Peripheral large or giant fusiform middle cerebral artery aneurysms: report of our experience and review of literature.

Peripheral large and giant middle cerebral artery (MCA) aneurysms are rare and difficult to treat. We report our and others' experience with different possible modalities used to treat such lesions. Three patients were treated differently at our institution. One harboured a giant fusiform aneurysm on a peripheral branch of the superior trunk of the left MCA, and was treated by extracranial-intracranial (EC-IC) bypass and trapping of the aneurysm. The second patient was harbouring a large fusiform aneurysm on a peripheral branch of the inferior trunk of the right MCA, which was treated by trapping and excision without the need of an EC-IC bypass as assessed pre- and intraoperatively, while the last case was harbouring a giant fusiform aneurysm at the junction of M2-M3 and was treated by EC-IC bypass and end-to-end anastomosis after resection of the aneurysm. The aneurysms proved to be neither mycotic nor dissecting. The patients were clinically intact during their perioperative course without any postoperative complications and required no further treatment. Follow-up angiography demonstrated a functioning EC-IC bypass. Based on the surgical experience in these 3 cases and a review of the reported literature, the authors propose that when considering surgical treatment for such rarely encountered aneurysms, careful pre- and intraoperative evaluation including aneurysm trapping with or without EC-IC bypass when possible should be performed to obtain a satisfactory result without complication.

Hemorrhagic cerebral dissecting aneurysms: surgical treatments and results.

INTRODUCTION: Cerebral dissecting aneurysms are an increasingly recognized etiology of subarachnoid hemorrhage SAH and cerebral stroke. Hemorrhagic dissecting aneurysms of the anterior circulation have been considered to be somewhat different to those of the posterior circulation not only in terms of their pathophysiology, but also in terms of their management. Herewith our series of hemorrhagic dissecting aneurysms of the internal carotid artery ICA, vertebral artery VA, basilar artery BA and some of those of distal cerebral arteries is presented and compared to the series reported in the literature. Therapeutic consideration in the light of our experiences emphasizing the significance of aneurysm entrapment in combination with bypass surgery is presented. MATERIAL AND METHODS: During the last 13 years over 1000 patients with cerebral aneurysms were treated surgically in our department. Hemorrhagic dissecting aneurysms were diagnosed in 26 patients. Diagnosis was based on neuroradiological findings as well as intraoperative findings. All patients underwent surgical intervention. Clinical findings of these patients were analysed retrospectively. Follow-up outcomes were evaluated according to the Glasgow Outcome Scale GOS at 3 months after treatments. RESULTS: Location of 26 dissecting aneurysms was: ICA 11 cases (42%), VA 9 cases (35%), BA 3 cases, MCA 2 cases and PCA (P1 segment) one case. Primary surgical treatments were performed on day 3.7 of SAH on average. Clinical manifestation of dissecting aneurysms of the ICA and their outcome was more severe compared with those of the VA (p < 0.01): WNFS grade 3.1 vs 2.4 and GOS score 3.4 vs 4.3. As a conventional neck clipping procedure was problematic or impossible (aneurysm recurrence after clipping, premature rupture at the time of exposure or clipping), entrapment (or proximal ligation) plus EC-IC bypass procedure was the most frequent final definitive method of surgical treatment (9/26 35%: ICA 6/11, VA 1/9 and MCA 2/2) followed by proximal ligation or trapping only 7/26, neck clipping 7/26 and coating 4/26. CONCLUSIONS: Hemorrhagic dissecting aneurysms still remain problematic in their diagnosis and treatment. One has to be aware of the diagnostic possibility of dissecting aneurysms as an etiology of SAH. Neurosurgeons have to be prepared to be able to manage complex surgical situations also by the use of EC-IC bypass, as its combination with entrapment procedure can be the final treatment of choice. Less invasive endovascular technique is in evolution but its availability and superiority are still to be settled.

Emergency extra-intracranial bypass surgery in the treatment of cerebral aneurysms.

