Method to perform IV injections on mice using the facial vein.

A novel technique for gaining IV access in a mouse model is presented. Using a cut-down approach, the facial vein is identified through an incision from anterior to the external auditory meatus to posterior to the lateral ispilateral canthus. A small gage needle (30gauge) may be inserted to inject medications. A high success rate (93%) as determined by direct visualization is achieved. The technique would prove especially useful for animals slated for kinematic testing as the incision does not interfere with the animal's ventral surface.

Effects of adenosine and 2-chloroadenosine on cerebral collateral vessels.

Adenosine is a potent cerebral vasodilator. We tested the hypothesis that dilatation of collateral vessels in cerebrum, in response to topical adenosine and 2-chloroadenosine (2-CAD), would increase blood flow to collateral-dependent cerebrum. In dogs anesthetized with halothane, a branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally. The collateral-dependent area at risk for infarction was perfused from a reservoir with microsphere-free blood, and blood flow to normal cerebrum and to cerebrum dependent on collateral flow was measured with radioactive microspheres injected into the left ventricle through a femoral artery catheter. Perfusion through the cannulated MCA branch was stopped, and flow to normal and collateral-dependent cerebrum was measured after adenosine (10(-2) M) or 2-CAD (10(-4) M) was added to the superfusate over the cerebrum. In normal cerebrum, topical application of adenosine increased flow to outer but not inner layers. Topical application of adenosine had little effect on flow to collateral-dependent tissue. In normal cerebrum, 2-CAD increased flow to outer layers, whereas flow to inner layers tended to increase. During 2-CAD, flow to outer cortical layers of collateral-dependent cerebrum increased from 140 +/- 20 ml/100 g/min (mean +/- SD) to 231 +/- 68, whereas flow to the inner collateral-dependent tissue did not change. The findings indicate that, after occlusion of a cerebral artery, topical 2-CAD increases blood flow to outer layers of collateral-dependent and normal cerebrum.(ABSTRACT TRUNCATED AT 250 WORDS)

Augmentation of blood flow through cerebral collaterals by inhibition of nitric oxide synthase.

We examined the influence of nitric oxide (NO) on normal and collateral cerebral blood flow after occlusion of the middle cerebral artery (MCA). Effects of NG-nitro-L-arginine (nitroarginine), an inhibitor of NO synthase, were examined during normotension and hypotension (arterial pressure, 50 mm Hg) in 49 anesthetized dogs. Following a craniotomy, a branch of the MCA was cannulated, and collateral-dependent tissue was identified using the shadow-flow technique. Regional cerebral blood flow was measured with microspheres, and pial artery pressure was measured with a micropipette. Intravenous nitroarginine reduced blood flow to normal cerebrum by approximately 40% (p < 0.05) during normotension and hypotension, with aortic pressure maintained constant after nitroarginine administration. Injection of nitroarginine during hypotension, without control of pressor effects, increased aortic and pial artery pressure approximately twofold. Concurrently, blood flow to normal cerebrum decreased (p < 0.05), while flow to collateral-dependent cerebrum increased (p < 0.05). Phenylephrine was infused during hypotension to increase arterial pressure to values similar to those achieved following nitroarginine. Blood flow to collateral-dependent cerebrum increased (p < 0.05), but flow to normal cerebrum was not altered during infusion of phenylephrine. Thus, inhibition of NO synthase during hypotension increases arterial pressure, decreases blood flow to normal cerebrum, and increases blood flow to collateral-dependent cerebrum. Phenylephrine also increases perfusion pressure and blood flow to collateral-dependent cerebrum, but in contrast to nitroarginine, it does not redistribute blood flow from normal cerebrum.

Management of radiation-induced accelerated carotid atherosclerosis.

Patients with long survival following cervical irradiation are at risk for accelerated carotid atherosclerosis. The neurologic presentation in these patients mimics naturally occurring atheromatous disease, but patients often present at younger ages and with less concurrent coronary or systemic vascular disease. Hypercholesterolemia also contributes to this accelerated arteriosclerosis. Angiographic findings in this disorder include disproportionate involvement of the distal common carotid artery and unusually long carotid lesions. Pathologic findings include destruction of the internal elastic lamina and replacement of the normal intima and media with fibrous tissue. This article describes two surgical patients with radiation-induced accelerated carotid atherosclerosis who typify the presentation and characteristics of this disease.

