Biomedical subjects
Publications and source records attributed to K Puvanendran.
We present a case of episodic stupor associated with a myriad of neuropyschiatric manifestations that baffled doctors until they were recognized as sleep attacks. Continuous monitoring and recognition of a cyclical pattern of symptoms and signs helped to uncover the underlying cause of a rapidly cycling bipolar disorder. The symptoms abated quickly and persistently when treated by olanzapine and lithium.
We report our experience, using mycophenolate mofetil (MyM) as an adjunctive immunosuppressive therapy in patients with severe, refractory and high dose steroid-dependent myasthenia gravis (MG). Five patients were commenced on MyM in addition to other immunosuppressive therapies. All had significant clinical improvement and no subsequent myasthenic crisis requiring intensive care unit admission. MyM was well tolerated and no serious adverse effects were observed. MyM is an effective adjunctive therapy for the treatment of severe, refractory and steroid-dependent MG in our experience.
House officers are known to endure marked levels of sleep deprivation in administration of their duties. We aim to establish sleep patterns of local house officers while on the job and the impact it might have on their mood and sleepiness state. We also studied their sleep during their final year of medical school and pre-university for identification of any prior sleep deprivation. Questionnaires were used to assess sleep and mood change. Sleepiness levels on the day after call were assessed using the Stamford Sleepiness Scale. Subjects were found to sleep a median of only 1.0 (+/- 2.0) h per night on call and 6.0 h (+/- 1.0) per non-call night. They suffered median of 5 interruptions (+/- 5) during sleep on one night call. Night call was found to adversely affect mood in 89.5% of the subjects while daytime sleepiness levels following call were found to increase the more the time spent at work after call. Subjects were found to have had 6.5 h (+/- 1.0) of sleep per night during final year of medical school and 8.0 h (+/- 1.0) in final year of pre-university. House officers enter the profession chronically sleep-deprived. The call schedule and general work regime further add to the existent sleep deprivation and may have adverse consequences on patient care and doctor's health. This calls for measures to be instituted for provision of proper sleep and work hours for them.
INTRODUCTION: The aims of the study were to determine the demographic, clinical, and polysomnographic characteristics of narcolepsy, and to address the difficulties in diagnosing narcolepsy and cataplexy, which is a cardinal symptom. We also ventured to investigate the differences between narcolepsy with and without cataplexy. MATERIALS AND METHODS: Data were collected retrospectively from patients diagnosed with narcolepsy at the Sleep Disorder Unit of Singapore General Hospital over 5 years. Each patient had had a detailed clinical evaluation and overnight polysomnography (PSG) followed by a multiple sleep latency test (MSLT). RESULTS: A total of 28 cases were studied. Males made up 85.7% of the total and females, 14.3%. The mean age was 30.9 years. All had excessive daytime sleepiness. Other manifestations were cataplexy (48.1%), sleep paralysis (51.9%), hypnogogic hallucinations (84%), disturbed night sleep (29.2%), automatisms (17.4%) and catnaps (95.8%). The mean duration of symptoms was 7.24 years. In the MSLT, the mean values for mean sleep latency and number of sleep onset rapid eye movement (REM) periods (SOREMP) were 4.3 minutes and 2.7, respectively. Narcolepsy was associated with obstructive sleep apnoea and periodic limb movement disorder (35.7%). All the variables were compared between those who had narcolepsy with cataplexy and without cataplexy. The duration of presenting complaint, REM latency, respiratory disturbance index, number of SOREMPs and the presence of sleep paralysis were significantly different in the 2 groups. CONCLUSIONS: Narcolepsy predominantly affects young males. Concurrence of other sleep disorders is not uncommon. Some differences are evident between those who have narcolepsy with and without cataplexy.
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OBJECTIVE: To describe a patient from Southeast Asia with the optic-spinal phenotype of multiple sclerosis who developed syringomyelia and resultant complex regional pain syndrome (formerly named reflex sympathetic dystrophy). DESIGN: Case report. SETTING: Department of neurology at a tertiary care hospital in the Republic of Singapore. PATIENT: A 53-year-old Chinese woman with a history of optic neuritis developed an episode of left hemiparesis leading to a diagnosis of multiple sclerosis. Serial neuroimaging studies revealed an active demyelinating plaque in the cervical area that later progressed into a syrinx. Over a period of 1 year she also developed signs of sympathetic dysfunction including Horner syndrome of the left eye and complex regional pain syndrome in the left hand. CONCLUSIONS: A case of the optic-spinal phenotype of multiple sclerosis that is commonly observed in Southeast Asia is described. This characteristically tissue-destructive form of multiple sclerosis resulted in syringomyelia complicated by a complex regional pain syndrome. Possible pathogenic mechanisms for these associations are discussed.
We have no information on snoring and obstructive sleep apnea (OSA) in our population, which is predominantly Chinese. Our perception is that sleep apnea syndrome is more common than the 2-4% prevalence (Young et al., 1993) often quoted, judging from the experience in our sleep disorder unit. We studied the snorers in an adult population in Singapore and then went on to see how many snorers suffer pathological apnea and sleep apnea syndrome. Room partners, 220 of them aged 30-60 years, were interviewed for their observation of snoring among each other. 106 consecutive habitual loud snorers of a similar age group in the same population were studied with polysomnography in our sleep laboratory. An apnea index greater than 5 was considered pathological. 24.09% were loud habitual snorers. 87.5% of loud habitual snorers had significant obstructive apneas on the polysomnogram and 72% of these apneics complained of excessive daytime sleepiness (EDS). Given the clinical observation that all apneics snored, by extrapolating these figures, we guess that sleep apnea syndrome affects about 15% of the population. Multiple Sleep Latency Tests validated EDS in our cases with clinical hypersomnia. Hypersomnolence was significantly related to the poor delta wave sleep. Contrary to what was believed, OSA occurred predominantly in stage 1 and 2 non-rapid eye movement (NREM) sleep rather than in REM sleep. The frequent arousals prevented sleep going beyond stage 1 and 2.
