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Thomas Feasby

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Papers by Thomas Feasby

Endarterectomy for Asymptomatic Carotid Stenosis in the Real World

Canadian Journal of Neurological Sciences, Feb 1, 2000

Studies of carotid endarterectomy (CE) in the United States' and more recently in Canada2 showing... more Studies of carotid endarterectomy (CE) in the United States' and more recently in Canada2 showing that up to 67% of procedures were either of uncertain value or inappropriate suggest that case selection is of critical importance. The major clinical decision to make in cases of carotid stenosis is whether to operate upon those with asymptomatic disease. This problem can be considered with the aid of an efficacy-t effectiveness cycle. The steps are as follows: 1. Proof of efficacy (outcome of randomized clinical trials (RCTs));

Incidence of Guillain-Barre syndrome in Alberta, Canada: an administrative data study

Journal of Neurology, Neurosurgery, and Psychiatry, Mar 1, 2008

To examine the epidemiology of Guillain-Barré syndrome (GBS) in Alberta between 1994 and 2004 wit... more To examine the epidemiology of Guillain-Barré syndrome (GBS) in Alberta between 1994 and 2004 with data derived from hospital administration procedures. Data from 3,959,857 individuals (1,956,841 females and 2,003,016 males) aged 1-110 years and residing in Alberta, Canada, were included in the analysis. A Poisson regression analysis was performed to determine the predictors of GBS events. After age and sex standardisation to the 2001 Canadian census population, incidence rates ranged from 0.97 to 2.32 per 100,000 over the course of the 11-year period, with a mean incidence of 1.6 per 100,000. Significant effects of gender, age group and year were found. Males were found to be 1.5 times more likely to acquire GBS than females. Relative to those in their first decade, the risk of acquiring GBS increased with advancing age, whereby the incidence in males peaked in the 7th decade of life and in females in the 8th decade of life. The incidence fluctuated over the 11-year period, with a minimum in 1998 and a maximum in 2004. The incidence of GBS in Alberta between 1994 and 2004 fluctuated within a narrow range, was similar to that previously reported worldwide, demonstrated a male preponderance and increased in elderly patients.

Treating stroke - Response

Canadian Medical Association Journal, May 2, 2000

Effectiveness of tissue-type plasminogen activator for acute ischemic stroke: Consequences of protocol violation

Stroke, 1999

Conduction Block and Denervation in Guillain-Barré Polyneuropathy

Brain, 1984

The two main electrophysiological abnormalities seen in the first two weeks of the acute Guillain... more The two main electrophysiological abnormalities seen in the first two weeks of the acute Guillain-Barré syndrome (GBS) were conduction block and, in some patients, low maximum M response amplitudes. In this study period, maximum motor and sensory conduction velocities were often in the normal range and temporal dispersion was relatively less common. The conduction block was generalized in its distribution in some peripheral nerves, while in others the block was predominantly proximal or distal in location. Conduction abnormalities in excess of those proximal or distal to it were frequent at common sites of entrapment. Very low M response amplitudes early in the course of the disease correlated well with the subsequent development and frequency of denervation in the muscle(s) and unfavourable clinical recovery. We conclude that conduction block is the main cause of the acute paralysis and sensory loss in the GBS. Axonal degeneration contributes variably to the acute disorder, but is the main cause of lasting disability.

Simultaneous carotid endarterectomy and coronary artery bypass surgery in Canada

Neurology, Apr 25, 2005

ABSTRACT Stroke neurologists are commonly asked to review patients who require coronary artery by... more ABSTRACT Stroke neurologists are commonly asked to review patients who require coronary artery bypass grafting (CABG) but who also have comorbid severe carotid stenosis; such patients may be offered simultaneous carotid endarterectomy (CEA). In Canada, 0.51% of CABG procedures were combined CEA-CABG. The adjusted stroke and death rate was 2.67-fold greater in the combined CEA-CABG group compared to CABG alone. Randomized trials of the combined procedure are needed.