Pulmonary embolization and infarction. An iatrogenic complication of transcatheter embolization of a cerebral arteriovenous malformation with polyvinyl alcohol sponge.

Transcatheter embolization therapy of vascular abnormalities is a well-accepted technique. It is particularly useful in the preoperative management of cerebral arteriovenous malformations, in which the risk of significant hemorrhage at surgery would otherwise be unacceptably high. A patient developed symptomatic pulmonary emboli and infarction following an uneventful embolization using polyvinyl alcohol particles. The authors believe this to be the first reported case of this complication of embolic therapy using polyvinyl alcohol.

Technical controversies in carotid artery surgery.

Carotid endarterectomy has become a routine and safe therapeutic strategy in most neurovascular centers. Wide diversity of opinion and considerable debate, however, persists concerning the ideal methods of anesthetic management, cerebral protection, intraoperative monitoring, and arterial repair. We have examined and summarized the current status of these controversies and have identified several new techniques that hold promise for further development.

Posterior interosseous nerve palsy after brachiocephalic arteriovenous fistula construction: report of two cases.

Two cases of delayed posterior interosseous nerve palsy after brachiocephalic arteriovenous fistula creation are presented. Both patients suffered from end-stage renal disease, necessitating chronic hemodialysis. After fistula construction, both developed progressive weakness of the muscles innervated by the posterior interosseous nerve. One patient also demonstrated sensory loss in the distribution of the superficial radial nerve. Electrophysiological studies confirmed posterior interosseous mononeuropathies in both cases. Surgical exploration demonstrated posterior interosseous nerve continuity, with severe compression from the hypertrophied venous limb of the arteriovenous fistula. The superficial radial nerve was also compressed in one patient. After neurolysis and fistula revision, both patients recovered neurological function.

Technical issues in carotid artery surgery 1995.

In reviews in the 1980s, we discussed both indications for and surgical techniques in carotid endarterectomy. Significant changes in the practice of extracranial cerebrovascular reconstruction have occurred over the past few years. The newest indications and cooperative study data have recently been discussed by Camarata and Heros in this topic review series. In this article, we aim to review the advances in operative monitoring and surgical techniques of the last decade. We would be remiss, however, not to note that the latest Asymptomatic Carotid Atherosclerosis Study data, released in September 1994, indicate that carotid endarterectomy is significantly superior to medical therapy for asymptomatic stenosis of > 60%. These data, along with the North American Symptomatic Carotid Endarterectomy Trial results, will revitalize and lend scientific validity to carotid artery reconstruction.

Bilateral (mirror-image) aneurysms at the origin of the posteroinferior cerebellar artery: case report.

OBJECTIVE AND IMPORTANCE: This case demonstrates mirror-image aneurysms at the origin of the posteroinferior cerebellar arteries. To the best of our knowledge, this location has not been previously described. Identification of this entity is important for surgical planning. CLINICAL PRESENTATION: The patient presented with a history of a sentinel headache 1 week before his Grade I subarachnoid hemorrhage occurred. Before operative intervention, the patient developed acute deterioration of his mental status from hydrocephalus. After appropriate treatment for the hydrocephalus, he maintained a stable neurological course throughout evaluation and therapy. INTERVENTION: The patient underwent bilateral clipping of his aneurysms in a prone position without consequence. CONCLUSION: This case demonstrates a highly unusual mirror-image aneurysm of the proximal posteroinferior cerebellar arteries. Although multiple aneurysms are commonplace, to the best of our knowledge, this is the first reported case of bilateral posteroinferior cerebellar artery aneurysms at their origin. Also, the surgical approach is unique and allows bilateral clipping at the same operative setting.

Effect of N-methyl-D-aspartate and inhibition of neuronal nitric oxide on collateral cerebral blood flow after middle cerebral artery occlusion.

