PubMed Health⌕ Search

Biomedical subjects

J I Ausman

Publications and source records attributed to J I Ausman.

At least 19 recordsLinked to original sources
PubMed1992

Microsurgical anatomy of the lower basilar artery.

This study was designed to study the microvascular anatomy of the basilar artery between the superior cerebellar artery and the vertebrobasilar junction (i.e. the lower basilar artery). Twenty unfixed brains were injected with silicone rubber solution and studied with a Zeiss OPMI microscope. The length of this segment of the basilar artery was 28.1 + 1.35 mm and its course was straight in 9 (45%) brains, curved in 7 (35%) and tortuous in 4 (20%). The total number of perforators found in 20 brains was 340 with an average of 17 per brain. Of these, 118 (34.7%) were median and 222 (65.2%) were lateral. Median branches had a mean length of 5.8 + 1.25 mm, whereas left and right lateral branches had a mean length of 16 + 1.25 mm and 16 + 1.58 mm respectively.

Autopsy↗
PubMed1992

Stereotactic management of midline brain lesions.

Eighty-seven patients, aged 10 months to 92 years, with midline brain lesions were treated using stereotactic techniques at our institution between January 1987 and June 1990. A total of 119 stereotactic procedures were performed with no operative mortality. Procedures included 53 biopsies only, 22 endoscopic laser decompressions, 8 stereotactic microsurgical resections, 9 permanent implants of 125I, 12 temporary implants of 125I, 11 cyst aspirations, 2 cystoperitoneal shunts and 2 intracavitary 32P. The morbidity rate was 4.21%. Local anesthesia was used in 106 of the procedures (89%). Accurate diagnosis was achieved in all cases. Image guidance and stereotactic techniques open new frontiers in the diagnostic and therapeutic management of deep-seated midline intraparenchymal lesions.

Biopsy↗
PubMed1992

In vivo and in vitro study of the lesions produced with a computerized radiofrequency system.

For many years, radiofrequency-generated lesions have been used for the treatment of pain and abnormal movements. However, the reliability of this method has been questioned because of the variation in the size of lesions produced by the electrode at different times and temperatures. A 500-kHz radiofrequency generator with different electrodes was used to determine the size of lesions, using different time and temperature exposures. A computerized feedback mechanism kept the tip temperature constant during the production of the lesion, regardless of varying tissue impedance. Eight electrodes of different size and tip characteristics were evaluated at different temperatures and time settings, both in vitro and in vivo. Graphic display of the curves in time were obtained at 65, 70, 75, 80, 85 and 90 degrees C. The effects of thermo-coagulation were studied in vitro in fresh egg whites, using time intervals of 20, 40, 60, 80 and 100 s, and in vivo, in the subcortical white matter of 20 adult New Zealand white rabbits. Animals were sacrificed after 7 days. Lesions were photographed and measured under magnification. In all cases, the coagulated masses were ellipsoid, with regular, well-demarcated borders. A two-way statistical analysis of variance was done. The coagulum size increased with higher temperatures and with larger probes. The increase was significant in both diameter and length (p = 0.001). In contrast, the use of different times at the same level of temperature showed no significant increase in most of the electrodes. There were two statistical significant time effects, for both diameter and length, with the monopolar 2-mm electrode. The use of real-time monitoring with graphic display and the feedback information provided for the computerized control of power and current allows high precision of the temperature at the electrode tip during the production of the lesion.

Analysis of Variance↗
PubMed1992

Intracerebral penetration of infrared light. Technical note.

Near infrared transmission spectroscopy of the human cerebrum may allow noninvasive evaluation of cerebral hemoglobin saturation in humans. The emerging spectroscopy configuration for this application is a side-by-side source-receiver construct. The ability of this spectroscopy paradigm to detect changes in intracerebral attenuation by selective injection of the infrared tracer indocyanine green into the internal and external carotid arteries during endarterectomy is evaluated in five adult patients. In all five, simultaneous two-channel infrared transmission spectroscopy over the ipsilateral hemisphere documented tracer bolus transit with a signal-to-noise ratio greater than 100:1. In addition, the two channels could be configured to achieve depth resolution of the collected spectra.

