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Biomedical subjects

D McGill

Publications and source records attributed to D McGill.

13 recordsLinked to original sources

Magnetic resonance imaging-guided neurosurgery in the magnetic fringe fields: the next step in neuronavigation.

OBJECTIVE: We describe the development of an alternative approach to intraoperative magnetic resonance imaging (iMR)-guided neurosurgery and report our initial experience with 22 craniotomies and 16 brain biopsies. The advantages and disadvantages of each approach are examined. METHODS: An iMR suite houses a 0.2-T open configuration system (Siemens Medical Systems, Erlangen, Germany) and is equipped with anesthetic gases and a magnetic resonance imaging (MRI)-compatible anesthesia machine and monitor. Standard operating instruments and equipment were tested for safety and compatibility in the magnetic fringe fields surrounding the open MRI system. We then performed brain biopsies and craniotomies in the iMR suite. RESULTS: Standard operating equipment functioned properly in the 0.5- to 10-mT zone and was not affected by the magnet's attractive force. Twenty-two craniotomies and 16 brain biopsies were performed in the interventional suite, using serial intraoperative MRI guidance, without injury to patients or operating room staff. CONCLUSION: Full neurosurgical procedures may be performed in the weak fringe fields surrounding an MRI system, using standard operating room equipment. This approach to iMR-guided neurosurgery offers a significant cost advantage over retrofitting an entire operative suite with "MRI-compatible" surgical equipment. The surgeon's familiarity with standard equipment and the reliability of the equipment are additional advantages. Neurosurgery in the fringe fields allows the neurosurgeon to utilize serial MRI with a minimum of inconvenience, disruption, and change to the standard neurosurgical procedure. Serial intraoperative imaging to visualize the changes in the brain that are associated with neurosurgical intervention seems to enhance the ability to safely and effectively accomplish neurosurgical goals.

Adolescent↗

Selective neck dissections for squamous carcinoma of the upper aerodigestive tract: patterns of regional failure.

BACKGROUND: Surgeons have been using selective neck dissections in the treatment of squamous carcinoma of the upper aerodigestive tract for over 20 years. To date, no data is available that can answer the question "What are the patterns of failure in the neck following a selective neck dissection and is a selective neck dissection a reliable procedure for metastatic disease?" METHODS: To answer this question, the medical records of all patients with squamous carcinoma of the oral cavity, oropharynx, larynx, and hypopharynx treated at The University of Texas M. D. Anderson Cancer Center from January 1, 1985-December 31, 1990, with a selective neck dissection were reviewed. Five hundred seventeen neck dissections were analyzed: suprahyoid (41), supraomohyoid (284), and anterolateral (192). The end point of the study was regional failure and survival. RESULTS: Regional recurrence in patients treated with a suprahyoid dissection was 43% with pathologically positive nodes. The regional recurrence in the patients treated with a supraomohyoid neck dissection was 1.9% with pathologically negative nodes, 35.7% with path N1 without postoperative radiation therapy, and 5.6% with postoperative radiation therapy. The neck staged pathologically N2B failed with and without postoperative radiation, 8.3% and 14%, respectively. Thirteen percent of the anterior/lateral neck dissections failed regionally. If multiple pathologically positive nodes (N2B) were present, the regional failure with postoperative radiation was 30% and 33.3% without postoperative radiation. CONCLUSION: The results of this retrospective study suggest that a selective neck dissection is a satisfactory staging procedure and is a definitive operation if all the nodes are pathologically negative. However, if a node is found to be invaded with cancer, the use of postoperative radiation is advisable.

Carcinoma, Squamous Cell↗

Anticoagulant therapy, anti-platelet agents and gastrointestinal endoscopy.

BACKGROUND: The increasing use of anticoagulant therapy and anti-platelet agents in the primary and secondary prevention of cardiovascular, cerebrovascular and venous thromboembolic disease has increased the need for guidelines for managing these agents prior to gastrointestinal endoscopy, particularly if therapeutic manoeuvres are required. The continuation of anticoagulant therapy increases the risk of haemorrhagic complications of gastrointestinal endoscopy. Temporary suspension of anticoagulant therapy exposes the patient to the risk of thromboembolism associated with the underlying condition requiring anticoagulant treatment. CONCLUSIONS: This article reviews the literature and proposes guidelines for the management of patients taking anticoagulant and anti-platelet agents who require gastrointestinal endoscopy.

