Age related alterations in the response of the pial arterioles to adenosine in the rat.

To evaluate the effects of aging on vasoreactivity of pial arterioles to adenosine and barium chloride, an hydraulically intact cranial window preparation was developed in the rat. The microvasculature of anesthetized 3- and 24-month-old Fischer-344 rats was studied during superfusion with artificial cerebrospinal fluid with and without test agents and results determined by videomicroscopy techniques. In both cohorts, the response of pial arterioles to adenosine was both dose and vessel size dependent: arteriolar dilation increased with increasing concentrations of adenosine and at any given concentration the percent increase in diameter was greater in the smaller vessels. During adenosine superfusion the absolute changes and percent increase in vessel caliber were greater in the young rats. Arteriolar vasoconstriction due to barium chloride was vessel size dependent but there were no significant differences in response between young and aged rats. The results indicated an attenuated cerebrovascular response in aged rats to adenosine, but not to barium chloride. This may be due to a difference in the mode of action in these two compounds. Venules did not respond to adenosine at any concentration.

Carotid occlusion in cysticercosis.

A man without orthostatic hypotension had transient ischemic attacks that were initiated by upright posture. CT showed a cystic mass in the interhemispheric fissure and basilar cisterns. Cerebral angiography demonstrated supraclinoid occlusion of the right internal carotid artery. At frontal craniotomy, cysticercosis cysts were found adherent to a pulseless right internal carotid artery. This is the first antemortem documentation of a large artery occlusion directly related to Cysticercosis racemosus.

Examination of the spatial and temporal distribution of sensory cortical activity using a 100-electrode array.

This paper introduces improved techniques for multichannel extracellular electrophysiological recordings of neurons distributed across a single layer of topographically mapped cortex. We describe the electrode array, the surgical implant techniques, and the procedures for data collection and analysis. Neural events are acquired through an array of 25 or 100 microelectrodes with a 400-microm inter-electrode spacing. One advantage of the new methodology is that implantation is achieved through transdural penetration, thereby reducing the disruption of the cortical tissue. The overall cortical territory sampled by the 25-electrode array is 1.6 x 1.6 mm (2.56 mm2) and by the 100-electrode array 3.6 x 3.6 mm (12.96 mm2). Using a recording system with 100 channels available, neural activity is simultaneously acquired on all electrodes, amplified, digitized, and stored on computer. In our data, average peak-to-peak signal/noise ratio was 11.5 and off-line waveform analysis typically allowed the separation of at least one well-discriminated single-unit per channel. The reported technique permits analysis of cortical function with high temporal and spatial resolution. We use the technique to create an 'image' of neural activity distributed across the whisker representation of rat somatosensory (barrel) cortex.

Coil embolization of a trigeminal-cavernous fistula.

A 53-year-old woman spontaneously incurred a right trigeminal artery-cavernous sinus fistula, manifested by an intracranial bruit and right sixth nerve palsy. This lesion was successfully managed by coil embolization via the transvenous and transarterial routes.

Carotid-cavernous sinus fistulas and venous thrombosis.

Radiographic signs of cavernous sinus thrombosis were found in eight consecutive patients with an angiographic diagnosis of carotid-cavernous sinus fistula; six were of the dural type and the ninth case was of a shunt from a cerebral hemisphere vascular malformation. Diagnostic features consisted of filling defects within the cavernous sinus and its tributaries, an abnormal shape of the cavernous sinus, an atypical pattern of venous drainage, and venous stasis. Progression of thrombosis was demonstrated in five patients who underwent follow-up angiography. Because of a high incidence of spontaneous resolution, patients with dural-cavernous sinus fistulas who show signs of venous thrombosis at angiography should be followed conservatively.

Arachnoid cyst rupture producing subdural hygroma and intracranial hypertension: case reports.