Multiple sclerosis (MS) is an uncommon disease in Singapore. We retrospectively reviewed our experience from a large single medical institution to identify prominent clinical features and forms of this disease. Of the 21 patients entered into the study, 10 patients developed optic-spinal symptoms over the course of their illness. None of these patients with optic-spinal symptoms had Devic's disease. Unusual clinical manifestations included paroxysmal symptoms either at presentation or during the course of their illness in 3 patients. While cerebrospinal fluid oligoclonal bands were present in only 4 patients, the majority of patients had abnormal neurophysiology and neuroimaging studies. Due to the presence of autoimmune markers in a significant number of cases, we recommend that as part of the initial evaluation for MS, an underlying collagen vascular disorder should be excluded.
Though epilepsy is recognised as a major medical and social problem in Singapore, there is no epidemiological survey to realise the size of the problem. We studied this problem from data collected from hospitals, school health clinics and from military statistics. The prevalence varied in the three sample populations studied. The most accurate data for prevalence study were obtained in army recruits. A life-time prevalence of 3.8 per 1000 was noted. The prevalence variation with age, sex and races is discussed. The mortality from epilepsy was 0.5 per 100,000. The types of epilepsies and the treatment patterns are discussed.
Magnetic stimulation of the peripheral nerves is a recently developed technique and has exciting prospects in clinical neurophysiology. An experiment was performed comparing the conventional electric stimulation with magnetic stimulation of the median nerve of a normal population. Magnetic stimulation produced comparable results as far as latency, amplitudes and configuration of action potentials in most patients. The technique of magnetic stimulation is discussed. Its shortcomings are in locating the magnetic coil's point of stimulation on the nerve and difficulty in achieving supramaximal stimulation. Its great advantage is that it is painless and that deep nerves can be reached.
Multiple sclerosis is an uncommon demyelinating condition in Singapore. The commonest mode of presentation here is in the form of Devic's syndrome. Although our patients here have shown classical findings with respect to clinical features, neuroimaging studies and electrophysiologic tests, abnormal cerebrospinal fluid changes have not been reported locally. We report the first case of multiple sclerosis with abnormal cerebrospinal fluid changes. We also reviewed cerebrospinal fluid changes in multiple sclerosis and recent advances in laboratory techniques of cerebrospinal fluid analyses.
We describe a 40 year-old man with optic perineuritis due to secondary syphilis. This condition which is due to inflammation of the optic nerve sheath is often mistaken for papilloedema or papillitis. We discuss its diagnosis and stress the importance of recognising it because it is easily treated by a course of Penicillin.
This case report describes a patient with Melkersson-Rosenthal Syndrome. The clinical manifestation and current aetiological postulates are discussed.
We present an interim report of an ongoing, single-blind study of the effectiveness and safety of bromocriptine mesylate (Parlodel) in 15 patients, 14 of whom had severe idiopathic Parkinson's disease (Stages 4 and 5 on the Hoehn and Yahr Scale). The patients had never received levodopa, amantadine, or bromocriptine. Gradually increasing doses of bromocriptine were assessed: Initial daily dosage was 1.25 mg, with weekly increments of 1.25 mg/day until either the clinical response was satisfactory or a maximum of 15 mg/day was reached. The patients were on no other antiparkinsonian agents, except trihexyphenidyl HCl (Artane). Response to treatment was scored on the Columbia Scale. The patients discussed in this report had been in the study for varying times, ranging from 1 month to 3 years. Only one patient who entered this study dropped out because his response to bromocriptine was unsatisfactory; he had taken the drug for 2 weeks. No serious adverse reactions were noted with the gradually increasing dosage regimen. Response on the whole was very satisfactory; patients improved by at least two stages on the Hoehn and Yahr Scale. Improvement began within 48 h of onset of treatment with 1.25 mg daily. The preliminary results of this study indicate that low-dose bromocriptine as a first-line drug in severe Parkinson's disease is definitely warranted.
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It is commonly believed that diabetic optic neuropathy is very rare and visual loss in diabetes usually is attributed to other causes. We studied the extent of optic nerve involvement in 16 diabetics with no retinopathy or ocular disease and having an almost visual acuity, using visual evoked responses produced by pattern reversal stimulation. Comparing the responses with a group of 35 healthy subjects, the latency was increased by more than one standard deviation in 13 diabetics (81%) and by more than three standard deviations in 10 diabetics (62.5%), often associated with marked reduction in amplitude. There was good correlation between conduction in the optic nerve and peripheral sensory nerve. No correlation was noted to occur with duration of diabetes or diabetic control except perhaps with juvenile onset diabetes. Normal visual acuity was noted in many cases with severely slowed conduction showing early subclinical affection of optic nerves in diabetes. The extent of central nervous system involvement in diabetes has only recently been realised because of lack of physiological techniques and study of optic nerves in diabetes has not been attempted so far. The high incidence of abnormality of visual evoked potentials in diabetes could invalidate the usefulness of this test in diagnosing multiple sclerosis.
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