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Biomedical subjects

M B Horowitz

Publications and source records attributed to M B Horowitz.

36 records · Page 2Linked to original sources
PubMed1998

Dyspnea ratings for prescription of cross-modal exercise in patients with COPD.

STUDY OBJECTIVE: To investigate the ability of patients with COPD to reproduce an exercise intensity accurately on the treadmill using dyspnea ratings obtained during incremental exercise on the cycle ergometer (cross-modal exercise prescription). DESIGN: Five visits over an 8-week period. PATIENTS: Thirteen symptomatic patients with stable COPD. Age was 67+/-6 years (mean+/-SD). FEV1 was 1.15+/-0.22 L (45+/-7% predicted). INTERVENTIONS: At each visit, patients performed spirometry and exercise. Visit 1 was a practice incremental exercise test on the cycle ergometer. At visit 2 (1 week later), patients estimated the intensity of dyspnea using the 0 to 10 category-ratio scale during an incremental exercise test on the cycle ergometer (cycle estimation trial). Visit 3, 5 weeks later, was a practice session on the treadmill. At visit 4, 1 week later, patients were instructed to produce specific intensities of dyspnea (ie, dyspnea targets) at 50% and at anaerobic threshold (AT) or 80% of peak oxygen consumption (VO2) as calculated from results at visit 2 (treadmill production trial). Visit 5, 1 week later, was the treadmill estimation trial. MEASUREMENTS AND RESULTS: Lung function was stable at all visits. Dyspnea ratings were 1.9+/-0.9 at 50% of VO2 and 5.6+/-1.5 at AT/80% of peak VO2 (17.5+/-3.3 mL/kg/min). The VO2 at the treadmill production trial (761+/-185 mL/min) was significantly higher than at the cycle estimation trial (612+/-159 mL/min) at the low dyspnea target (p < 0.0002; upward bias, 26+/-16%). In contrast, there was no significant difference in VO2 values (929+/-176 mL/min vs 948+/-259 mL/min) at the high dyspnea target (p > 0.5; 0+/-11% bias). CONCLUSIONS: Patients with COPD can use dyspnea ratings from an incremental cycle ergometry test to regulate exercise on the treadmill without systematic bias at an intensity of 80% of peak VO2, but exceed the desired VO2 when using the dyspnea rating at an intensity of 50% of peak VO2.

Aged↗
PubMed1997

Scanning electron microscopic findings in a basilar tip aneurysm embolized with Guglielmi detachable coils.

With the growing use of endovascular therapy for intracranial aneurysms, it is important that we understand at a cellular level the processes that lead to lesion obliteration. We present autopsy findings, including electron and light microscopic studies, of a basilar artery aneurysm that was successfully embolized with the Guglielmi detachable coil system 4 weeks before the patient died.

Aged↗
PubMed1996

Radiation dermatitis after spinal arteriovenous malformation embolization: case report.

Few cases of radiation injury related to lengthy interventional neuroradiologic procedures have been reported, although concern has been heightened, as evidence by a 1994 FDA Public Health Advisory. We report a case of radiation-induced dermatitis in a patient undergoing multiple diagnostic and embolization procedures for treatment of a spinal arteriovenous malformation.

Adult↗
PubMed1996

Dyspnea ratings for prescribing exercise intensity in patients with COPD.

