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Biomedical subjects

M Dujovny

Publications and source records attributed to M Dujovny.

At least 181 records · Page 10Linked to original sources
PubMed1984

Microsurgical anatomy of the recurrent artery of Heubner.

The recurrent arteries of Heubner were studied in 30 unfixed human brains (60 hemispheres) obtained from routine autopsies of individuals with a mean age of 34 years. The arteries were injected with tinted polyester resin via cannulation of the internal carotid arteries, and dissected under microscopic magnification. The recurrent artery of Heubner was absent in two hemispheres and double in seven hemispheres, either with a separate origin (in two) or from a common stem (in five). The artery of Heubner had a mean outer diameter of 0.8 +/- 0.04 mm (range 0.3 to 1.5 mm) and a mean length of 23.4 +/- 1.1 mm (range 12 to 38 mm). It originated from the A2 segment of the anterior cerebral artery (ACA) in 57% of the specimens, from the junction of the ACA and the anterior communicating artery in 35%, and from the A1 segment of the ACA in 8%. Three types of recurrent courses were observed. In the Type I or superior course, seen in 41 (63%) of the 65 arteries, the artery followed the superior wall of the A1 segment of the ACA. In the Type II or anterior course, the arteries found in 22 (34%) of specimens maintained a rostral position in relation to the A1 segment. In the Type III or posterior course, taken by two (3%) arteries, a posterior course of the vessel in the anterior perforated substance was found. The branching pattern was identified down to a range of 100 to 200 mu, and the average number of branches was 6.5 +/- 0.4 (range 3 to 12). Four groups of branches were observed. The olfactory group was represented in 91% by a single olfactory branch, with a mean outer diameter of 0.3 +/- 0.03 mm. On average, 1.9 +/- 0.27 frontal branches were found with a mean diameter of 0.13 +/- 0.01 mm. The branches penetrating the anterior perforated substance had a larger outer diameter (mean 0.4 +/- 0.03 mm) with an average number of 2.5 +/- 0.2 branches. The Sylvian fissure branches were more numerous (mean 3 +/- 0.3) with a mean outer diameter of 0.4 +/- 0.03 mm. The point of penetration of the main trunk was found to be constant at the level of the lateral perforated substance-medial Sylvian fissure in 85% of the cases. This report emphasizes the advantages of the intravascular casting resin injection technique in unfixed human brains over other conventional methods. It also describes the application of these anatomic data to the surgical strategy for the anterior circle of Willis, including the possible use of the recurrent artery of Heubner for microvascular reconstructive procedures.

Adult↗
PubMed1984

Microsurgical anatomy of the proximal segments of the middle cerebral artery.

The microvascular anatomy of the proximal segments (M1 and M2) of the middle cerebral artery (MCA) was studied in 70 unfixed brain hemispheres from 35 cadavers. The arteries were injected with a tinted polyester resin and dissected under magnification by microsurgical techniques. The authors studied the outer diameter (OD), length, site of origin, and pattern of branching of the main trunk, secondary trunks, and the initial insular portion of the cortical branches of the MCA. The degree of mobilization of the arteries lying over the insular cortex was also assessed. The main trunk of the MCA, which had an OD of 3 +/- 0.1 mm bilaterally and a length of 15 +/- 1.1 mm in the right hemisphere and 15.7 +/- 1.3 mm in the left hemisphere, could be divided into four groups: Group I: absence of a main division (that is, a single-trunk type of MCA) (in 6% of cases); Group II: bifurcation (64%); Group III: trifurcation (29%); and Group IV: quadrifurcation (1%). The secondary trunks resulting from the division of the main trunk of the MCA had a mean OD ranging from 1.4 to 2.3 mm and a mean length that varied from 12.1 to 14.9 mm. The mean OD of the cortical branches measured near their origin in the main and secondary trunks indicated that the angular artery was the largest vessel, with a mean OD of 1.5 mm on both sides of the brain. The temporopolar artery was the smallest, with a mean OD of 0.8 mm in the right hemisphere and 0.9 mm in the left hemisphere. The authors also describe the patterns of origin of the cortical vessels from the main trunk (early branches) and from the secondary trunks, as well as their branching pattern at the site of origin (single vessels and common stems). These anatomical data indicate that it is possible to perform microvascular reconstructive procedures, such as anastomosis, grafting, and reimplantation of branches in the insular area. The advantages of using unfixed specimens, intravascular injections, and magnification to reproduce in vivo conditions as closely as possible are also discussed.

