Natural history of dural arteriovenous shunts.

BACKGROUND AND PURPOSE: Dural arteriovenous shunts with cortical venous reflux or drainage may cause neurological symptoms and death with or without intracranial hemorrhage. Present knowledge about the natural history of these lesions is limited, however. We investigated the incidences of intracranial hemorrhage, progressive dementia syndrome, and death in patients diagnosed in our neurovascular center. METHODS: We evaluated the records of 85 patients with dural arteriovenous shunts with cortical venous drainage or reflux hospitalized in our institution from 1978 to 2007. The annual incidences of intracranial hemorrhage, progressive dementia syndrome, and death were calculated. RESULTS: Fifty-three patients did not have an intracranial hemorrhage as the presenting event. One of these patients bled after diagnosis. Thirty-two patients had an intracranial hemorrhage as the presenting event. Three patients bled after diagnosis. One of these patients died. Apart from deficits caused by hemorrhage, no patient reported adverse neurological symptoms. In patients presenting with an intracranial hemorrhage the annual risk for hemorrhage is approximately 7.4% and in those not presenting with a hemorrhage it is approximately 1.5%. CONCLUSIONS: The risk of intracranial hemorrhage from a dural arteriovenous shunt with cortical venous drainage is most likely smaller than previously proposed. Presentation with hemorrhage is a risk factor for hemorrhage. The risks of developing neurological symptoms not related to hemorrhage are also less than previously reported.

Gamma knife surgery for dural arteriovenous shunts: 25 years of experience.

OBJECT: The aim of this study was to assess the clinical efficacy of gamma knife surgery (GKS) in the treatment of dural arteriovenous shunts (DAVSs). METHODS: From a database of more than 1600 patients with intracranial arteriovenous shunts that had been treated with GKS, the authors retrospectively and prospectively identified 53 patients with 58 DAVSs from the period between 1978 and 2003. Four patients were lost to follow-up evaluation and were excluded from the series. Thus, this study is based on the remaining 49 patients with 52 DAVSs. Thirty-six of the shunts drained into the cortical venous system, either directly or indirectly, and 22 of these were associated with intracranial hemorrhage on patient presentation. The mean prescription radiation dose was 22 Gy (range 10-28 Gy). All patients underwent a clinical follow-up examination. In 41 cases of DAVS a follow-up angiography study was performed. At the 2-year follow-up visit, 28 cases (68%) had angiographically proven obliteration of the shunt and in another 10 cases (24%) there was significant flow regression. Three shunts remained unchanged. There was one immediate minor complication related to the administration of radiation. Furthermore, one patient had a radiation-induced complication 10 years after treatment, although she recovered completely. There was one posterior fossa bleed 2 months after radiosurgery; a hematoma, as well as a lesion, was evacuated, and the patient recovered uneventfully. A second patient had an asymptomatic occipital hemorrhage approximately 6 months postradiosurgery. The clinical outcome after GKS was significantly better than that in patients with naturally progressing shunts (p < 0.01, chi-square test); figures on the latter have been reported previously. CONCLUSIONS: Gamma knife surgery is an effective treatment for DAVSs, with a low risk of complications. Major disadvantages of this therapy include the time elapsed before obliteration and the possibility that not all shunts will be obliterated. Cortical venous drainage from a DAVS, a risk factor for intracranial hemorrhage, is therefore a relative contraindication. Consequently, GKS can be used in the treatment of both benign DAVSs with subjectively intolerable bruit and aggressive DAVSs not responsive to endovascular treatment or surgery.

Deep and brainstem cavernomas: a consecutive 8-year series.

OBJECT: The goal of this study was to provide epidemiological and clinical data on the management of cavernomas of the basal ganglia and brainstem from a long-term series at one institution. METHODS: All 68 patients who were referred to the authors' department between 1992 and 2000 for deep cavernomas were evaluated by clinic examinations, review of neuroimaging examinations, and review of charts and operative notes. Twenty-nine patients underwent microsurgical procedures, which carried a 69% risk of transitory neurological deterioration. Radical excision was achieved in 25 of these patients, as determined by a review of neuroimages; the remaining four patients all experienced new hemorrhages that led to increased morbidity or even to mortality. Surgical results were better if surgery was performed early, within 1 month posthemorrhage, than if operations were postponed. In selected patients, deep lesions not reaching a pial surface could be safely removed from the thalamus, basal ganglia, or medulla oblongata. Of five patients who underwent gamma knife surgery, two experienced hemorrhages, one at 2 and the other at 5 years following treatment. Patients who did not undergo surgery had a yearly incidence of hemorrhage that was 2% in cases of incidental cavernomas and 7% in symptomatic ones. CONCLUSIONS: Over the long term, outcomes were worse following conservative treatment or shunt insertion surgery than after microsurgery of symptomatic cavernomas. Incidental cavernomas carried a low risk of neurological deterioration. Surgery should follow generally accepted indications, but only with the confidence that total removal can be safely achieved. Surgery that is performed within 10 to 30 days following ictus may be preferable to delayed surgery.