OBJECTIVE: To study the role of N-methyl-D-aspartate (NMDA) receptor activation and selective inhibition of neuronal nitric oxide synthase with 7-nitroindazole (7-NI) on blood flow to collateral-dependent tissue (CDT) after middle cerebral artery (MCA) occlusion. METHODS: A left craniotomy was performed in each of 11 dogs with the animals under halothane anesthesia. A branch of the MCA was occluded and cannulated distally for determination of CDT, using a "shadow flow" technique. Cerebral blood flow (CBF) and vascular pressures were measured and used to calculate vascular resistance. TECHNIQUE: Our shadow flow model has the ability to identify an area of CDT, with minimal contamination from overlap flow within a morphologically identified "risk area" for MCA branch occlusion. RESULTS: NMDA increased blood flow to CDT by 56.2%, while normal ipsilateral and contralateral cerebrum increased by at least 35% from baseline. 7-NI caused a significant drop in regional CBF, with the greatest drop of 41.7% occurring in the CDT. Normal ipsilateral and contralateral CBF was reduced by 31.7 and 23.9%, respectively. The dilator response to NMDA was significantly attenuated after 7-NI administration, except in CDT where flow increased ("inverse steal"). Cerebral vascular resistance decreased in response to NMDA and increased with 7-NI. CONCLUSION: Neuronal nitric oxide production seems to play an important role in regulating vascular tone and CBF to CDT after MCA occlusion. Selective preservation of blood flow to CDT seems to be mediated by NMDA receptor activation but independent of neuronal nitric oxide production.

Current status of carotid endarterectomy for atheromatous disease.

The authors discuss the indications for both elective and emergency carotid endarterectomy. Reports on the surgical treatment of asymptomatic bruit and contralateral carotid stenosis are reviewed. The results of endarterectomy for symptomatic carotid disease, including transient ischemic attacks, acute neurological deficit, and complete carotid occlusion, are discussed. The complications and risks of carotid surgery are also presented.

Effects of etomidate administration on cerebral collateral flow.

OBJECTIVE: Augmentation of blood flow to collateral-dependent tissue (CDT) as a result of selective vasodilation of collateral vessels has been shown to occur with various stimuli after middle cerebral artery occlusion. Etomidate, a carboxylated imidazole derivative, is a nonbarbiturate anesthetic that is used clinically both as an anesthetic and as a neuroprotective agent. The effect etomidate has on collateral cerebral vessels is unknown. The purpose of our studies was to test whether etomidate selectively augmented cerebral blood flow (CBF) to CDT during ischemia as an additional mechanism of neuroprotection. METHODS: A left craniotomy was performed in each of 14 dogs, with the animals under halothane anesthesia. A branch of the middle cerebral artery was occluded and cannulated distally for determination of CDT using a "shadow flow" technique. CBF and vascular pressures were measured and used to calculate vascular resistance. An etomidate infusion (0.1 mg/kg of body weight/min administered intravenously) was started, and CBF and vascular pressures were measured at 10 and 40 minutes. Hypotension was then induced, and CBF and pressures were again measured. RESULTS: CBF was significantly reduced in all regions of the brain, including CDT, when etomidate was infused. CDT showed a 53.7% reduction in flow, whereas normal CBF was reduced by at least 63.4%. During hypotension, blood flow to CDT was reduced by an additional 42.7%, whereas normal cerebrum was reduced by at least 22.7%. Vascular resistance was increased in all vessels during etomidate infusion. CONCLUSION: The neuroprotective effects of etomidate do not seem to be through the augmentation of collateral or global CBF.

Hemangioblastoma of the third ventricle.

A case of intraventricular hemangioblastoma not associated with von Hippel-Lindau disease is presented. Only one other case of intraventricular hemangioblastoma has been reported. The literature on supratentorial hemangioblastomas is reviewed, and the problems of histological identification of such lesions are discussed.

Management of plasmacytomas of the spine.

