Suchergebnisse

Abstract
Background A pial arteriovenous fistula (PAVF) is a rare neurovascular pathology consisting of a direct connection between one or more arterial feeders and a single venous channel. A PAVF was previously considered a subtype of an arteriovenous malformation (AVM). In the current literature these are distinguished as two independent entities with different clinical, physiopathologic, and structural characteristics. We report a case of a surgically treated 37-year-old woman with an extremely rare combination of an unruptured PAVF and AVM.
Patient The AVM was mainly supplied by feeders of the middle cerebral artery and drained into the sigmoid sinus via an abnormally dilated and tortuous vein. Following its resection, intraoperative digital subtraction angiography (DSA) in the hybrid operating room revealed the presence of a PAVF that had not been noted during the preoperative planning. Hence the PAVF was completely disconnected as confirmed by DSA again.
Conclusion This is the second reported case of an AVM-associated PAVF. Without the intraoperative DSA in the hybrid operating room, this unusual complex cerebrovascular entity would likely have been missed.

Abstract
Objective The objective of this study was to determine the performance of the standard alarm criterion of motor evoked potentials (MEPs) of the facial nerve in surgeries performed for resections of vestibular schwannomas or of other lesions of the cerebellopontine angle.
Methods This retrospective study included 33 patients (16 with vestibular schwannomas and 17 with other lesions) who underwent the resection surgery with transcranial MEPs of the facial nerve. A reproducible 50% decrease in MEP amplitude, resistant to a 10% increase in stimulation intensity, was applied as the alarm criterion during surgery. Facial muscular function was clinically evaluated with the House–Brackmann score (HBS), pre- and postsurgery at 3 months.
Results In the patient group with vestibular schwannoma, postoperatively, the highest sensitivity and negative predictive values were found for a 30% decrease in MEP amplitude, that is, a criterion stricter than the 50% decrease in MEP amplitude criterion, prone to trigger more warnings, used intraoperatively. With this new criterion, the sensitivity would be 88.9% and the negative predictive value would be 85.7%. In the patient group with other lesions of the cerebellopontine angle, the highest sensitivity and negative predictive values were found equally for 50, 60, or 70% decrease in MEP amplitude. With these criteria, the sensitivities and the negative predictive values would be 100.0%.
Conclusion Different alarm criteria were found for surgeries for vestibular schwannomas and for other lesions of the cerebellopontine angle. The study consolidates the stricter alarm criterion, that is, a criterion prone to trigger early warnings, as found previously by others for vestibular schwannoma surgeries (30% decrease in MEP amplitude).

Abstract
Background The optimal management of posterior fossa arteriovenous malformations (pfAVMs) is a matter of debate. To advance this discussion, we present our clinical series and the results of a systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.
Methods Fourteen consecutive patients with pfAVMs were admitted between 2007 and 2018. Preoperative status, radiologic parameters, and outcome were assessed. A systematic literature review was performed according to the PRISMA-P guidelines.
Results Ten patients presented with rupture (71%), of whom three had associated aneurysms (AAs). The treatments were microsurgery (n = 4), endovascular (n = 3), radiosurgery (n = 2), a combination of two or three treatment modalities (n = 3), or conservative (n = 2). At discharge, all four patients (100%) with unruptured pfAVMs had a good outcome (modified Rankin Scale [mRS]: 0–2). In contrast, in ruptured pfAVM cases, mRS was 0 to 2 in four patients (40%), mRS 3 to 4 in two (20%), mRS 5 in three (30%), and one patient (10%) died within 30 days after gamma knife treatment due to pancreatitis secondary to chronic alcohol abuse. At discharge, four patients (29%) had persistent preinterventional cranial nerve and/or focal neurologic deficits. The literature review identified 63 articles with 1,753 pfAVM patients. Overall, 66% of pfAVMs presented with rupture, and AAs were found in 20% of the cases, which is higher than in supratentorial AVMs (stAVMs).
Conclusions Because pfAVMs are associated with higher rates of hemorrhagic presentation, higher rates of morbidity and mortality when ruptured, and have a higher incidence of AAs compared with stAVMs, early curative treatment is recommended as soon as the diagnosis is established, regardless of rupture status.