The need of an emergency bypass in hazardous situations during treatment of intracranial aneurysms has rarely been addressed in the literature. We report our 10 year experience with emergency bypass for aneurysm treatment. We retrospectively analyzed the data of patients who underwent emergency bypass surgery for the treatment of an intracranial aneurysm and compared the results with patients treated with bypass as a planned procedure during the same time period. Three groups were formed: group I, emergency bypass during clipping procedure; group II, emergency bypass for therapy refractory vasospasm; group III, planned bypass surgery. Sixteen patients (35%) out of 46 were treated with emergency bypass. In group I (11 patients) mortality was 37% and a good outcome (GOS 4 & 5) was achieved in 36%. In group II (5 patients) mortality was 20% and good outcome was reached in 60%. In group III (30 patients) mortality was 10% and good outcome was achieved in 86.6%. Outcome was worse in patients with additional SAH. An emergency bypass procedure as part of the aneurysm treatment should be considered in risky situations. Accurate timely decision-making is crucial combined with a fast and secure bypass technique. Treatment of refractory vasospasm with emergency bypasses may help to improve outcome in selected patients.

Management of ruptured aneurysms combined with coexisting aneurysms.

In patients suffering from subarachnoid haemorrhage (SAH) and presenting with multiple intracranial aneurysms (MIA) two questions have to be decided on: 1st when is the ideal moment to eliminate the ruptured aneurysm and 2nd when to treat the coexisting aneurysms. In our series we retrospectively analysed 124 SAH-patients presenting with a total of 323 aneurysms. In 57 patients the ruptured aneurysm and all coexisting aneurysms were clipped during the first operation, whereas in 9 patients only some of the coexisting aneurysms (group-A; age in median 55 years) were clipped besides the ruptured one. In 55 patients (group-B; age in median 55 years) the first operation was restricted to clipping the ruptured aneurysm, dealing with the coexisting aneurysm subsequently. Immediately after admission 3 patients passed away. One of the 64 patients waiting (average 60 days, median 14 days) for the subsequent clipping of the not yet secured aneurysms suffered a SAH. Six to 12 months after the initial SAH, 78% of the cases in both groups reached a Glasgow Outcome Score of 4 or 5. Even if in patients with coexisting unruptured intracranial aneurysms the elimination of each and every aneurysm is recommended, the advantages of an unstaged procedure versus the additional strain caused by the prolongation of the procedure, e.g. approach over the midline, 2 or more craniotomies, and the risk of additional ischemic damage to the brain, caused by increased manipulation of cerebral arteries and brain tissue, have to be carefully considered. This is of special importance in dealing with patients in higher Hunt and Hess grades.

Basilar bifurcation aneurysms. Lessons learnt from 40 consecutive cases.

Basilar bifurcation aneurysms are lately treated frequently with endovascular technique. Microsurgical clipping occlusion technique has, however, still its solid position because of its completeness. This standard technique is required often due to unfeasibility and/or incompleteness at the time of application of the endovascular technique for aneurysms of this location. The authors suggest following strategies and tactics for safe and secure occlusion of aneurysms of this location: pterional approach, selective extradural anterior clinoidectomy SEAC, no transection of the posterior communicating artery, isolation of perforating arteries at the time of neck clipping with oxycellulose and combination of the use of fenestrated clip and conventional clip (especially for aneurysms projected posteriorly), controlled hypotension (systolic pressure of around 100 mmHg), temporary clipping (trapping) procedures of usually less than 15 min. All these are aimed for prevention of intraoperative premature rupture, and of injury of perforating arteries and for complete occlusion of aneurysms in the narrow depth of the operative field.

Three cases of AVM at eloquent areas finally treated with conventional microsurgical method.

Three special cases of AVM finally treated with conventional microsurgical method are presented. Two cases of medium sized AVMs were located at the central region, one of them was primarily treated with Gamma-knife followed by endovascular embolization having been complicated with growing cyst formation followed ultimately by microsurgical removal. The AVM of another case was embolized three times, followed by removal of the residual nidus under awake surgery. The third AVM located at the hypothalamus in the vicinity of the optic nerve was considered unsuitable for embolization and Gamma-knife therapy, and therefore removed by microsurgery using special approaches after a trial of embolization. In terms of microsurgical removal, preoperative embolization, embolization material, awake surgery and selection of special approaches are discussed.

Conventional microsurgical treatment of paraclinoid aneurysms: state of the art with the use of the selective extradural anterior clinoidectomy SEAC.

Surgical treatment of paraclinoid aneurysms is considered to be difficult due to their complicated anatomical location in the vicinity of important neural, vascular and bony structures. We present our clinical experience of the past 10 years of conventional microsurgical treatment of 81 paraclinoid aneurysms in 75 patients with the use of selective extradural anterior clinoidectomy SEAC and discuss the method of therapy option by reviewing recent reports on results of endovascular coiling method and the combination of these with conventional microsurgical therapy. The favorable surgical results with the use of SEAC and no recurrence of the treated aneurysm after clipping procedure in our series indicate that direct surgery can still be a standard technique for paraclinoid aneurysms in view of the fact that the endovascular aneurysm coiling methods are still associated with a considerable percentage of incomplete occlusion and present the problem of coil packing.