Brain↗
PubMed1991

The management of arteriovenous malformations in children.

Between January 1941 and June 1989, 46 children below the age of 18 with an arteriovenous malformation (AVM) were managed. There were 7 patients with AVM diagnosed before the age of 2; 10 patients were diagnosed between the ages of 3 and 10; and 29 patients were diagnosed between 11 and 18. There were equal numbers of male and female patients. Twenty-five of the AVMs were large (greater than 5 cm longest diameter). All 7 AVMs diagnosed before the age of 2 were large. The usual clinical presentation was congestive heart failure, bruit and an enlarging head. Three patients underwent excision with 2 deaths and 1 excellent result. In 11 patients (aged 3-18) with AVM without history of hemorrhage, 3 had excision with 2 excellent and 1 fair result. Four remained stable. Four developed progressive deficits or hemorrhage. In 10 patients (aged 3-18) with AVM and hemorrhage who were treated medically, 7 (70%) had an episode of re-hemorrhage. Three patients had excision of AVM after re-hemorrhage, but before the age of 18 with an excellent result. Eighteen patients (aged 3-18) with AVM and a single episode of hemorrhage underwent excision with 17 excellent or good results and 1 fair result. The overall mortality was 7%. Eighty-five percent of the children with excision of AVM had an excellent or good result. The best treatment for AVM in children is surgical excision.

Adolescent↗
PubMed1991

The anterior cavernous sinus space.

The anterior cavernous sinus space is the venous space anterior to the cavernous carotid artery. It is tetrahedral in shape with the anterior apex at the superior orbital fissure. The superomedial wall is formed by the base of the anterior clinoid process. The inferomedial wall is formed by the sphenoid bone. The lateral wall consists of two layers of dura with the oculomotor, trochlear, ophthalmic and abducens nerves in the inner layer. Medially, the posterior wall consists of the cavernous carotid artery. Laterally, it communicates with the lateral cavernous sinus space. Paraclinoid and carotid cave aneurysms may occupy this space and its microanatomy is important in the surgery of these aneurysms.

Carotid Arteries↗
PubMed1991

Temporary clipping in aneurysm surgery: technique and results.

The use of temporary clipping has become an established tool in the armamentarium of the aneurysm surgeon. Our experience with 62 consecutive patients is presented, detailing operative protocols and results. Twenty-two had unruptured aneurysms (35%), 15 were grade I (24%), 16 grade II (25%), five grade III (8%), and four grade IV (7%). The aneurysms were mainly located in the middle cerebral artery (29 patients) and the anterior communicating artery (13 patients). Eleven of our 62 patients (17%) developed a new, persistent postoperative deficit. However, in only one case (2%) was temporary clipping felt to be implicated in the development of the deficit. In three other patients (5%), the effect of temporary clipping, although unlikely, could not be excluded. Overall, 92% of our patients with temporary clipping had good to excellent outcome, with 3% mortality and 5% morbidity. We believe that temporary clipping is a safe procedure that contributes significantly to a better outcome.

Adult↗
PubMed1991

Measurement of regional cerebrovascular haemoglobin oxygen saturation in cats using optical spectroscopy.

We describe the use of optical spectroscopy in the near infra-red light range to non-invasively measure regional cerebral haemoglobin oxygen saturation (rSHbO2) in cats during progressive cerebral hypoxia. This technique differs from spectroscopic techniques previously described in that the concentration ratio--percentage haemoglobin: oxygen saturation--is quantified. This saturation is the weighted summation of saturation in the cerebrovascular system: arterial, venous, and capillary beds. In a cat model of progressive cerebral hypoxia, a positive linear correlation between this regional measurement of cerebral saturation and actual saturation, calculated from cerebral arterial and mixed venous blood, was noted (n = 20, r = 0.88, p less than 0.01). The spectroscopic measurement rSHbO2 is also used to index cerebral oxygen extraction. During hypoxia spectroscopic indexed oxygen extraction (iOE) and cerebral arterial-venous difference in oxygen content were simultaneously measured. A least-squares positive linear correlation between these two parameters was noted [AVDO2 = iOE (0.05) + 4.4] (n = 40, r = 0.6, s = 1.2). Objective measurement of 'regional cerebrovascular haemoglobin saturation' and an index of cerebral oxygen extraction are possible using optical spectroscopy.

