摘要:

&NA;In this experimental study the feasibility of microsurgical laser‐assisted repair of the oculomotor nerve in the cat was investigated. The 3rd cranial nerve was explored after a temporobasal craniectomy from its exit at the brain stem to its entrance into the cavernous sinus and transected. The cut nerve ends were loosely reapproximated and welded together with a CO2milliwatt laser using a power setting of 80 to 90 mW and a spot size of 150 &mgr;. Regeneration of the oculomotor nerve within an observation period of 12 months as assessed by weekly examination of the pupil diameter was excellent in 4 animals and satisfactory in 2. In the two control groups consisting of 6 animals in which the nerve reconstruction had been performed with fibrin glue or by simple nerve reapproximation minimal nerve regeneration could be observed only in one animal. The histomorphological examinations revealed good regeneration across the laser anastomosis including new formation of a perineural sheath without any significant scarring effect or constriction at the anastomotic site. It is concluded that the CO2milliwatt laser might be a useful tool for the microsurgical repair of cranial nerves and should possibly be incorporated into the neurosurgical armamentarium of reconstructive cranial nerve surgery. (Neurosurgery25:579‐583,1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;End‐to‐side, laser‐assisted vascular anastomosis (LAVA) using a Nd:YAG laser was successfully performed on rat carotid arteries. A midline neck incision allowed isolation and approximation of both carotid arteries in an end‐to‐side fashion using four 10‐0 nylon stay sutures. The laser parameters used for vessel fusion were 0.3‐second 5‐W pulses at a spot size of 600 &mgr;m. Anastomoses were analyzed at various time intervals from 1 day to 6 months by angiogram and histological examination. The anastomotic patency was 86%. Aneurysm formation occurred in 23%. Histological examination revealed an acute/subacute transmural injury both at the anastomotic site and several hundred microns away, with delayed re‐endothelialization and some attempt at muscular and elastic regeneration. Histological assessment of the aneurysms demonstrated a total loss of the internal elastic lamina and muscularis. A brief discussion comparing Nd:YAG LAVA to other LAVA techniques follows. (Neurosurgery25:584‐589, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;Premature lysis of subarachnoid blood clots by thrombolytic substances such as urokinase and plasmin has been shown to be efficacious in preventing cerebral vasospasm in clinical and experimental investigations. Recently, tissue plasminogen activator (rtPA) derived from recombinant deoxyribonucleic (DNA) technology has been introduced as a new thrombolytic substance. With its high affinity for fibrin‐bound plasminogen and low affinity for circulating plasminogen by which a clot‐selective fibrinolysis can be achieved without the danger of inducing systemic fibrinogenolysis, rtPA might be the ideal substance for the postoperative lysis of cisternal blood accumulations after subarachnoid hemorrhage. The efficacy of rtPA in preventing delayed cerebral vasospasm after experimental subarachnoid hemorrhage using a single intracisternal bolus injection of this agent was investigated. With a single injection of 25 &mgr;g of rtPA into the cisterna magna 48 hours after the first and 6 hours after the second injection of blood in the two‐hemorrhage model of cerebral vasospasm, angiographic spasm of the basilar artery was completely prevented in all animals so treated whereas in the control group severe vasospasm occurred. Autopsy studies of the experimental animals demonstrated that the subarachnoid blood clots were almost completely removed by intracisternal rtPA application. Additionally the pathomorphological signs of proliferative vasculopathy present in all animals of the control group were not demonstrable in the rtPA group. As intracisternal bolus injection of rtPA is highly efficacious in preventing angiographic as well as pathomorphological vasospasm, it is concluded that use of this thrombolytic substance might be a promising approach for pharmacological blood clot removal. (Neurosurgery25:590‐598, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;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. (Neurosurgery25:599‐605, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;Perturbations in cerebral hemodynamics at the time of ablation of an arteriovenous shunt have been regarded as important in the pathogenesis of swelling and hemorrhage complicating resection of arteriovenous malformations (AVMs). A carotid‐jugular fistula model in the rat had previously been investigated and found to simulate in part the nonhemorrhagic pathophysiology of a large cerebral arteriovenous fistula. Utilizing this model and measuring cerebral blood flow in 14 regions with a [14C]iodoantipyrine autoradiographic technique, the effects of hypocapnea on the cerebral circulation in opened and closed fistulas were investigated. Regional cerebral blood flow (rCBF) in control animals ranged from a median of 53 to 64 ml/100 g/min at a partial arterial carbon dioxide pressure (PaCO2) of 28 ± 2 mm Hg and 85 to 112 ml/100 g/min at a PaCO2of 40 ± 5 mm Hg. In animals with an open carotid‐jugular fistula created 12 weeks before the study, these median rCBF values at comparable PaCO2levels