Biomedical subjects
Publications and source records attributed to Y Y Sitoh.
We present a case of an elderly lady with a symptomatic large intra-axial right frontoparietal arachnoid cyst displacing the corticospinal tract (CST) posteromedially on diffusion tensor imaging. This information assisted the surgeons in confirming the symptomatic nature of the lesion, in planning an appropriate surgical procedure, as well as in prognostication of recovery.
INTRODUCTION: Recent advances in magnetic resonance (MR) diffusion tensor imaging technique enable evaluation of the anisotropy of white matter tracts in-vivo, as well as the integrity of fibre tracts and their orientation. We describe our initial experiences with diffusion tensor imaging and MR tractography techniques to evaluate the structural degeneration of white matter tracts following stroke. METHODS: Diffusion tensor imaging data were acquired in 11 cases with stroke on a 3T MR imaging scanner, with three-dimensional diffusion tensor imaging-based colour maps and MR tractography performed offline. We evaluated the spatial relationships of the eloquent white matter tracts to the infarcts and areas of haemorrhage, and classified therewith the tracts as either disrupted or displaced. We compared these with the clinical severity of the neurological deficits and prognosis. RESULTS: A good correlation was found between tractography findings and patient's clinical recovery. All the patients with disruption of white matter tracts had residual deficits on clinical follow-up, whereas the patients with displaced tracts had near complete neurological recovery. CONCLUSION: Diffusion tensor imaging and MR tractography provide a novel and useful method to directly visualise changes in the white matter tracts in stroke. This can potentially allow clinical-imaging correlation with prognostic potential.
This paper describes the classification of gait patterns among descending stairs, ascending stairs and level walking activities using accelerometers arranged in antero-posterior and vertical direction on the shoulder of a garment. Gait patterns in continuous accelerometer records were classified in two steps. In the first step, direct spatial correlation of discrete dyadic wavelet coefficients was applied to separate the segments of gait patterns in the continuous accelerometer record. Compared to the reference system, averaged absolute error 0.387 s for ascending stairs and 0.404 s for descending stairs were achieved. The overall sensitivity and specificity of ascending stairs were 98.79% and 99.52%, and those of descending stairs were 97.35% and 99.62%. In the second step, powers of wavelet coefficients of 2 s time duration from separated segments of vertical and antero-posterior acceleration signals were used as features in classification. Our results proved a reliable technique of measuring gait patterns during physical activity.
Magnetic resonance angiography (MRA) at 3T offers increased signal to noise ratio with better background suppression, leading to exquisite depiction of the intracranial circulation. We present a pictorial review of the normal variations and anomalies of the intracranial circulation detected on MRA performed on a high field 3T clinical scanner using parallel imaging techniques. The salient imaging features of these anomalies and normal variations are discussed with relevance to clinical practice.
BACKGROUND AND OBJECTIVE: To evaluate whether individual falls risk could be predicted in a frail elderly population. STUDY DESIGN AND SETTING: We developed and tested an assessment tool and falls risk score for predicting falls based on a multivariate regression model in a prospective cohort study of intermediate care residents. RESULTS: During the follow-up period, 1,736 falls by 1,107 subjects were recorded with an average of 170 falls per 100 person-years. Fifty percent of the study population had at least one fall within a year. Significant independent risk factors were poor balance, cognitive impairment, incontinence, higher illness severity rating, and older age. Twenty-two percent of participants with a falls risk score > or =7 accounted for 42% of the total falls, with a falls rate of 317 per 100 person-years. This rate was a sixfold increase from the falls rate of 52 per 100 person-years observed in participants with a score < 3. A high score (> or =7) indicated almost a 2 in 3 chance of falling, while a low score (<3) indicated approximately a 1 in 7 chance of falling within 6 months. CONCLUSION: The assessment tool and falls risk score could identify individuals in this frail elderly population at high risk of falls.
