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Biomedical subjects

D S Samson

Publications and source records attributed to D S Samson.

At least 19 recordsLinked to original sources
PubMed1999

Multidisciplinary approach to traumatic intracranial aneurysms secondary to shotgun and handgun wounds.

BACKGROUND: Traumatic intracranial aneurysms (TICAs) may develop following gunshot injuries to the head. Management of these lesions often combines various aspects of microneurosurgical and endovascular techniques to safely repair or obliterate vessel defects. METHODS: We reviewed our experience over the last 18 years and identified five cases of intracranial aneurysms following gunshot and handgun wounds that were treated surgically and/or endovascularly. RESULTS: All patients had successful obliteration of their lesions using a variety of therapeutic modalities aimed at preserving neurologic function while at the same time eliminating the aneurysm from the circulation. CONCLUSION: Both microneurosurgery and endovascular surgery have important roles to play in the management of TICAs. In some cases, both methods can be combined to eliminate lesions and maximize patient recovery in a safe, efficient, and effective fashion.

Adult↗
PubMed1994

Combined transsylvian-subtemporal exposure of cerebral aneurysms involving the basilar apex.

The surgical repair of cerebral aneurysms involving the apex of the basilar artery continues to undergo refinement and evolution. The inherent difficulty in accessing the basilar apex as well as the complexities of the microanatomy render this area a notoriously hazardous and technically challenging region in which to perform microsurgical clipping of cerebral aneurysms. Several operative approaches have been described and are constantly undergoing a state of evolution in the hopes of optimizing the exposure of the distal basilar artery and minimizing the inherent risks of surgery. The consistent decline in operative morbidity has paralleled improved understanding of the microvascular anatomy, both in this region and along the various corridors of approach. No single operative approach is universally superior, considering the wide variability of individual patient anatomy and vascular configurations. Each approach has strengths, weaknesses, and potential complications that must be considered in the though process of planning an operative attack on a basilar apex aneurysm. Intimate familiarity with the microvasculature and the microsurgical anatomy of the region is an imperative prerequisite for the application of any surgical approach to this region. This paper outlines a detailed review of the microsurgical anatomy that is pertinent to microsurgery of aneurysms in this region, and describes an approach referred to as the combined transsylvian-subtemporal approach. We have found this operative approach particularly useful in aneurysm surgery of the basilar apex but do not mean to imply that this single approach is suitable for all surgeons or all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Basilar Artery↗
PubMed1994

Surgery for paraclinoidal carotid artery aneurysms.

Aneurysms arising from the proximal carotid artery between the roof of the cavernous sinus and the origin of the posterior communicating artery pose conceptual and technical surgical problems with regard to acquisition of proximal control and safe intracranial exposure. Over the past 3 1/2 years, 89 patients with paraclinoidal aneurysms have been treated at the University of Texas Southwestern Medical Center. Thirty-nine (44%) of these patients presented with subarachnoid hemorrhage. A total of 149 aneurysms and six arteriovenous malformations have been identified in this patient group such that 38 (43%) of the patients suffered multiple vascular anomalies. Temporary artery occlusion has been employed during operation in 48 cases (54%), permanent carotid artery occlusion in four (4%), and hypothermic circulatory arrest in two (2%). Twenty-two patients harbored giant aneurysms, seven of which had ruptured. Outcome was considered good in 77 patients (86.5%), fair in eight (9%), and poor in three (3%); one patient died. This concentrated experience permitted a practical anatomical grouping of aneurysms into three types: carotid-ophthalmic artery aneurysms with a superior or superomedial projection (44 cases); superior hypophyseal aneurysms with a medial or inferomedial projection (26 cases); and proximal posterior carotid artery wall aneurysms projecting posteriorly or posterolaterally (19 cases). Despite the fact that paraclinoidal aneurysms often disobey the traditional teachings of aneurysm development, having no vessel of origin or clear hemodynamic cause, this practical grouping has allowed individualized and focused operative approaches unique to each aneurysm projection with good visual function and outcome in most patients.

