Surgical treatment of intracranial dural arteriovenous fistulae: role of venous drainage.

OBJECTIVE: This report focuses on the surgical management of aggressive intracranial dural arteriovenous fistulae (d-AVFs), which are defined as fistulae with arterialized leptomeningeal veins (red veins). Particular attention is paid to the accurate identification of the venous drainage pattern and to the choice of the proper treatment strategy. METHODS: Thirty-four consecutive patients with aggressive intracranial d-AVFs were treated between 1994 and 1998. Angiographic studies allowed the identification of two main types of aggressive lesions, i.e., d-AVFs with sinus drainage and reflow into leptomeningeal veins (12 patients), which we designated sinus fistulae, and d-AVFs drained exclusively by leptomeningeal veins without sinus interposition (22 patients), which we designated nonsinus fistulae. All patients underwent surgical treatment, which consisted of resection of the fistulous sinus tract in 12 cases of sinus fistulae and interruption of the draining veins at their dural origin in 22 cases of nonsinus fistulae. Surgical preparation via multistage transarterial embolization was required in all 12 cases of sinus fistulae and in 4 of 22 cases of nonsinus fistulae. RESULTS: The mortality rate was 0%, and there were no instances of lasting morbidity. Radioanatomic cures were achieved in all cases. There was no case of venous hypertension or venous infarction after resection of the affected sinus or interruption of the draining veins. No arteriovenous shunts recurred during the follow-up period. CONCLUSION: Careful preoperative identification of the venous drainage pattern seems critical for planning of the correct surgical strategy to treat aggressive intracranial d-AVFs. If the fistula exhibits sinus drainage with reflow into leptomeningeal veins, surgical excision of the fistulous sinus segment represents a safe and definitive treatment option. In these cases, the affected sinus may be safely removed, provided that preoperative angiograms demonstrate participation of the sinus in drainage of the lesion, indicating that the sinus is nonfunctional. Conversely, if the fistula exhibits pure leptomeningeal drainage, the sinus does not participate in drainage of the lesion and cannot be excised. In these cases, the best treatment involves interruption of the draining veins at the point at which they exit the dural wall of the sinus. This simple easy treatment has been proven to be safe and highly effective in permanently eliminating arteriovenous shunts.

Transbasal approaches to aneurysms of the vertebro-basilar junction.

The most difficult aneurysms to be surgically treated are those of the vertebro-basilar junction area. This is due to their deep location and the proximity of brain stem and cranial nerves. Recently, new transbasal surgical approaches have been developed in order to realize a shorter and more direct access. Clival lesions, such as neoplasms, angiomas, and aneurysms, can now be safely faced through these routes. In this paper, we report our recent experience in transbasal approaches for the management of six consecutive patients, with aneurysms in this area. In four of these patients, the initial treatment consisted of an attempt at endovascular aneurysm obliteration using the Guglielmi Detachable Coil system, whereas, in the other two patients (basing on age, aneurysm size and neurological conditions), surgery was considered as the treatment of choice. Unfortunately, the endovascular treatment failed in all cases, and all patients had to be eventually operated on. In all cases, surgical clipping was performed through the combination of a transmastoid (asterional) approach with the suboccipital lateral approach. By this route, in all cases, parent arteries proved well delineated, the aneurysms could always be correctly clipped. Good long-term results were achieved in all cases but one. When surgery is to be performed, the importance of a thorough wide exposure of the whole vertebro-basilar junction area, as well as the importance of having multiple accesses to the lesion, cannot be overemphasized.

Multidisciplinary (surgical and endovascular) approach to intracranial aneurysms.

In spite of the availability of the new endovascular technique (GDC) to manage cerebral aneurysms, to date, the crucial question "which is the proper treatment in a given patient?" still remains unsettled. In order to check whether an answer is possible, we retrospectively reviewed a personal series of 192 consecutive patients with cerebral aneurysms (1993-1995). We found 164 patients who had been considered eligible for active aneurysm treatment. Treatment modality has been chosen case by case on the basis of patient conditions, and aneurysm size and location. Four groups of patients were identified: Group 1: 104 patients (63.4%) with subarachnoid hemorrhage (SAH) in whom the treatment of choice was surgery; Group 2: 27 SAH patients (16.4%) in whom the first choice was GDC; Group 3: 7 SAH patients (4.2%) who died before the scheduled treatment; Group 4: 26 patients (15%) with not ruptured aneurysm who had either surgery or GDC. Based on the results of this series (improvement of the overall results through the multidisciplinary approach), we have developed the guidelines to prospectively manage future cases of cerebral aneurysms with the purpose to rationalize the management, thus further improving the overall results.

