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Biomedical subjects

S J Peerless

Publications and source records attributed to S J Peerless.

At least 55 records · Page 3Linked to original sources
PubMed1982

Platelet interaction within giant intracranial aneurysms.

Turbulence within intracranial aneurysms may result in tearing of the aneurysmal wall, exposing the subendothelial matrix to circulating platelets. In this study, platelet interaction in giant intracranial aneurysms was evaluated by a dual-isotope technique employing In-labeled platelets and Tc-labeled red blood cells. The use of two isotopes allows the subtraction of the blood pool and the calculation of the ratio indium deposited:indium blood pool (In(D)/In(BP)). A ratio greater than zero indicates platelet deposition within aneurysm. Thirteen patients were evaluated in this way, with platelet deposition demonstrated in six. In these six patients, the ratio In(D)/In(BP) was found to be significantly elevated, with a mean value of 0.96 +/- 0.65. Three of these six patients has symptoms of recurrent transient neurological deficits; one of these three suffered a complete stroke following documentation of platelet deposition. In this case, the aneurysm was obtained at surgery and was found to contain intraluminal platelet aggregation when viewed by scanning electron microscopy. In the remaining seven patients, the ratio IN(D)/In(BP) was found not to be significantly elevated (mean -0.03 &/- 0.06), indicating the absence of active platelet deposition. Two of these patients had prior symptoms of cerebral ischemia; one of these was found to have an ulcer in the ipsilateral internal carotid artery which was probably responsible for thromboembolic events to the hemisphere. The authors conclude that platelet aggregation occurs more frequently than previously recognized in giant intracranial aneurysms, and their data substantiate the hypothesis that platelet metabolic products or thrombi originating from a large aneurysm may embolize to distal cerebral vessels.

Adult↗
PubMed1981

Trigeminal neuralgia: a comparison of the results of percutaneous rhizotomy and microvascular decompression.

Seventy-five patients were treated between March 1976 and June 1980 for classical idiopathic tic douloureux. Fifty-five patients underwent percutaneous trigeminal rhizotomy (PTR) and twenty-four had posterior fossa microvascular decompression (MVD) of the trigeminal nerve. Four patients had both procedures. In the PTR group, 4% were immediate failures, 42% had a delayed recurrence of pain, while 54% remained totally pain free with an average follow-up of 30 months. In the MVD group, 12% were immediate failures, 17% had a delayed recurrence of pain, and 71% have remained free of pain with a average follow-up of 28 months. Neither procedure can be regarded as ideal surgical treatment for patients with pain refractory to medical treatment. Percutaneous rhizotomy has an established place because of its safety, particularly in elderly patients. A high rate of recurrent pain is to be expected. Microvascular decompression has appeal in younger patients because of its non-destructive nature but the long term efficacy of the procedure is not known.

Aged↗
PubMed1981

Continuous suture method for microvascular anastomosis: technical note.

A continuous suture technique for microvascular end-to-side anastomosis was tested in an animal model. Twenty-five Wistar rats underwent carotid-to-carotid end-to-side anastomoses using the conventional interrupted suture technique, and another 25 animals underwent similar operations using a continuous suture method. Anastomosis patency, growth, and vessel clamp time during the operation were recorded. The continuous suture technique was found to have equivalent growth and patency figures and to be much faster than the interrupted suture method.

Animals↗
PubMed1981

[Protective effect of fluosol-DA in acute cerebral ischemia (author's transl)].

Fluosol-DA (Perfluorochemical Blood Substitutes) are small particle fluorocarbons suspended in an emulsion and have a high propensity for carrying oxygen and carbon dioxide. Fluosol-DA was investigated for the modification of acute focal cerebral ischemia and compared with mannitol. A total of 36 adult cats was divided into three groups and underwent transorbital microtourniquet ligation of the middle cerebral artery (MCA). Control animals were given intravenous isotonic saline. Animals in the experimental groups were treated with either intravenous Fluosol-DA or Mannitol. All animals were nursed in an oxygen chamber and four cats from each group were sacrificed at 1, 3 and 6 hours after MCA occlusion. The results of macroscopic and histological examination of the brain suggested Fluosol-DA had a remarkable protective effect on acute focal cerebral ischemia which was in keeping with the observed neurological outcome. It is suggested that Fluosol-DA may support flow in the microcirculation and the small particles of Fluosol-DA may be able to reach the area of ischemia via collaterals by decreasing blood viscosity, preventing narrowing of the arteriolar and capillary lumen and increasing the cerebral blood flow.

Acute Disease↗
PubMed1980

Treatment of ischemic deficits from cerebral vasospasm with high dose barbiturate therapy.

In 12 patients with life-threatening neurological deficits from vasospasm refractory to other measures, high dose barbiturate therapy was used in an attempt to prevent permanent changes in the brain. In each case angiography was performed and intracranial pressure was measured. Dexamethasone, a low molecular weight dextran, and mannitol were administered. If intracranial pressure (ICP) was elevated, drainage of cerebrospinal fluid and hyperventilation were used. Arterial pressure was maintained at not less than 140/90 preoperatively and 180/100 postoperatively. Barbiturate therapy was continued until vasospasm decreased angiographically and ICP was normal. Eleven of the 12 patients perished. One had a fatal rebleed. One died of an iatrogenic hemothorax. Four died from uncontrollable intracranial hypertension. One improved slightly and then died from a cardiac arrhythmia. One died of increased ICP when her ventriculostomy malfunctioned. One improved and was responding purposefully to pain, only to die suddenly with a low ICP. Two patients became awake and responsive to verbal commands; 1 of these died from Klebsiella meningitis and the other died from an intracerebral hematoma. In the 3 patients in whom hypothermia was also used, profound alterations in acid-base and fluid electrolyte balance occurred. These discouraging results are most likely a reflection of the severity of the patients' condition at the beginning of therapy. There may be some benefit of barbiturates in the management of vasospasm, and the potential effectiveness of barbiturates may be more obvious if therapy is started at an earlier stage. However, until further evidence of the usefulness of this modality becomes manifest, it should be limited to patients with life-threatening impairments unresponsive to all other measures.

Adolescent↗
PubMed1976

The reactivity of canine cerebral arteries to O2 and CO2 in vitro.

The responses of canine middle cerebral arteries to changes in pCO2 and pO2 were tested in vitro. It was found that there was no response to changes in pCO2 from 38.1 mm. Hg to 26.6 mm. Hg, but there was some constriction of the vessels with lowering of the pCO2 below 26.6 mm. Hg and there was minimal dilatation of the vessels when the pCO2 was increased from 38.1 mm. Hg to 87.2 mm. Hg. There was no response to changes in pO2 from more than 55 mm. Hg to 59.6 mm. Hg, but when pO2 was lowered below 50 mm. Hg there was a sudden, massive constriction of the arteries tested. It is postulated that this constriction is due to build-up of a substance (substances) during a period of hypoxia (pO2 less than 50 mm. Hg). The significance of the results obtained are discussed.

Animals↗