Biomedical subjects
Publications and source records attributed to D B Clarke.
The authors describe a technique of stereotactic transtentorial hiatus ventriculoperitoneal shunting for the treatment of the sequestered fourth ventricle, used successfully in the care of four patients. They recommend it as a safe, effective treatment of patients suffering from an isolated fourth ventricle.
Using quantitative anatomical techniques, we show that after intraorbital optic nerve transection in adult rats, virtually all retinal ganglion cells (RGCs) survive for 5 d and then die abruptly in large numbers, reducing the RGC population to approximately 50% of normal by day 7 and to less than 10% on day 14. During this period of rapid cell loss, some RGCs show cytochemical alterations indicative of apoptosis ("programmed cell death"), a change not previously categorized after axotomy in adult mammals. With intracranial lesions 8-9 mm from the eye, the onset of cell death is delayed until day 8 and is greater with cut than crush. The demonstration that axotomy results in apoptosis, the long interval between axonal injury and RGC death, and the different time of onset of the massive RGC loss with optic nerve lesions near or far from the eye suggest that axonal interruption triggers a cascade of molecular events whose outcome may be critically dependent on the availability of neuronal trophic support from endogenous or exogenous sources. The role of such molecules in RGC survival and the reversible nature of these injury-induced changes is underscored by the temporary rescue of most RGCs by a single intravitreal injection of brain-derived neurotrophic factor during the first 5 d after intraorbital optic nerve injury (Mansour-Robaey et al., 1994). The delayed pattern of RGC loss observed in the present experiments likely explains such a critical period for effective neurotrophin administration.
Spontaneous spinal epidural hematomas are well-recognized but rare entities. The standard treatment for these hematomas has been prompt surgical evacuation. The authors report a case of a 76-year-old man who precipitously became paraplegic secondary to a spontaneous spinal epidural hematoma and then experienced the complete resolution of his neurological deficit and the hematoma. We conclude that conservative (nonoperative) management of spontaneous spinal epidural hematomas may be appropriate in those instances in which there is early and sustained neurological recovery confirmed by radiological resolution of the lesion.
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Two patients with protein C deficiency developed symptomatic pulmonary hypertension secondary to chronic pulmonary embolism. They were successfully treated by thromboendarterectomy.
We report the first recorded case of a colo-pericardial fistula and of a colo-caval fistula following interposition of colon after resection of the oesophagus.
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Over a 7-year period, sternal wound dehiscences occurring in 26 patients were treated by a modified wire closure technique. This method is described and the results presented.
A 67 year old woman with a permanent pacemaker was admitted with pulmonary oedema and mitral valve incompetence two months after a myocardial infarction. Echocardiograms showed good left ventricular function and a large coil of apparent thrombus in the right atrium prolapsing into the right ventricle. Intermittent loss of pacemaker sensing and capture was noticed on admission and probably caused the supraventricular tachycardia and ventricular fibrillation that occurred before an exploratory bypass operation. At operation rupture of the papillary muscle was found and the mitral valve was replaced. A large piece of thrombus was retrieved from the right pulmonary artery. The right heart contained no clot and the pacemaker wire was not displaced. It is envisaged that the strand of venous thrombus was caught in the permanent pacing wire at the tricuspid valve level resulting in an unusual case of pacemaker malfunction. The eventual poor outcome was almost certainly influenced by the arrhythmias and pulmonary embolism caused by the clot and might have been avoided by early operation.
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For the past 25 years an emergency pulmonary embolectomy service has been offered to the hospitals serving a conurbation of 1.5 million. Fifty-five of these procedures have been performed during a short period of normothermic circulatory standstill produced by clamping the superior and inferior venae cavae. Of 36 patients who underwent pulmonary embolectomy without an episode of asystole or ventricular fibrillation, 35 survived the operation (97.2%). However, there were seven deaths during the postoperative period, three related to pulmonary embolism and four to other causes (mortality 20%). Conversely, in a group of 19 patients who had an episode of cardiac arrest, 14 died during or after the operation of pulmonary embolism and two of unrelated causes (mortality 73.7%). In properly selected patients this technique achieves a satisfactory measure of success. It can be used in hospitals that do not have cardiac surgical facilities and, because of its simplicity, it can be performed during the early period after pulmonary embolism when the risk of death is greatest.
Clinical experience with the Omniscience prosthesis from two regional cardiac units in England is presented. Actuarial analysis suggests a prohibitive incidence of prosthetic thrombosis of the mitral valve, this complication occurring in 14 of a total of 96 (15%) patients studied over a mean period of approximately 1 1/2 years. Aortic valve implantations were frequently complicated by prosthetic dehiscence, which occurred in nine of a total of 88 (10%) patients who received this valve. Our results with this prosthesis contrasts markedly with our favorable experience with other types of prostheses and lead us to question the suitability of the Omniscience valve for further clinical use.
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Forty-two patients who had sustained massive pulmonary embolism were treated by emergency pulmonary embolectomy using normothermic venous inflow occlusion circulatory arrest. Of 26 patients who had not had cardiac arrest before surgery 25 survived the operation, but 7 later died from various causes. Only 1 of 16 patients who had sustained cardiac arrest survived. In all, 19 patients (45.2%) left hospital alive. This simple and widely applicable technique has enabled an emergency pulmonary embolectomy service to be offered to all the hospitals in a metropolitan area.
A method is presented for the endoscopic intubation of malignant tumors of the trachea and main bronchi with a Souttar tube. This is appropriate when urgent relief of respiratory obstruction is necessary and when the tumor is unsuitable for resection. Eight patients have been so treated, with relief of symptoms for up to 70 weeks in seven. The method failed in one patient. There were no operative deaths.
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Explore the source record for details and available documents.