Complex arteriovenous fistula of the brain in an infant. Case report.

A rare case of complex cerebral arteriovenous fistula in an infant is reported. An 8-month-old boy first presented with a syndrome of increased intracranial pressure. Neuroradiological assessment showed a direct intracerebral arteriovenous shunt with marked venous engorgement. No hemorrhage was evident. Direct surgical treatment was decided. Clinical and radioanatomical cure was achieved. The main angiographic and pathophysiologic features of this unusual entity, as well as the available therapeutic options, are reviewed and discussed.

Delayed complications of ethmoid fractures: a "growing fracture" phenomenon.

Delayed complications of ethmoid fractures are considered relatively rare. However, meningitis, recurrence of previously ceased cerebrospinal fluid rhinorrhea and delayed onset of cerebrospinal fluid rhinorrhea are possible even years after trauma. We report 10 consecutive patients with delayed complications of ethmoid fractures, whom we treated over the past 11 years. All patients had previously sustained a closed head injury and had remained anosmic. Variously after trauma (ranging from 2 months to 31 years), these patients were re-admitted because of meningitis (6 cases), recurrence of previously ceased cerebrospinal fluid rhinorrhea (3 cases), and delayed onset of cerebrospinal fluid rhinorrhea (1 case). In all cases the delayed complications were associated with relatively large defects of the ethmoid bone. These bone lesions were now evident even in those patients whose radiological assessments had been normal after trauma. All patients underwent a successful surgical repair and remained well during the follow-up. We discuss the possibility that delayed complications of ethmoid fractures are due to a mechanism like that of "growing fractures" in children.

Superficial temporal artery to proximal middle cerebral artery anastomosis: clinical and angiographic long term results.

Anastomosis of the superficial temporal artery (STA) with a proximal segment of the middle cerebral artery (MCA) has been proposed as a new cerebral revascularization technique alternative to the conventional bypass on the cortical surface. We introduced this procedure in our surgical practice in 1982 for patients with internal carotid artery (ICA) aneurysms not suitable for direct repair in whom occlusion of the ICA is considered necessary. One patient died because a conventional STA-MCA bypass did not prevent a major stroke caused by a therapeutic ICA occlusion. We are reporting our surgical technique and the immediate and long term clinical and angiographic results in five cases operated on during the period June 19, 1982, through January 19, 1983. The early and late patency rates were good. No neurological complications were observed after the bypass procedure or during a 3-year follow-up period. In our opinion, the use of proximal segments of the MCA as recipient arteries for supratentorial revascularization is a good alternative to the use of cortical surface arteries and, in selected cases, could be the first choice technique.

Role of EEG monitoring and cross-clamping duration in carotid endarterectomy.

The usefulness of electroencephalographic (EEG) monitoring as well as the significance of the period of cross clamping in carotid endarterectomy have not been completely defined. In particular, the clinical importance of major EEG changes has not been fully investigated and some recent studies seem to indicate that the method has little value. As to the duration of cross clamping, there is strong evidence that occlusion times of about 15 minutes are tolerated under general anesthesia, but no information is available regarding longer periods of occlusion. The authors describe a consecutive series of 141 carotid endarterectomies in which the patients with EEG changes were shunted only when occlusion was anticipated to last longer than 30 minutes. Early major EEG changes (during the first 4 minutes) occurred in 14% of the cases. In the absence of EEG changes, long occlusion periods of 40 to 50 minutes were well tolerated. In contrast, the 20 patients with major persistent EEG changes did not tolerate protracted occlusion and three of them had immediate postoperative neurological complications. It seems that, in these circumstances, the incidence of neurological deficit is a function of the duration of cross clamping: these three patients had undergone occlusion for 15 to 30 minutes. Their deficits partially resolved. On the basis of these results it is concluded that: EEG recording is a reliable monitoring system in carotid artery cross clamping. No major strokes due to temporary carotid artery occurred in the series. The clinical significance of major persistent EEG changes is not negligible. Cross clamping for longer than 15 minutes in the presence of significant EEG alterations is potentially dangerous.