K. ter Brugge

Management and clinical outcome of posterior fossa arteriovenous malformations: report on a single-centre 15-year experience

Objectives: Posterior fossa brain arteriovenous malformations (PFbAVMs) are rare lesions. Management is complicated by eloquence of adjacent neurological structures, multimodality treatment is often necessary, and obliteration is not always possible. We describe a 15-year experience in the management of posterior fossa brain AVMs with a focus on clinical outcome. Methods: From 1989 to 2004, prospectively collected information on 106 patients with diagnosis of a PFbAVMs was obtained. Clinical and angioarchitectural characteristics, management options and complications are described and reviewed to evaluate their impact on final outcome as measured by the Modified Rankin Score (mRS). Results: Ninety-eight patients were followed for an average of 3.3 years (1–14.6). The male-to-female ratio was 1:1. Ninety-five out of 98 patients (96.9%) were symptomatic at presentation, with 61 (62.2%) intracranial haemorrhages. Sixty-two patients were treated (46 cerebellar, 16 brainstem). Ten haemorrhages occurred in follow-up (4.1%/year). The mRS was obtained in 62 patients and was classified as low (good, mRS⩽2) or high (poor, mRS⩾3). Haemorrhage was the only predictor of poor mRS at presentation (p = 0.0229). A poor clinical outcome was correlated with the presence of AA (p = 0.0276), a poor initial mRS (p<0.0001) and the number of treatments needed (p = 0.0434). Patients were significantly more likely to improve than to deteriorate over time (p = 0.0201). Conclusion: The final clinical outcome in PFbAVMs relates directly with the presence of associated aneurysms, number of treatments needed to obliterate the AVM and mRS at presentation. Despite the fact that patients tend to improve after brain AVM haemorrhage, the relationship of MRS at presentation and final outcome suggests that an expedited, more definitive treatment is probably a better choice, especially in patients with good grades after the initial bleeding.

Transvenous Embolization of Intracranial Dural Arteriovenous Shunts through Occluded Venous Segments: Experience in 51 Patients

BACKGROUND AND PURPOSE: DAVFs with cortical venous reflux carry a high risk of morbidity and mortality. Endovascular treatment options include transarterial embolization with a liquid embolic agent or transvenous access with occlusion of the involved venous segment, which may prove difficult if the venous access route is thrombosed. The aim of this article is to describe the technique and results of the transvenous approach via thrombosed venous segments for occlusion of DAVFs. MATERIALS AND METHODS: Our study was a retrospective analysis of 51 patients treated with a transvenous approach through an occluded sinus that was reopened by gentle rotational advancement of a 0.035-inch guidewire, which opened a path for a subsequently inserted microcatheter. RESULTS: Of 607 patients with DAVFs, the transvenous reopening technique was attempted in 62 patients in 65 sessions and was successful in 51 patients and 53 sessions. Immediate occlusion was seen in 42 patients; on follow-up, occlusion was seen in 49 patients, whereas 2 patients had reduced flow without cortical venous reflux. No permanent procedure-related morbidity was noted. CONCLUSIONS: The reopening technique to gain access to isolated venous pouches or the cavernous sinus for the treatment of DAVFs is a safe and effective treatment, which should be considered if transarterial approaches fail or are anticipated to result only in an incomplete anatomic cure.

Intrasellar Rupture of a Paraclinoid Aneurysm With Subarachnoid Hemorrhage: Usefulness of MR Imaging in Diagnosis

SUMMARY: Characterization of paraclinoid aneurysms may be difficult because of the complexity of anatomic structures involved, and differentiation between intradural and extradural lesions is crucial. We report a case of a patient with a unique presentation of a paraclinoid aneurysm with intrasellar hemorrhage in which the presence of intrasellar blood and the relationship of the paraclinoid aneurysmal neck and sac to the dural rings were elegantly demonstrated on MR imaging and were critical in choosing the target lesion for treatment.

Focal Lesion in Splenium of Corpus Callosum on FLAIR MRI: Common Findings in Aged Patients

Focal high signal intensity in the splenium of the corpus callosum on fluid-attenuated inversion-recovery (FLAIR) images is generally considered an abnormal MR finding. The aim of this study was to determine the frequency of this finding in elderly patients and review the differentiation from other diseases with the similar findings. FLAIR images of 132 patients with suspect CNS disease were retrospectively reviewed. The changes in the splenium of corpus callosum, deep white matter lesions, periventricular matter lesions, infarcts, atrophy and age were analyzed, as well as history. Among the initial 132 patients, focal high signal intensity in the splenium was associated with aging, white matter changes, atrophy, and cognitive disorders. Focal high signal intensity in the splenium of the corpus callosum on FLAIR image is a common finding in elderly patients, especially in aged patients with cognitive disorders. The pathologic alterations were commonly described by the term of “leukoaraiosis”. Knowledge of this finding and differentiation from other lesions focusing on the splenium of corpus callosum may help avoid unnecessary invasive diagnostic and therapeutic intervention.