Algorithms↗
PubMed1991

Dominant A1: angiographic and clinical correlations with anterior communicating artery aneurysms.

It has been observed but never proven that anomalies of the anterior communicating artery complex are associated with anterior communicating artery aneurysms (ACAA). Therefore, in an effort to understand the significance of haemodynamic factors in the genesis, as well as the clinical course of ACAA, we evaluated the correlation between certain angiographic patterns of flow in the anterior circulation and the clinical findings of 51 patients with ACAA compared with 50 matched controls. Four significant associations which have never been validated were identified: 1) a dominant A1 (filling both A2's) was found in 57% of ACAA patients versus 14% of controls (p less than 0.001). 2) Unilateral hypoplasia of the opposite A1 was present in 24% of ACAA patients versus 6% of controls (p = 0.01). 3) Exclusive filling of the ACAA from one A1 occurred in 78%. 4) No statistically significant relationship was found between the anatomic flow patterns studied and the patients clinical presentation including age, sex, or grade. We conclude that anterior communicating artery aneurysms are significantly related in a majority of patients with the presence of a dominant A1, probably as the result of enhanced haemodynamic stress caused by this anatomic abnormality in the circulation. However, this association is not constant, and a dominant pattern of flow did not correlate with the clinical course. This is probably a reflection of the differences between factors initiating aneurysm formation and those influencing its growth, as well as of the relative limitations of angiography when pathophysiological extrapolations are attempted.

Adolescent↗
PubMed1991

Noninvasive cerebral optical spectroscopy for monitoring cerebral oxygen delivery and hemodynamics.

OBJECTIVE: To present an algorithm for noninvasive measurement of cerebral oxygen saturation (cerebral oximetry) and cerebral hemodynamics with near infrared spectroscopy. DESIGN: In vitro correlation of oximetry measurements with reference measurements; illustrative cases of hemodynamic and oximetric recordings. SETTING: Tertiary care neuroscience ICU. PATIENTS: Brain-injured patients with a prolonged, decreased level of consciousness chosen as illustrative examples. INTERVENTIONS: Two-channel multiple wavelength diffuse infrared transmission spectroscopy was interfaced with the scalp using adhesive. Transmission data were collected with gross superficial-to-deep spatial resolution. Saturation calculation based on the deep signal was observed longitudinally in the patient. With the same technology, arterial input and cerebral response functions, generated by iv tracer bolus, were deconvoluted to measure mean cerebral transit time. MEASUREMENTS AND MAIN RESULTS: A positive linear regression fit between diffuse transmission oximetry and measured blood oxygen saturation over the range 23% to 99% (r2 = .98, p less than .001) was noted. CONCLUSIONS: The approach used overcomes previously identified difficulties with cerebral oximetry, and demonstrates excellent in vitro correlation. The technique can be performed clinically without difficulty. A simultaneous measure of mean cortical transit time is possible.

Brain↗
PubMed1991

Anatomy of the sympathetic pathways in the carotid canal.