STUDY OBJECTIVE: We tested the hypothesis that patients with COPD can use dyspnea ratings obtained from a prior graded exercise test as a target to reliably produce specific exercise intensities. DESIGN: Four visits over a 7-week period. SETTING: Pulmonary function and cardiorespiratory exercise laboratory at a university hospital. PATIENTS: Fifteen symptomatic patients with stable COPD. Age was 68 +/- 7 (mean +/- SD) years. FEV1 was 1.12 +/- 0.22 L (45 +/- 8% predicted). INTERVENTIONS: At each visit, patients estimated the heaviness of weights to evaluate their magnitude estimation of a nonrespiratory task; after pulmonary function testing was completed, patients were tested on the cycle ergometer. At estimation trial 1 (day 0), patients estimated the intensity of dyspnea using the 0 to 10 category-ratio scale during an incremental exercise test. Estimation trial 2 (day 5 to 7) was the same as the previous trial. At production trials 1 (day 10 to 14) and 2 (day 40 to 44), patients were instructed to produce specific intensities of dyspnea (ie, dyspnea targets) at 50% and at anaerobic threshold (AT) or 80% of peak oxygen consumption (Vo2) as calculated from results at estimation trial 2. MEASUREMENTS AND RESULTS: Lung function was stable at all visits. Dyspnea ratings were 1.8 +/- 0.9 (range, 1 to 3) at 50% of peak Vo2 and 5.5 +/- 1.5 (range, 4 to 8) at AT/80% of peak Vo2 (17.0 +/- 3.4 mL/kg/min) at estimation trial 2. The individual percent changes in Vo2 at the lower dyspnea target were 12 +/- 19% and 11 +/- 19% for production trials 1 and 2, respectively, compared with estimation trial 2. At the higher dyspnea target, the corresponding individual percent changes in Vo2 were -4 +/- 9% and -7 +/- 11%, respectively. For all 15 patients, there were borderline statistical differences for the Vo2 values at the lower (p = 0.04 and p = 0.07) and at the higher (p = 0.04 for each production trial) dyspnea targets for production trials 1 and 2 compared with estimation trial 2. Two patients showed 50% or greater variability in the calculated exponent for magnitude estimation of weights. In a subgroup analysis of the 13 patients with reproducible magnitude estimation of the heaviness of weights, there were no significant differences in Vo2 for the two production trials compared with estimation trial 2 at both exercise intensities. CONCLUSIONS: Dyspnea ratings obtained from an incremental exercise test can be used as a target for patients with COPD to regulate/monitor the intensity of exercise training. The ability of patients with COPD to achieve a desired Vo2 based on an individual dyspnea target was generally more accurate at the higher exercise level (AT/80% of peak Vo2) compared with the lower intensity (50% of peak Vo2). Acceptable accuracy was maintained over a 5-week time period.

Aged↗
PubMed1996

Use of intravascular stents in the treatment of internal carotid and extracranial vertebral artery pseudoaneurysms.

The management of extracranial carotid or vertebral artery pseudoaneurysms is controversial. Although some of these lesions resolve spontaneously, many clinicians opt to treat them with trapping procedures that result in vessel sacrifice. We describe two cases in which an intravascular stent was used to obliterate an aneurysm of the extracranial vertebral artery and the internal carotid artery, respectively, while maintaining the patency of the parent vessel. The technique, which has been successful in experimental animal models, shows promise for application in humans.

Aneurysm, False↗
PubMed1995

Acute disseminated encephalomyelitis (ADEM) or ADEM-like inflammatory changes in a heart-lung transplant recipient: a case report.

Acute disseminated encephalomyelitis (ADEM) is a white matter inflammatory disease which usually follows a viral infection or pharmaceutical intervention. We describe a case of presumed ADEM in a heart/lung transplant patient, the etiology of which cannot be elucidated. The fascinating aspect is the mode of clinical presentation and the rapid resolution of radiologic abnormalities. Histologic examination of the brain is provided in an attempt to elucidate the radiographic abnormalities.

Adult↗
PubMed1995

Intraoperative urokinase infusion for embolic stroke during carotid endarterectomy.

Embolic stroke is an infrequent complication of carotid endarterectomy. Somatosensory evoked potential monitoring detected delayed acute neurological deterioration during endarterectomy performed on a 71-year-old woman. Intraoperative arteriography performed via an indwelling shunt revealed thrombus within the middle cerebral artery and distal branches. A microcatheter was placed into the internal carotid artery via the arteriotomy and advanced into the middle cerebral artery. Urokinase was infused into and around the thrombus until almost complete thrombolysis had been achieved. The patient recovered quickly and was discharged without neurological deficit.

Aged↗
PubMed1994

Thoracic discectomy using video assisted thoracoscopy.

STUDY DESIGN: The applicability of using video assisted thoracoscopic surgery (VATS) to resect thoracic discs was investigated. A laboratory study was conducted using two human cadavers and three live pigs as surgical specimens. A total of nine thoracic levels were decompressed. OBJECTIVE: To study the feasibility of performing thoracic resections using VATS. SUMMARY OF BACKGROUND DATA: VATS has been used by thoracic surgeons since 1991 to resect pulmonary lesions. As far as we know, VAT has not yet been used to resect thoracic discs. METHODS: Surgical resections of nine disc levels were carried out in two human cadavers and three anesthetized pigs. VATS was used to provide the surgeon with visualization of the surgical site. Large thoracotomy incisions were not necessary. RESULTS: Five of seven cadaver disc spaces and two of three porcine disc spaces were adequately evacuated of disc material. One episode of dural violation occurred. One animal died during the procedure from an anesthetic complication. CONCLUSION: VATS provides a useful means of performing thoracic discectomies using a small thoracotomy incision. The decrease in invasiveness provided by this new technology may reduce operative morbidity, hospitalization time, and costs. More work is needed, especially in the design of instrumentation, before this becomes a viable alternative to current surgical procedures.

