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Biomedical subjects

A P McGeorge

Publications and source records attributed to A P McGeorge.

14 recordsLinked to original sources
PubMed1990

Tc99m HM-PAO single photon emission computed tomography in temporal lobe epilepsy.

We present the results of single photon emission computed tomography (SPECT) in 40 patients with temporal lobe epilepsy and normal computed transmission tomography (CT). Abnormalities of regional cerebral blood flow were found in 26 patients. There was focal hypoperfusion alone in 14, focal hyperperfusion alone in 6, and both types of abnormality in 6. In 4 patients there were bilateral abnormalities. Repeat SPECT showed persistence of interictal hyperperfusion in 5/12 patients. There were no significant correlations between SPECT findings and clinical parameters, and no relation between the persistence of interictal hyperperfusion and time since last seizure or seizure frequency. Where SPECT and multiple surface EEG recordings were both lateralising, agreement between them was good. The results of this study support the usefulness of HMPAO SPECT in detecting lateralising abnormalities in temporal lobe epilepsy. Interictal hyperperfusion may be commoner than previous publications suggest, and may be persistent in some cases.

Adolescent↗
PubMed1990

CT, MR and SPECT imaging in temporal lobe epilepsy.

Cranial computed tomography (CT) with modified temporal lobe technique, 0.15T magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) were carried out on 30 patients with intractable temporal lobe epilepsy. Lateralising abnormalities were detected in 21/30 patients overall. Specific lesions were detected by CT in one patient and by MRI in seven patients (in one case bilateral). In addition CT detected asymmetry of the sylvian fissures or temporal horns in 10 patients, and MRI in eight patients. SPECT detected lateralising abnormalities in 19 patients (in five cases bilateral). It is concluded that low field MRI is superior to modified CT in demonstrating subtle structural lesions of the temporal lobe. Functional scanning with SPECT supports the evidence of origin of an epileptic focus in a substantial proportion of cases and may improve the selection of patients for surgery.

Adolescent↗
PubMed1979

Effects of increasing arterial pressure on cerebral blood flow in the baboon: influence of the sympathetic nervous system.

The influence of stimulation of the cervical sympathetic chain on the response of cerebral blood flow to hypertension induced by the intravenous infusion of angiotensin was studied in anaesthetised baboons. Cerebral blood flow was measured by the intracarotid 133Xenon injection technique. Possible lesions of the blood-brain barrier were studied by injecting Evans blue towards the end of the experiment and ischaemic brain damage was assessed following perfusion fixation. In a control group of five baboons blood flow increased by 53 +/- 9% (mean +/- S.E.) from the base line values in the arterial pressure range 130-159 mm Hg. In four baboons subjected to unilateral sympathetic stimulation flow increased by 16 +/- 4% in the same pressure range. In three baboons subjected to bilateral sympathetic stimulation there were no significant increases in flow until the arterial pressure had increased above 159 mm Hg. Disruption of the blood-brain barrier in the parietooccipital regions was only seen in the control animals but not in the stimulated baboons. Ischaemic brain damage was not observed with the exception of one small lesion in a single stimulated baboon. These findings provide strong support for the observations of Bill and Linder (1976) that activation of the cervical sympathetic can modify the level at which breakthrough of cerebral blood flow occurs in association with systemic hypertension.

Angiotensin II↗
PubMed1979

Electroencephalography--use and abuse.

The E.E.G. is a reliable, safe and readily available test, especially for screening purposes in hospitals where brain scan and EMI scan facilities are not available. Its reliability becomes less when unreasonable demands are made regarding the nature of pathology, precise localisation and extent of a lesion. A detailed clinical history is mandatory for the neurophysiologist to make a useful interpretation of the E.E.G.

Adolescent↗
PubMed1978

Anaesthesia for studies of the cerebral circulation: a comparison of phencyclidine and althesin in the baboon.

The effects of phencyclidine on cerebral blood flow, cerebral metabolic rate for oxygen and carbon dioxide reactivity were compared with those of Althesin in six baboons. Under similar and stable levels (Stage 1) of electroencephalographic activity cerebral blood flow and the cerebral metabolic rate for oxygen were significantly less during the infusion of Althesin when compared with the values obtained during the infusion of phencyclidine. Reactivity to carbon dioxide was present and similar during the infusion of either drug.

Alfaxalone Alfadolone Mixture↗
PubMed1978

Electroencephalography and computerised tomography in vascular and non-vascular dementia in old age.

Nine normal elderly subjects and 81 patients with dementia have been studied by computerised tomography (CT) and electroencephalography (EEG). There was a broad relationship between slowing of the basic frequency of the EEG and the severity of mental impairment. Localised slow-wave activity was found in 19% of those with non-vascular dementia and 72% of those with dementia of vascular origin. The mean size of the ventricles, as determined from CT scans, was larger in the vascular than in the non-vascular group. Within the vascular group it was larger in those without than in those with visible infarcts. There was no relationship in either group between ventricular size and dominant EEG frequency.

Aged↗
PubMed1976

Transfer-factor therapy in multiple sclerosis.

The effect of transfer factor prepared from relatives of patients with multiple sclerosis (M.S.) and from unrelated donors on the clinical course of M.S. has been studied in fifteen male and fifteen female patients. Some patients were given transfer factor and some placebo (physiological saline). Results of three independent clinical examinations by different neurologists and subjective assessments by the patients showed no difference between those given transfer factor and those given placebo.

Adolescent↗
PubMedDate not supplied

Effects of hemorrhagic hypotension on the cerebral circulation. II. Electrocortical function.

The effects of graded hemorrhagic hypotension on electrocortical function was investigated in 12 cats anesthetized with alpha-chloralose. Cerebral function was assessed both in terms of spontaneous activity (EEG) and the somatosensory evoked response. No significant changes in the EEG trace or in the amplitude of the positive/negative waves of the primary evoked response were observed at mean arterial pressures of between 120 mm Hg and 40 mm Hg. At levels of systemic arterial pressure of less than 40 mm Hg cortical rhythms became slower as pressure was decreased and an isoelectric EEG was recorded in the pressure range 10--30 mm Hg. The earliest sign of any change in the amplitude of the primary evoked responses was observed at arterial pressures of approximately 35--40 mm Hg. Below this value the amplitude decreased with decreasing systemic pressure and became zero in the pressure range 15--25 mm Hg.

Animals↗