Cerebral Arteries↗
PubMed1983

Mechanical and metallurgical properties of vascular clips designed for temporary use.

Six commonly used surgical clips (Kleinert-Kutz, Pivot, Vari-Angle, Yasargil, Biemer, and Acland) that have been designated by their manufacturer as being suitable for temporary occlusion were studied in terms of their mechanical and metallurgical properties. Opening and closing forces were determined for all of the clips. Significant variations in clip force with respect to blade gap were found in all of the pivot-type clips. Metallurgical testing showed that all six clips exhibited properties that contraindicate long-term implantation.

Corrosion↗
PubMed1983

The surgical management of vertebrobasilar insufficiency.

Vertebrobasilar insufficiency may result from structural lesions anywhere along the vertebrobasilar system. Recently developed techniques in angiography and microsurgery have made the vertebrobasilar system more accessible to surgical therapy. The syndrome of vertebrobasilar insufficiency is discussed, and our experience with the surgical treatment of lesions from the vertebral origin to the distal basilar region is reviewed.

Anticoagulants↗
PubMed1983

Combined reconstruction of the vertebral and carotid artery in one single procedure.

Patients suffering from vertebrobasilar insufficiency frequently have multiple areas of involvement in the extracranial circulation. Eight patients admitted to Henry Ford Hospital had symptoms suggestive of vertebrobasilar insufficiency and angiograms showing multiple abnormalities. A combined operation that reconstructed the carotid and vertebral circulations in one single procedure was completed in all patients with minimal morbidity and no mortality. The surgical procedure is described in detail.

Aged↗
PubMed1983

Angiographic demonstration of postoperative cortical artery stenosis induced by Biemer temporary clips.

Five patients underwent cerebral revascularization operations during which Biemer clips were used to occlude temporarily a branch of the middle cerebral artery. Postoperative angiograms revealed stenoses at the sites where the clips were applied. Excessive clip closing forces may have caused significant endothelial injury, which then produced the stenoses. Clips that exert a minimal occlusive force would avoid this response and are recommended for temporary occlusion of cortical arteries.

Adult↗
PubMed1982

Cerebral blood flow changes with diuretic therapy in elderly subjects with systolic hypertension.

It has been feared that lowering the blood pressure (BP) of elderly patients with systolic hypertension (SH) may compromise cerebral perfusion. To test this hypothesis, BP, cerebral blood flow (CBF), plasma renin activity (PRA), blood counts, urinary and serum electrolytes and other blood chemistries were measured in fifteen elderly patients (ages 61-76 years) with SH (systolic BP greater than 170 and diastolic BP less than 100 mmHg). Gray matter flow (Fg) was calculated from clearance curves of inhaled 133-Xenon. All subjects were studied while untreated, as well as during long-term treatment (average 15 weeks) with hydrochlorothiazide. BP fell during treatment from 186/90 to 160/86 while average Fg and cerebrovascular resistance (CVR) were not significantly changed. There was some suggestion, however, that in patients who became normotensive the CVR decreased (p less than 0.05) while in those who did not Fg fell (p less than 0.05). Cerebrovascular response to 5% CO2 inhalation was impaired during both the treated and untreated states. Individual changes in Fg and CVR did not correlate with changes in BP or with changes in PRA, electrolytes or other chemistries. In general, cautious, gradual reduction of BP with a thiazide diuretic in SH of the elderly seems not to impair cerebral perfusion, but individual differences exist and further studies are needed to characterize them.

Aged↗
PubMed1982

Failure of a Heifetz aneurysm clip.

A 16-year-old girl died from an acute subarachnoid hemorrhage following the fracture of a blade of a Heifetz aneurysm clip. The clip was manufactured from 17-7PH steel, which on metallurgical testing was found to be highly sensitive to intergranular corrosion. The fracture mechanism was stress corrosion, brought on by the combination of a stress load, an electrolytic environment, and a susceptible steel.

Adolescent↗
PubMed1982

Histological structural abnormalities of superficial temporal arteries used for extracranial-intracranial anastomosis.

Histological evaluation of the superficial temporal artery resected at the time of extracranial-intracranial anastomosis was performed in 64 consecutive patients. A neuropathologist who was not aware of the medical condition of these patients studied all specimens under light microscopy with hemotoxylin and eosin, Verhoff, and Mallory strains. Intimal proliferation was observed in 62 samples, intimal fibrosis in 56, fragmentation of the internal elastic lamina in 45, splitting of the internal elastic lamina in 41, fragmentation of the media in 38, and fragmentation of the minimal external elastic tissue in 17. Stenosis of the vessel was observed, and graded from 0% to 50%, with a mean of 20%. The development of intraluminal stenosis was considered to be secondary to the development of intimal fibrosis and hyperplasia. The changes observed were progressive and conformed with those previously described; there was no evidence of correlation with sex, diabetes, or hypertension. The implications for the development of occlusion of the anastomosis or stroke, and for patient survival are discussed.

