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Biomedical subjects

W C Clark

Publications and source records attributed to W C Clark.

At least 55 records · Page 3Linked to original sources

Reformatted sagittal images in the differential diagnosis of meningiomas and pituitary adenomas with suprasellar extension.

Approximately 3 to 4 times a year, a tumor with suprasellar extension escapes classification on high resolution coronal and transaxial computed tomography. When arteriography failed to determine the diagnosis, the differential choices were usually meningioma or pituitary adenoma. The authors report the use of sagittal reformatted images in this differential diagnosis and conclude that these images may aid in the distinction between pituitary tumors with suprasellar extension and meningiomas located in this area.

Adenoma↗

Mycobacterium tuberculosis meningitis: a report of twelve cases and a literature review.

Twelve recent cases of Mycobacterium tuberculosis meningitis were presented, and the literature was reviewed. There are no particularly new or unique therapies or approaches to the management of this most serious disease. The major obstacle to successful diagnosis and treatment of tuberculous meningitis continues to be a lack of clinical suspicion of its presence. As illustrated in the cases presented, it has been our experience that patients already moribund or nonresponsive do not respond, regardless of the intervention undertaken. The most sensitive and economical method of detecting M. tuberculosis in the CSF may be LPA. However, this has not yet been widely validated or accepted. Larger volumes of CSF should be sent to the laboratory for testing and centifuged to about 5x concentrations before both acid-fast bacilli staining and culture are attempted. If tuberculous meningitis is suspected, three-drug therapy can be started immediately without jeopardizing subsequent culture confirmation of the presence of the TB bacillus. In addition, these patients must be followed closely to detect hydrocephalus at the earliest possible moment. When patients fail to respond to appropriate antituberculosis and pressure-reducing therapy, hydrocephalus should be actively sought by either CT or radioisotope cisternography. Although the decision to proceed to ventricular drainage or shunting must be individually made in adult patients with infection-related hydrocephalus, we agree with others that surgical intervention should be considered early and should be performed if the level of consciousness deteriorates, intracranial pressure increases, or ventricular enlargement or enhancing basal exudates are identified on CT.

Adult↗

Analysis of 76 civilian craniocerebral gunshot wounds.

A retrospective analysis of 76 civilian craniocerebral gunshot wounds treated over a 20-month period is presented. The authors report a 62% mortality rate and conclude that the admission Glasgow Coma Scale (GCS) score is a valuable prognosticator of outcome. Other important findings were: patients with a GCS score of 3 invariably died, with or without surgical intervention; and the presence of intracranial hematomas, ventricular injury, or bihemispheric wounding was associated with a poor outcome. Standardized methods of data reporting should be adopted in order to allow multicenter trials or comparisons that might lead to management practices that could improve results.

Adolescent↗

Comparing ambulatory care practices of primary care and traditional medicine residents.

Although special residency programs preparing internists for primary care have been in existence for a decade, little is known about whether these tracks have achieved their goals. As part of a multicenter evaluation of ambulatory care at four university hospitals, 1,040 patient care encounters were reviewed for 16 primary-care and 41 traditional medicine residents. Using a chart-based audit, the authors examined 16 discrete items of patient care to assess resident management in the following areas: screening for colorectal carcinoma, management of hypertension, benzodiazepine drug prescribing, and management of chronic lung disease. Their hypothesis that primary care residents would score higher than traditional medicine residents in the areas of screening, prevention, and prescribing of drugs was not supported. There was no association between type of training and performance of a task with the following exception: second-year primary care residents screened for colorectal carcinoma in 86% (126) of patients whose charts were audited, while second-year traditional medicine residents did so in 77% (160) (P less than 0.025). This difference was not maintained when the residents were reaudited 1 year later. Both groups of residents scored high in all areas with the following exceptions: documentation of the amount of sedative dispensed and immunization of susceptible patients against pneumococcus and influenza. The ambulatory practices of both groups of residents exceeded expectations, probably because of the wider influence of primary care training.

Ambulatory Care↗

Nonsurgical management of small and intracanalicular acoustic tumors.

Although surgical removal is generally regarded as the management strategy of choice for acoustic tumors, there remains a small group of patients usually with small or intracanalicular tumors in whom nonoperative management may be a desirable alternative to operation. The authors present a series of six such cases and discuss criteria that may aid in the selection of patients suitable for initial nonoperative management.

Aged↗

Aspiration of blood from the jugular vein during intracarotid drug infusion in monkeys. Implications for extracorporeal drug removal.