Carotid Artery Diseases↗
PubMed1992

The transcranial Doppler appearance of acute carotid artery occlusion.

Transcranial Doppler ultrasound is a noninvasive technique of cerebral blood velocity measurement that is being increasingly used to detect untoward hemodynamic changes. In this report, we describe striking transcranial Doppler ultrasound changes occurring in 2 patients after cervical carotid artery occlusion that led to cerebral infarction. These changes consist of the sudden appearance of a Doppler signal of extremely low pulsatility and moderately high velocity in the middle cerebral artery distribution. In 1 patient, this signal was the first sign of carotid occlusion. We suggest that these transcranial Doppler ultrasound changes can provide an early warning of carotid artery compromise.

Acute Disease↗
PubMed1991

Emergent aneurysm surgery without cerebral angiography for the comatose patient.

Neurologically based clinical grading scales offer excellent prognostic information for the patient suffering diffuse subarachnoid hemorrhage (SAH). These grading scales are less applicable to patients with life-threatening intraparenchymal hematomas after aneurysmal rupture. During the last 3 years, four patients in a comatose state with brain stem compression syndromes documented by computed tomographic scans have undergone emergent operation in our neurosurgical service. Each patient was so critically ill that we believed it unwise to delay craniotomy for diagnostic angiography. The average delay from the onset of coma to skin incision was 3.02 hours (range, 1.67-6.5 hours), and the average delay from arrival in our unit until skin incision was 1.8 hours (range, 0.75-2.5 hours). The condition of two arousable patients deteriorated while they were in the emergency room, presumably from new bleeding. Each patient underwent craniotomy for hematoma evacuation, definitive aneurysm clipping, and lobectomy for decompression. Temporary clipping was employed in one patient, and intraoperative rupture occurred in two others. Three patients survived but retain significant disability. Emergent craniotomy with empiric exploration of appropriate subarachnoid cisterns after hematoma decompression may be life-saving in some cases. The delay imposed for diagnostic angiography may be avoided in attempts to save vital minutes of severe brain stem compression.

Adult↗
PubMed1990

Retrograde suction decompression of giant paraclinoidal aneurysms. Technical note.

Giant paraclinoidal carotid artery aneurysms frequently require temporary interruption of local circulation to facilitate safe occlusion. Due to brisk retrograde flow through the ophthalmic artery and cavernous branches, simple trapping of the aneurysm by cervical internal carotid artery clamping and intracranial distal clipping may not adequately soften the lesion. The authors describe a retrograde suction method of aspiration of this collateral supply which they have used in over 40 cases. After temporary trapping, a No. 18 angiocatheter is inserted into the cervical internal carotid artery. This catheter is then connected to a wall suction point allowing rapid aneurysm deflation. This technique, accomplished by the surgical assistant, permits the surgeon the freedom to use both hands in dealing quickly with the aneurysm.

Carotid Artery Diseases↗
PubMed1989

Evidence of redistribution of cerebral blood flow during treatment for an intracranial arteriovenous malformation.

The presence of an intracranial arteriovenous malformation has a dramatic impact on local circulatory dynamics. Treatment of some arteriovenous malformations can result in disastrous hyperemic states caused by redistribution of previously shunted blood. This report describes serial hemodynamic measurements of both cerebral blood flow and flow velocity in 3 patients during treatment for arteriovenous malformations. Measurements of cerebral blood flow were made by computed tomographic scan employing the stable xenon inhalation technique; flow velocity, including autoregulatory characteristics, was measured by transcranial Doppler ultrasonogram. Substantial hyperemia developed in one patient (Case 1) after resection and in another (Case 3) after embolization. Embolization resulted in restoration of normal regional cerebral blood flow in a patient who demonstrated hypoperfusion before treatment (Case 2). In Patient 1, postoperative hyperemia was associated with persistently elevated flow velocities, and may have been accompanied by hemispheric neurological deficits. Sequential hemodynamic measurements may predict patients at risk of perioperative complications, and may become useful clinical guidelines for the extent and timing of embolization and for the timing of surgery after intracranial hemorrhage or preoperative embolization procedures.