Animals↗
PubMed1994

Management of a giant middle cerebral artery fusiform serpentine aneurysm with distal clip application and retrograde thrombosis: case report and review of the literature.

Giant fusiform aneurysms are rare vascular anomalies that due to their size are often difficult to manage. We describe one such aneurysm that was managed with a superficial temporal to middle cerebral artery bypass followed by the application of a single clip just distal to the vascular dilation. Follow-up angiography has shown aneurysm obliteration by the process of retrograde thrombosis.

Adult↗
PubMed1994

Perception of breathlessness during exercise in patients with respiratory disease.

The perception of breathlessness during physical activities is a frequent and disturbing complaint for patients with chronic respiratory disease. Psychophysical principles can be applied to quantitate the severity of dyspnea during cardiopulmonary exercise testing. Power production (or work) appears to be the most appropriate stimulus for measuring the dyspnea response. The 0-10 category-ratio (CR-10) scale and the visual analog scale (VAS) are two instruments for measuring the intensity of breathlessness. Studies demonstrate that the slope and/or intercept of the power production-breathlessness relationship provide a valid, reliable, and responsive approach for measurement. Ratings of dyspnea during exercise are useful to determine the severity of breathing difficulty and to assess the efficacy of therapy.

Chronic Disease↗
PubMed1994

Vein of Galen aneurysms: a review and current perspective.

Our approach to treating a patient with a vein of Galen aneurysm is, of course, influenced greatly by the age of the patient, the clinical symptoms, and the angiographic architecture of the malformation. Therapeutic options are primarily based on whether a true AVM is present or if the malformation represents an arteriovenous fistula involving the vein of Galen. Arterial endovascular approaches, microneurosurgery, and/or radiosurgery are preferred for management of the former; the transvenous endovascular approach has become the cornerstone of treatment in the latter. The most critical group, however, is the neonates in extreme cardiovascular distress. In this case our therapeutic intervention is initially endovascular from the venous side, either transfemoral or transtorcular. The immediate goal is to increase resistance to right ventricular output. Advantages of this approach over a transarterial approach include a shorter anesthesia time, minimal fluid and/or contrast administration, and creation of a wire "basket" or "bird's nest" on the venous side that helps prevent emboli that may be deposited on the arterial side in subsequent embolizations from passing through the malformation. The transvenous approach can be easily repeated multiple times and may be supplemented by transarterial embolizations. Endovascular coils have been the mainstay for such venous embolizations. The end point of treatment is not complete occlusion of the fistula but improvement in cardiac function. Often, more than one stage is required to reach our goal. The results in recent years have been encouraging and are to a large degree attributable to the advances in endovascular approaches. With future improved tools for diagnosis and treatment, perhaps the prognosis for this difficult malady also will continue to improve.

Arteriovenous Fistula↗
PubMed1994

Clinical evaluation of exertional dyspnea.

The medical history is the first step in the clinical evaluation of exertional dyspnea. It should include pertinent questions about the characteristics of dyspnea, especially descriptive qualities, onset, frequency, severity, and activities that provoke the symptom. Based on this information, along with the physical examination, the health care provider should be able to categorize the cause of exertional dyspnea as suspected cardiac disease, suspected respiratory disease, or as unexplained. Laboratory testing is ordered using a logical approach to diagnose the most probable cause of dyspnea. Cardiopulmonary exercise testing is indicated to differentiate cardiac and respiratory limitation, to document deconditioning, and to identify psychogenic dyspnea. The measurement of dyspnea and leg discomfort during exercise testing can be performed using the Borg 0 to 10 category-ratio scale or the visual analog scale. These perceptual responses can provide useful information about symptom limitation, which is complementary to physiologic data.

Adult↗
PubMed1993

Occipital neuralgia treated by intradural dorsal nerve root sectioning.

The term occipital neuralgia was first used in 1821 to describe a characteristic pain in the region innervated by the greater occipital nerve. Since that time numerous authors have failed to reach a consensus concerning the presentation, cause, and treatment of this entity. Review of these previous works reveals that the term occipital neuralgia encompasses a collection of signs and symptoms which develop secondary to a variety of different disease processes. We have treated nine patients suffering from severe occipital pain with associated C2 hypesthesia, unilateral retro-orbital pain, and occipital or C2 tubercle trigger points by intradurally sectioning the C1-C4 dorsal rootlets (C4 if shoulder pain existed). All patients had been treated previously with various modalities without success. This paper discusses the results obtained in these patients.