The risks of inappropriate carotid endarterectomy

Annals of Neurology, 1998

Spinal Cord Swelling in Multiple Sclerosis

Canadian Journal of Neurological Sciences, May 1, 1981

Predicting Outcome in Guillain-Barré Syndrome

Neurology, Dec 22, 2021

Background and Objectives The clinical course and outcome of the Guillain-Barré syndrome (GBS) ar... more Background and Objectives The clinical course and outcome of the Guillain-Barré syndrome (GBS) are diverse and vary among regions. The modified Erasmus GBS Outcome Score (mEGOS), developed with data from Dutch patients, is a clinical model that predicts the risk of walking inability in patients with GBS. The study objective was to validate the mEGOS in the International GBS Outcome Study (IGOS) cohort and to improve its performance and region specificity.

To test or not to test?

Neurology, Dec 1, 1999

ED406436 - To Test or Not To Test: That Is the Question.

Textbook of Clinical Neuropharmacology and Therapeutics

Annals of Internal Medicine, 1992

nomena that Pavlovian conditioning is not able to explain. An important question that the author ... more nomena that Pavlovian conditioning is not able to explain. An important question that the author raises is whether or not the opponent-process states are predictable. He is convinced that they are and analyzes the process of food intake and obesity following the logic of opponent-process theory. Neurobiology ofLearning, Emotion, and Affect is a well organ

Optic neuritis and multiple sclerosis

Acta Ophthalmologica Scandinavica, 2001

PURPOSE Review of the association between optic neuritis (ON) and multiple sclerosis (MS). RESULT... more PURPOSE Review of the association between optic neuritis (ON) and multiple sclerosis (MS). RESULTS MS often presents as acute unilateral ON. While it is clear that many patients with ON suffer from a generalized disease of the central nervous system that will go on to clinically definite MS (CDMS), it is also clear that others do not. With more and more well-informed patients and the emerging pharmacotheraphy for MS, the distinction between those patients with ON who have MS and those who do not, has become more important than ever before. Recently, a large randomized clinical trial on patients with ON or other clinically isolated syndromes suggestive of MS and evidence of prior subclinical demyelination on magnetic resonance imaging of the brain, found that treatment with recombinant interferon-beta-1a is beneficial by reducing the development of CDMS. CONCLUSION Ophthalmologists should refer their patients with acute ON to a neurologist for MS-directed investigations and decisions regarding early institution of disease modifying therapy.

<b> <i>Helicobacter pylori</i> </b> and Cerebrovascular Disease

Stroke, Aug 1, 2001

Demyelination and axonal degeneration in Lewis rat experimental allergic neuritis depend on the myelin dosage

PubMed, Jul 1, 1988

We describe the clinical and pathologic features of experimental allergic neuritis in Lewis rats ... more We describe the clinical and pathologic features of experimental allergic neuritis in Lewis rats inoculated with varying doses of myelin, ranging from 0.5 to 20 mg. The clinical scores were assessed daily. On days 18 and 19 or 28 postimmunization, the rats were perfused with fixative and samples of cervical and lumbar roots and sciatic nerves were processed and embedded in Epon. Tissues were examined by light and electron microscopy and the degree of edema, inflammation, demyelination, and axonal degeneration was assessed quantitatively. We found that the severity of clinical and pathologic experimental allergic neuritis correlated positively with the dose of myelin used for immunization. High dose tolerance was not observed. Demyelination prevailed in nerve roots and increased with higher doses of antigen. Accompanying axonal degeneration was seen only with high doses of myelin. The pathology of sciatic nerves differed. Sciatic nerves of rats immunized with 0.5 and 1 mg of myelin were either normal or showed perivenular lymphocytic infiltrates and demyelination, but nerves from rats with higher immunizing doses of myelin showed increasingly severe axonal degeneration. The axonal degeneration in nerve roots paralleled the degree of inflammation and demyelination and may have been a nonspecific product of the inflammatory reaction. However, the much more severe axonal destruction seen in sciatic nerves with high myelin doses was probably due to other pathogenetic mechanisms.