Adult↗
PubMed1989

Causes of morbidity and mortality from surgery of aneurysms of the distal basilar artery.

Despite modern neurosurgical technology and neuroanesthetic care, treatment of aneurysms of the distal basilar artery remains fraught with complications. Between 1982 and 1988, 126 patients with aneurysms of the distal basilar artery who had been treated by 2 surgeons were retrospectively analyzed to determine the causes of morbidity and mortality from this disease and its treatment. Ten patients (8%) died, and 14 patients (11%) suffered permanent neurological disability after treatment. The causes of failed management could be grouped into the following categories: 1) direct effects of hemorrhage; 2) errors in surgical timing; 3) conceptual errors; 4) technical errors; 5) morbidity from delayed cerebral ischemia; and 6) complications of hypertensive/hypervolemic therapy for symptomatic vasospasm; a small group of patients who died despite having received what we consider excellent management were grouped under a seventh category, "bad luck." Frequently, patients who did poorly suffered from multiple complications, each of which contributed to their overall morbidity. It is our hope that increased awareness of these potential pitfalls and the further evolution of intravascular technique in selected cases will, in time, improve the outlook for patients suffering from these dangerous lesions.

Adult↗
PubMed1989

Microfibrillar collagen model of canine cerebral infarction.

A new canine model of focal cerebral ischemia has been developed employing intravascular delivery of microfibrillar collagen via femoral catheterization. In 13 dogs, dose-effect studies showed neurologic deficits (ranging from mild hemiparesis to death) related to the dose of microfibrillar collagen delivered. In another 10 dogs, 0.5 ml of 60 mg/ml microfibrillar collagen was injected into the common carotid artery; neurologic assessment over 48 hours revealed a survivable stroke syndrome in seven dogs, death at 40 hours in one dog and at less than 12 hours in another, and no clinical effect in one dog. The eight surviving dogs were sacrificed at 48 hours; nine of the 10 dogs had middle cerebral artery distribution infarcts (two grossly hemorrhagic and five grossly nonhemorrhagic) on histologic examination. Angiography in three dogs demonstrated no significant major vascular occlusion. All seven dogs with survivable strokes demonstrated a dense hemiparesis at 24 hours that improved to ambulatory status at 48 hours. The use of microfibrillar collagen to produce middle cerebral artery strokes in dogs provides a new opportunity to study cerebral ischemia without surgery involving the cervical or cranial vasculature. Dogs have larger brains than other common animal models and thus are more amenable to study with imaging modalities. A model with a measurable but survivable insult provides an opportunity for short- and long-term clinical follow-up and for the investigation of therapeutic interventions.

Animals↗
PubMed1989

Reversible middle cerebral artery embolization in dogs without intracranial surgery.

Using dogs, we developed an intravascular model for reversible middle cerebral artery occlusion that does not involve intracranial surgery or enucleation. Using silicone plastic plugs with a suture embedded within them, we embolized the middle cerebral artery in 19 dogs via the cervical carotid artery. The free end of the suture remained accessible in the neck, and after variable dwell times traction was placed on the suture and the plug was withdrawn. Placement of the plug in the middle cerebral artery produced ischemia in the basal ganglia. The degree and distribution of cortical ischemia were variable as evidence by the pathologically documented scattered nature of infarcts that resulted when the plug was left permanently in the middle cerebral artery and when it was removed after 1 or 2 hours. Angiography demonstrated occlusion of the middle cerebral artery with the plug in place as well as reperfusion when the plug was withdrawn. This modification of a previously described model of middle cerebral artery occlusion provides an opportunity to study structural, physiologic, and biochemical events occurring in acutely hypoperfused cerebral tissue as well as critical changes leading to irreversible injury without the disadvantages of surgical manipulation required by all previous models of reversible cerebral ischemia.

Animals↗