Female↗
PubMed1991

Central nervous system germinomas. A review.

The germinoma represents a less malignant form of germ cell tumor. Depending on the individual's age, this neoplasm constitutes approximately 0.1% to 3.4% of all intracranial tumors. The embryologic origin remains a mystery; however, current theories implicate an aberration in primordial germ cell migration. Clinical presentation depends on tumor location and may involve endocrine, hypothalamic, visual, and cognitive dysfunction. In evaluating midline intracerebral masses, it is imperative that one be aware of the various radiologic appearances, endocrinologic changes, and chemical markers that help to distinguish germinomas from other neoplasms that appear in the pineal, suprasellar, and periventricular regions. Only through the careful evaluation of all available studies can the physician institute appropriate therapies such as biopsy, radiation, and chemotherapy. This article focuses on the epidemiology, embryology, clinical presentation, means of diagnosis, treatment, and outcome of this rare neoplasm.

Brain Neoplasms↗
PubMed1991

Mineral spirits inhalation associated with hemolysis, pulmonary edema, and ventricular fibrillation.

A previously healthy 42-year-old woman developed severe dyspnea, chest discomfort, and malaise several hours after prolonged exposure to concentrated vapors from mineral spirits. On the way to the hospital, she sustained a cardiopulmonary arrest; on arrival several minutes later, she was found to be in ventricular fibrillation and was resuscitated. Her hospital course included slowly resolving cardiac abnormalities, amnesia, noncardiogenic pulmonary edema, abrupt hemolytic anemia, sustained rhabdomyolysis, and other metabolic abnormalities. It is highly probable that this syndrome represented acute and near-lethal toxicity caused by the inhalational exposure to the petroleum distillate known as mineral spirits. It is important that physicians be aware of this syndrome in order to recognize it on presentation and to warn patients of the risk of such toxic exposure.

Administration, Inhalation↗
PubMedDate not supplied

Acute cerebellitis: case report and review.

We report a case of acute cerebellitis in a 7-year-old male presenting with headache, vomiting, ataxia and life-threatening hydrocephalus requiring emergent placement of an external ventricular drain. Unlike earlier reported cases which did not provide radiographic correlation of this disease, this report documents changes in the cerebellum with serial magnetic resonance and computer tomography scans. The signs, symptoms and differential diagnosis of this rare, self-limiting condition are briefly discussed.

Cerebellar Ataxia↗
PubMedDate not supplied

Calcium 45 autoradiography and dual-isotope single-photon emission CT in a canine model of cerebral ischemia and middle cerebral artery occlusion.

PURPOSE: To determine whether transient ischemia can be separated from permanent ischemia via calcium 45 autoradiography and to assess the applicability of dual isotope single-photon emission CT (SPECT) in the evaluation of cerebral blood flow. METHODS: We examined calcium influx in 12 dogs (group A) by using whole-brain calcium 45 autoradiography: Animals received 250 microCi/kg 24 hours after 30-minute (n = 6) or permanent (n = 6) middle cerebral artery (MCA) occlusion. Forty-eight hours after MCA occlusion, 5-mm coronal brain sections were fixed for either autoradiography or pathologic examination. In a separate study, 9 mongrel dogs (group B) were given 250 microCi/kg calcium 45 and a mean dose of 700 microCi/kg technetium Tc 99m hexamethylpropyleneamine oxime intravenously. A silicone plug was then injected into the internal carotid artery and angiography was performed to verify MCA occlusion. A 10th (control) animal did not undergo occlusion. In an 11th animal, placement of the plug could not be achieved and a slurry of microfibrillar collagen was injected into the carotid artery. No angiography was performed in animals 10 and 11. After occlusion, each animal was injected with a mean dose of 126 microCi/kg simultaneous acquisition for technetium 99m and 123I-iodoamphetamine. RESULTS: In group A, all animals who had permanent MCA occlusion showed infarction and increased calcium 45 uptake in infarcted territories. None of the animals who had 30-minute occlusion had either increased calcium 45 uptake or infarction at 48 hours. In group B, 7 or 10 dogs had SPECT findings that were consistent with the calcium autoradiographic marker for ischemia. One animal died during the procedure and 1 dog served as a control. CONCLUSION: Calcium 45 autoradiography allowed distinction between areas of temporary and permanent occlusion. Iodoamphetamine imaging was not consistently sensitive to that level of ischemia. Timing of calcium influx may lead to insight that could impact timing of pharmacologic or endovascular intervention.

Amphetamines↗