P2-peptide induced experimental allergic neuritis: a model to study axonal degeneration

Acta Neuropathologica, Jun 1, 1991

In experimental allergic neuritis (EAN) severity of clinical disease and pathology correlate with... more In experimental allergic neuritis (EAN) severity of clinical disease and pathology correlate with the dose of antigen (Hahn et al., Lab Invest 59:115-125, 1988). To avoid axonal membrane contamination of the antigen, EAN was induced with a synthetic peptide, corresponding to residues 53-78 of bovine P2 myelin protein. Severity of EAN correlated with the dose of peptide in the inoculate. The relationship between demyelination, inflammation and axonal degeneration was studied. Low doses resulted in pure demyelination. Axonal degeneration occurred only with high doses of antigen and in association with very active mononuclear inflammation. The role of macrophages in producing axonal damage is discussed.

Treatment of Experimental Allergic Neuritis With Prednisolone

Canadian Journal of Neurological Sciences, Feb 1, 1987

Obstetrical lumbosacral plexus injury

Muscle & Nerve, Aug 1, 1992

Injuries to the lumbosacral plexus during labor and delivery have been reported in the literature... more Injuries to the lumbosacral plexus during labor and delivery have been reported in the literature for years, but have lacked electrophysiologic testing to substantiate the location of the nerve injury. We report 2 cases with comprehensive electrophysiologic testing which localizes the site of this obstetrical paralysis to the lumbosacral trunk (L4-5) and S-1 root where they join and pass over the pelvic rim. The paralysis may be mild or severe. Small maternal size, a large fetus, midforceps rotation, and fetal malposition may place the mother at risk for this nerve injury.

Passive transfer studies in Guillain-Barre polyneuropathy

Neurology, Oct 1, 1982

Serum and lymphocytes from patients with acute Guillain-Barré polyneuropathy were injected into r... more Serum and lymphocytes from patients with acute Guillain-Barré polyneuropathy were injected into rat sciatic nerves. Serum from 13 of 17 patients produced perivenular demyelination, associated with lymphocytic infiltration. The pattern of demyelination differed from that caused by experimental allergic neuritis serum. The level of serum demyelinating activity as greatest early in the disease and then decreased. The demyelinating factor was heat-labile but not complement-dependent. Circulating lymphocytes did not cause demyelination in eight patients.

Multiple sclerosis and autoimmune diseases

Neurology, 1983

BACKGROUND AND PURPOSE: White matter alteration in iNPH has not been well-investigated. TBSS is a... more BACKGROUND AND PURPOSE: White matter alteration in iNPH has not been well-investigated. TBSS is a voxelwise statistical analysis developed for DTI data. We aimed to elucidate the cerebral white matter alteration in patients with iNPH by using DTI and to test the accuracy of TBSS analysis. MATERIALS AND METHODS: DTI data were obtained from 20 patients with iNPH and 20 age-and sex-matched controls. The FA values were evaluated by using TBSS, region-of-interest and tract-specific analysis of the CST. The accuracy of TBSS analysis was tested by using "back-projection" of TBSS results and by comparing the TBSS analysis results with those of region-of-interest and tract-specific analysis. RESULTS: Back-projection of the TBSS results showed accurate registration of the whole brain, with the exception of parts of the thalamus, fornix, and white matter around the posterior body of the lateral ventricle. The TBSS analysis results were consistent with those of the region-of-interest analysis and tract-specific analysis. In patients with iNPH compared with control subjects, the FA values were significantly decreased in parts of the corpus callosum, periventricular white matter, and juxtacortical white matter in the frontal and parietal lobes. In contrast, FA values were significantly increased in the internal capsule, extending to the white matter in the centrum semiovale. CONCLUSIONS: Our results suggest that patients with iNPH have various patterns of white matter damage and that TBSS analysis is a promising tool for performing accurate voxelwise statistical analysis of the iNPH brain, with the exception of misregistered areas. ABBREVIATIONS: CST ϭ corticospinal tract; FA ϭ fractional anisotropy; iNPH ϭ idiopathic normal pressure hydrocephalus; MNI ϭ Montreal Neurological Institute; MMSE ϭ Mini-Mental State Examination; SLF ϭ superior longitudinal fasciculus; TBSS ϭ tract-based spatial statistics; TFCE ϭ threshold-free cluster-enhancement

Intracerebral haemorrhage and angiographic beading following ingestion of catecholaminergics