Experimental axonal injury triggers interleukin-6 mRNA, protein synthesis and release into cerebrospinal fluid.

Diffuse axonal injury is a frequent pathologic sequel of head trauma, which, despite its devastating consequences for the patients, remains to be fully elucidated. Here we studied the release of interleukin-6 (IL-6) into CSF and serum, as well as the expression of IL-6 messenger ribonucleic acid (mRNA) and protein in a weight drop model of axonal injury in the rat. The IL-6 activity was elevated in CSF within 1 hour and peaked between 2 and 4 hours, reaching maximal values of 82,108 pg/mL, and returned to control values after 24 hours. In serum, the levels of IL-6 remained below increased CSF levels and did not exceed 393 pg/mL. In situ hybridization demonstrated augmented IL-6 mRNA expression in several regions including cortical pyramidal cells, neurons in thalamic nuclei, and macrophages in the basal subarachnoid spaces. A weak constitutive expression of IL-6 protein was shown by immunohistochemical study in control brain. After injury, IL-6 increased at 1 hour and remained elevated through the first 24 hours, returning to normal afterward. Most cells producing IL-6 were cortical, thalamic, and hippocampal neurons as confirmed by staining for the neuronal marker NeuN. These results extend our previous studies showing IL-6 production in the cerebrospinal fluid of patients with severe head trauma and demonstrate that neurons are the main source of IL-6 after experimental axonal injury.

EEG reactivity in the prognosis of severe head injury.

We compared reactivity of EEG to external stimuli--an easily and quickly available measure--with the central conduction time (CCT) of the somatosensory evoked potentials, currently the most-used electrophysiologic method to predict outcome in severe head injury (SHI), and with the initial Glasgow Coma Scale (GCS) score. In 50 patients, comatose subsequent to SHI, we measured EEG reactivity and CCT within 48 to 72 hours and compared them with the outcome after 1.5 years. Using discriminant analysis, EEG reactivity correctly classified 92%, CCT classified 82%, and both measures together classified 98% of the patients into globally good or bad outcome groups. GCS allowed a correct classification in only 72% and, combined with either of the two electrophysiologic measures, did not further increase predictability. EEG reactivity is an excellent long-term global outcome predictor in SHI, superior to CCT and GCS. When the two electrophysiologic measures are combined, a prognostic accuracy is achieved that is better than that of any other reported method.

Detectable concentrations of Fas ligand in cerebrospinal fluid after severe head injury.

When the cell surface molecule Fas is triggered by its agonist Fas ligand the result is apoptosis of these cells and tissue destruction. To elucidate the pathophysiological relevance of Fas ligand in patients with cerebral oedema caused by trauma, we examined its concentrations in cerebrospinal fluid in 18 patients using specific ELISA. Serum and cerebrospinal fluid from healthy people and injured patients without head trauma did not contain detectable Fas ligand. In contrast, cerebrospinal fluid from patients with severe brain injury contained high concentrations of Fas ligand without detectable concentrations in serum. Soluble Fas ligand concentrations in cerebrospinal fluid correlated significantly with severity of brain injury. The Fas-Fas ligand-system may have a pivotal role in causing oedema and local tissue destruction in the brain after severe head injury.

Intrathecal and serum interleukin-6 and the acute-phase response in patients with severe traumatic brain injuries.

Patients with severe traumatic brain injury (TBI) show a profound acute-phase response. Because interleukin-6 (IL-6) is an important mediator of these pathophysiological changes, IL-6 levels were monitored in the cerebrospinal fluid (CSF) and serum of 20 patients with severe isolated TBI. All patients received indwelling ventricular catheters for intracranial pressure monitoring and for release of CSF when intracranial pressure exceeded 15 mmHg. CSF and blood samples were drawn daily for up to 14 days. The CSF/serum albumin ratio (QA) served as a parameter of blood brain barrier dysfunction. Differential blood counts as well as the acute-phase proteins C-reactive protein, alpha 1-antitrypsin, and fibrinogen were recorded. IL-6 was detected in all CSF samples and reached values of up to 31,000 pg/mL, while serum levels remained significantly lower (alpha < or = .01) and never exceeded 1,100 pg/mL the entire study period. A correlation between CSF and serum IL-6 was found initially after the trauma and corresponded to a severe dysfunction of the blood brain barrier (r = .637, p = .001). Maximum IL-6 concentrations in serum correlated with peak levels of acute-phase proteins (C-reactive protein, alpha 1-antitrypsin, and fibrinogen). With regard to blood cell count, an initial leukocytosis combined with a borderline lymphocytopenia was observed. Thrombocytes decreased to a subnormal level during the first few days, but reached supranormal numbers by the end of the study period. Our results show that the increase of IL-6 levels in CSF and serum is followed by a profound acute-phase response in patients with TBI. Because cytokine concentrations are significantly lower in serum compared with CSF, we hypothesize that IL-6 produced in the central nervous system may play a role in initiating the acute-phase response.