Cavernous Sinus Segment Internal Carotid Artery Aneurysms: Whether and How to Treat

Cavernous Sinus Segment Internal Carotid Artery Aneurysms: Whether and How to Treat W.J. Van Rooij describes the single-institution management strategy and outcome of active intervention of 86 cavernous sinus segment (CS) ICA aneurysms in the article entitled “Endovascular Treatment of Cavernous Sinus Aneurysms.” Twenty-one of the aneurysms treated were asymptomatic, while 56 presented with cranial neuropathy, 8 with a carotid cavernous fistula, and 1 with subarachnoid hemorrhage. Treatment consisted of endosaccular coiling in 31 (36%) of the aneurysms, while parent vessel occlusion was performed in 50 (64%), with procedures done following bypass surgery because of test balloon occlusion intolerance. Treatment-related neurologic complications did not occur in the group that underwent endosaccular coiling, but 2 patients (4%) developed transient neurologic deficits following parent vessel occlusion, while 1 patient (2%) developed a permanent neurologic deficit as the result of the treatment, for a total of 6% periprocedural neurologic sequel. There was no mortality. All 8 cavernous sinus fistulas were closed with coils. In 52 of 56 (93%) patients presenting with symptoms of mass effect, symptoms were alleviated (n 23) or improved (n 29) at follow-up, and 34 of 50 aneurysms (68%) were substantially decreased or completely obliterated. This article brings to our attention once again the frequent modern management dilemma of knowing whether to provide treatment for a condition of which we do not know the natural history. The prevalence of CS ICA aneurysms in the general population is not exactly known, and certainly we have all seen, in the past few years, many more such aneurysms, incidentally discovered at the time of noninvasive imaging performed for unrelated symptoms. Very few natural history studies have been performed, and most included small numbers of patients. Linskey et al prospectively followed 20 CS ICA aneurysms for an average of 2.4 years and demonstrated that only 1 of 10 asymptomatic lesions became symptomatic to the point of requiring treatment, while 4 of the symptomatic lesions became asymptomatic in time. Kupersmith et al prospectively followed 12 asymptomatic CS ICA aneurysms, and all remained asymptomatic with time. On the other hand, Goldenberg-Cohen et al reported that among 10 asymptomatic patients, 7 worsened on long-term follow-up. It is unfortunate that in the current series, 19 patients were excluded because no active treatment was performed and unfortunately no follow-up on these patients was available, which could have provided some much-needed insight into the natural history of this disorder. In addition, there continues to be a tendency to lump all aneurysms together without making a proper distinction between their various etiologies, which almost certainly will lead to different natural histories (dissecting, dysplastic, arteriosclerotic, iatrogenic pseudoaneurysm, and so forth). This lack of detailed information remains an obstacle to the understanding of previously published literature and its implications for management. Consequently, a properly conducted natural history study would be tremendously helpful and is long overdue. The indication for active treatment of asymptomatic CS ICA aneurysms is, therefore, questionable, and any decision to treat should be carefully considered in view of our very limited knowledge of their natural history and the small but definite immediate potential risk associated with their treatment. There is little scientific evidence to support treatment of an asymptomatic CS ICA aneurysm, irrespective of size or age. There is certainly no indication for treatment if the aneurysm is small and the patient is in the elderly age group. The indication for active treatment of symptomatic CS ICA aneurysms is questionable when neurologic symptoms are stable and well-tolerated and the patient is in the older age group. On the other hand, active intervention is well-accepted for those patients with CS ICA aneurysms who present with progressive neurologic symptoms, pain syndromes that are not clinically tolerated, or aneurysms associated with rupture into the adjacent cavernous sinus, sphenoid sinus, or subarachnoid space. With respect to the treatment choice, several reports in the literature as well as the current study have documented variable outcome results as well as procedural risks. Endosaccular coiling of the aneurysm alone was associated with a cure rate on follow-up of approximately 80% with no associated neurologic deficits in the meta-analysis study of 316 CS ICA aneurysms, while parent vessel occlusion resulted in a 98% cure rate, but the procedure-related neurologic deficits were 5%. Stent-assisted coiling resulted in a 75% cure rate on follow-up and was associated with a 3.5% risk for neurologic deficits in a recent series of 113 patients with CS ICA aneurysms, 47% of which were treated by stent placement and coiling. The experience with flow-diverting stents under these circumstances is still evolving, and while conceptually intriguing, the early results show excellent ability to exclude the aneurysm lumen but unpredictable outcome with respect to mass effect reduction and neurologic improvement. As new treatment options become available, the risk-management strategy will need to include a consideration of which type of treatment (parent vessel occlusion, coiling, stent placement, flow-diverting stent, and so forth) would be most efficient for alleviating symptoms at the lowest possible associated risk. As is the case with intradural aneurysms, our focus has been mostly on fixing (obliterating) the lumen of the aneurysm, while a more recent investigation by Krings et al suggests that vessel wall disorders may be the primary pathology responsible for luminal enlargement, at least in certain aneurysms, and that modern imaging can be used to distinguish various vessel wall pathologies and to establish whether the aneurysm wall is inactive and stable versus active and vulnerable. This distinction may also help us to be more precise in selecting which patients with CS ICA aneurysms should be treated. As the current study documents, it is certainly interesting to observe the strong female sex predominance of CS ICA aneurysms, which is similar to the strong female preponderCO M M EN TA RY