Anticoagulants↗

Frequency and therapeutic implications of "skip metastases" in the neck from squamous carcinoma of the oral tongue.

BACKGROUND: Supraomohyoid neck dissection is an adequate operation for the elective treatment of the neck for patients with oral cavity cancer. Squamous cell carcinoma of the oral tongue, however, metastasize to clinically negative nodes in 20% to 30% of patients. These nodes usually are located in levels I-III. METHODS: The medical records of 277 previously untreated patients with squamous cell carcinoma of the oral tongue were reviewed between the years 1970 and 1990. All patients had a glossectomy and neck dissection as part of their initial treatment. Patients were evaluated as to the findings in their neck. The following group of patients were included: (1) patients who had level III nodes positive, without disease in levels I and II; (2) patients with disease in level IV; (3) patients with disease in level IIB or IIIB, and; (4) patients who were electively dissected and whose neck did not demonstrate any pathologically involved nodes, but level IV was not included in the dissection and the patient subsequently developed pathologically positive nodes in level IV. RESULTS: Of all patients, 15.8% had either level IV metastasis as the only manifestation of disease in the neck or the level III node was the only node present without disease in level I-II. CONCLUSION: The usual supraomohyoid neck dissection is inadequate for a complete pathologic evaluation of all the nodes at risk for patients with squamous carcinoma of the oral tongue. This may create a dilemma in determining whether postoperative radiotherapy is necessary. Consequently, all patients with squamous cell carcinoma of the oral tongue should have levels I-IV nodes removed if an elective neck dissection is part of their initial therapy.

Carcinoma, Squamous Cell↗

Thallium-201 myocardial SPECT in myocardial bridging.

Myocardial bridging is an uncommon condition where a major coronary artery is bridged by a band of muscle and narrows during systole, particularly during rapid heart rates. We present a patient with typical angina and angiographically proven 60% systolic bridging of the left anterior descending artery distal to the first perforator. Postexercise SPECT 201TI scanning demonstrated a severe reduction of perfusion to the septum and a moderate reduction of perfusion to the anterior wall of the left ventricle. Redistribution images demonstrated good reversibility of the perfusion defects indicating reversible myocardial ischemia. This case provides additional supportive evidence that myocardial bridging may cause myocardial ischemia.

Adult↗

Inclusion of alcoholism and drug abuse content in curricula of varied health care professions.

Alcoholism and drug abuse are prevalent health problems in the United States. Practitioners in nursing, medicine, and dentistry need to be cognizant of the insidious signs of chemical dependency. A descriptive survey using a researcher-designed questionnaire yielded a sample which consisted of 11 medical schools, 2 dental schools, 25 baccalaureate and higher degree nursing programs, and 38 associate degree nursing programs. The survey findings indicated that the curricula for nursing, medicine, and dentistry were inadequate in chemical dependency content. This survey evidenced the need for a stronger educational effort addressing both knowledge of alcoholism/drug abuse and impaired professional practice in the curricula of the health professional programs examined.

Alcoholism↗

Platelet function and exercise-induced myocardial ischaemia in coronary heart disease patients.

Divergent reports of the effects of exercise-induced myocardial ischaemia on platelet function require clarification. This study examines the relationship between exercise, exertional myocardial ischaemia, and in vivo and ex vivo platelet function in 27 male patients, aged 35 to 69, with stable coronary heart disease (CHD). All medications were ceased at least 5 days prior to a maximal exercise test. Blood was sampled before and after exercise to measure plasma and serum thromboxane B2 (TXB2), plasma beta-thromboglobulin (BTG), platelet count ratio (PCR), platelet count (PC), haemoglobin (Hb), haematocrit (Hct) and white cell count (WCC). The exercise test and blood measurements were repeated 5 weeks later, under the same conditions to confirm the reproducibility of any changes. Thirteen patients had a positive test for ischaemia and 14 a negative test. The PC, Hb, Hct and WCC increased in all patients after exercise, confirming earlier reports. The BTG level increased (25 +/- 9 to 30 +/- 15 ng/ml, p less than 0.05; and 24 +/- 9 to 32 +/- 8 ng/ml, p less than 0.004 in the repeat test) and was unrelated to exertional ischaemia. A decrease in the PCR only occurred in the non-ischaemic group in the initial test (0.84 +/- 0.14 to 0.78 +/- 0.13, p less than 0.02) but was not reproducible (0.84 +/- 0.10 to 0.82 +/- 0.13). No change occurred in plasma TXB2 levels. Serum TXB2 increased after exercise in the ischaemic group (255 +/- 150 to 314 +/- 190 ng/ml, and 240 +/- 139 to 370 +/- 169 ng/ml, p less than 0.05) but not in the negative test group (467 +/- 255 to 441 +/- 174 ng/ml, and 421 +/- 299 to 464 +/- 297 ng/ml, p greater than 0.1). Serum TXB2 discriminated poorly between individuals with positive and negative exercise tests. Thus, stable exertional ischaemia does not activate circulating platelets nor is it associated a priori with activated platelets. It may be associated with an increase in maximum thromboxane A2 production capability. Brief strenuous exercise may activate platelets in CHD patients independent of exertional ischaemia.