Intraoperative complications in aneurysm surgery: a prospective national study.

OBJECT: With increasing use of endovascular procedures, the number of aneurysms treated surgically will decline. In this study the authors review complications related to the surgical treatment of aneurysms and address the issue of maintaining quality standards on a national level. METHODS: A prospective, nonselected amalgamation of every aneurysm case treated in five of six neurosurgical centers in Sweden during 1 calendar year was undertaken (422 patients; 7.4 persons/100,000 population/year). The treatment protocols at these institutions were very similar. Outcome was assessed using clinical end points. In this series, 84.1% of the patients underwent surgery, and intraoperative complications occurred in 30% of these procedures. Poor outcome from technical complications was seen in 7.9% of the surgically treated patients. Intraoperative aneurysm rupture accounted for 60% and branch sacrifice for 12% of all technical difficulties. Although these complications were significantly related to aneurysm base geometry and the competence of the surgeon, problems still occurred apparently at random and also in the best of hands (17%). The temporary mean occlusion time in the patients who suffered intraoperative aneurysm rupture was twice as long as the temporary arrest of blood flow performed to aid dissection. CONCLUSIONS: The results obtained in this series closely reflect the overall management results of this disease and support the conclusion that surgical complications causing a poor outcome can be estimated on a large population-based scale. Intraoperative aneurysm rupture was the most common and most devastating technical complication that occurred. Support was found for a more liberal use of temporary clips early during dissection, regardless of the experience of the surgeon. Temporary regional interruption of arterial blood flow should be a routine method for aneurysm surgery on an everyday basis. A random occurrence of difficult intraoperative problems was clearly shown, and this factor of unpredictability, which is present in any preoperative assessment of risk, strengthens the case for recommending neuroprotection as a routine adjunct to virtually every aneurysm operation, regardless of the surgeon's experience.

Management of patients with brain arteriovenous malformations.

Arteriovenous malformations (AVMs) of the brain, which are probably genetically determined, are errors in the development of the vasculature that, together with the effects of blood flow, may lead to a focal arteriovenous shunt. Clinically, the adult patient may present with acute or chronic neurological symptoms-fixed or unstable-such as deficits, seizures or headache. Sometimes the lesion is an incidental finding. In about half of the patients, the revealing event is an intracranial haemorrhage. The prevalence of AVM in the western world is probably <0.01% and the detection rate is about one per 100,000 person-years. Most AVMs are revealed in patients 20-40 years of age. Therefore, the risk of developing neurological symptoms from an AVM, usually because of haemorrhage, increases with patient age. In the young adult population, AVMs are significant risk factors for hemorrhagic stroke. This risk increases with AVM volume and is higher in centrally located AVMs. Almost all patients with AVM are subjected to treatment, either by surgery, radiosurgery or embolisation, with the functional aim of reducing the risk of haemorrhage or to alleviate neurological symptoms with an acceptable treatment risk. Few neurocentres have physicians highly skilled in all treatment modalities. Therefore, the prescribed treatment may not be defined from an objective assessment of what is optimal for each individual patient, but rather from local expertise. In this context, more and better data about the natural history and the outcome of different treatments, as well as predictive models, would be valuable to help to optimise the management. Management strategies obviously differ according to local preferences, but results presented in the literature suggest the following strategy: (I) cortically located AVMs with a nidus volume <10 ml could be operated, with or without presurgical embolisation, unless there is a single feeder that can easily be catheterised and embolised for obliteration or other obvious target for embolisation, such as pseudoaneurysms or large fistulae; (II) centrally located AVMs with a nidus volume <10 ml should be treated by radiosurgery, unless suitable for embolisation as indicated above; (III) patients harbouring AVMs with a nidus volume >10 ml could benefit from targeted partial embolisation followed by radiosurgery or surgery, depending on the angioarchitecture; and (IV) AVMs >20 ml nidus volume usually have a high treatment risk with any treatment modality and are not obvious targets for treatment at all.