Vascular Malformations Involving the Mesencephalic Region (Review of 26 Personal Cases)

The diagnosis and treatment involving the mesencephalic region are particularly challenging. Deeply located, and containing vital functions, the mesencephalic region regroups most of the problems that can be encountered in CNS vascular malformations (Smith and Rolla 1982): “cortical” lesions (temporal lobe—cerebellum) “deep” lesions (diencephalon—brain stem) dural structures (tentorium—falx) involvement cranial nerves (IIIrd, IVth and Vth) involvement

SU‐E‐T‐577: Stereotactic Radiosurgery for AVMs: Impact of Embolization Media on Radiation Dose

Purpose: We investigate the dosimetric impact of surgical embolization of Arteriovascular‐malformations (AVMs) on further follow‐up Stereotactic Radiosurgery. Two embolization media are studied. By introducing a tissue inhomogeneity, the breakdown in electron equilibrium at the interface impacts actual tissue dose within a few mm. As this is the precise location of the target tissue the dose departure from standard prescription is to be quantified. Methods: Inhomogeneity phantoms were constructed to model regions of various thickness 2mm – 16mm. Each phantom was constructed of a tissue equivalent material while drilled embolization cavities were filled with 4 different admixtures of embolizing media: Onyx (TM) with contrast‐ to‐polymer ratio 18% and 34%; and Embucrilate (TM) (33% and 50%). Near tissue‐equivalent radiochromic film was placed in planes 0, 1, and 2mm up‐beam and down‐beam from the inhomogeneity. The simulated embolizations and films were then irradiated in a 6MV radiosurgery beam at tissue depth of 7cm. Results: In a narrow beam geometry, we observe an immediate depletion of dose at the interface downstream of the Onyx medium of up to 20% compared to 18% for the Embucrilate. The dose enhancement immediately upstream of the embolization medium interface is typically 25% for the Onxy and 15% for Embucrilate. Conclusions: While radiosurgery beams are typically directed from a large range of angles, the two connected dose interface effects tend to cancel only laterally. Typical beam arrangements have a superior‐to‐inferior directional bias and the inhomogeneity interface effects on dose will have an effect on the target tissue at those aspects of the embolized portions of the AVM lesion.

Arterial and Venous Angioarchitecture of Cerebral AVM in Adults

During the last ABC course, in January 1994 Georges Rodesch had presented the angioarchitecture in an exhaustive pictural fashion. The cortical A VM, cortico-sub-cortical, cortico-ventricular, cortico-callosal, deep seeted and choroi:dal plexus constituted the gross localisations presented and widely accepted. 10 years ago, the concept developed in Bicetre for angioarchitecture expressing the high flow angiopathy was made to balance the technical classifications to obtain proper control of the flow in order to deliver embolic agents. The features that we have described (non sprounting angiogenesis, lepto-meningeal circulation, transdural supply, variations, stenoses, moya-moya aspect, vasopasm, associated aneurysm, flow related aneurysm, dysplastic aneurysm, false aneurysm) were attempting to introduce the concept of time elapsed since the arteriovenous maformation had developed on the cerebral vasculature. We know today that these pathological changes described by John Pile-Spellman in 1986 constitutes the result of stress striggers generated by the shunt and applied to normal functioning endothelial cells. The abnormality of the message sent to these cells create the abnormal of their response. The clinical eloquence of this dysfunction is a long time undetected. Today however we can read with a great accurracy these abnormalities and understand their significance in the production of the natural history. We have taken as an exemple the brain AVM to illustrate the progressive alteration that angiography can demonstrate and its association to clinical manifestations. It is interesting to see that a given type of complication can be the expression of very different angioarchitectural disorders. The capacity to disclose which type of abnormality is responsible for the symptoms constitutes part of the pre requisite in interventional neuroradiology. Each type of arterial disorder (from stenotic and enlargement, to impairment) will be illustrated with some relevant cases. One could assess that brain A VMs in children are very different than in adults; it is true for the most part but the mistake would be to consider that children are small adults. It is in fact adults that are big children. Understanding of what has developed in children allows to nuance the concept of «congenital defect»; morphologically occult A VM, are triggered during childhood or even adulthood.