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Biomedical subjects

N E Anderson

Publications and source records attributed to N E Anderson.

At least 19 recordsLinked to original sources
PubMed2006

Ethnic differences in syringomyelia in New Zealand.

OBJECTIVE: To determine the prevalence of syringomyelia in a defined population in New Zealand and measure the prevalence of syringomyelia in the three main ethnic groups (Maori, Pacific people and Caucasians/others) living in this region. METHODS: A retrospective study of all confirmed cases of syringomyelia diagnosed in residents of northern New Zealand from 1961 to 2003. RESULTS: In all, syringomyelia was diagnosed in 137 patients. The mean age at onset of symptoms was 27.5 years and mean age at diagnosis was 32.6 years. The incidence of new cases increased from 0.76/100,000 a year between 1962 and 1971 to 4.70/100,000 a year by 1992-2001. The prevalence of syringomyelia in 2003 was 8.2/100,000 people: 5.4/100,000 in Caucasians or others, 15.4/100,000 in Maori and 18.4/100,000 in Pacific people (chi2 = 37.0, p<0.0001). Syringomyelia was more often associated with an isolated Chiari I malformation in Pacific people (84.4%) as compared with 42.9% of Maori and 38.2% of Caucasians or others (chi2 = 62.3, p<0.0001). CONCLUSION: The prevalence of syringomyelia is higher in northern New Zealand than in studies carried out before the advent of magnetic resonance imaging. The prevalence is particularly high in Maori and Pacific people. The cause of the ethnic differences in the prevalence of syringomyelia identified in this study is unexplained and warrants further investigation.

Adolescent↗
PubMed2006

Leptomeningeal infiltration as the presenting manifestation of a malignant glioma.

Infiltration of the leptomeninges by a malignant glioma typically occurs with recurrent supratentorial tumors, but patients may present with leptomeningeal gliomatosis before the primary tumor is diagnosed. This report describes two patients who presented with headache and signs of multifocal neurological disease. One of the patients had neurofibromatosis type I. In both patients the cerebrospinal fluid examination showed a mild pleocytosis, but malignant cells were not detected. The diagnosis of leptomeningeal gliomatosis was not confirmed until autopsy, but in retrospect imaging showed a small, asymptomatic primary tumor in both patients. Leptomeningeal gliomatosis should be considered in the differential diagnosis of chronic meningitis, if the patient is afebrile and if there are multifocal neurological signs, even when a primary tumor is not obvious.

Anti-Inflammatory Agents↗
PubMed2006

Changing attitudes to the management of ischaemic stroke between 1997 and 2004: a survey of New Zealand physicians.

AIM: In 1997, a survey of New Zealand physicians' opinions on the management of stroke was carried out. Since then, there have been a number of advances in stroke therapy. We have repeated the 1997 survey to assess changes in physicians' opinions on stroke management. METHODS: A questionnaire was sent to 293 physicians responsible for patients admitted with acute stroke to hospitals throughout New Zealand. It included questions on the management of acute stroke and secondary prevention and was based on the 1997 questionnaire. RESULTS: Responses were received from 211 physicians of whom 174 (82%) managed patients with an acute stroke. The number of respondents who thought that stroke units were efficacious has increased (57% in 1997 to 89%, P < 0.001). The use of aspirin acutely (P < 0.001) and intravenous tissue plasminogen activator (P = 0.006) has also increased. In 2004, antihypertensive therapy for secondary stroke prevention would be commenced if the blood pressure was 150/90 by 98% of respondents and 140/90 by 70% of respondents. In 2004, a statin would be commenced if the total cholesterol level was 4.0 mmol/L by 56% of respondents and 5.0 mmol/L by 91% of respondents. CONCLUSIONS: This survey has shown important changes in the management of ischaemic stroke over the past 7 years.

Antihypertensive Agents↗
PubMed2005

Detection of focal cerebral hemisphere lesions using the neurological examination.

