring of oral capsule phenytoin were studied in a three-month data collection period. Out of the 17 subjects in our study, there are 13 male subjects (76.47%) and 4 female subjects (23.53%). A total 11 Malay subjects (64.71%), 4 Chinese subjects (23.53%) and 2 Indian subjects (11.76%) were included. Median Vmax and Km were found to be 8.25 mg/kg/day and 3.80 mg/l. Male subjects have a higher Vmax (8.30 mg/kg/day) but a lower Km (3.3 mg/l). Chinese population has the highest Vmax (8.80 mg/kg/day). For Km, Indian population is the highest, with a value of 5.5 mg/l. From our study, gender does not correlate with Vmax and Km of phenytoin (p-value > 0.05). Ethnicity was also found to have no association with Vmax and Km (p-value > 0.05). Local Vmax (8.25 mg/kg/day) is higher and Km (3.8 mg/l) is lower when compared with standard Vmax (7 mg/kg/day) and Km (4 mg/l) obtained from Caucasian population.
A South East Asian perspective of neuropsychiatric startle syndromes of latah

Lim TT, Tan K, Eow GB, Bhidayasiri R

Parkinsonism Relat Disord, 2022 Jan 26.
PMID: 35120841 DOI: 10.1016/j.parkreldis.2022.01.013

Latah is a culture-specific syndrome characterized by exaggerated startle response, echolalia, palilalia, echopraxia, coprolalia, forced obedience and involuntary vocalization in response to startle. Latah is stimulus-induced and is associated with behavior and psychiatric features. The aim of this review is to provide a comprehensive description on latah from a regional perspective based on previous literature and clinical experiences and highlight the clinical characteristics of latah from a movement disorders perspective. The pathophysiology of latah is complex and poorly understood although psychological stressors have been implicated. In view of the distressing psychosocial impact of latah, this neuropsychiatric startle syndrome warrants further studies to understand the pathophysiology and identify the appropriate treatments.
A previously misdiagnosed cohort of aquaporin 4 antibody-positive neuromyelitis optica spectrum disorder with disease duration of >10 years in multi-ethnic Penang, Malaysia: Clinical features and disease course

Hor JY, Lim TT, Chow HB, Tan K, Cheah CF, Ching YM, et al.

Mult Scler Relat Disord, 2016 Jan;5:89-90.
PMID: 26856950 DOI: 10.1016/j.msard.2015.11.008
Thymoma-associated myasthenia gravis and LGI1-encephalitis, with nephrotic syndrome post-thymectomy

Hor JY, Lim TT, Cheng MC, Chia YK, Wong CK, Lim SM, et al.

J Neuroimmunol, 2018 04 15;317:100-102.
PMID: 29395322 DOI: 10.1016/j.jneuroim.2018.01.011

Thymoma is associated with a wide spectrum of autoimmune paraneoplastic syndromes, though it is uncommon for multiple paraneoplastic syndromes to be present in a single individual. We report a rare case of an elderly gentleman who was found to have thymoma-associated myasthenia gravis and LGI1-encephalitis with myokymia, who presented with nephrotic syndrome (minimal change glomerulopathy) after thymectomy. The latter two paraneoplastic syndromes had manifested when prednisolone was tapered down to low dose. This case serves to remind neurologists that apart from paraneoplastic neurological manifestations, thymoma may also be associated with renal disease. Nephropathy in myasthenia patients with thymoma should be properly evaluated, as it is treatable with immunotherapy, and it may even occur post-thymectomy.
Prevalence of neuromyelitis optica spectrum disorder in the multi-ethnic Penang Island, Malaysia, and a review of worldwide prevalence

Hor JY, Lim TT, Chia YK, Ching YM, Cheah CF, Tan K, et al.

Mult Scler Relat Disord, 2018 Jan;19:20-24.
PMID: 29100047 DOI: 10.1016/j.msard.2017.10.015

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) occurs worldwide in all ethnicities. Recently, population-based studies have shown that NMOSD is more common among non-White populations. There is scarce data about NMOSD prevalence in South East Asian populations.
METHODS: (1) A population-based study was undertaken to estimate NMOSD prevalence in the multi-ethnic Penang Island, Malaysia, comprising Chinese, Malays, and Indians. Medical records of NMOSD patients followed up at the Penang General Hospital (the neurology referral centre in Penang Island) were reviewed. The 2015 diagnostic criteria of the International Panel for NMO Diagnosis were used for case ascertainment. (2) A review of population-based prevalence studies of NMOSD worldwide was carried out. PubMed and conference proceedings were searched for such studies.
RESULTS: Of the 28 NMOSD patients, 14 were residents of Penang Island on prevalence day [13 (93%) Chinese and one (7%) Malay]. All 14 patients were females and aquaporin 4 seropositive. The prevalence of NMOSD in Penang Island was 1.99/100,000 population; according to ethnicities, the prevalence in Chinese was significantly higher than in Malays (3.31/100,000 vs 0.43/100,000, respectively, p = 0.0195).
CONCLUSION: Based on our and other population-based studies, among Asians, East Asian origin populations (Chinese and Japanese) appear to have higher NMOSD prevalence than other Asian ethnic groups. Worldwide, Blacks seem to have the highest NMOSD prevalence. More studies in different geographical regions and ethnic groups will be useful to further inform about potential factors in NMOSD pathogenesis.
Fulltext Biomechanical System Versus Observational Rating Scale for Parkinson's Disease Tremor Assessment

Chan PY, Mohd Ripin Z, Abdul Halim S, Kamarudin MI, Ng KS, Eow GB, et al.

Sci Rep, 2019 05 31;9(1):8117.
PMID: 31148550 DOI: 10.1038/s41598-019-44142-1

There is a lack of evidence that either conventional observational rating scale or biomechanical system is a better tremor assessment tool. This work focuses on comparing a biomechanical system and the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale in terms of test-retest reliability. The Parkinson's disease tremors were quantified by biomechanical system in joint angular displacement and predicted rating, as well as assessed by three raters using observational ratings. Qualitative comparisons of the validity and function are made also. The observational rating captures the overall severity of body parts, whereas the biomechanical system provides motion- and joint-specific tremor severity. The tremor readings of the biomechanical system were previously validated against encoders' readings and doctors' ratings; the observational ratings were validated with previous ratings on assessing the disease and combined motor symptoms rather than on tremor specifically. Analyses show that the predicted rating is significantly more reliable than the average clinical ratings by three raters. The comparison work removes some of the inconsistent impressions of the tools and serves as guideline for selecting a tool that can improve tremor assessment. Nevertheless, further work is required to consider more variabilities that influence the overall judgement.