ranged, respectively, from 15 to 39 ml/100 g/min and 50 to 68 ml/100 g/min (the 25th percentile for the open fistula in the hypocapneic group was 15 ml/100 g/min in 5 of the 14 regions studied). In contrast, median rCBF in the closed fistula group ranged from 73 to 100 ml/100 g/min in hypocapneic animals and from 118 to 187 ml/100 g/min in normocapneic animals. These results demonstrate the preservation of CO2reactivity; hypoperfusion in the presence of a carotid‐jugular fistula, hyperemia on fistula occlusion, and the potential to induce cerebral ischemia with hyperventilation in this model of a cerebral arteriovenous fistula. These data caution against the use of hyperventilation during surgery in patients with cerebral arteriovenous malformations. (Neurosurgery25:606‐612, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;The existence of uric acid in mammalian brain was recently reported, but it has not yet become a consensus. The mammalian brain has been thought to lack xanthine oxidase, which catalyzes hypoxanthine to xanthine and xanthine to uric acid as the last steps of ATP degradation in other tissue. Using high‐performance liquid chromatography, we performed assays for hypoxanthine, xanthine, and uric acid in rat brain after cerebral ischemia. It was confirmed that all three substances showed significant augmentation in the removed brains and that the chronological order of those increases corresponded to the order in the metabolic pathway. Allopurinol, a specific inhibitor of xanthine oxidase, significantly suppressed the increases in uric acid and xanthine, and a compensatory accumulation of hypoxanthine was observed. From these results, it was concluded that uric acid does exist in the brain, increases after ischemia, and is possibly the end product of purine degradation in the brain. Furthermore, it is suggested that xanthine oxidase exists in the brain and catalyzes the reaction from hypoxanthine to xanthine and then to uric acid. These reactions catalyzed by xanthine oxidase are considered to be a source of free radicals and may play important roles in the pathogenesis of cerebral ischemic injury. (Neurosurgery25:613‐617, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;A review of the development and current methods of surgical revascularization of the cerebral circulation is presented. In addition to the conventional superficial temporal artery to middle cerebral artery (STA‐MCA) bypass, the techniques of interposition vein grafting and vertebrobasilar revascularization are discussed. The results and implications of the International Cooperative Study are reviewed. Extracranial‐intracranial (EC‐IC) bypass grafting remains an essential procedure in the treatment of many cerebrovascular conditions, including Moya Moya disease and giant intracranial aneurysms. The efficacy of interposition vein grafts, as well as the EC‐IC bypass in the treatment of vertebrobasilar insufficiency, acute cerebral ischemia, cerebral vasospasm, and multi‐infarct dementia, remains to be determined. Several alternative revascularization procedures, including proximal MCA anastomosis and omental transposition, are in development. (Neurosurgery25:618‐629, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;Three patients with excruciating glossopharyngeal neuralgia underwent microsurgical operations in the posterior cranial fossa. In each patient, neurovascular compression was found involving the posteroinferior cerebellar artery and involving the 9th and 10th cranial nerves. In two of the patients, the compression was caused by arachnoiditis and in the other by an arterial loop. In each patient, neuralgia was successfully eliminated by microvascular decompression and by section of the upper rootlets of the vagus nerve. In one patient, partial section of the 9th cranial nerve was also performed. Because of the frequent involvement of the vagus nerve in the pathogenesis of this condition, open surgery should be preferable to percutaneous thermorhizotomy, which is unable to act selectively on the 10th cranial nerve. (Neurosurgery25:630‐632, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;Heterotopia of the cerebral cortex, a disorder of neuronal migration, may be associated with medically intractable seizures. We report on a patient with bihemispheric cortical heterotopia who had medically intractable atonic seizures that were successfully treated by corpus callosotomy. The clinical and radiographic aspects of cortical heterotopia and the surgical management of seizures associated with heterotopia are discussed. (Neurosurgery25:633‐636, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

&NA;Three patients with different neurological complaints were studied by magnetic resonance imaging. Coincidentally, all studies showed cystic changes within the pineal bodies. These cysts appeared hypointense on T1‐weighted, spin‐echo pulse sequences and hyperintense on T2‐weighted images. Spin‐density sequences displayed them as hypointense areas, with relaxation times similar to those of the CSF, suggesting their cystic nature. The increased use of magnetic resonance imaging may result in coincidental imaging of involutional cystic pineal changes of many individuals; their characteristic appearance will allow the differentiation between them and pineal neoplastic conditions. (Neurosurgery25:636‐640, 1989)

ISSN:0148-396X    

出版商:OVID    

年代:1989

数据来源: OVID