Stroke, Jul 1, 1985

Endarterectomy for Asymptomatic Carotid Stenosis in the Real World

Canadian Journal of Neurological Sciences, Feb 1, 2000

Studies of carotid endarterectomy (CE) in the United States' and more recently in Canada2 showing... more Studies of carotid endarterectomy (CE) in the United States' and more recently in Canada2 showing that up to 67% of procedures were either of uncertain value or inappropriate suggest that case selection is of critical importance. The major clinical decision to make in cases of carotid stenosis is whether to operate upon those with asymptomatic disease. This problem can be considered with the aid of an efficacy-t effectiveness cycle. The steps are as follows: 1. Proof of efficacy (outcome of randomized clinical trials (RCTs));

Incidence of Guillain-Barre syndrome in Alberta, Canada: an administrative data study

Journal of Neurology, Neurosurgery, and Psychiatry, Mar 1, 2008

To examine the epidemiology of Guillain-Barré syndrome (GBS) in Alberta between 1994 and 2004 wit... more To examine the epidemiology of Guillain-Barré syndrome (GBS) in Alberta between 1994 and 2004 with data derived from hospital administration procedures. Data from 3,959,857 individuals (1,956,841 females and 2,003,016 males) aged 1-110 years and residing in Alberta, Canada, were included in the analysis. A Poisson regression analysis was performed to determine the predictors of GBS events. After age and sex standardisation to the 2001 Canadian census population, incidence rates ranged from 0.97 to 2.32 per 100,000 over the course of the 11-year period, with a mean incidence of 1.6 per 100,000. Significant effects of gender, age group and year were found. Males were found to be 1.5 times more likely to acquire GBS than females. Relative to those in their first decade, the risk of acquiring GBS increased with advancing age, whereby the incidence in males peaked in the 7th decade of life and in females in the 8th decade of life. The incidence fluctuated over the 11-year period, with a minimum in 1998 and a maximum in 2004. The incidence of GBS in Alberta between 1994 and 2004 fluctuated within a narrow range, was similar to that previously reported worldwide, demonstrated a male preponderance and increased in elderly patients.

Treating stroke - Response

Canadian Medical Association Journal, May 2, 2000

Effectiveness of tissue-type plasminogen activator for acute ischemic stroke: Consequences of protocol violation

Stroke, 1999

Conduction Block and Denervation in Guillain-Barré Polyneuropathy

Brain, 1984

The two main electrophysiological abnormalities seen in the first two weeks of the acute Guillain... more The two main electrophysiological abnormalities seen in the first two weeks of the acute Guillain-Barré syndrome (GBS) were conduction block and, in some patients, low maximum M response amplitudes. In this study period, maximum motor and sensory conduction velocities were often in the normal range and temporal dispersion was relatively less common. The conduction block was generalized in its distribution in some peripheral nerves, while in others the block was predominantly proximal or distal in location. Conduction abnormalities in excess of those proximal or distal to it were frequent at common sites of entrapment. Very low M response amplitudes early in the course of the disease correlated well with the subsequent development and frequency of denervation in the muscle(s) and unfavourable clinical recovery. We conclude that conduction block is the main cause of the acute paralysis and sensory loss in the GBS. Axonal degeneration contributes variably to the acute disorder, but is the main cause of lasting disability.

Simultaneous carotid endarterectomy and coronary artery bypass surgery in Canada

Neurology, Apr 25, 2005

ABSTRACT Stroke neurologists are commonly asked to review patients who require coronary artery by... more ABSTRACT Stroke neurologists are commonly asked to review patients who require coronary artery bypass grafting (CABG) but who also have comorbid severe carotid stenosis; such patients may be offered simultaneous carotid endarterectomy (CEA). In Canada, 0.51% of CABG procedures were combined CEA-CABG. The adjusted stroke and death rate was 2.67-fold greater in the combined CEA-CABG group compared to CABG alone. Randomized trials of the combined procedure are needed.

