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Biomedical subjects

P Macpherson

Publications and source records attributed to P Macpherson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Fibrous dysplasia of the skull: disease activity in relation to age.

Eighteen of 19 patients with histologically confirmed fibrous dysplasia of the skull seen at the Institute of Neurological Sciences, Glasgow, in the past 20 years have been reviewed and recent radiographs obtained. Sex, age at presentation and at follow-up were recorded, in addition to the site, type and extent of cranial involvement. The findings have been related to disease activity and progression. In comparison with other reports we found the proportion of patients with activity in adulthood to be relatively high (37%). Overall, there was an equal sex distribution, but of seven patients presenting as adults, six were female as were six of seven patients with evidence of disease activity in adulthood.

Adolescent↗
PubMed1990

Coregulation of the human O6-methylguanine-DNA methyltransferase with two unrelated genes that are closely linked.

The loss of expression of the enzyme O6-methylguanine-DNA methyltransferase (the Mex- phenotype), which often results from cellular transformation, confers hypersensitivity to alkylating agents. We have observed two unrelated examples in which human cell lines have undergone a spontaneous alteration in their Mex phenotype during propagation in vitro. The change was reversible and was not the result of mutation. In both cases a loss of methyltransferase expression was accompanied by a simultaneous loss of expression of two metabolically unrelated enzymes: thymidine kinase and galactokinase. "Reversion" to methyltransferase expression was accompanied by simultaneous reexpression of both kinase activities. A third example of this coordinate gene regulation was seen with the Burkitt's lymphoma cell line Raji which expresses methyltransferase, thymidine kinase, and galactokinase at high levels. A thymidine kinase- Raji cell line derived by bromodeoxyuridine mutagenesis that is also Mex- was found to be galactokinase-. It appears that methyltransferase expression may in some instances be coordinately regulated with the tk and glk loci which are closely linked on human chromosome 17.

Adenosine Triphosphatases↗
PubMed1990

Gadolinium-DTPA enhanced magnetic resonance imaging in human head injury.

We used low field magnetic resonance imaging and Gadolinium-DTPA to study 10 recently head injured patients. On the pre-contrast images we identified 36 abnormalities in 9 of the 10 patients. After contrast enhancement was seen in 9 of these lesions in 3 patients imaged 5-6 days after injury. Altered blood brain barrier permeability to gadolinium was not seen in 6 patients studied within 4 days of trauma. We did not identify any lesions with gadolinium that were not present on the pre-contrast images. We do not think that the routine use of contrast in head injury is justified since clinically important lesions will be present on routine sequences. However the use of gadolinium may provide information about the nature and timing of the underlying pathophysiological changes. In human head injury cytotoxic oedema occurs early and vasogenic oedema does not occur until 5-6 days after injury.

Adult↗
PubMed1990

CT scanning and surgical treatment of 1551 head injured patients admitted to a regional neurosurgical unit.

Computed tomographic (CT) scans of 1551 recently head injured patients transferred to a regional neurosurgical unit (NSU) were reviewed. Some 90% of first scans were done outside normal working hours. More than a third of first scans were normal including a fifth of the patients who were in deep coma. Haematoma was found in 50%, contusion 28%, shearing injuries 13% and general swelling in 9%. In 22% the first scan led to urgent surgical evacuation of an intracranial haematoma. More than one scan was done in 41% of patients and more than two in 10%, making 2608 scans in all. Repeat scans were more often done when the first scan was abnormal. In only five of 554 patients (1%) whose first scan had been normal were contusions or haematomas seen on subsequent scans, and in none of these was surgery required. Of 997 patients whose first scan had been abnormal a new lesion (contusion, haematoma and/or infarction) was seen on a subsequent scan in 103 cases (10%). Surgery was required (for the first time), in 57 patients whose abnormal first scans had not indicated the necessity for surgery at that time. The implications of these and other findings for the scanning of recently head injured patients in general hospitals, as scanners become more widely available, are discussed in our accompanying paper on p. 88.

Brain Concussion↗
PubMed1990

Implications of scanning recently head injured patients in general hospitals.

Increasing availability of computed tomography (CT) in general hospitals makes it appropriate to scan certain categories of acutely head injured patients in these hospitals. Policies should be devised locally indicating which types of patient should be scanned there, and what circumstances require transfer to the neurosurgical unit (NSU). Consideration must be given to the implications for training, staffing and other CT scanner commitments. The paper discusses these issues in the light of a study of the CT scans and surgical treatment of 1551 patients admitted to an NSU over a five year period, and provides models for discussion.

Brain Injuries↗
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↗
PubMed1990

Cerebral radiation necrosis complicating stereotactic radiosurgery for arteriovenous malformation.