Interleukin-6 released in human cerebrospinal fluid following traumatic brain injury may trigger nerve growth factor production in astrocytes.

Cytokines are involved in nerve regeneration by modulating the synthesis of neurotrophic factors. The role played by interleukin-6 (IL-6) in promoting nerve growth factor (NGF) after brain injury was investigated by monitoring the release of IL-6 and NGF in ventricular cerebrospinal fluid (CSF) of 22 patients with severe traumatic brain injuries. IL-6 was found in the CSF of all individuals and remained elevated for the whole study period. NGF appeared in the CSF if IL-6 levels reached high concentrations and was often detected simultaneously with or following an IL-6 peak. The amounts of NGF correlated with the severity of the injury, as indicated by the clinical outcome of the patients. The functional relationship of IL-6 and NGF was investigated utilizing cultured mouse astrocytes. The CSF of 8 patients containing IL-6 induced NGF production in astrocytes, whereas control CSF without IL-6 had no effect. The induction of NGF was inhibited up to 100% by adding anti-IL-6 antibodies. These results were corroborated when astrocytes were exposed to recombinant IL-6 at different concentrations resulting in NGF production. Thus, the production of IL-6 within the injured brain may likely contribute to the release of neurotrophic factors by astrocytes.

Are unilateral right posterior cerebral lesions sufficient to cause prosopagnosia? Clinical and radiological findings in six additional patients.

Controversy has arisen regarding the neuropathological basis of prosopagnosia. Some investigators suggest that bilateral lesions are needed to cause the deficit, whereas others felt that a unilateral right posterior lesion is sufficient. Six patients with prosopagnosia with clinical and radiological evidence of unilateral right posterior lesions are presented. Our observations together with evidence from similar cases described in the literature suggest that an appropriately placed right hemispheric lesion may be sufficient to produce prosopagnosia.

Persistent cervical intersegmental artery as a cause of recurrence of a traumatic carotid-cavernous fistula: case report, with emphasis on Doppler ultrasound diagnosis.

In a 16-year-old boy, minor symptoms of an arteriovenous shunt into the cavernous sinus recurred 3 months after the performance of a trapping operation of the internal carotid artery on the side of a traumatic carotid-cavernous sinus fistula. An arterial and venous cerebrovascular Doppler examination demonstrated increased blood flow in the periorbital veins of both sides, with a pathological flow direction, i.e., from intra- to extracranial. Furthermore, an internal-like artery was found at the level of the carotid bifurcation on the side of the trapped internal carotid artery, and increased blood flow was registered in the homolateral vertebral artery. Angiography confirmed occlusion of the internal carotid artery 0.5 cm distal to the carotid bifurcation, but showed blood flow from the homolateral vertebral artery through a persistent 3rd cervical intersegmental artery into the trapped portion of the internal carotid artery. The latter fed blood into the cavernous sinus through the still-existing arteriovenous fistula. Insufficient involution of the 3rd cervical intersegmental artery was assumed. Obviously, this collateral artery dilated in the presence of a major blood pressure gradient between the vertebral artery and the trapped segment of the internal carotid artery. Thus, a persistent cervical intersegmental artery can be a cause for a recurrent carotid-cavernous sinus fistula.

Scanning electron microscopic evaluation of variably angled end-to-side microvascular anastomoses.

A comparison of right-angled and opposing oblique-angled end-to-side microvascular anastomoses with both patent and occluded recipient vessels was performed in rats. Patency rates after 3 weeks were comparable in all types of anastomoses (average, 92%). However, scanning electron microscopic evaluation revealed a variety of both nonspecific (pits, craters, folds, etc.) and angle-dependent (mounds, erosions, bridges, etc.) endothelial alterations. It is concluded that, in proximally patent recipient vessels, the functional integrity of the anastomosis is not related to the grafting angle; however, in proximally occluded recipient vessels, retrograde-directed oblique angles may lead to progressive embarrassment of anastomotic function.