OBJECTIVE: To determine the sensitivity and specificity of clinical tests for detecting focal lesions in a prospective blinded study. METHODS: 46 patients with a focal cerebral hemisphere lesion without obvious focal signs and 19 controls with normal imaging were examined using a battery of clinical tests. Examiners were blinded to the diagnosis. The sensitivity, specificity, and positive and negative predictive values of each test were measured. RESULTS: The upper limb tests with the greatest sensitivities for detecting a focal lesion were finger rolling (sensitivity 0.33 (95% confidence interval, 0.21 to 0.47)), assessment of power (0.30 (0.19 to 0.45)), rapid alternating movements (0.30 (0.19 to 0.45)), forearm rolling (0.24 (0.14 to 0.38)), and pronator drift (0.22 (0.12 to 0.36)). All these tests had a specificity of 1.00 (0.83 to 1.00). This combination of tests detected an abnormality in 50% of the patients with a focal lesion. In the lower limbs, assessment of power was the most sensitive test (sensitivity 0.20 (0.11 to 0.33)). Visual field defects were detected in 10 patients with a focal lesion (sensitivity 0.22 (0.12 to 0.36)) and facial weakness in eight (sensitivity 0.17 (0.09 to 0.31)). Overall, the examination detected signs of focal brain disease in 61% of the patients with a focal cerebral lesion. CONCLUSIONS: The neurological examination has a low sensitivity for detecting early cerebral hemisphere lesions in patients without obvious focal signs. The finger and forearm rolling tests, rapid alternating movements of the hands, and pronator drift are simple tests that increase the detection of a focal lesion without greatly increasing the length of the examination.

Adult↗
PubMed2003

Experimental evidence for anisotropic double-gap behavior in MgB2.

The behavior of a type II superconductor in the presence of a magnetic field is governed by two characteristic length scales, the London penetration depth and the coherence length. We present magnetization measurements on MgB2 powder showing an anisotropy in the upper critical field and hence the coherence length of 6. Using the technique of small angle neutron scattering we show that this anisotropy is not mirrored in the London penetration depth, which is almost isotropic. This result can be explained by the superconductivity residing in two distinct electronic bands of the material, only one of which is highly anisotropic.

Journal Article↗
PubMed2002

Subacute measles encephalitis in an immunocompetent adult.

Subacute sclerosing panencephalitis (SSPE) and subacute measles encephalitis (SME) are both rare complications of measles virus infection. SSPE typically affects immunocompetent children, has an insidious onset and follows a steadily progressive course. SME mainly occurs in immunosuppressed children and has a rapidly progressive course. We describe a 43 year old immunocompetent man who presented with a rapidly progressive fatal encephalopathy. Histological examination of the brain showed a meningoencephalitis with inclusion bodies. Complement fixing antibody to measles virus was present in his serum and CSF. Measles virus RNA was found in the brain, spinal cord and eye, but not in the CSF. Analysis of the nucleoprotein gene isolated from this patient did not show similarity to SSPE strains of the measles virus. This patient demonstrates that subacute encephalitis secondary to measles virus infection can develop in an immunocompetent adult host.

Adult↗
PubMed2001

Is there a temporal pattern in the occurrence of subarachnoid hemorrhage in the southern hemisphere? Pooled data from 3 large, population-based incidence studies in Australasia, 1981 to 1997.

BACKGROUND AND PURPOSE: Publications on the temporal pattern of the occurrence of subarachnoid hemorrhage (SAH) have produced conflicting results. Variations between studies may relate to the relatively small numbers of SAH cases analyzed, including those in meta-analyses. METHODS: We identified all cases of SAH from 3 well-designed population-based studies in Australia (Adelaide, Hobart, and Perth) and New Zealand (Auckland) during 3 periods between 1981 and 1997. The diagnosis of SAH was confirmed with CT, cerebral angiography, cerebrospinal fluid analysis, or autopsy in all cases. Information on the time of occurrence of each event was obtained. Risk ratios (RRs) and 95% CIs were calculated using Poisson regression, with age, sex, smoking status, and history of hypertension entered in the model as covariates. RESULTS: A total of 783 cases of SAH were registered. Age- and sex-adjusted RRs of SAH occurrence were highest in the period between 6 AM and 12 MIDNIGHT (RR 3.2, 95% CI 2.4-4.3) and in winter and spring (RR 1.3, 95% CI 1.1-1.5; RR 1.3, 95% CI 1.1-1.5; respectively). No particular pattern of SAH occurrence was observed according to the day of the week. Restriction of the analyses to proved aneurysmal SAH did not substantially change the point estimates. CONCLUSIONS: Circadian and circaseptan (weekly) fluctuations of SAH occurrence in the southern hemisphere are similar to those in the northern hemisphere, but the occurrence of SAH in Australasia exhibits clear seasonal (winter and spring) peaks.

Age Distribution↗
PubMed2000

Pravastatin therapy and the risk of stroke.