OBJECTIVE: To analyze the association between arachnoid cysts and subdural hygromas. METHODS: We reviewed five cases of arachnoid cysts that ruptured, producing acute subdural hygromas. The surgical management and diagnostic methods used are assessed. RESULTS: Five male patients ranging in age from 6 to 25 years sustained the rupture of arachnoid cysts, which produced acute subdural hygromas. Four of the patients had incurred blunt head trauma. All patients presented with symptoms referable to intracranial hypertension. The pathognomonic features of a middle fossa arachnoid cyst (MFAC) were noted on the computed tomographic scans and/or magnetic resonance images of each patient. The hygroma exerted mass effect on the ipsilateral hemisphere and was noted to be under significant pressure at the time of surgical intervention in each case. Two of the five cases are unique in the literature. In one, a coexisting quadrigeminal cyst ruptured, producing a subdural hygroma ipsilateral to the MFAC and dilating the basal cisterns. In the other, the MFAC ruptured into the basal cisterns as well as into the subdural space. The MFAC in each of the remaining three patients ruptured into the subdural space alone. All patients were treated with drainage of the subdural space. In the two patients in whom the basal cisterns were involved, both the hygromas and the MFACs failed to change significantly in size. The hygromas resolved completely and the MFACs decreased in size considerably in the three patients without cisternal involvement. CONCLUSION: The rupture of an arachnoid cyst can produce a subdural hygroma and intracranial hypertension. The latter mandates emergent drainage of the subdural space. In patients in whom the basal cisterns are not dilated by cyst rupture, both the MFACs and hygromas resolve after subdural drainage.

Total morbidity and mortality rates of patients with surgically treated intracranial aneurysms.

The authors report their recent experience in treating 80 patients with intracranial aneurysms. A total of 83 surgical procedures were performed with a surgical mortality of 4.8%. Fifty-six patients had suffered a subarachnoid hemorrhage. Total mortality for this group was 14.2% regardless of clinical grade. Early surgical intervention, meticulous preoperative monitoring, and control of circulatory dynamics were used to improve the perioperative morbidity and mortality rates. We believe that any major improvements in the outcome of patients with aneurysms will come from advances in perioperative management.

Computerized tomography in Reye's syndrome: evidence for pathological cerebral vasodilatation.

The authors present two children with Reye's syndrome who were studied with serial computerized tomographic (CT) scanning. Scans performed with contrast enhancement during the acute phase of this disease showed evidence of pathological cerebral vasodilatation. The possible mechanism for this vasodilatation and the increased intracranial pressure (ICP) seen in Reye's syndrome are discussed.

Microanatomical study of the extradural middle fossa approach to the petroclival and posterior cavernous sinus region: description of the rhomboid construct.

The extradural middle fossa transpetrosal approach has been used to access lesions of the petroclival and posterior cavernous sinus regions by several neurosurgical groups, including our own. This is a technically demanding approach that provides a relatively wide extradural corridor interposed between the 5th cranial nerve and the cranial nerve VII-VIII complex, which minimizes brain retraction. We performed a microanatomical study to determine the limits of this exposure and in particular how the removal of the petrous bone could be maximized through this approach. Dissection of 15 fixed human cadaveric heads and 8 isolated temporal bones was performed to yield 38 sides studied. We identified a rhomboid-shaped construct of middle fossa landmarks that serve as a guide to maximally removing the petrous apex. The points defining this construct are as follows: 1) the junction of the greater superficial petrosal nerve and the trigeminal nerve; 2) the lateral edge of the porus trigeminus; 3) the intersection of the petrous ridge and arcuate eminence; and 4) the intersection of the lines extended along the axes of the greater superficial petrosal nerve and arcuate eminence. A morphometric analysis determined the average lengths of the respective sides of the complex to be 13.2 mm +/- 2.6 x 22.2 mm +/- 2.8 x 16.4 mm +/- 3.4 x 16.6 mm +/- 1.5 (beginning at "1" and proceeding sequentially), with an approximate area of the construct equal to 2.9 square centimeters.(ABSTRACT TRUNCATED AT 250 WORDS)

Progressive visual loss after electrothrombosis treatment of a giant intracranial aneurysm: case report.