A patient presented with symptoms and signs of raised intracranial pressure and increasing focal deficit 13 months after stereotactic radiosurgical treatment of an arteriovenous malformation (AVM). Computed Tomography (CT) showed a mass lesion at the site of the previous abnormality typical of radiation necrosis, but with features identical to those of a malignant neoplasm. Biopsy confirmed cerebral radiation necrosis. The radiation dose was 25 Gray to the periphery of two overlapping 14 mm collimator fields, delivered in a single dose. Treatment with steroids led to improvement in the symptoms and signs of raised intracranial pressure, but not the focal deficit. Radiation necrosis is a consequence of the large doses required to obliterate AVMs and is a limiting factor in their treatment. It is important for clinicians referring patients for stereotactic radiosurgery to be aware of this complication, and to be able to recognise and treat it.

Adult↗
PubMed1990

Non-invasive radiological investigation for oculomotor palsy.

An application of computed tomography (CT) is described in which multiplanar high resolution images of the terminal carotid and basilar arteries are obtained. This has been applied in a series of 32 patients with IIIrd nerve palsy in whom the underlying pathology was thought to be a posterior communicating artery aneurysm. The results of the CT were compared with conventional angiography. Seventeen aneurysms were detected in 13 patients by CT and all were confirmed by angiography. Vessels considered to be normal on CT were confirmed to be normal by angiography. This CT technique is a simple non invasive first line investigation for IIIrd nerve palsy with the ability to exclude or predict an aneurysm.

Adolescent↗
PubMed1989

Comparison of magnetic resonance imaging and computed tomography in suspected lesions in the posterior cranial fossa.

OBJECTIVE: To compare computed tomography and magnetic resonance imaging in investigating patients suspected of having a lesion in the posterior cranial fossa. DESIGN: Randomised allocation of newly referred patients to undergo either computed tomography or magnetic resonance imaging; the alternative investigation was performed subsequently only in response to a request from the referring doctor. SETTING: A regional neuroscience centre serving 2.7 million. PATIENTS: 1020 Patients recruited between April 1986 and December 1987, all suspected by neurologists, neurosurgeons, or other specialists of having a lesion in the posterior fossa and referred for neuroradiology. The groups allocated to undergo computed tomography or magnetic resonance imaging were well matched in distributions of age, sex, specialty of referring doctor, investigation as an inpatient or an outpatient, suspected site of lesion, and presumed disease process; the referring doctor's confidence in the initial clinical diagnosis was also similar. INTERVENTIONS: After the patients had been imaged by either computed tomography or magnetic resonance (using a resistive magnet of 0.15 T) doctors were given the radiologist's report and a form asking if they considered that imaging with the alternative technique was necessary and, if so, why; it also asked for their current diagnoses and their confidence in them. MAIN OUTCOME MEASURES: Number of requests for the alternative method of investigation. Assessment of characteristics of patients for whom further imaging was requested and lesions that were suspected initially and how the results of the second imaging affected clinicians' and radiologists' opinions. RESULTS: Ninety three of the 501 patients who initially underwent computed tomography were referred subsequently for magnetic resonance imaging whereas only 28 of the 493 patients who initially underwent magnetic resonance imaging were referred subsequently for computed tomography. Over the study the number of patients referred for magnetic resonance imaging after computed tomography increased but requests for computed tomography after magnetic resonance imaging decreased. The reason that clinicians gave most commonly for requesting further imaging by magnetic resonance was that the results of the initial computed tomography failed to exclude their suspected diagnosis (64 patients). This was less common in patients investigated initially by magnetic resonance imaging (eight patients). Management of 28 patients (6%) imaged initially with computed tomography and 12 patients (2%) imaged initially with magnetic resonance was changed on the basis of the results of the alternative imaging. CONCLUSIONS: Magnetic resonance imaging provided doctors with the information required to manage patients suspected of having a lesion in the posterior fossa more commonly than computed tomography, but computed tomography alone was satisfactory in 80% of cases...

Brain Diseases↗
PubMed1989

Pituitary microadenomas. Does Gadolinium enhance their demonstration?

Ten patients with biochemical evidence of a hormonally active pituitary adenoma were examined by dynamic contrast enhanced computed tomography (CT) and then by pre and post Gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging (MRI). Excluding one false positive case, CT and unenhanced MRI were comparable in the detection of microadenoma. Post Gd-DTPA examination gave more clear evidence of the actual adenoma in two patients and aided in the demonstration of a third. However, in two others all imaging techniques failed to demonstrate the microadenoma subsequently found at surgery. On the post enhancement MRI it was easier to assess the relationship of a tumour to the cavernous sinus and to visualise the relationships of the parasellar carotid arteries.

