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S Wiebe

Publications and source records attributed to S Wiebe.

36 records · Page 2Linked to original sources
PubMed2000

The principles of evidence-based medicine.

Evidence-based medicine (EBM) integrates individual clinical expertise with the best available external evidence in the care of individual patients. By enabling clinicians to directly appraise and apply current clinical research, EBM deals with the problems of deterioration in clinical performance, information overload, and lag in application of research findings to clinical practice. Thus, EBM is a useful tool to address the problems faced by clinicians attempting to provide optimum, current care for their patients. The rationale for EBM, its principles and application, as well as some limitations, are described here.

Education, Medical, Continuing↗
PubMed2000

Evidence-based analysis of a migraine treatment drug comparison trial.

Patients present with specific problems against a background of their particular situation. The applicability of a treatment to a specific case may be difficult to assess in the light of the information available on that treatment. Evidence-based medicine is a discipline developed to achieve the best informed treatment decisions in clinical situations. In this paper, we illustrate a logical approach to reaching a decision regarding which of two migraine treatments should be used in a clearly defined patient. The information evaluated is a comparative trial between sumatriptan (100 mg), rizatriptan (5 and 10 mg) and placebo. The use of the analytical tools of evidence-based medicine is demonstrated in this exercise. The example was chosen because this is an area of great current interest in the field of neurology.

Adult↗
PubMed1999

The periodicity of lateralized epileptiform discharges.

OBJECTIVES: Although the term periodic lateralized epileptiform discharges (PLEDs) was introduced in 1964, there has been little discussion about the definition of periodicity, whether the degree of periodicity has clinical significance, and whether electroencephalographers can accurately assess periodicity. The objectives of this study were to determine if a mathematical descriptor of periodicity could analyse PLEDs and whether such has clinical relevance, to correlate the degree of periodicity with underlying etiology and to assess the accuracy of sight recognition of periodically occurring EEG events. METHODS: A 6 year retrospective analysis of EEGs on patients with PLEDs was undertaken. The coefficient of variation of inter-complex intervals was calculated for all records. The relative periodicity of each record was rated by electroencephalographers. Corresponding hospital records were reviewed with regard to clinical and pathological information. RESULTS: In cases of acute viral encephalitis, discharges were more periodic than in other etiologies (P = 0.013). Age, clinical state, and time of last seizure did not influence periodicity but 40 (70%) of 57 recordings with PLEDs were done within 2 days of a seizure. A history of seizures was present in 42 (89%) of 47 patients. Electroencephalographers' assessment of periodicity correlated well with measured periodicity (r = -0.49, P = 0.0001). However, EEGers were more likely to assess records as periodic if: discharges occurred frequently (r = -0.48, P = 0.0001), or the complexes were visually assessed to have a uniform morphology (r = 0.31, P = 0.02), even though neither of these factors influenced the periodicity of discharges. CONCLUSIONS: PLEDs were objectively measured to be more periodic when they were associated with acute viral encephalitis than with other etiologies. Nonetheless, the considerable overlap of values among the several presenting disorders diminished specificity. Electroencephalographers were able to recognize periodically occurring discharges. However, they were strongly influenced by discharge frequency and their perception of the uniformity of discharge morphology.

Adolescent↗
PubMed1999

Burden of epilepsy: the Ontario Health Survey.

BACKGROUND: Few data exist on the frequency and burden of epilepsy in Canada and on the impact of self-reported epilepsy in the general population. We assess the frequency, general health, psychosocial function, and health care resource use among self-identified epileptic persons in the general population. METHOD: The 1990 Ontario Health Survey is an omnibus, extensive health survey of 61,239 subjects representing the Ontario population. Self-reported epileptic subjects are compared with three groups, i.e., those with > or = 1 other chronic illnesses, the general population, and those with no health problems. RESULTS: The point prevalence of self-reported epilepsy was 5.8 per 1,000 population, a figure similar to that of active epilepsy in other studies. Quality of life, family function and social support were worse in epileptic than in other chronically ill subjects. Similarly, the epilepsy population had more disability days and limitations in activities, and lower annual income than all other groups, including the chronically ill. Accidents were no more common among epileptic subjects than among controls. Epileptic persons were high users of health care resources, including hospitalization, emergency room, psychological/social work, nursing services and telephone contact with health professionals. Barriers to health care were experienced infrequently. Small area variations in health status and care are explored. CONCLUSIONS: The health profile of self-reported epileptic subjects is similar to that obtained in studies involving defined epilepsy patients. In the general population, self-identification as having epilepsy carries a significant burden of illness, reflected in poorer health, psychosocial function, and quality of life, and higher health care resource use.