Blood Platelets↗

Comparison of nicardipine and propranolol for chronic stable angina pectoris.

In a double-blind, randomized, crossover clinical trial, a new calcium antagonist, nicardipine (90 mg/day in 3 divided doses), was compared with propranolol (120 mg/day in 3 divided doses) in 25 patients with chronic stable angina. The mean weekly frequency of angina episodes decreased from 7.8 +/- 1.2 (+/- standard error of the mean) with placebo to 3.8 +/- 1.2 with nicardipine treatment and 3.5 +/- 1 with propranolol treatment (p less than 0.001). With exercise testing, 5 patients receiving nicardipine and 3 receiving propranolol had no angina or ST-segment changes. Comparing paired samples of both drugs with placebo, significant improvement occurred in exercise duration (nicardipine, 1.3 +/- 0.3 minutes, p less than 0.001; propranolol, 1.0 +/- 0.4 minutes, p less than 0.01), time to onset of angina (nicardipine, 1.5 +/- 0.4 minutes, p less than 0.001; propranolol, 1.5 +/- 0.5 minutes, p less than 0.001), maximal ST-segment changes (nicardipine, 0.7 +/- 0.1 mm, p less than 0.01; propranolol, 0.06 +/- 0.1 mm, p less than 0.01) and time to 1 mm of ST depression (nicardipine, 2.5 +/- 0.4 minutes, p less than 0.01; propranolol, 2.0 +/- 0.3 minutes, p less than 0.01). One patient receiving propranolol and 2 receiving nicardipine withdrew from the study because of transient side effects. Mild side effects occurred in 10 patients receiving propranolol and 5 receiving nicardipine. Nicardipine proved to be safe and effective for patients with chronic stable angina; it had fewer side effects than propranolol in the doses used.

Adult↗

Breast carcinoma metastatic to paranasal sinuses.

BACKGROUND: Breast cancer affects 150,000 women a year in the United States. Breast carcinoma that is metastatic to the paranasal sinus (PNS) is rare. A patient with breast cancer treated recently at the University of Texas M. D. Anderson Cancer Center developed bilateral metastasis to the ethmoid sinuses. This case prompted a review of the incidence of this disease, its treatment, and outcome. METHODS: A review of the published reports dating back to 1939 of breast carcinoma that was metastatic to the PNS was performed. In addition, autopsy series in the breast oncology literature were reviewed for cases of breast carcinoma that was metastatic to the PNS. RESULTS: From this review, we identified only eight cases of breast carcinoma that was metastatic to the PNS. All cases were unilateral and presented as mass lesions. Despite treatment, all patients died soon after diagnosis. CONCLUSIONS: We conclude that breast carcinoma metastatic to the PNS is rare and has been uniformly fatal because, as disseminated disease, it does not respond well to conventional systemic therapies.

Adult↗

Cambodian refugee adolescents: cultural factors and mental health nursing.

Cambodian adolescents in America are a high-risk group for physical, psychosomatic, and drug-related problems. Communication with the Cambodian community is a challenge to mental health nurses due to fundamental differences in American and Cambodian perceptions about parental roles and causation and treatment of illness. The authors focus on the Cambodian cultural theme of equilibrium in treatment of illness, management of stress, and patterns of parenting. Conflicts faced by Cambodian adolescents and nursing intervention strategies are identified.

Adolescent↗