Adolescent↗
PubMed1982

Implanted pulsatile balloon device for simulation of neurovascular compression syndromes in animals.

A self-contained neurovascular compression simulator (NCS) has been designed to function as an artificial artery that pulsates with the heart. When implanted in animals, this device simulates those naturally occurring situations in which there is compression of nervous elements in the region of the brain stem or other areas by aberrant, or ectatic branches of normal arteries. The NCS consists of an intra-aortic balloon, a smaller (cephalic) balloon, a connecting tube, and an injection port, all fabricated of polyurethane-silicone compounds. With each heart systole, the rise in intra-aortic pressure is transmitted to the smaller cephalic balloon in the form of a pulsation. Thus, part of the cardiac ejection energy is transferred to the desired nervous structures. The performance of each NCS is tested in vitro in a pulse duplicator system. The NCS was chronically implanted for up to 2 years in four dogs and 10 baboons. The cephalic balloon was placed intracranially in the subarachnoid space on the ventrolateral medulla adjacent to the entry zone of the ninth and 10th cranial nerves on the left side of baboons and on the right side of dogs. The position of the balloons was checked by fluoroscopy. Following implantation, the NCS could be inflated or deflated at will using the injection port which served to restart or discontinue the pulsations. No occlusion of the aorta or reduction of blood flow to the lower limbs or trunk was detected. By means of the NCS, an experimental model of neurogenic hypertension was produced in baboons.

Animal Diseases↗
PubMed1982

Angina-like cardiac disturbances of hypothalamic etiology in cat, monkey, and man.

Angina-like phenomena of CNS etiology were studied. Data were collected and analyzed from clinical cases of cerebral hematoma, concussion, and tumors in which cardiological disturbances were observed consequent to compressive brain lesions or surgical brain manipulations. The cases in which the disturbances were largely angina-like and without ectopic beats or arrhythmias were chosen for study. The brain region most significantly related to this phenomenon seemed to be the hypothalamus. Experiments conducted in cats and monkeys showed that stimulation of specific sites in the hypothalamus resulted in angina-like manifestations with no other cardiac changes. These data support our working hypothesis that a cerebrally induced syndrome that is conspicuously angina-like must be related to hypothalamic involvement. In the awake monkey hypothalamic stimulation caused angina-like ECG changes and behavior suggestive of referred pain. In some cases, repetitions of the stimulations or irritations in all of the species resulted in permanent pathological myocardial changes, mostly bleeding into the myocardium. In some animals there were minute hemorrhagic necroses that were subepicardial in distribution. It is significant that the most severe or permanent pathological changes were found in cases in which the angina-like ECG alterations were persistent. There were also cases, however, with persistent angina-like ECG changes that showed no such pathology.

Adolescent↗
PubMed1981

Reduced vascular trauma after temporary occlusion with modified Biemer and Yasargil clips.

The Biemer and Yasargil microvascular clips that are currently available commercially can traumatize the vascular endothelium. In an effort to resolve this problem, both clip designs were structurally modified by changing the length, width, and surface of the clip blades in various ways. Also, the occlusion force of the clips was set at either 15 or 30 g. Studies on the carotid arteries of 140 rats showed a correlation between the structural and mechanical alterations of the clips and the degree of endothelial trauma produced by temporary occlusion for 1 hour. The most favorable results were obtained with a Biemer clip that had long, wide, smooth blades and an occluding force of 15 g.

Animals↗
PubMed1981

A variable-force microvascular clip.

An easily adjustable, variable-force microvascular clip is described. This clip is superior to other clips currently available because it is essentially three clips in one. Its advantages are that it can reduce the amount of table area needed to store clips during surgery and it offers the surgeon greater flexibility in the selection of clips with different closing forces. This clip was developed by modifying the segments of a basic alpha-type clip, designing a computer program to analyze the force contributions made by each segment of the clip, constructing several clips with different blade lengths, and testing them in a microvascular surgery research program. The clip we have developed is easy to use, reduces clutter on the instrument table, aand offers the surgeon a wide choice of closing forces with a minimal number of clips.

Humans↗