A case of worsening visual deficit after endovascular electrothrombosis therapy for a giant aneurysm of the internal carotid artery ophthalmic segment is presented. Possible pathophysiological mechanisms are suggested. The need for both collaboration between the neurovascular surgeon and the interventionalist and appropriate case selection is emphasized.

Translabyrinthine removal of cerebellopontine angle meningiomas.

The authors report two cases of the microscopic total removal of meningiomas in the region of the cerebellopontine angle using the translabyrinthine approach. Although both tumors were larger than 4 cm, the only resulting neurological deficit was ipsilateral hearing loss. The translabyrinthine approach may be an alternative measure in dealing with these difficult lesions.

Hematoporphyrin uptake in atherosclerotic plaques: therapeutic potentials.

Atherosclerotic plaques were induced in abdominal aortas of rabbits. At 8 weeks, 5 mg of dihematoporphyrin ether (Photofrin II) per kg was injected intravenously followed by sacrifice of the animal, fluorescence microscopy, and quantitative assay of porphyrin in the plaque-containing aortas at 1, 12, 24, 48, and 72 hours. Photofrin II was taken up preferentially by the plaque, with the highest plaque to normal wall ratio occurring at 48 hours. Phototherapy was carried out in 13 animals in each of which two plaques had been induced. With a 630-nm light source 48 hours after the infusion of Photofrin, one of the pair of plaques was treated while the other served as a control. Animals were killed at 2, 4, and 6 weeks. The 6-week specimens showed the most dramatic reduction in plaque in comparison to controls. Photodynamic therapy may provide an alternate strategy in dealing with focal atherosclerosis.

Monitoring of infectious intracranial aneurysms by sequential computed tomographic/magnetic resonance imaging studies.

To monitor the course of infectious intracranial aneurysms, repeated cerebral angiography has been recommended every 2 weeks during intravenous antibiotic therapy until the aneurysm has resolved or an operation has been performed. However, serial cerebral angiograms are not without some risk to the patient. We have prospectively studied five patients harboring a total of six infectious intracranial aneurysms by sequential computed tomography (CT) and/or magnetic resonance imaging (MRI) studies. All infectious aneurysms were initially identified by cerebral angiography and were treated with 6 to 8 weeks of intravenous antibiotics. The aneurysm size ranged from 4 to 10 mm. Sequential CT scans and/or MRI studies were obtained at 2- to 3-week intervals to monitor the course of the aneurysms. Three aneurysms enlarged during antibiotic therapy, and one remained unchanged in size. These four aneurysms were treated surgically. The two remaining aneurysms resolved with intravenous antibiotic therapy. Cerebral angiograms were obtained routinely preoperatively and were used to verify the resolution of the infectious aneurysms when they were no longer visible on CT or MRI. On the basis of this prospective study, we conclude that sequential thin-slice CT and/or MRI can effectively and safely monitor the course of infectious intracranial aneurysms once identified by cerebral angiography. This may reduce the need for serial angiography and reduce the ultimate risk in the management of infectious intracranial aneurysms.

Application of photodynamic therapy to the treatment of atherosclerotic plaques.

Photodynamic therapy is a therapeutic modality long studies for its application to the treatment of malignant neoplasms. Recently, studies have suggested its potential use in the treatment of atherosclerosis. In this study, two atherosclerotic plaques were induced in the abdominal aortas of 35 rabbits. The animals then received Photofrin II (Quadralogic Technologies Inc., Pearl River, NY), a photosensitizer, at doses of 5 mg/kg and 2.5 mg/kg. After 48 hours, the plaques were irradiated by a fiberoptic connected to an argon ion laser. Fluency rates from 32 mW to 256 mW and energy doses from 1.6 to 60 joules were applied. Only one of the paired plaques was irradiated, the other remaining as a control. Four weeks after treatment, the vessels were assessed. Of 26 plaques treated with photodynamic therapy, 22 were no longer grossly visible, while the nine animals that received light irradiation but no Photofrin II all had visible plaque (P < 0.001). Studies of the vessel sections confirmed a reduction in intimal thickness from 0.74 +/- 0.15 mm in matched controls as compared with 0.51 +/- 0.13 mm in animals with treated plaques. There was a concomitant enlargement of the luminal diameter from 1.13 +/- 0.51 to 1.41 +/- 0.72. On the microscopic level, plaque reduction was most complete in the groups treated with 40 and 60 joules. Different fluency rates and drug dosages did not lead to differing outcomes. Our findings indicate that photodynamic therapy with dihematoporphyrin ether met our goal of reducing plaque size and may represent a means of treating atherosclerotic plaques.