BACKGROUND: Several epidemiologic studies have concluded that there is no relation between total cholesterol levels and the risk of stroke. In some studies that classified strokes according to cause, there was an association between increasing cholesterol levels and the risk of ischemic stroke and a possible association between low cholesterol levels and the risk of hemorrhagic stroke. Recent reviews of trials of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors have suggested that these agents may reduce the risk of stroke. METHODS: In a double-blind trial (the Long-Term Intervention with Pravastatin in Ischaemic Disease study), we compared the effects of pravastatin on mortality due to coronary heart disease (the primary end point) with the effects of placebo among 9014 patients with a history of myocardial infarction or unstable angina and a total cholesterol level of 155 to 271 mg per deciliter (4.0 to 7.0 mmol per liter). Our goal in the present study was to assess effects on stroke from any cause and nonhemorrhagic stroke, which were secondary end points. RESULTS: There were 419 strokes among 373 patients over a follow-up period of six years. A total of 309 strokes were classified as ischemic, 31 as hemorrhagic, and 79 as of unknown type. Among the patients given placebo, the risk of stroke was 4.5 percent, as compared with 3.7 percent among those given pravastatin (relative reduction in risk, 19 percent; 95 percent confidence interval, 0 to 34 percent; P=0.05). Non-hemorrhagic stroke occurred in 4.4 percent of the patients given placebo, as compared with 3.4 percent of those given pravastatin (reduction in risk, 23 percent; 95 percent confidence interval, 5 to 38 percent; P=0.02). Pravastatin had no effect on hemorrhagic stroke (incidence, 0.2 percent in the placebo group vs. 0.4 percent in the pravastatin group; P=0.28). CONCLUSIONS: Pravastatin has a moderate effect in reducing the risk of stroke from any cause and the risk of nonhemorrhagic stroke in patients with previous myocardial infarction or unstable angina.

Adult↗
PubMed2000

Relation between troponin T concentration and mortality in patients presenting with an acute stroke: observational study.

OBJECTIVE: To assess whether a raised serum troponin T concentration would be an independent predictor of death in patients with an acute ischaemic stroke. DESIGN: Observational study. SETTING: Auckland Hospital, Auckland, New Zealand. SUBJECTS: All 181 patients with an acute ischaemic stroke admitted over nine months in 1997-8, from a total of 8057 patients admitted to the acute medical service. MAIN OUTCOME MEASURES: Blood samples for measuring troponin T concentration were collected 12-72 hours after admission; other variables previously associated with severity of stroke were also recorded and assessed as independent predictors of inpatient mortality. RESULTS: Troponin T concentration was raised (>0.1 microgram/l) in 17% (30) of patients admitted with an acute ischaemic stroke. Thirty one patients died in hospital (12/30 (40%) patients with a raised troponin T concentration v 19/151 (13%) patients with a normal concentration (relative risk 3.2 (95% confidence 1.7 to 5. 8; P=0.0025)). Of 17 possible predictors of death, assessed in a multivariate stepwise model, only a raised troponin T concentration (P=0.0002), age (P=0.0008), and an altered level of consciousness at presentation (P=0.0074) independently predicted an adverse outcome. CONCLUSIONS: Serum troponin T concentration at hospital admission is a powerful predictor of mortality in patients admitted with an acute ischaemic stroke.

Acute Disease↗
PubMed1999

Management of stroke in Auckland Hospital in 1996.

AIMS: To review the management of stroke in Auckland Hospital; compare current management with practice in Auckland in 1991/92; and determine how many patients may be suitable for treatment with aspirin or tissue plasminogen activator (t-PA). METHODS: Retrospective review of case notes for all patients over the age of 15 years presenting during four months in 1996 with symptoms and signs of an acute stroke. Subarachnoid haemorrhages were excluded. RESULTS: There were 184 stroke events (135 ischaemic strokes, 26 intracerebral haemorrhages, 23 unspecified strokes) in 179 patients. The time between the onset of symptoms and arrival in hospital was available for 109 patients: the overall median time was three hours, two hours for intracerebral haemorrhages, three hours for ischaemic strokes, four hours for unspecified strokes. Most patients (78%) were admitted to a general medical ward. Only 10% of the patients managed on a non-neurological ward were referred to a neurologist. Computed tomography (CT) was obtained in 88% of the patients. The median time from the onset of symptoms to CT was 19 hours (11 hours for intracerebral haemorrhages, 21 hours for ischaemic strokes). Only 11 patients (10%) were scanned within three hours of the onset of symptoms. Of the 135 patients who had an ischaemic stroke, 36% were treated with aspirin and 6% with heparin in the first 48 hours. Thirty-two patients (17%) died in hospital, 87 (47%) returned home, 37 (20%) were transferred to a rest home or private hospital and 28 (15%) were transferred to other places. CONCLUSIONS: Compared with 1991, the rate of CT scanning after a stroke increased from 42% to 88%. At present, no more than 5% of all patients presenting with a stroke are suitable for consideration of treatment with t-PA. Routine treatment with aspirin in the first 48 hours could be achieved without other major changes in management.

