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Noel F. Fanning, Robert A. Willinsky and Karel G. terBrugge

Object

Symptomatic local inflammation, aseptic meningitis, and hydrocephalus are reported in a group of patients treated with second generation/modified platinum coils. The purpose of this study was to define the frequency and determinants of magnetic resonance (MR) imaging findings of aneurysm wall enhancement, perianeurysmal edema, and hydrocephalus in a cohort of coil-embolized intradural cerebral aneurysms treated with bare platinum or modified platinum coils (Matrix or HydroCoils).

Methods

The authors retrospectively reviewed 359 Gd-enhanced MR follow-up studies of 181 treated aneurysms (125 ruptured) for mural enhancement. Univariate and multivariate logistic regression analyses were used to define mural enhancement associations with demographic, clinical, angiographic, treatment, and follow-up data. Embolization-related edema and hydrocephalus were defined in 95 MR imaging studies of 56 unruptured aneurysms.

Results

Asymptomatic wall enhancement was observed in lesions treated with all coil types, occurring in 21 (18.6%) of 113 bare platinum coil–treated aneurysms. Independent associations were HydroCoil treatment (odds ratio [OR] 9.75, 95% confidence interval [CI] 3.45–30.75) and increasing aneurysm size (OR 3.58, 95% CI 1.99–6.95). Five (8.9%) unruptured aneurysms had asymptomatic de novo edema, and 3 (5.3%) demonstrated hydrocephalus; all had been treated with HydroCoils. Hydrocephalus presentation was delayed (8–31 months) and symptomatic in 2 patients.

Conclusions

Asymptomatic aneurysm wall enhancement occurred in 18.6% of embolizations performed with bare platinum coils, and probably represents a normal healing response. Perimural edema and hydrocephalus were observed only in patients treated with HydroCoils, but have been reported in patients treated with other modified platinum coils. These symptoms appear to represent an exaggerated inflammatory response during aneurysm healing. Increased vigilance for delayed hydrocephalus is required. Judicious clinical use of modified platinum coils is warranted until results of randomized trials are published.

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J. Marc C. Van Dijk, Karel G. TerBrugge, Robert A. Willinsky and M. Christopher Wallace

Object. Dural arteriovenous fistulas (AVFs) are a well-known pathoanatomical and clinical entity. Excluding bilateral involvement of the cavernous sinus, multiple dural AVFs are rare, with isolated reports in the literature. The additional risk associated with multiplicity is unknown, although it has been claimed that there is a greater risk of hemorrhage at presentation. In a group of 284 patients with dural AVFs consecutively treated at a single center, the occurrence of multiplicity is investigated and its risk factors for hemorrhage are identified.

Methods. Among the 284 patients with both cranial and spinal dural AVFs, 20 patients with multiple fistulas were found. Nineteen (8.1%) of 235 patients with cranial AVFs had multiple cranial fistulas, and one (2%) of 49 patients with spinal AVFs harbored two spinal fistulas. Twelve patients were found to have a lesion at two separate sites, seven patients had them at three locations, and one patient had four fistulas, each at a different site.

In the subgroup with multiple AVFs the percentage of hemorrhage at presentation was three times higher than in the entire group (p = 0.01). Cortical venous drainage in cranial fistulas was present in 84% of patients with multiple lesions compared with 46% of patients with solitary lesions (p < 0.005).

Conclusions. Multiple dural AVFs are not rare. In this group of 284 patients it was found in 8.1% of all patients with cranial dural AVFs. Multiplicity was associated with a higher percentage of cortical venous drainage, a pattern of drainage reportedly yielding a higher risk for hemorrhage.

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Farhad Pirouzmand, M. Christopher Wallace and Robert Willinsky

✓ A spinal epidural arteriovenous fistula with secondary reflux into the perimedullary veins is a rare entity. The authors present such a case with a discussion of its pathophysiology and treatment. The mechanism for formation of a spinal dural arteriovenous fistula is outlined based on the anatomical substrates in this region.

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J. Marc C. van Dijk, Karel G. TerBrugge, Robert A. Willinsky and M. Christopher Wallace

Object. A single-institution series of 119 consecutive patients with a dural arteriovenous fistula (DAVF) and cortical venous reflux was reviewed to assess the overall clinical outcome of multidisciplinary management after long-term follow up. The selective disconnection of the cortical venous reflux compared with the obliteration of the entire DAVF was evaluated.