Adolescent↗
PubMed1999

Meningioangiomatosis. A comprehensive analysis of clinical and laboratory features.

Meningioangiomatosis (MA) is a rare, benign, focal lesion of the leptomeninges and underlying cerebral cortex characterized by leptomeningeal and meningovascular proliferation. It may occur sporadically or in association with neurofibromatosis type 2. Previous reports have emphasized histological and imaging features. Data on the management of these patients are sparse, and electrophysiological features of MA lesions have not been published. We assessed the clinical, electrophysiological, histopathological and imaging features as well as the surgical outcome in MA, and compared MA with and without neurofibromatosis. Seven patients with MA at our centre were investigated and their outcome was assessed. A review of the literature is included. MA exhibits a wide range of clinical, imaging, histopathological and electrophysiological features, making the diagnosis difficult. Sporadic MA cases are not associated with neurofibromatosis and the two disorders are genetically distinct. Medically refractory, localization-related epilepsy is the commonest presentation in sporadic cases, but atypical presentations also occur. Unlike sporadic cases, MA with neurofibromatosis is often found incidentally, does not produce seizures, occurs less frequently (ratio of 1:4), and is multifocal. MRI findings in MA correspond to the histological picture. However, the appearance on imaging is non-specific and may suggest cystic atrophy, angioma and tumours. Several abnormalities have been found in close proximity to MA lesions, i.e. meningioma, oligodendroglioma, arteriovenous malformation, encephalocoel and orbital erosion. In spite of histopathological diversity, MA lesions are either predominantly cellular or vascular. Immunohistochemical results are inconsistent among cases, add little to the diagnosis, and do not support a meningeal origin. Electrocorticographic recordings from the surface and within MA lesions revealed a spectrum of electrophysiological expressions. Intrinsic epileptogenicity of MA lesions was documented in some cases. Epileptogenicity was confined to the perilesional cortex in some patients and it was complex (extralesional, multifocal, generalized) in others. Only 43% of our patients became seizure-free postoperatively compared with 68% previously reported, and >70% of our patients and those in the literature continued to require antiepileptic drugs. This is in keeping with the diverse electrophysiology of MA and suggests a less optimistic postoperative outcome than previously recognized.

Adolescent↗
PubMed1999

Referral patterns of family physicians may allow population-based incidence studies of childhood epilepsy.

PURPOSE: To evaluate the burden of illness of childhood epilepsy on patient, care giver, and society, representative incidence cohorts must be followed longitudinally. Case ascertainment through pediatricians and neurologists would be a valid method if family physicians refered all new cases of childhood epilepsy. The study objective was to determine whether family physicians' referral patterns in Southwestern Ontario make it possible to conduct a population-based incidence study of childhood epilepsy by sampling only from specialists' practices. METHODS: Of the 1,718 family physicians practicing in Southwestern Ontario, a systematic sample participated in a mailed survey. Case simulations describing seven types of childhood seizures were presented to physicians with instructions to respond as to whether they would investigate/manage without referral; refer to a specialist only if problems occurred; or refer to a specialist always. RESULTS: Of 214 family physicians, 185 (86.4%) returned completed surveys; 86% would not refer a child with a febrile seizure. Referral to a specialist would be made always by 93% of family physicians for patients with status epilepticus, 95% for worsening partial epilepsy, 82% for a first, brief, generalized clonic seizure, 80% for absence epilepsy, and 99% for neonatal seizures. Only 50% of family physicians would always refer a neurodevelopmentally abnormal child with generalized clonic epilepsy, but a further 37% would refer if problems occurred. CONCLUSIONS: It is feasible to recruit a representative population-based cohort of recently diagnosed patients for epidemiologic studies of childhood epilepsy by surveying pediatricians and neurologists. These survey results could be used to adjust estimates of incidence obtained through specialists' practices for the bias in case ascertainment that may result from this practical method.