It is recognised that the focus of health-care interventions for frail older persons should not be restricted to increasing longevity, but should encompass measures aimed at improving or maintaining the health-related quality of life (HRQoL) of these individuals. We studied the HRQoL profile of 612 frail older persons residing in nursing homes and hostels in northern Sydney, Australia, and sought to ascertain some of the factors that affect their perceived quality of life. Our findings suggest that common health states that may cause loss of independence and dignity (e.g. presence of osteoarthritis, presence of urinary incontinence, previous fracture, Parkinson's Disease and increasing frailty as reflected by residence in nursing homes) are strongly, and independently, associated with the HRQoL of institutionalised older persons. Some of these conditions may be amenable to intervention.
INTRODUCTION: We studied the prevalence of postoperative complications in a series of consecutive patients who received surgery for hip fractures in a major public hospital in Singapore. We also studied the predictors for the occurrence of complications and the impact of these complications on patient outcomes. MATERIALS AND METHODS: A retrospective chart review of patients admitted with hip fracture, from March to November 2001, was carried out. Patients were classified as having postoperative complications if they developed any of the following conditions after surgery: dislocation of prosthesis, deep vein thrombosis, postoperative confusion, foot drop, stroke, cardiac arrhythmias or acute myocardial infarctions, urinary retention, urinary tract infection, pneumonia, wound infection and incident pressure sores. RESULTS: Of the 180 patients studied, 60 developed postoperative complications. Significant predictors of complications after logistic regression included being of female gender [odds ratio (OR), 2.79; 95% confidence interval (CI), 1.13 to 6.89] and pre-fracture mobility status (OR for independent ambulators 0.45; 95% CI, 0.23 to 0.87), but not the age of the patients. Postoperative complications significantly affected the length of stay within the acute hospital (beta coefficient, 6.42; 95% CI, 2.55 to 10.29), but were not associated with a decline in mobility status at 3 months post-fracture, eventual discharge destination or readmission within 1 year. CONCLUSION: Postoperative complications are common after surgery for hip fractures and result in significantly longer hospitalisation periods. Significant predictors for such complications include being of female gender and pre-fracture mobility. Age, in itself, does not result in a higher risk of complications and should not preclude older hip fracture patients from surgical management.
Flaviviruses are among the most important emerging viruses known to man. Dengue is the most common flavivirus infection in Singapore, and is transmitted between humans by the Aedes mosquito. We report a 25-year-old man with dengue fever complicated by selective hippocampal involvement manifesting as amnesia. This has not been described in the literature previously. Dengue polymerase chain reaction and serology were positive. Magnetic resonance imaging of the brain showed bilateral hippocampal involvement.
Clinically mild encephalitis with a reversible lesion in the central splenium of the corpus callosum (SCC) is a recently-described clinicoradiological entity. We report a 20-year-old man presenting with fever and a single episode of generalised seizures. Initial magnetic resonance (MR) images showed an ovoid lesion with T1 and T2 signal prolongation, restricted diffusion and decreased apparent diffusion coefficient values in the centre of the SCC, which resolved completely on a repeat MR imaging done three months later. Clinically, the patient had a mild clinical course and made a full recovery. This clinicoradiological entity with an excellent prognosis is elaborated with possible differential diagnoses given. Emphasis is placed on avoiding unnecessary invasive investigation or therapeutic intervention.
The role of nitric oxide (NO) in post-ischemic cerebral infarction has been extensively examined, but few studies have investigated its role on the neurological deficit. In the present study, we investigated the effect of spermine on the temporal evolution of infarct volume, NO production and neurological deficit using magnetic resonance imaging in a model of permanent focal cerebral ischemia in rats. Spermine given at 10 mg/kg 2 h after ischemia reduced the infarct volume by 40% and abolished brain NO production and improved the neurological score 24 h, 48 h and 72 h after ischemia. Spermine also reduced the neurological deficit as evaluated by rotamex, grip strength and neurological severity score tests.
Behçet's disease is an idiopathic multi-systemic, inflammatory disorder that may affect major organs, including the central nervous system. It is a clinical diagnosis, and a history of recurrent oral and genital ulcers should be elicited, especially in cases of unexplained uveitis with atypical neurological symptoms. We describe the rapid neurological recovery and neuroimaging changes following high-dose systemic corticosteroids in a 44-year-old man with recurrent oral ulcers, panuveitis, and acute neuro-Behçet's, presenting with meningoencephalitis. Early diagnosis with the aid of appropriate neuroimaging and immunosuppressive therapy prevented long-term neurological complications. Appropriate neuroimaging can facilitate early diagnosis and treatment, and provide prognostic information on neuro-Behçet's.