The sympathetic fibers in the carotid canal were studied in 30 unfixed specimens from human cadavers. Thirty petrous internal carotid arteries were injected with red silicone rubber, and the course of the sympathetic fibers was examined after removal of the inferior and superior wall of the carotid canal. The internal carotid artery was removed completely, leaving the sympathetic fibers intact as much as possible. Instead of a plexus-like configuration of the sympathetic fibers around the petrous carotid artery in all specimens, an anterosuperior group and a posteroinferior group of sympathetic fibers were found together, and both closed on the inferior-anterior side of the terminal portion of the horizontal part of the carotid canal. Seventy-three percent of the anterosuperior group of sympathetic fibers consisted of one large bundle, and 27% consisted of two smaller bundles. The majority of the posteroinferior group of sympathetic fibers consisted only of one bundle (93%). In 60% of the specimens, the majority of sympathetic fibers in the carotid canal were found in the anterosuperior group, 20% were found in the posteroinferior group, and in 20%, there was an equal distribution. The formation of the petrous bone and the related structures of the skull base play an important role in the configuration of these groups of sympathetic fibers. This study shows that, in cases of operative intervention in the carotid canal, the anterosuperior group of sympathetic fibers may be encountered. Damage to this bundle may result in sympathicoparesis, as it often contains the most sympathetic fibers. This group of sympathetic fibers can be easily separated from the internal carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Artery, Internal↗
PubMed1991

Microvascular anatomy of foramen caecum medullae oblongatae.

The foramen caecum (FC) is a triangular-shaped fossa situated in the midline on the base of the brain stem, at the pontomedullary junction. Although this area is known to have a very high concentration of brainstem perforating vessels, its microvascular anatomy has not been studied in detail. The purpose of this study was to detail the microvasculature of this territory. Twenty unfixed brains were injected with silicone rubber solution and dissected under a microscope equipped with a camera. The origin, course, outer diameter, and branching pattern of the perforators were examined. The total number of perforators found in the 20 brains was 287, with an average (+/- standard deviation) of 14.35 +/- 1.24 perforators per brain (range seven to 28). Their origin was as follows: right vertebral artery in 52 perforators (18.11%); left vertebral artery in 35 (12.19%); basilar artery below the anterior inferior cerebellar artery (AICA) in 139 (48.43%); basilar artery above the AICA in 46 (16.02%); AICA in 10 (3.48%); and anterior spinal artery in five (1.74%). Most of the perforators arose as sub-branches of larger trunks; their average outer diameter was 0.16 +/- 0.006 mm while that of trunks was 0.35 +/- 0.02 mm. These anatomical data are important for those wishing 1) to study the pathophysiology of vascular insults to this area caused by atheromas, thrombi, and emboli; 2) to plan vertebrobasilar aneurysm surgery; 3) to plan surgery for vertebrobasilar insufficiency; and 4) to study foramen magnum neoplasms.

Arteriovenous Anastomosis↗
PubMed1991

Disabling cerebral transient ischemic attacks.

The surgical management of an emerging clinical entity, namely disabling transient cerebral ischemic attacks, is described. A series of 19 patients treated in a 2-year period (12 with anterior circulation dysfunction and seven with posterior insufficiency) met the following criteria: 1) stereotypical recurrent episodes of transient neurological dysfunction related to the anterior or posterior circulation distribution; 2) failure of maximum medical therapy to control the transient neurological dysfunction; 3) four-vessel cerebral angiography demonstrating an isolated vascular territory corresponding to patient symptoms; 4) inhalation xenon cerebral blood flow studies with at least three of eight probe-pairs showing significant asymmetries in the initial slope index, localizing an area of relative oligemia to the symptomatic hemisphere (anterior circulation only); and 5) severe restriction of lifestyle due to transient ischemic attacks (TIA's). Seventeen patients underwent surgical bypass therapy: deep sylvian superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in nine; surface STA-MCA bypass in three; STA-superior cerebellar artery bypass in three; STA-posterior cerebral artery bypass in one; and aorta-carotid artery bypass in one. There was one perioperative death and four perioperative strokes (two ipsilateral and two contralateral to the operated side). The average follow-up period was 14 months. Of the 16 surviving surgically treated patients, 13 (81%) have had an excellent to good outcome with complete resolution of TIA's and minimal neurological deficits. Three patients had a poor outcome with either a significant persistent neurological deficit or continued TIA's. The two patients not treated surgically continue to have vertebrobasilar insufficiency episodes while receiving oral anticoagulation medication. The overall mortality rate (5.5%) and stroke morbidity rate (22.2%) of surgical therapy for disabling TIA's are high in this neurologically unstable group of patients, but are associated with an 81% excellent to good response. Although the natural history of disabling TIA's is not known, these patients present with significant to total disability due to their symptoms. It is concluded that disabling TIA's respond to surgical revascularization and may represent an indication for cerebral revascularization surgery.