Epidural plasmacytoma often reflects systemic myelomatous involvement and usually has a poor prognosis. The isolated spinal plasmacytoma, however, is a lesion with the potential for long term remission or even cure in some cases. We report six patients with isolated plasmacytoma of the low thoracic or lumbar region, all of whom presented with pain and minimal neurological deficits. Our approach to such cases included a complete medical work-up and radiographic definition of the lesion with a bone scan, a skeletal survey, myelography, computed tomography, and, in some instances, spinal angiography. All of these patients underwent laminectomy and spinal fusion with autologous bone and Harrington rods. There was no morbidity associated with the procedure, which was designed to prevent possible collapse during subsequent radiotherapy or chemotherapy, with its attendant potential for neurological catastrophe. Several patients have developed systemic involvement necessitating chemotherapy, but in follow-up extending now to 4 years all patients remain ambulatory and pain-free. We are encouraged by the potential for symptomatic relief and neurological improvement of patients with isolated spinal plasmacytomas who are treated with an aggressive medical and surgical approach.

Cystic supratentorial gliomas: natural history and evaluation of modes of surgical therapy.

The management of cystic supratentorial gliomas is hampered by lack of documentation of the natural history of these lesions and by a lack of evaluation of modes of surgical therapy. We analyzed these factors in 25 patients with solitary cysts operated upon over a 20-year period. Two distinctive patterns of symptoms were seen: short duration (increased pressure and hemiparesis), most often heralding a malignant lesion, and long duration (commonly seizure disorder), associated more often with a benign pathological condition. Large solitary cysts were found in tumors of all histological grades. Surgical procedures included extirpation, biopsy/partial resection, cyst communication to ventricle or marsupialization, burr hole aspiration, aspiration via an indwelling reservoir, and cyst-peritoneal shunting. Radiotherapy, given in all cases, did not prevent cyst recurrence. Of the 25 patients, 76% are alive and remain cyst free at follow-up intervals of 1 to 16 years (mean, 3.2). Five patients died from their tumors, with a mean survival of 33 months after decompression. In 7 of 8 patients with cysts largely or entirely within the basal ganglia or thalamus, successful operative cyst control was achieved. Patients with solitary cystic gliomas seem to have a favorable prognosis, and vigorous efforts to control cyst recurrence and limit disability are warranted. Analysis of our data suggests that craniotomy for tumor resection, cyst decompression, and tissue diagnosis is the initial procedure of choice. Cyst recurrence without major solid tumor should be controlled by computed tomography-guided tap or shunt drainage. Reexploration is indicated when cyst reaccumulation is accompanied by clear regrowth of a solid component.

Motilin-related immunoreactivity in mammalian adenohypophysis.

Motilin, a gut peptide recently demonstrated in the mammalian brain and anterior pituitary, was localized immunocytochemically in rat, guinea pig, and human anterior pituitary glands with two antisera to synthetic porcine motilin. Adjacent sections of normal glands were immunostained for motilin, growth hormone, and prolactin reactivity. Motilin reactivity was consistently seen in somatotrophic regions of the mammalian glands and in many instances was colocalized in individual somatotrophs traced in adjacent sections stained for growth hormone. There was no motilin activity discerned in prolactin-secreting regions of the gland. These studies reinforce the close relationship of motilin or a motilin-like peptide with growth hormone in normal somatotrophs. Further anatomical and in vitro studies with tumor material will be useful in elucidating the physiological relationship of motilin to growth hormone.

Seizures during the immediate postoperative period.

Twenty-three of 538 patients undergoing elective craniotomy had a seizure within 24 hours after operation. The lesion had been located extra-axially in 15 patients and intra-axially in 8 patients. Except for 1 patient who had a parietal craniotomy for an arteriovenous malformation, all patients had a frontal or temporal exposure. Only 5 patients had a previous history of seizures. Adequate levels of anticonvulsant medication were not present in 19 of the 23 patients before operation. No major postoperative metabolic abnormalities were noted in any of the 23 patients. Thirteen of the 23 patients underwent computed tomography to evaluate the etiology of their seizures; none had a significant intracerebral or extracerebral hematoma. This review suggests that an early postoperative seizure is unlikely to be due to a postoperative hematoma or to metabolic abnormality. The most common association in this series was with inadequate anticonvulsant prophylaxis. An approach to postoperative seizure prophylaxis and management is presented.

Technical note: in vitro evaluation of an in-line Doppler flow-metering system for carotid artery shunts.