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Very frail older people constitute an increasing proportion of ageing populations and often have vitamin D deficiency. Falls are frequent in this population and have usually been associated with vitamin D deficiency. In this prospective study we measured serum 25-hydroxyvitamin D (25OHD), serum PTH, and falls in 637 ambulatory subjects living in institutional aged care facilities (intermediate-care hostels or nursing homes). The study sample comprised 121 men (mean age, 82.1 yr) and 516 women (mean age, 86.7 yr). Two hundred and seventy-four subjects fell one or more times over a mean duration of follow-up of 10.2 months. Vitamin D deficiency, defined as a serum 25OHD level below 39 nmol/liter was present in 73.6%. Baseline serum 25OHD and PTH were significantly associated with falls in univariate analyses. In multivariate analyses that also corrected for balance and health status, PTH remained a significant predictor of falls independent of 25OHD. Serum PTH is a predictor of time to first fall in the frail elderly independent of vitamin D status and measures of general health.
Enhancement of intracranial thrombosed aneurysms is an uncommon finding on magnetic resonance (MR) imaging, and can present diagnostic difficulties and complicate management decisions. We report a 46-year-old man who had an enhancing thrombosed intracranial aneurysm observed on 3T MR imaging. There was angiographical correlation, with follow-up serial MR imaging documenting regression and improvement. Findings are typical for benign intravascular papillary endothelial hyperplasia. Differential diagnoses of giant serpentine intracranial aneurysm and malignant angiosarcoma are discussed.
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INTRODUCTION: Diffusion-weighted magnetic resonance (MR) imaging (DWMRI) is valuable in the assessment of acute cerebral infarction and may be useful for other diseases of the central nervous system (CNS). In this study, we present the DWMRI appearance of intracranial infection. MATERIALS AND METHODS: Thirty patients with clinical diagnosis of CNS infection were reviewed. All patients underwent conventional contrast-enhanced MR examination and DWMRI using single-shot echo-planar imaging at b = 1000 s/mm2. RESULTS: Cerebral abscess, tuberculoma, subdural empyema and epidural abscess were hyperintense on DWMRI. Neurocysticercosis showed hypointense lesions on DWMRI. Four of 5 patients with encephalitis showed DWMRI hyperintensity; the appearance of toxoplasmosis lesions was variable. Patients suffering from meningitis without parenchymal involvement did not exhibit any abnormality of diffusion. One patient with tuberculous meningitis developed abnormality on DWMRI from acute cerebral infarction. CONCLUSION: DWMRI increased lesion conspicuity and may be useful in assessment of cerebral infection. There were striking differences in the DWMRI appearances caused by different organisms and diseases.
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INTRODUCTION: Aged care services have been rapidly and systematically established in Singapore over the past two decades in anticipation of the challenges that will accompany the rapid ageing of our population. This paper presents an overview of the geriatric services that have developed in Singapore, funding for these services, and aged care-related training programmes for doctors and nurses in Singapore. METHODS: A non-systematic review of journal articles, local conference proceedings and state publications was undertaken. RESULTS: Geriatric services have evolved rapidly with the establishment of 3 acute geriatric medicine units covering the different sectors of Singapore. Apart from the provision of acute medical care for older persons, geriatricians have also been increasingly involved in the enhancement of community aged care services under the Framework for Integrated Health Services for the Elderly. Concurrently, community services for the elderly have blossomed under the leadership provided by various voluntary welfare organisation. Innovative systems of funding the healthcare needs of older persons have also evolved over the past few years. In recognition of the increasing needs of our ageing population, the medical training curriculum is being continually reviewed to enhance the skills of medical practitioners in Singapore. CONCLUSION: Over a short span of 20 years, a comprehensive framework of services has been developed to meet the needs of our ageing population. While much has been accomplished, there is a need for continuous review of our services and healthcare policies to identify areas for further improvement.