Ambulatory Care↗
PubMed1998

Non-photochemical quenching of chlorophyll fluorescence in photosynthesis. 5-hydroxy-1,4-naphthoquinone in spinach thylakoids as a model for antenna based quenching mechanisms

In vivo mechanisms of non-photochemical quenching that contribute to energy dissipation in higher plants are still a source of some controversy. In the present study we used an exogenous oxidized quinone, 5-hydroxy-1,4-naphthoquinone to induce quenching of chlorophyll excited states in photosynthetic light-harvesting antenna and to elucidate the mechanism of non-photochemical quenching of chlorophyll fluorescence by this quinone. Excitation dynamics in isolated spinach thylakoids in the presence of an exogenous fluorescence quencher was studied by a combined analysis of data gathered from independent techniques (fluorescence yields, effective absorption cross-sections and picosecond kinetics). The application of a kinetic model for photosystem II to a combined data set of fluorescence decay kinetics and absorbance cross-section measurements was used to quantify antenna quenching by a model antenna quencher, 5-hydroxy-1,4-naphthoquinone. We observed depressions in F0 and photosystem II absorption cross-sections, paralleled with an increase of the rate constant for excitation decay in antenna. This approach is a first step towards quantifying the amount of antenna quenching contributing to non-photochemical quenching in vivo, evaluation of the contributions of antenna and reaction centre mechanisms to it and localization of the sites of non-photochemical energy dissipation in intact plant systems. Copyright 1998 Elsevier Science B.V.

Journal Article↗
PubMed1997

"Periodic" seizures.

PURPOSE: To describe regularly recurring ictal phenomena as recorded in a single patient whose seizure disorder related to a left temporal cavernous angioma. METHODS: Seizures were recorded by left temporal subdural strip electrodes which were bilaterally placed because of ambiguous seizure origin and right temporal memory dysfunction at Wada testing. Seizure length, interseizure intervals, and interseizure onset intervals were visually assessed. The coefficient of variation was used as an estimate of variability in seizure periodicity. RESULTS: Mean seizure durations varied from 68 to 95 s; coefficients of variation varied from 0.08 to 0.18, values similar to other periodic biological phenomena. Mean daily seizure intervals varied from 96 to 152 s with coefficients of variation ranging from 0.12 to 0.35. Interseizure onset intervals had smaller coefficients of variation (0.03-0.20). Manifestations of these simple partial seizures included a rising epigastric sensation and nausea. CONCLUSIONS: Previously described periodic EEG phenomena are interictal events or appear with peripheral events of similar cadence. Therefore, we remain unaware of any documentation of periodic ictal electrographic events. The restricted propagation and duration of these recorded seizures may have simplified their pathophysiology allowing a stereotyped involvement of excitatory and inhibitory mechanisms producing the periodicity.

Adult↗
PubMed1997

Outcome assessment in epilepsy: comparative responsiveness of quality of life and psychosocial instruments.

PURPOSE: Few data exist on the ability of instruments to detect within-patient change over time in epilepsy, a property referred to as responsiveness. Our aim was to compare the responsiveness of three instruments [i.e., Epilepsy Surgery Inventory-55 (ESI-55) and Washington Psychosocial Inventory (WPSI), both epilepsy specific, and Symptom Checklist-90-Revised (SCL-90-R), non-epilepsy specific]. METHODS: Instruments were administered at baseline and at 1 year in a prospective cohort of surgically (43) and medically (14) treated patients with temporal lobe epilepsy. Coefficient of Responsiveness and relative efficiency were computed for each scale and for the dimensions of mental health, physical health, and role function. RESULTS: The ESI-55 contained the most responsive scales, whereas SCL-90-R contained the largest number of scales with moderate responsiveness. The largest number of scales with low responsiveness belonged to the WPSI. Sensitivity to between-treatment differences in change was highest for ESI-55 and SCL-90-R. The most efficient scales in detecting differences between treatment groups in the mental, physical, and role-function dimensions were ESI-55 emotional well-being, ESI-55 health perceptions, and SCL-90-R hostility, respectively. CONCLUSIONS: Our results support the responsiveness of ESI-55 scales and suggest that SCL-90-R is a responsive tool for the assessment of psychologic function and distress in epilepsy. Comparatively, WPSI is relatively unresponsive to small or medium-size changes.