Carotid artery shunts are used extensively during carotid artery surgery to maintain cerebral perfusion. Blood flow through such shunts may be compromised by thrombosis, incorrect placement, or inadvertent clamping of the shunt. Currently, however, no direct method exists to detect poor shunt flow that might precipitate cerebral ischemia. A carotid artery shunt system that continuously monitors blood flow rates has been developed. This system utilizes a Doppler crystal embedded in the wall of a silicone elastomer shunt. The crystal ranges through a "liquid lens" that enables it to be placed without violation of the shunt lumen. Because the crystal is at a fixed angle (45 degrees) to the axis of blood flow and the diameter of the lumen remains constant, a linear relationship should exist between flow rates and the Doppler velocity signal. This hypothesis was tested in vitro using a pulsatile pump and both a starch-water solution and whole blood. Doppler velocity meter readings were compared to timed volume collections over a wide range of flow rates. A direct linear relationship between the Doppler flowmeter and timed volume collections existed, and the system was accurate to within 4.7%. This device may be useful in laboratory studies of carotid shunt dynamics and in clinical practice for early detection of correctable shunt flow abnormalities that could lead to cerebral injury.

Carotid endarterectomy in symptomatic elderly patients.

Fifty-three of 203 consecutive carotid endarterectomies (26%) performed on the Neurosurgical Service at the University of Iowa were in patients over 70 years of age (mean age, 73.4). This series included 38 men and 15 women. Thirty-three patients (62%) presented with transient ischemic attacks, and the remaining 38% were functional stroke patients. Medical risk factors in this group included hypertension in 70%, previous myocardial infarction in 26%, angina in 17%, peripheral vascular disease in 23%, and diabetes in 13%. Sixty-four per cent of the patients had been previously treated with antihypertensive drugs, 43% with antiplatelet agents, and 4% with anticoagulants. Noninvasive vascular evaluation was performed in 25 of 53 (47%) patients, and all underwent angiography before operation. There were no angiographic complications. All patients were operated on with full-channel electroencephalographic (EEG) monitoring. Indwelling shunts were required in 6 of 53 (11%) cases. Intraoperative heparin was given and not reversed; the mean dose was 5100 units. The mean clamp time was 48 minutes. Patch grafts, fashioned from common facial or saphenous veins, were used in 2 patients. Eight patients had contralateral carotid occlusions, but only 2 (25%) required indwelling shunt placement based on EEG criteria. There were no perioperative deaths in this series. One patient had a postoperative stroke, and 1 patient had a postoperative nonfatal myocardial infarction. Transient surgical complications included 3 wound hematomas, 1 wound abscess, and 2 self-limited cranial nerve palsies (13%).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of regional cerebral blood flow and somatosensory evoked potentials in a canine model of hemispheric ischemia.

Regional cerebral blood flow (rCBF) was studied using the radiolabeled microsphere technique in a canine model of hemispheric ischemia that others have previously examined morphologically with carbon perfusion. It was our goal to ascertain whether this ischemic model, which involves easily accessible occlusions of the ipsilateral circle of Willis, could produce reproducible and significant reduction of hemispheric cerebral blood flow. Seven animals underwent the surgical procedure with measurements of rCBF at base line, after arterial microdissection and brain retraction only, and finally after creation of the lesion. Simultaneous somatosensory evoked potential recordings were also obtained. Bilateral symmetrical flow decreases were referable to anesthetic normalization and maintenance alone before creation of the lesion. The arterial occlusions, however, produced further significant decreases in flow on the ipsilateral side only, sparing all contralateral structures and sparing the brain stem and cerebellum bilaterally. Evoked responses, which had shown no changes in latency or amplitude after dissection and retraction procedures, were completely abolished 15 minutes after the arterial occlusion. Control animals that underwent surgical positioning and anesthesia alone did not show concomitant decreases is rCBF. This model of open craniotomy and direct vascular occlusion is suitable for studies of cerebral ischemia where the therapeutic intervention proposed (such as cerebral revascularization) involves similar surgical manipulations. By this method, a standard and reproducible ischemic lesion is achieved through the surgical field without the need for exposure of the basilar artery.