Management of intraoperative rupture of aneurysm without hypotension.

A retrospective analysis was performed on all aneurysms operated on by one of us (SLG) from July 1980 to October 1988 to determine the factors that govern outcome from the intraoperative rupture of aneurysms. A total of 276 consecutive surgical procedures for 317 intracranial aneurysms produced 41 perioperative or intraoperative ruptures for analysis. Five cases were pre-exposure ruptures, 3 of which occurred during anesthetic induction. Four of these patients died, and 1 made a good recovery. Of the remaining 36 cases, outcome was analyzed in terms of the adjuncts used to deal with the intraoperative rupture. There was no statistically significant difference in outcome between those cases in which tamponade was used to control hemorrhage versus temporary clipping; however, those cases in which hypotension was used did less well than those in which it was not used. From October 1986 to October 1988, 108 operations for 132 aneurysms were performed without the use of induced hypotension. There were 16 intraoperative ruptures (14.8%). All 16 of these patients made a good recovery. In the group before 1986, of which there were 20 intraoperative ruptures (of 168 operations, 11.9%), 11 of those 20 patients suffered a permanent deficit or died. We conclude that hypotension may not be a necessary adjunct to the management of intraoperative rupture of aneurysms.

Carotid endarterectomy: technical improvements.

The immediate surgical results of 163 consecutive carotid endarterectomies performed in a neurosurgical training center are presented. The mortality rate was 0.6% and the permanent neurological morbidity rate was 2.5%. Several factors in the surgical technique including the use of magnified vision, full heparinization, the liberal use of intimal tacking sutures, and the employment of an indwelling shunt are thought to be responsible in part for the improved surgical results. (Neurosurgery, 7: 309-312, 1980).

Microsurgical anatomy of the inner surface of the petrous bone: neuroradiological and morphometric analysis as an adjunct to the retrosigmoid transmeatal approach.

The retrosigmoid transmeatal technique remains the approach of choice for hearing preservation during the removal of acoustic neuromas that protrude from the porus acusticus. However, encroachment into the bony labyrinth in an effort to remove the tumor in the lateral end of the internal auditory canal (IAC) continues to compromise hearing in certain cases. The limits in the safe removal of the posterior wall of the IAC are not generally agreed on. To address this problem, we have performed a morphometric analysis of 32 fixed cadaveric temporal bones by microsurgical dissection and measurement with fine-cut bone window computed tomographic (CT) scans. The morphometric relationships of identifiable surface landmarks were first determined. Fine cut bone window CT scans were next performed on each bone and the distances between the fundus, the vestibule, and the common crus (CC) with the internal auditory meatus (IAM) were determined. Additionally, the thickness of the bone overlying the posterior semicircular canal at the CC was measured. From a retrosigmoid trajectory, employing a 4-cm craniotomy, the posterior wall of the IAC was removed with a high-speed drill, limiting removal to the distance from the vestibule to the IAM, as determined by CT measurement. Preservation of the integrity of deep structures was confirmed by inspection. The length of the actual IAC unroofed was measured and was compared with the IAC length, from IAM to fundus, measured by CT. The average canal length by CT measured 10.0 mm +/- 1.8 (range, 6.6-14.0). The length of the canal uncovered averaged 5.9 mm +/- 1.4 (4.0-8.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Propylene glycol toxicity following continuous etomidate infusion for the control of refractory cerebral edema.