The risks of inappropriate carotid endarterectomy

Annals of Neurology, 1998

Spinal Cord Swelling in Multiple Sclerosis

Canadian Journal of Neurological Sciences, May 1, 1981

Predicting Outcome in Guillain-Barré Syndrome

Neurology, Dec 22, 2021

Background and Objectives The clinical course and outcome of the Guillain-Barré syndrome (GBS) ar... more Background and Objectives The clinical course and outcome of the Guillain-Barré syndrome (GBS) are diverse and vary among regions. The modified Erasmus GBS Outcome Score (mEGOS), developed with data from Dutch patients, is a clinical model that predicts the risk of walking inability in patients with GBS. The study objective was to validate the mEGOS in the International GBS Outcome Study (IGOS) cohort and to improve its performance and region specificity.

To test or not to test?

Neurology, Dec 1, 1999

ED406436 - To Test or Not To Test: That Is the Question.

Textbook of Clinical Neuropharmacology and Therapeutics

Annals of Internal Medicine, 1992

nomena that Pavlovian conditioning is not able to explain. An important question that the author ... more nomena that Pavlovian conditioning is not able to explain. An important question that the author raises is whether or not the opponent-process states are predictable. He is convinced that they are and analyzes the process of food intake and obesity following the logic of opponent-process theory. Neurobiology ofLearning, Emotion, and Affect is a well organ

Optic neuritis and multiple sclerosis

Acta Ophthalmologica Scandinavica, 2001

PURPOSE Review of the association between optic neuritis (ON) and multiple sclerosis (MS). RESULT... more PURPOSE Review of the association between optic neuritis (ON) and multiple sclerosis (MS). RESULTS MS often presents as acute unilateral ON. While it is clear that many patients with ON suffer from a generalized disease of the central nervous system that will go on to clinically definite MS (CDMS), it is also clear that others do not. With more and more well-informed patients and the emerging pharmacotheraphy for MS, the distinction between those patients with ON who have MS and those who do not, has become more important than ever before. Recently, a large randomized clinical trial on patients with ON or other clinically isolated syndromes suggestive of MS and evidence of prior subclinical demyelination on magnetic resonance imaging of the brain, found that treatment with recombinant interferon-beta-1a is beneficial by reducing the development of CDMS. CONCLUSION Ophthalmologists should refer their patients with acute ON to a neurologist for MS-directed investigations and decisions regarding early institution of disease modifying therapy.

<b> <i>Helicobacter pylori</i> </b> and Cerebrovascular Disease

Stroke, Aug 1, 2001

Demyelination and axonal degeneration in Lewis rat experimental allergic neuritis depend on the myelin dosage

PubMed, Jul 1, 1988

We describe the clinical and pathologic features of experimental allergic neuritis in Lewis rats ... more We describe the clinical and pathologic features of experimental allergic neuritis in Lewis rats inoculated with varying doses of myelin, ranging from 0.5 to 20 mg. The clinical scores were assessed daily. On days 18 and 19 or 28 postimmunization, the rats were perfused with fixative and samples of cervical and lumbar roots and sciatic nerves were processed and embedded in Epon. Tissues were examined by light and electron microscopy and the degree of edema, inflammation, demyelination, and axonal degeneration was assessed quantitatively. We found that the severity of clinical and pathologic experimental allergic neuritis correlated positively with the dose of myelin used for immunization. High dose tolerance was not observed. Demyelination prevailed in nerve roots and increased with higher doses of antigen. Accompanying axonal degeneration was seen only with high doses of myelin. The pathology of sciatic nerves differed. Sciatic nerves of rats immunized with 0.5 and 1 mg of myelin were either normal or showed perivenular lymphocytic infiltrates and demyelination, but nerves from rats with higher immunizing doses of myelin showed increasingly severe axonal degeneration. The axonal degeneration in nerve roots paralleled the degree of inflammation and demyelination and may have been a nonspecific product of the inflammatory reaction. However, the much more severe axonal destruction seen in sciatic nerves with high myelin doses was probably due to other pathogenetic mechanisms.