The Stockholm 20-year follow-up of aneurysmal subarachnoid hemorrhage outcome.

OBJECTIVE: To assess the clinical and radiological long-term outcome after aneurysmal subarachnoid hemorrhage (SAH) in a defined referral area regarding recurrent SAH and de novo aneurysm formation. METHODS: One hundred and two 1-year survivors after aneurysmal SAH, who were treated at the Neurosurgical Clinic, South Hospital, Stockholm, Sweden, between 1983 and 1985, were followed for 20 years. Forty-nine surviving patients were reevaluated. Hospital records and death certificates were scrutinized for all 53 nonsurviving patients. Clinical history penetration, Mini Mental Status, Rankin Disability Score, and Barthel Index were used to evaluate the outcome. Computed tomographic angiography was used to investigate the cerebral arteries. RESULTS: One hundred and two patients were traced. Fifty-three patients were deceased. One patient had a hospital record of sustaining an aneurysmal SAH from a known but not clipped aneurysm. Three patients had nonaneurysmal intracerebral hemorrhage and two sustained traumatic SAH. There were 49 surviving patients. Six refused follow-up. None of these patients had hospital records of intracranial disease. Three of the 43 remaining patients could not be tested. None of the survivors had experienced a new SAH. Aneurysm base remnants were observed in 1% (eight patients, 790 person-years of follow-up) and de novo aneurysms were observed in 0.9% (seven patients, 790 person-years of follow-up). CONCLUSION: From this epidemiological survey of patients with aneurysmal SAH, it was found that none of the patients experienced a recurrent subarachnoid bleed from the treated aneurysm during a 20-year follow-up period. Thus, a routine extreme long-term follow-up period is not necessary. De novo aneurysm formation and possible enlargements of aneurysm base remnants were observed in almost 2% of patients per person year and should, therefore, be subject of a routine, long-term follow-up.

Neuronavigation for arteriovenous malformation surgery by intraoperative three-dimensional ultrasound angiography.

OBJECTIVE: Neuronavigational devices have traditionally used preoperative imaging with limited possibilities for adjustment to brain shift and intraoperative manipulation of the surgical lesions. We have used an intraoperative imaging and navigation system that uses navigation on intraoperatively acquired three-dimensional ultrasound data, as well as preoperatively acquired magnetic resonance imaging scans and magnetic resonance angiograms. The usefulness of this system for arteriovenous malformation (AVM) surgery was evaluated prospectively. METHODS: Nine consecutive patients with Spetzler Grade 1 (n = 3), 2 (n = 3), 3(n = 2) or 4 (n = 1) AVMs underwent operation using this intraoperative imaging and navigation system. The system provides real-time rendering of three-dimensional angiographic data and can visualize such projections in a stereoscopic (virtual reality) manner using special glasses. The experiences with this technology were analyzed and the outcomes assessed. Angiographic reconstructions of three-dimensional images were obtained before and after resection. RESULTS: Conventional navigation on the basis of preoperative magnetic resonance angiography was helpful to secure positioning of the bone flap; stereoscopic visualization of the same data represented a powerful means to construct a mental three-dimensional picture of the extent of the AVM and the feeder anatomy even before skin incision. Intraoperative ultrasound corresponded well to the intraoperative findings and allowed confirmation of feeding vessels in surrounding gyri and rapid identification of the perinidal dissection planes, regardless of brain shift. The latter feature was particularly helpful because the intraoperative navigational identification of surgical planes leads to minimal exploration into the nidus or dissection at a greater distance from the malformation. Application of the system was thought to increase surgical confidence. In two patients, postresection ultrasound prompted additional nidus removal. Ultrasound angiography seemed to allow some degree of resection control, although its sensitivity was not thought to be sufficient. All AVMs were radically removed without new permanent morbidity. CONCLUSION: The complexities of handling the pathological vessels of AVMs were ameliorated by intraoperative three-dimensional ultrasound and navigation because the three-dimensional outline of the vasculature (feeders, nidus, and draining veins) provided a means to adapt resection strategies, define dissection planes, and interpret intraoperative findings. It is difficult to provide a scientifically valid definition of "added value." However, in our experience, the added confidence and the improved mental image of the lesion that resulted from this technology improved the quality and flow of surgery.