Continued elevations in Intracranial Pressure (ICP) following traumatic or ischemic compromise are known to cause markedly increased morbidity and mortality. Because of the side effects of barbiturates including hypotension and prolonged recovery time, the use of shorter-acting anesthetic agents to control ICP has been considered. Etomidate, when administered by continuous infusion, has been shown to decrease cerebral metabolism resulting in a secondary decrease in cerebral blood flow with minimal changes in cerebral perfusion pressure. We initially intended to randomize 20 patients prospectively into a study protocol that would assess the effects of either pentobarbital or the cardioprotective agent etomidate on ICP and cardiac performance. Given the sequelae of the therapy, we were only able to randomize seven patients with cerebral edema refractory to medical management to receive either etomidate or pentobarbital in a blinded fashion. Three patients who received etomidate developed renal compromise (mean low creatinine clearance 41 ml/min, range 37-44 ml/min) which was initially noted at 24 hours. We believed that this represented an adverse effect that was probably related to the study drug and the study was stopped. Each patient received a 0.30 mg/kg IV induction of etomidate and then 0.02 mg/kg/min continuous infusion for 24-72 hours titrated burst suppression. All patients also received dexamethasone 2 mg IV every six hours to prevent the adrenocortical insufficiency that might occur as a consequence of etomidate-induced suppression of cortisol synthesis. Intracranial pressure decreased (mean = 12mmHg) following the initiation of etomidate. Cardiac parameters remained unchanged (cardiac output 4.8 +/- .6 liters/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid reversal of endothelin-1-induced cerebral vasoconstriction by intrathecal administration of nitric oxide donors.

OBJECTIVE: To determine the capability of donors of nitric oxide (NO) (sodium nitroprusside, nitroglycerine) to reverse endothelin-1 (ET-1)-induced cerebral vasoconstriction in vivo, when administered through the cerebrospinal fluid (CSF) to the adventitial side of the constricted blood vessel. METHODS: The rabbit basilar artery was exposed through a transcervical, transclival approach and subsequently subjected to pharmacological manipulations and direct observation of effects by videomicroscopy. Specific manipulations were suffusion of ET-1 (100 nmol/L, 1 ml/min) in synthetic CSF (sCSF) to provoke vasoconstriction and then either suffusion of an NO donor in sCSF (2 mg/ml/min), or sCSF alone. The second suffusion was always made separately and begun during the period of stable maximal vasoconstriction, which occurred between 20 and 30 minutes after beginning the first suffusion. Measurements of the diameter of the artery were made using an inline video caliper. RESULTS: Sodium nitroprusside and nitroglycerine, both donors of NO, rapidly and completely reversed ET-1-induced vasoconstriction without causing hypotension. The average value for maximal vasoconstriction by ET-1/sCSF was 50.4% of baseline arterial diameter and occurred between 20 and 30 minutes. The rate of vasodilatory response was 100% of significantly constricted arteries. The response was complete in less than 6 minutes in all preparations, as compared to the 60 minutes required for spontaneous relaxation (sCSF suffusion alone). CONCLUSION: NO donors are effective in reversing cerebral vasoconstriction when administered intrathecally, cause no significant hemodynamic change when so administered, and may represent an important therapeutic intervention for cerebral vasospasm.

Gradual carotid artery occlusion in the treatment of inaccessible internal carotid artery aneurysms.

The authors discuss 21 cases of large or surgically inaccessible internal carotid artery aneurysms treated with gradual occlusion of the cervical portion of the internal carotid artery. Eighty-five per cent of the patients experienced relief or marked improvement of their symptoms after treatment. Two early cases developed postligation ischemic deficits that partially resolved. After the introduction of expansion of circulating blood volume and induced hypertension as adjuncts to graded carotid occlusion, no ischemic complications occurred.