Circulation of blood in the ipsilateral jugular vein through an extracorporeal circuit for drug removal during intracarotid chemotherapy has recently been reported to decrease the systemic drug exposure. The reduced systemic exposure achieved by the use of this technique should permit a several-fold increase of the intracarotid dose of chemotherapy without increasing systemic toxicity. To determine the influence of the rate of blood removal from the jugular vein on the fraction of the blood flowing through the ipsilateral internal carotid artery (ICA) collected for extracorporeal drug removal, the authors aspirated blood from the jugular bulb into an extracorporeal circuit at varying rates during a constant infusion of the indicator dye, indocyanine green (ICG), into the ICA of rhesus monkeys. The fraction of the ipsilateral carotid blood channeled into the extracorporeal circuit increased linearly with the rate of aspiration of jugular blood. This suggests that the absence of valves in the intracranial venous system should permit increasing fractions of drug removal during intracarotid infusion by increasing the rate of collection of venous blood from the ipsilateral jugular bulb. The measurement of ICG concentrations in a similar manner in patients undergoing isolated perfusion may prove to be a clinically useful method for estimating the maximum safe dose in high-dose intra-arterial chemotherapy.

Animals↗

Reduced systemic drug exposure by combining intra-arterial chemotherapy with hemoperfusion of regional venous drainage.

Four patients with malignant cerebral gliomas received 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) into the internal carotid artery (ICA) while the ipsilateral jugular drainage was pumped extracorporeally through a hemoperfusion cartridge containing a nonionic adsorbant resin. Each patient received 220 mg/sq m BCNU, infused over 45 minutes through a toposcopic catheter positioned with the tip in the ICA beyond the origin of the ophthalmic artery. Jugular blood was pumped extracorporeally at 300 ml/min through a large-bore catheter in the jugular bulb. Plasma samples were obtained for BCNU measurement at frequent intervals from the right atrium. During a separate treatment, 6 weeks before or after the hemoperfusion treatment, the same dose of BCNU was infused into the ICA and atrial samples were obtained on a similar schedule. Hemoperfusion of the jugular blood during intracarotid infusion reduced the systemic exposure by 56% to 87% and increased total body clearance of BCNU by two- to eightfold. The calculated pharmacokinetic advantage (brain:body exposure ratio) was between 21 and 55:1 when the combined treatment was used.

Adolescent↗

Presentation of central nervous system sarcoidosis as intracranial tumors.

Five cases of sarcoid presenting as an intracranial tumor are reported. In one instance, the lesion presented as a tumor in the cerebellopontine angle, a site not previously reported for the initial presentation of sarcoid isolated to the central nervous system. The role of computerized tomography, surgery, and steroid therapy is discussed. In the absence of pulmonary involvement, serum angiotensin-converting enzyme levels do not appear to be helpful in predicting steroid response.

Adolescent↗

Transtemporal approaches to the cranial cavity.

A variety of surgical approaches through the temporal bone to the cranial cavity have been described in the past. We advocate creative modifications and combinations of these approaches in order to match the specific needs of particular tumors and other types of pathology. Two case examples demonstrating the need for such modifications are presented.

Adult↗

Comparative observations on effects of carbon dioxide laser-induced peripheral nerve lesions in the rat.

This study was conducted to determine any changes that might occur in the associated cell bodies and proximal nerve stumps of sciatic nerves cut with carbon dioxide laser radiation. These changes were then compared with the changes that occur when performed with cutting cautery and scalpel. Both the proximal stump and the related dorsal root ganglia were examined with light and electron microscopy. The sciatic nerve was severed in 10 rats with the carbon dioxide laser, a cutting cautery, or a scalpel. Subsequent histopathologic examinations revealed: (a) both myelin and axonal degeneration in scalpel cuts; (b) less degeneration of proximal stump myelin in laser cuts compared with cautery cuts; and (c) no abnormalities in the associated dorsal root ganglia of nerves cut with the carbon dioxide laser. It was concluded that both the carbon dioxide laser and cutting cautery result in less damage and degeneration than a scalpel when used to sever peripheral nerves. The difference between the laser and cautery lesions was more quantitative than qualitative in that both impart thermal energy to the nerve. The carbon dioxide laser resulted in the least amount of injury.

Animals↗

Use of the carbon dioxide laser for acoustic tumor surgery.

The carbon dioxide laser has been used clinically in both otorhinolaryngology and neurological surgery for approximately 10 years. Only recently, however, have technical modifications allowed its use with the operating microscope, providing the increased precision and control necessary for intracranial surgery. This paper reports the authors' experience with the carbon dioxide laser in the removal of acoustic tumors, details the surgical technique involved, and describes the advantages that may accompany the use of the laser in the removal of these difficult lesions.

Cranial Nerve Neoplasms↗

Acoustic tumor management--combined approach surgery with CO2 laser.

Our experience in surgical treatment of 105 patients with cerebellopontine angle tumors is reported. Major emphasis is placed on a combined surgical approach and use of the CO2 laser. Our approach to diagnosis is also emphasized, as is the method we have used in compiling and collecting the data resulting from the study. Postoperative results and complications are reported and discussed.

Adult↗

Contralateral intracranial aneurysm formation as a late complication of carotid ligation.

Ligation of the carotid artery was the treatment of choice for intracranial aneurysms for many years. While the literature recognizes many complications associated with this procedure, the late occurrence of aneurysms on the side opposite the ligation is only mentioned briefly. Animal studies are reviewed in an attempt to explain a possible cause of this observed phenomenon. The 3 cases presented seem to indicate that this complication may be more common than has been previously realized.

Carotid Arteries↗