Cerebral Revascularization↗
PubMed1990

Ethnic distribution of intracranial aneurysms.

The reported higher incidences of intracranial arterial aneurysms (IAA) in Africa and Asia raised the question of possible racial differences in aneurysm incidence. This prompted a retrospective study of the 244 cases of IAA seen at the Henry Ford Hospital (HFH) from 1979 to 1985. There were 171 whites and 73 blacks in the study group. The results showed a higher white to black case ratio (2.3:1) than the white to black hospital population ratio (1.14:1). If only bleeding aneurysms were considered, there were 81 whites and 52 blacks, with a white to black case ratio of 1.6:1, thus giving only a borderline racial difference. The peak age of aneurysm incidence was the fifth decade for blacks and the sixth decade for whites. The most common aneurysms sites were: [table: see text]

Adult↗
PubMed1990

Direct surgery for carotid bifurcation artery aneurysms.

Eighteen patients with bifurcation of internal carotid artery aneurysms were treated with direct surgery. In all cases the pterional approach was used. The strategy used in dissecting the aneurysm depends on the size of the aneurysm and the length of the intracranial internal carotid artery. When the aneurysm is small, the bifurcation of the internal carotid artery can be exposed by dissecting along the internal carotid artery from a proximal-to-distal direction. The aneurysm and the perforating vessels adjacent to it are identified before the aneurysm is clipped. When the aneurysm is not small or if the intracranial segment of the internal carotid artery is long, the sylvian fissure has to be dissected open before dissection of the aneurysm and perforators is undertaken. Using this dissection strategy, 18 bifurcations of internal carotid artery aneurysms were clipped with 16 excellent, one good, and one fair result. There was no mortality.

Adult↗
PubMed1990

Use of experimental aneurysms to evaluate wrapping materials.

Experimental venous pouch aneurysms in rats were wrapped with muscle, bovine collagen, muslin, cotton, or polyvinyl alcohol. The rats were killed 6 or 12 weeks later, and the aneurysms were compared with control aneurysms. Bovine collagen and muscle were reabsorbed and the aneurysms were similar to the control group. Cotton, muslin, and polyvinyl alcohol caused fibrosis around the aneurysm. However, giant aneurysms were found in the muslin and polyvinyl alcohol group. Cotton appears to be the most suitable material for wrapping aneurysms. The experimental venous pouch aneurysm model in rats can be used to evaluate wrapping materials.

Animals↗
PubMed1990

Giant intracranial aneurysm surgery: the role of microvascular reconstruction.

The surgical management of 62 anterior circulation giant intracranial aneurysms is presented. Women were affected three times as frequently as men. Thirty-two patients presented with local mass effect, which was the most common mode of presentation, while 26 patients had subarachnoid hemorrhage. Three patients presented with transient ischemic attacks and three patients presented with seizures. In 16 cases the giant intracranial aneurysm involved the cavernous sinus and indirect surgery was performed. Ten patients were treated with extracranial-intracranial bypass and gradual occlusion of the proximal internal carotid artery. Six patients were treated with extracranial-intracranial bypass and trapping of the aneurysm (sudden occlusion of internal carotid artery). Sudden occlusion was poorly tolerated, and 50% of the patients developed ischemic complications. In 46 cases of giant intracranial aneurysm without involvement of the cavernous sinus, direct surgery was undertaken. In 31 patients the aneurysm could be clipped without compromise to the surrounding vessels. In 15 patients there was compromise of surrounding vessels or the aneurysm sac was excised and so microvascular reconstruction was needed. Local intracranial reconstruction was preferred whenever feasible. The results of patients who needed reconstruction were similar to those who did not need reconstruction. Overall, 84% of patients had an excellent or good outcome after surgery. The mortality was 5%.

Adult↗