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Biomedical subjects

Andrew W McEvoy

Publications and source records attributed to Andrew W McEvoy.

6 recordsLinked to original sources
PubMed2006

Tonic GABA(A) receptor-mediated currents in human brain.

GABA(A) receptors can mediate both phasic (synaptic) and tonic (extrasynaptic) forms of inhibition. It has been proposed that tonic inhibition plays a critical part in controlling neuronal and network excitability. Although tonic GABA(A) receptor-mediated currents have been well characterized in rodents, their existence in human tissue has yet to be demonstrated. Here we show that tonic currents can be recorded from human tissue obtained from patients undergoing temporal lobectomies. Tonic GABA(A) receptor-mediated currents were present in pyramidal cells and interneurons in layer V-VI of temporal neocortex and granule cells in the dentate gyrus. These tonic currents have cell type-specific pharmacologies, opening up the possibility of targeted therapeutics.

Animals↗
PubMed2004

A comparison of risk factors in the etiology of mirror and nonmirror multiple intracranial aneurysms.

BACKGROUND: Pure mirror intracranial aneurysms represent a subgroup of multiple aneurysm patients where a congenital predisposition may play a major etiologic role. The aim of this study was to compare the pattern of prevalence of known risk factors for aneurysm disease between pure mirror and pure nonmirror multiple aneurysm populations. METHODS: Clinical records of all patients with multiple intracranial aneurysms admitted to our institution between January 1985 and September 2001 were reviewed. Age, localization of aneurysms, gender, and history of cigarette smoking or hypertension were noted and compared using Fisher's exact test and logistic regression analysis. RESULTS: There were 33 patients presented with pure mirror aneurysms (MirAn) and 49 with nonmirror multiple aneurysms (nMirAn). Average age of rupture occurred in the 5th decade in both groups. Female:male ratio was 3.1:1 in MirAn; 2.1:1 in nMirAn. In MirAn patients younger than 40 years it was 1:1. Smoking was the most prevalent risk factor in nMirAn (59.2%). In MirAn this was true only for patients in the 5th or 6th decades (65%), and hypertension was the most prevalent risk factor over that age (62.5%). A total of 80% of mirror aneurysm patients under 40 years had no known extrinsic risk factor, compared with 20% in nMirAn (p < 0.05). CONCLUSIONS: Differences in the relative prevalence of risk factors between both groups supports the hypothesis of a different etiologic process occurring in mirror aneurysm disease. Early rupture in patients with no extrinsic risk factors lends support to the role of a congenital predisposition over degenerative causes in these patients.

Adult↗
PubMed2003

A prospective study of the requirement for and the provision of epilepsy surgery in the United Kingdom.

PURPOSE: Of the 30,000 persons in whom epilepsy develops annually in the United Kingdom, in approximately 6000 (20%), intractability develops. Some of these patients will be appropriate for epilepsy surgery. We aimed to estimate the number of patients who should be considered surgical candidates, by extrapolation from a population-based study of prognosis and the number who are receiving epilepsy surgery, by a survey of U.K. neurosurgeons. METHODS: We identified the number of patients who may eventually require surgery from a prospective cohort of patients with newly diagnosed epilepsy. We identified all U.K. neurosurgeons who had performed any epilepsy surgery in the past year. Each identified surgeon prospectively recorded the number and types of operations carried out for 6 months. RESULTS: Of newly diagnosed patients each year, 450 (1.5%) may eventually require surgery. Thirty-two respondents (22% of all U.K. neurosurgeons) reported that they performed epilepsy surgery. The 211 operations were carried out in the 6 months surveyed (422 operations annually or 13 per surgeon per year). Temporal lobe resection (77%) was the most common procedure. CONCLUSIONS: Based on a prevalence of 5/1,000 persons with epilepsy, < or =4,500 patients in the U.K. require epilepsy surgery. Every year, 450 patients with newly diagnosed epilepsy who may eventually require surgery are added to this "surgical pool." At the current annual rate of operations, a large number of refractory patients remain untreated. This is probably partly because many patients are not referred for specialist care and therefore remain underinvestigated.

Adolescent↗
PubMed2002

Metastatic choroid plexus papilloma: a case report.

Choroid plexus papillomas (CPPs) are generally regarded as benign tumours, with a favourable long-term prognosis. Complete resection should result in cure. We present a case of diffuse craniospinal seeding from an apparently completely resected fourth ventricular primary tumour. A 51-year-old male is discussed, who presented 5 years following complete resection of a CPP from the fourth ventricle, with a progressive history of left sided tinnitus, hearing loss, impotence and recent low back pain. Imaging demonstrated multiple craniospinal lesions explaining his symptomatology. Differential diagnosis lay between long standing CSF seeding, malignant transformation in the primary tumour, or metastatic spread from an undefined source. He underwent whole body FDG-PET scan which demonstrated a single metabolically active lesion in the sacral canal. A subtotal excision biopsy of this sacral lesion was performed which was indistinguishable histologically from the primary tumour resected from the fourth ventricle. Histological and functional imaging characteristics of the primary tumour have been unhelpful in predicting its subsequent behaviour. The present case illustrates the extremely rare consequences of metastases from this histologically benign tumour and adds to the literature on metastatic craniospinal disease.

Cerebral Ventricles↗
PubMed2002

Intractable epilepsy and olfactory bulb hamartoma. A case report.

The objective of this case report is to demonstrate that a benign tumour arising solely from the olfactory bulb can act as a primary epileptic focus and to illustrate the difficulty in making a preoperative diagnosis of pathological lesions in this area. The case of a 29-year-old male with intractable epilepsy is presented. Radiological imaging demonstrated a conspicuous, calcified lesion in the mesial inferior frontal lobe. Electroclinical findings confirmed this to be the epileptogenic zone. Surgery and subsequent histology surprisingly revealed this focal lesion to be a benign hamartoma arising solely from the olfactory bulb. Resection resulted in seizure resolution. Tumours of the olfactory apparatus are extremely rare, but can present with epilepsy.

Adult↗