Methods. Dural arteriovenous fistulas in patients in this series were diagnosed between 1984 and 2001, and treatment was instituted in 102 of them. The outcome of adequately treated patients was compared with that of a control group consisting of those with persistent cortical venous reflux and with data found in the literature. In cases of combined dural sinus drainage and cortical venous reflux, a novel treatment concept of selective disconnection of the cortical venous reflux that left the sinus drainage intact, and thus converted the aggressive DAVF into a benign lesion, was evaluated.

Endovascular treatment, which was instituted initially in 78 patients, resulted in an obliteration or selective disconnection in 26 (25.5%) of 102 cases. In 70 cases (68.6%) the DAVFs were surgically obliterated or disconnected. In six cases (5.9%), patients were left with persistent cortical venous reflux. No lasting complications were noted in this series. Follow-up angiography confirmed a durable result in 94 (97.9%) of 96 adequately treated cases, at a mean follow up of 27.6 months (range 1.4–138.3 months).

Selective disconnection was performed in 23 DAVFs with combined sinus drainage and cortical venous reflux. These patients' long-term outcomes were equal to those with obliterated DAVFs, and the complication rate was lower.

Conclusions. Considering the ominous course of DAVFs with patent cortical venous reflux, multidisciplinary treatment of these lesions is highly effective and the complication rate is low. Selective disconnection provides a valid treatment option of DAVFs with combined dural sinus drainage and cortical venous reflux, as has been shown in cranial DAVFs with direct cortical venous reflux.

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Gary Redekop, Karel TerBrugge, Walter Montanera and Robert Willinsky

Object. The goal of this study was to develop a classification system for aneurysms associated with arteriovenous malformations (AVMs) based on their anatomical and pathophysiological relationships and to determine the incidence and bleeding rates for these aneurysms as well as the effects of AVM treatment on their natural history.

Methods. Of 632 patients with AVMs, intranidal aneurysms were found in 35 (5.5%) and flow-related aneurysms in 71 (11.2%). Patients with intranidal aneurysms presented more frequently with hemorrhage (72% compared with 40%, p < 0.001) and had a 9.8% per year risk rate of bleeding during follow-up review. Twelve (17%) of the patients with flow-related aneurysms associated with an AVM presented with hemorrhage from an aneurysm, whereas 15 (21%) bled from their AVM. Seventeen patients underwent angiography after AVM treatment (mean 2.25 years). Of 23 proximal aneurysms, 18 (78.3%) were unchanged, four (17.4%) were smaller, and one (4.3%) had disappeared, whereas four (80%) of five distal aneurysms regressed completely and one was unchanged. Sixteen patients underwent angiography after partial AVM treatment (mean 3.8 years). In cases with less than a 50% reduction in the AVM, no aneurysms regressed, although two enlarged and bled. In cases with greater than a 50% reduction in the AVM, two of three distal aneurysms disappeared and five proximal aneurysms were unchanged.

Conclusions. Arterial aneurysms associated with cerebral AVMs may be classified as intranidal, flow-related, or unrelated to the AVM nidus. Intranidal aneurysms have a high correlation with hemorrhagic clinical presentation and a risk of bleeding during the follow-up period that considerably exceeds that which would be expected in their absence. Patients with flow-related aneurysms in association with an AVM may present with hemorrhage from either lesion. Aneurysms that arise on distal feeding arteries near the nidus have a high probability of regressing with substantial or curative AVM therapy.

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Dittapong Songsaeng, Sasikhan Geibprasert, Karel G. ter Brugge, Robert Willinsky, Michael Tymianski and Timo Krings

Object

The goal was to investigate whether morphological features of aneurysms can be identified that determine initial success and recurrence rates of coiled aneurysms of the basilar artery tip, the posterior communicating artery (PCoA), and the anterior communicating artery.

Methods

The authors evaluated 202 aneurysms in connection with their pretreatment morphological features including size, neck-to-dome ratio, angulation of the aneurysm in relation to the parent artery, orientation of the aneurysm dome, and associated anatomical variations. The mean follow-up was 19 months (range 6–96 months) after endovascular coil occlusion. Using multivariate logistic regression, probabilities for initial complete occlusion and long-term stability of the treatment were calculated.