The terminal vascular bed in the superficial cortex of the rat. An SEM study of corrosion casts.

The capillaries in the vascular bed of the rat brain have been investigated by means of scanning electron microscopy of corrosion casts. A technique is described that allowed the finer ramifications to be observed. A series of representative sites from the arteriovenous terminal pathway are described in detail. Contrary to previous reports, the dichotomic pattern of vessel distribution is shown to prevail over the network pattern. Arteriovenous shunts of discrete size were not seen. "Thoroughfare channels" could be recognized. The findings are considered in light of current physiological knowledge, and their significance for microcerebrovascular flow is indicated.

Supracerebellar transtentorial approach to posterior temporomedial structures.

The supracerebellar transtentorial (SCTT) approach, a modification of the infratentorial supracerebellar approach, facilitates simple and minimally invasive access to posterior temporomedial structures without requiring retraction of the temporal or occipital lobe. The SCTT approach was used in 16 patients over a 3-year period. Eleven patients harbored tumors confined to, or located mainly within, the posterior hippocampal formation, three patients harbored aneurysms (one ruptured posterior cerebral artery [PCA] aneurysm at the P2-P3 junction, one ruptured giant PCA [P2] aneurysm, and one giant basilar artery-superior cerebellar artery aneurysm), one patient had juvenile-type moyamoya disease, and one patient suffered from medically intractable epilepsy. In these patients, the SCTT approach enabled tumor removal, aneurysm clipping, and vascular bypass procedures. The authors' experience suggests that this approach can be used routinely in treating lesions in the posterior temporomedial region.

Selective extradural anterior clinoidectomy for supra- and parasellar processes. Technical note.

Removal of the anterior clinoid process (ACP) facilitates radical removal of tumors or radical neck clipping of aneurysms in the supra- and parasellar regions by providing a wide operative exposure of the internal carotid artery (ICA) and the optic nerve and by reducing the need for brain retraction. Over a period of 3 years, anterior clinoidectomy was performed in 40 patients, 30 of whom harbored aneurysms (18 of the ICA and 13 of the basilar artery [one patient had two aneurysms]) and 10 of whom had tumors (four large pituitary tumors, four craniopharyngiomas, and two sphenoid ridge meningiomas). The ACP was removed extradurally in 31 cases and intradurally in nine cases. Extradural clinoidectomy was performed in all cases of pituitary adenoma and craniopharyngioma and in most cases of basilar artery aneurysm. Intradural clinoidectomy was performed in two cases of ICA-ophthalmic artery aneurysm, two cases of ICA-posterior communicating artery aneurysm, two cases of ICA cavernous aneurysm, one case of basilar artery aneurysm, and two cases of sphenoid ridge meningioma. The outcome was satisfactory in all patients, except for one patient who underwent clipping of a basilar tip aneurysm and suffered a thalamic and midbrain infarction. Three patients who underwent extradural clinoidectomy suffered a postoperative diminution of visual acuity or a visual field defect on the side of the clinoidectomy. These deficits may have been caused either by drilling of the ACP or by other operative manipulation of the optic nerve. Cerebrospinal fluid rhinorrhea, which required reoperation, occurred in one patient. The authors' experience suggests that the extradural technique of ACP removal is easier and less time consuming than the intradural one and provides better operative exposure. It can be used routinely in treating lesions in the supra- and parasellar regions.

Moyamoya disease in Europe, past and present status.

A questionnaire was distributed in early 1996 to 160 leading European neurological, neuro-pediatric and neurosurgical centers to assess the present status of Moyamoya disease in Europe. The response rate was 43%. Information was obtained on a total of 168 patients, of whom 110 had presented before 1992, and 58 from 1993 onward. 82% of the patients were Caucasian. In all other respects, the clinical findings were similar to those observed in Japan. The present study yields an incidence of 0.3 patients per center per year, which is approximately one-tenth of the incidence in Japan. Alongside these results, the history of the recognition and treatment of this disease in Europe is briefly discussed.

Experimental model for internal repair of arteriovenous fistulas.

An artificial arteriovenous fistula was created by performing an end-to-side anastomosis between the anterior facial vein and carotid artery of the rat. An intraarterial venous graft was then used to seal the fistula. In 8 of 10 rats, carotid artery flow was found to be maintained as judged by angiography, carried out 14 days after the operation. The fistula remained closed in each case. The vessels were also examined with a scanning electron microscope.