Adult↗
PubMed1996

Determinants of health-related quality of life after temporal lobe epilepsy surgery.

Temporal lobectomy appears to be an effective treatment for medically intractable epilepsy. However, the influences of pre-operative health status and post-operative reductions in seizure activity on post-surgical health-related quality of life (HRQOL) are not well understood. We used the Epilepsy Surgery Inventory 55 (ESI-55) to evaluate changes between pre- and post-operative HRQOL in 47 temporal lobectomy patients. Patients exhibited significantly improved scores in five HRQOL domains: health perceptions; energy fatigue; social function; cognitive function and role limitations due to physical problems. Although significant improvements in HRQOL were observed, this was not the case for all patients. Specifically, patients with low or medium pre-operative HRQOL scores were found to have the greatest degree of improvement post-operatively. Patients with high pre-operative scores did not exhibit these same improvements, although they continued to report high scores. The results indicate that the ESI-55 is a satisfactory instrument to measure change in HRQOL but also emphasizes that the magnitude of change in post-operative HRQOL scores tends to vary according to baseline scores. The outcome of temporal lobectomy is not entirely based upon the procedure's ability to reduce the frequency of seizures, but is also influenced by level of HRQOL prior to surgery.

Activities of Daily Living↗
PubMed1996

Psychiatric disorders in candidates for surgery for epilepsy.

OBJECTIVE: To provide a descriptive analysis of the prevalence and pattern of psychiatric morbidity among 300 consecutive epileptic patients refractive to treatment and admitted during a six year period for evaluation of their candidature for surgery. METHODS: Patients underwent detailed observation of their seizure and standardised psychiatric assessment. Patients were considered to be refractory to treatment if they continued to manifest seizures with an average frequency of at least once every month even with polytherapy using up to three different anti-convulsants for a period of at least two years. Of the 300 patients, 231 had a temporal lobe focus, 43 had a non-temporal lobe focus, and 26 patients had a generalised and multifocal seizure onset. RESULTS AND CONCLUSIONS: With the DSM-III-R criteria 142 (47.3%) patients emerged as psychiatric cases. A principal axis I diagnosis was made in 88 (29.3%), and an axis II diagnosis (personality disorder) in another 54 (18.0%) patients. The most common axis I diagnosis was anxiety disorders (10.7%). A schizophrenia-like psychosis was seen in 13 (4.3%). Most patients with personality disorders showed dependent and avoidant personality traits. There was a significantly higher psychotic subscore on the present state examination in the temporal than with the non-temporal group of patients. These findings were not significant when compared with patients with a generalised and multifocal seizure disorder. There were no significant findings between the different seizure focus groups on the neurotic subscores. The findings with regard to laterality of seizure focus and the neurotic or psychotic subscores were not significant.

Adult↗
PubMed1992

Serial cranial and spinal cord magnetic resonance imaging in multiple sclerosis.

Twenty-nine mildly disabled patients with multiple sclerosis underwent serial clinical and magnetic resonance imaging (MRI) evaluations (pre- and postgadolinium cranial and spinal cord MRI) on at least 3 occasions at 13-week intervals and during periods of suspected relapse. Using clinical judgment of the presence of recent active disease as the gold standard, combined MRI studies confirmed the clinical impression of active disease in 93% of follow-up visits (sensitivity) and the absence of active MS in 63% of follow-up visits (specificity). None of the cranial and spinal MRI-detected abnormalities disappeared. Gadolinium administration particularly increased the yield of spinal MRI. Cranial MRI alone detected 80% of the MRI-active visits. Clinical and MRI concordance was significantly better for the presence of recent disease activity than for the anatomical localization of the presumed site of activity. MRI evidence of apparent ongoing disease activity was seen more frequently in patients believed to have active multiple sclerosis in the preceding year (13 of 21) than in patients who had been in clinical remission for at least the 2 preceding years (2 of 8). Although clinical evidence of new disease activity was much less common in patients with active, chronic-progressive disease (1 of 8) than in patients with active, relapsing disease (9 of 13), the proportion of patients with either infrequent relapses, frequent relapses, or slow chronic-progressive disease in the preceding year in whom MRI activity developed and the pattern of this new MRI activity was similar between these types of active patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