Adenoma↗
PubMed1989

Can computed tomography be relied upon to detect skull fractures?

Skull fractures were detected on plain films in 63 of 100 consecutive head-injured patients admitted to a neurosurgical unit. On routine computed tomographic (CT) lateral scout films, only 58% of lateral fractures were detected and there was a false positive rate of 12%. None of the anterior or posterior fractures was seen. On the routine axial CT cuts only 22.5% of fractures were detected. When examined at bone window settings, 76% of vertical and 37.5% of oblique linear fractures were detected but none of the horizontal fractures. All comminuted and depressed fractures were demonstrated when the axial cuts were examined at bone window settings and in all but one case by the scanogram and at routine brain window settings. Basal fracture extent was better shown by axial CT than on plain films, especially at bone window settings. Recommendations are made regarding the use of CT in the detection of skull fractures.

Humans↗
PubMed1989

Delayed deterioration in patients with traumatic frontal contusions.

The clinical course of 18 head injured patients in whom CT had shown frontal contusions without diffuse brain injury or intracranial haematoma was reviewed. All 10 patients with unilateral frontal contusion made a good recovery. Only two of five patients with limited bilateral frontal contusions made a good recovery. Two of three patients with extensive bilateral frontal contusions deteriorated more than 24 hours after injury, and one died. Delayed deterioration is an important complication of extensive traumatic bifrontal contusions.

Adolescent↗
PubMed1989

Diagnosis and management of delayed traumatic intracerebral haematomas.

In a retrospective study of 888 consecutive patients with traumatic intracranial haematomas, we identified 23 (2.6%) who had developed a delayed intracerebral haematoma after admission to hospital. The initial CT scan within 48 h of injury had been abnormal in all 23 cases; a haematoma had been evacuated in eight (35%) and intracranial pressure (ICP) had been monitored in 14 (61%). A delayed intracerebral haematoma had been diagnosed by repeat CT scan between 4 h and 10 days later, and nine of these had been evacuated on clinical grounds. Patients with persistently elevated ICP were rescanned more quickly than those who deteriorated clinically or failed to improve. Seven patients (30%) died, and the main cause of death was severe primary brain damage. Overall outcome was better in this series than in other reported series of delayed haematomas. We conclude that delayed haematomas occur only when the initial CT scan has been abnormal, and that clinically important ones are uncommon. ICP monitoring offers earlier diagnosis, but it remains to be established that this affects outcome.

Adult↗
PubMed1988

CT demonstration of a 5th ventricle--a finding to KO boxers?

The reported prevalence of 5th ventricles based on air studies varies from 1-12% and ranges up to 60% as an autopsy finding. The prevalence of what is usually an incidental anomaly has not been determined by computed tomography (CT). 5th ventricles are however known to be more common in brain damaged boxers and with the introduction of compulsory CT scanning for certain boxers it is necessary to know what significance to attach to the finding of a cavum in these individuals. To ascertain the prevalence and morphology of 5th ventricles as detected by CT in the population, a thousand consecutive scans were analysed for the presence or absence of a 5th ventricle and other associated midline developmental abnormalities and correlations made with any pathology found. A 5th ventricle was present in 5.5% of the group and in most cases was less than 3 mm wide. An apparent association with other pathology was found only in patients under the age of 15. A 6th ventricle was found in 0.5% while a cavum velum interpositum was present in 9.5%. The isolated finding of a small 5th ventricle on the CT scan of a young active boxer almost certainly represents a persistent congenital anomaly of no significance.

Adolescent↗
PubMed1988

Magnetic resonance imaging of acute subarachnoid hemorrhage.

The feasibility, safety, and diagnostic value of magnetic resonance (MR) imaging versus computerized tomography (CT) scanning were compared in 30 patients with clinical evidence of subarachnoid hemorrhage. Subarachnoid blood was identified more often and more information was available about the site and source of the hemorrhage on MR imaging than on CT. Magnetic resonance imaging could be used safely both before and after the operation, provided that nonferromagnetic clips were used and that comprehensive monitoring and cardiorespiratory support were available. Postoperative studies showed that artifacts from metallic implants and from patient movement caused less image degradation on MR images than on CT scans.

Acute Disease↗
PubMed1987

Invasive v non-invasive assessment of the carotid arteries prior to trans-sphenoidal surgery.

Imaging studies in 47 patients who were to undergo trans-sphenoidal surgery were analysed with reference to the vascular structures in the parasellar region. The results of cavernous sinography, dynamic contrast enhanced Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) showed good correlation with each other and with the appearances found at operation. CT and MRI, both non-invasive investigations, are therefore reliable preliminary screening methods for identifying the small proportion of patients on whom other imaging techniques need to be performed.

Carotid Artery, Internal↗