P2-peptide induced experimental allergic neuritis: a model to study axonal degeneration

Acta Neuropathologica, Jun 1, 1991

In experimental allergic neuritis (EAN) severity of clinical disease and pathology correlate with... more In experimental allergic neuritis (EAN) severity of clinical disease and pathology correlate with the dose of antigen (Hahn et al., Lab Invest 59:115-125, 1988). To avoid axonal membrane contamination of the antigen, EAN was induced with a synthetic peptide, corresponding to residues 53-78 of bovine P2 myelin protein. Severity of EAN correlated with the dose of peptide in the inoculate. The relationship between demyelination, inflammation and axonal degeneration was studied. Low doses resulted in pure demyelination. Axonal degeneration occurred only with high doses of antigen and in association with very active mononuclear inflammation. The role of macrophages in producing axonal damage is discussed.

Treatment of Experimental Allergic Neuritis With Prednisolone

Canadian Journal of Neurological Sciences, Feb 1, 1987

Obstetrical lumbosacral plexus injury

Muscle & Nerve, Aug 1, 1992

Injuries to the lumbosacral plexus during labor and delivery have been reported in the literature... more Injuries to the lumbosacral plexus during labor and delivery have been reported in the literature for years, but have lacked electrophysiologic testing to substantiate the location of the nerve injury. We report 2 cases with comprehensive electrophysiologic testing which localizes the site of this obstetrical paralysis to the lumbosacral trunk (L4-5) and S-1 root where they join and pass over the pelvic rim. The paralysis may be mild or severe. Small maternal size, a large fetus, midforceps rotation, and fetal malposition may place the mother at risk for this nerve injury.

Passive transfer studies in Guillain-Barre polyneuropathy

Neurology, Oct 1, 1982

Serum and lymphocytes from patients with acute Guillain-Barré polyneuropathy were injected into r... more Serum and lymphocytes from patients with acute Guillain-Barré polyneuropathy were injected into rat sciatic nerves. Serum from 13 of 17 patients produced perivenular demyelination, associated with lymphocytic infiltration. The pattern of demyelination differed from that caused by experimental allergic neuritis serum. The level of serum demyelinating activity as greatest early in the disease and then decreased. The demyelinating factor was heat-labile but not complement-dependent. Circulating lymphocytes did not cause demyelination in eight patients.

Multiple sclerosis and autoimmune diseases

Neurology, 1983

BACKGROUND AND PURPOSE: White matter alteration in iNPH has not been well-investigated. TBSS is a... more BACKGROUND AND PURPOSE: White matter alteration in iNPH has not been well-investigated. TBSS is a voxelwise statistical analysis developed for DTI data. We aimed to elucidate the cerebral white matter alteration in patients with iNPH by using DTI and to test the accuracy of TBSS analysis. MATERIALS AND METHODS: DTI data were obtained from 20 patients with iNPH and 20 age-and sex-matched controls. The FA values were evaluated by using TBSS, region-of-interest and tract-specific analysis of the CST. The accuracy of TBSS analysis was tested by using "back-projection" of TBSS results and by comparing the TBSS analysis results with those of region-of-interest and tract-specific analysis. RESULTS: Back-projection of the TBSS results showed accurate registration of the whole brain, with the exception of parts of the thalamus, fornix, and white matter around the posterior body of the lateral ventricle. The TBSS analysis results were consistent with those of the region-of-interest analysis and tract-specific analysis. In patients with iNPH compared with control subjects, the FA values were significantly decreased in parts of the corpus callosum, periventricular white matter, and juxtacortical white matter in the frontal and parietal lobes. In contrast, FA values were significantly increased in the internal capsule, extending to the white matter in the centrum semiovale. CONCLUSIONS: Our results suggest that patients with iNPH have various patterns of white matter damage and that TBSS analysis is a promising tool for performing accurate voxelwise statistical analysis of the iNPH brain, with the exception of misregistered areas. ABBREVIATIONS: CST ϭ corticospinal tract; FA ϭ fractional anisotropy; iNPH ϭ idiopathic normal pressure hydrocephalus; MNI ϭ Montreal Neurological Institute; MMSE ϭ Mini-Mental State Examination; SLF ϭ superior longitudinal fasciculus; TBSS ϭ tract-based spatial statistics; TFCE ϭ threshold-free cluster-enhancement

Intracerebral haemorrhage and angiographic beading following ingestion of catecholaminergics

Stroke, Jul 1, 1985