Acute Disease↗
PubMed1999

Superficial siderosis of the central nervous system: a late complication of cerebellar tumors.

OBJECTIVE: To describe the clinical and radiologic features of superficial siderosis of the CNS after treatment of a cerebellar tumor. METHODS: Clinical assessment and MRI in four patients with superficial siderosis were performed. RESULTS: Four patients with superficial siderosis had been treated for a primary cerebellar tumor (astrocytoma in three patients, medulloblastoma in one patient) during childhood. All patients were treated with surgery and three received radiotherapy. Slowly progressive bilateral sensorineural hearing loss, gait ataxia, and limb ataxia appeared 8 to 22 years after diagnosis of the cerebellar tumor. Other clinical features were mild cognitive impairment, dysarthria, nystagmus, optic neuropathy, anosmia, and upper motor neuron signs. The CSF contained erythrocytes and increased protein. MRI with fast spin-echo T2-weighted and gradient-echo T2* sequences showed a hypointense rim of iron coating the surface of the cerebellum and brainstem. Twenty-one other patients who had survived more than 5 years after treatment of a primary cerebellar tumor did not have symptoms or signs suggestive of superficial siderosis. CONCLUSIONS: Superficial siderosis is an uncommon late complication of the treatment of a childhood cerebellar tumor, but it is probably underrecognized. The diagnosis should be suspected in patients who present with slowly progressive sensorineural hearing loss and ataxia many years after eradication of a childhood cerebellar tumor.

Adolescent↗
PubMed1999

Variations in dose to the extremities of vascular/interventional radiologists.

An evaluation was performed to determine the distribution of radiation dose received by vascular/interventional radiologists, hence forth called radiologists, to their hands and arms during interventional radiology procedures. During 87 patient procedures, measurements were made using thermoluminescent dosimeters to determine the distribution of dose to the hands and forearms. Measurements were made on a finger, the palm, wrist, elbow, and the mid-humerus of both hands and arms. Results suggested a non-uniformity of dose with the maximum dose being measured on the left hypothenar (fleshy side of the palm). The left hand receives a higher dose than the right hand due to positioning of the radiologist with respect to the patient.

Arm↗
PubMed1999

Opinion of New Zealand physicians on management of acute ischaemic stroke: results of a national survey.

BACKGROUND: Randomised trials have evaluated various treatments for acute ischaemic stroke, but it is unclear how the results of these studies are used in everyday practice. AIMS: To obtain the opinions of physicians on the management of acute ischaemic stroke. METHODS: A questionnaire was sent to 368 New Zealand Fellows of the Royal Australasian College of Physicians. The survey included questions about the availability of hospital services for stroke patients, management of acute ischaemic stroke and opinion on the efficacy of treatments used in acute ischaemic stroke. RESULTS: Of the 293 physicians who responded to the questionnaire, 171 managed patients in the first week after stroke. Forty-seven per cent of these physicians were general physicians. Ninety-five per cent usually managed these patients in a general medical ward. Only five physicians admitted patients to an acute stroke unit and only 57% considered acute stroke units were beneficial. Aspirin was usually or sometimes used for patients with acute ischaemic stroke by 92% of physicians, intravenous heparin by 43%, low-dose subcutaneous heparin by 41%, low-molecular-weight heparin by 25% and tissue-plasminogen activator (t-PA) by 3%. Two thirds considered that aspirin was definitely beneficial, but most were uncertain about the efficacy of intravenous heparin, low-dose subcutaneous heparin, low-molecular-weight heparin and t-PA. Sixty-two per cent were prepared to begin aspirin and 21% subcutaneous heparin before computerised tomography (CT). Twenty-three per cent used anti-hypertensive treatment in the first few hours after an ischaemic stroke. CONCLUSIONS: Several common deficiencies in the management of acute ischaemic stroke were identified. The widespread lack of stroke units, use of aspirin and heparin before CT, and lowering of blood pressure after an acute ischaemic stroke differed from accepted guidelines. Many physicians used heparin despite lack of evidence from randomised trials that it is beneficial. The development of stroke units and the appointment of physicians with a special interest in the management of stroke may improve the management of patients with acute stroke.

Anticoagulants↗
PubMed1998

Idiopathic steroid responsive chronic lymphocytic meningitis--clinical features and long-term outcome in 17 patients.