Results

Recanalization occurred in 49 of 202 cases. Favorable factors for long-term stability included small aneurysms with small necks. However, additional factors related to local hemodynamic forces could be identified for the different aneurysm locations, which may influence initial success rates and long-term stability of aneurysm treatment with endovascular coiling. These factors were a medial dome orientation and a symmetrical disposition of both A1 segments (for the anterior communicating artery), a posteroinferior dome orientation and a small-size PCoA (for the PCoA), and a cranial symmetrical fusion (for the basilar artery tip).

Conclusions

A detailed pretreatment analysis of morphological features of aneurysms may help to determine those aneurysms that are more prone to recurrence, which could add to the treatment decision and the follow-up algorithm.

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Amir R. Dehdashti, Leodante B. Da Costa, Karel G. terBrugge, Robert A. Willinsky, Michael Tymianski and M. Christopher Wallace

Dural arteriovenous fistulas are the most common vascular malformations of the spinal cord. These benign vascular lesions are considered straightforward targets of surgical treatment and possibly endovascular embolization, but the outcome in these cases depends mainly on the extent of clinical dysfunction at the time of the diagnosis. A timely diagnosis is an equally important factor, with early treatment regardless of the type more likely to yield significant improvements in neurological functioning. The outcomes after surgical and endovascular treatment are similar if complete obliteration of the fistulous site is obtained. In the present study, the authors evaluated the current role of each modality in the management of these interesting lesions.

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Phillip J. Porter, Robert A. Willinsky, William Harper and M. Christopher Wallace

✓ Despite recent studies of the natural history of cavernous malformations, there remains significant uncertainty concerning hemorrhage rates and the importance of lesion location. Controversy arises over varying definitions of “hemorrhage.” What is ultimately important to the patient is the occurrence of a neurological event, which may or may not be associated with radiologically documented hemorrhage, as well as the chance of recovery after such an event. The purpose of this study was to determine the rates of occurrence and sequelae of neurological events in 173 patients referred to our vascular malformation clinic with cavernous malformations.

All patient data were entered into a database. The mean age at presentation for the 173 patients was 37.5 years. The lesion location was deep (brainstem, cerebellar nuclei, thalamus, or basal ganglia) in 64 patients (37%) and superficial in 109 (63%). Thirty-one patients (18%) had multiple lesions. Disease presentation was due to seizures in 62 patients (36%), hemorrhage in 44 (25%), focal neurological deficit without documented hemorrhage in 35 (20%), headache alone in 11 (6%), and incidental findings in 21 patients (12%). The results obtained in the 110 patients eligible for follow-up review were used to derive information on the rates of hemorrhage and neurological events. An interval event (neurological deterioration) required both symptoms and signs. The total mean follow-up period was 46 months, the majority (65%) of which was prospective. There were 18 interval events in 427 patient-years of follow-up review, for an overall annual event rate of 4.2%. Location was the most important factor for predicting interval event occurrence, with significantly higher rates for deeply located (10.6%/year) compared with superficially located lesions (0%/year) (p = 0.0001). Of patients suffering a neurological event, only 37% had complete resolution of their deficits.

This largely prospective study indicates that deep cavernous malformations carry a worse prognosis than superficial lesions with respect to annual rates of neurological deterioration. The alarming rate of adverse clinical events occurring in patients with deep lesions is punctuated by the fact that less than one-half of them recover fully during long-term follow-up review.

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Charles S. Haw, Karel terBrugge, Robert Willinsky and George Tomlinson

Object

The goal of this study was to determine the rates of mortality and morbidity associated with the embolization of arteriovenous malformations (AVMs) of the brain and to analyze the factors related to embolization-related complications.

Methods

The University of Toronto Brain Vascular Malformation Study Group database was reviewed. Three hundred six patients underwent 513 embolization sessions between November 1984 and September 2002. The combined rate of death and any permanent disabling neurological deficit was 3.9% per patient. Location of the AVM in an eloquent part of the brain, presence of a fistula, and a venous deposition of glue were related to complications. A clinically important reduction in the rate of death and disabling morbidity occurred in the second half of the study period.

Conclusions

Embolization of AVMs in the brain is associated with low overall rates of mortality and disabling morbidity.