BACKGROUND: Some patients with chronic lymphocytic meningitis appear to respond to corticosteroid treatment, but investigations fail to identify the cause. The use of corticosteroids in patients with chronic meningitis is controversial and the long-term outcome is unclear. AIM: To review the long-term outcome in 17 patients with the syndrome of idiopathic steroid responsive chronic lymphocytic meningitis. METHODS: Review of patients' records and examination of surviving patients 1.5 to 17.5 years (median 8.8 years) after presentation. RESULTS: The cause of the steroid responsive chronic meningitis was found during follow up in two of the 17 patients: Wegener's granulomatosis and multiple sclerosis in one patient each. A cause was not found in the other 15 patients. Seven of these patients eventually recovered and corticosteroids were withdrawn after six weeks to six years without a recurrence of symptoms. Four patients improved transiently, but died six months to 26 years after starting treatment; in two, steroids were withdrawn a few weeks before death. Four patients had active chronic meningitis and reduction in the dose of corticosteroids was associated with a recurrence of symptoms. Leptomeningeal and brain biopsy in eight patients showed non-specific abnormalities which were not helpful in the diagnosis. CONCLUSIONS: A subgroup of patients with idiopathic chronic lymphocytic meningitis responds to corticosteroids. Leptomeningeal biopsy and long-term follow up seldom identify the underlying cause in these patients. Steroid treatment must be undertaken with caution, even after infective causes of chronic meningitis have been excluded.

Adult↗
PubMed1998

Changes in subarachnoid hemorrhage mortality, incidence, and case fatality in New Zealand between 1981-1983 and 1991-1993.

BACKGROUND AND PURPOSE: As with total stroke, mortality rates from subarachnoid hemorrhage (SAH) have declined in New Zealand since the mid-1970s. Data from the Auckland Region Stroke studies allow an understanding of reasons for the change, as SAH incidence and 28-day case fatality rates were measured as part of population-based stroke registers. METHODS: National death registrations were used to describe the trends in mortality rates from SAH (International Classification of Diseases [ICD] code 430) among men and women in New Zealand. Changes in incidence and case fatality rates were determined from 2 large-scale population-based stroke registries carried out in 1981-1983 and 10 years later in Auckland. Similar methodology and case ascertainment techniques were used in both studies. RESULTS: The mortality rates from SAH declined in both men and women after the mid-1970s. The mortality rate remained higher among women than men. The incidence of SAH was lower in 1991-1993 (11.3 per 100,000) compared with 1981-1983 (14.6 per 100,000). In the younger age groups, the decrease was mostly due to a lower incidence among men, whereas in the older age groups women older than 65 years had a lower incidence. There was no consistent change in case fatality rates between the 2 periods in either men or women. CONCLUSIONS: Mortality rates from SAH have decreased in both men and women. This decrease may be explained by a decrease in the incidence of SAH, because case fatality rates showed no change.

Adolescent↗
PubMed1997

Early management and outcome of acute stroke in Auckland.

BACKGROUND: Studies of acute stroke management in stroke units and tertiary referral hospitals may not accurately reflect practice within the population. Reliable information on the management of stroke within a population is sparse. AIMS: To compare clinical practice in acute stroke management in Auckland with guidelines for the management and treatment of stroke in other countries; to provide a baseline measure against which future changes in management can be evaluated. METHODS: All new stroke events in Auckland residents in 12 months were traced through multiple case finding sources. For each patient, a record of investigations and treatment during the first week of hospital admission was kept. RESULTS: One thousand eight hundred and three stroke events (including subarachnoid haemorrhages) occurred in 1761 patients in one year. Twenty-seven per cent of all events were managed outside hospital and 73% of the stroke events were treated in an acute hospital. Of the 1242 stroke events admitted to an acute hospital in the first week, only 6% were managed on the neurology and neurosurgery ward, 83% were managed by a general physician or geriatrician and 42% had computed tomography (CT). Of 376 validated ischaemic strokes, 44% were treated with aspirin and 12% with intravenous heparin. Of the 690 unspecified strokes (no CT or autopsy), 38% received aspirin and 0.5% heparin. The 28 day in-hospital case fatality for all stroke events admitted to an acute hospital during the first week was 25%. CONCLUSIONS: In Auckland, management of acute stroke differed from clinical guidelines in the high proportion of patients managed in the community, the low rate of neurological consultation, and the low frequency of CT scanning. Despite these deficiencies in management, the 28 day hospital case fatality in Auckland was similar to other comparable studies which had a high proportion of cases evaluated by a neurologist and CT.

Adolescent↗