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BACKGROUND Management of complex thrombosed aneurysms of the middle cerebral artery (MCA) is challenging. Lesions not amenable to endovascular techniques or direct clipping might require a bypass procedure with subsequent aneurysm occlusion. Various bypass techniques followed by surgical or endovascular closure of the aneurysm are available, but an unpredictable extension of the thrombus to the parent vessel and/or to perforator vessels can occur. We present a multidisciplinary technique with the aim to reduce invasiveness and complications. METHODS We present two patients, harboring a thrombosed giant MCA bifurcation aneurysm, who were treated with a minimally invasive three-steps multimodality procedure. In both cases, through a limited exposure of the sylvian fissure, a side-to-side anastomosis between the two M2 branches was performed, followed in the immediate post-op by an endovascular occlusion of the frontal M2 branch, with the aim of transforming a bifurcation aneurysm in a sidewall aneurysm, that was then treated a few days later by flow diverter deployment. RESULTS Both patients had excellent outcomes and were discharged after 7 days without neurological deficits. CONCLUSIONS Treatment of complex thrombosed MCA aneurysms is challenging. Side- to-side M2 anastomosis with the aim of transforming a bifurcation aneurysm in a sidewall aneurysm, suitable to be treated few days later by flow diverter deployment, offers a minimally invasive multimodal approach with the possibility of reducing serious complications.

Background Giant calcified thoracic disk herniation (GCTD) is an uncommon event, which requires surgical treatment in less than 1% of patients. GCDTs are a specific subgroup of herniated thoracic disks occupying more than 40% of the spinal canal showing calcifications associated with a certain degree of ossification. In this paper, we are reporting our whole experience in the surgical management of GCTDs through anterior approaches. We believe that they present characteristics that associate them to the circumscribed type of Ossified Posterior Longitudinal Ligament (OPLL) with a possible common pathophysiology consisting in the dural violation. Methods Twenty-three consecutive patients with GCDTs were managed through anterior approaches during the period 1996-2019 at the Niguarda Hospital - Milan, Italy. Clinical data, radiological features, surgical reports, histological findings, and outcomes were reviewed. Results There was no mortality, whereas permanent morbidity consisted of 1 cases of worsened paraparesis due to accidental spinal cord contusion. One patient required reoperation to repair a postoperative cerebrospinal fluid (CSF) leakage. All patients underwent postoperative MRI which showed excellent decompression of cord and dural sac in all cases. Histological study of en-bloc removed GCTD showed typical calcification patterns of the PLL. Conclusions GCDTs may be assimilated to the so-called "circumscribed type" of OPLL. The GCDTs may show the same radiological CT and MRI pattern of OPLL. The anterior accesses now represent the standard of care for GCTDs. The use of operative microscope and intraoperative monitoring is mandatory. The risk of CSF leakage can be markedly reduced by meticulous reconstruction of the dura and the placement of spinal drainage. Adequate exposition may sometimes require one or two levels of corpectomy with consequent vertebral body reconstruction and fixation of anterior column of the spine.

Arteriovenous malformations (AVMs) are rare entities and therefore considered the main challenge for a neurosurgeon. Since the publication of the ARUBA study, one of the most popular debate regards the actual surgical indication for unruptured AVMs. Our group recently published a multicenter review of more than 500 cases underlying the important role of surgery. Over the last few decades, the expanding technologies used in the treatment of AVMs have shown an ongoing improvement overcoming some of the existing difficulties and shortcomings. In this paper, we reviewed the present literature to illustrate the main contemporary tools that, in our opinion, are crucial to obtain the best surgical and clinical outcome. Indocyanin green is nowadays considered a gold standard to identify arterial feeders, draining veins, and to detect any eventual residual. The use of non-stick, bipolar, 2-mm blade microclips, and thulium laser allows to obtain a better bleeding control and nidus removal. The development of the intraoperative ultrasound with neuronavigation, angiosonography, and color-Doppler improves the accuracy of AVM resection. Moreover, improvements have been developed with the use of intraoperative micro-Dopplers combined with flow measurements, which consent to verify the gradual reduction of flow through draining veins. The possibility to perform functional preoperative studies and intraoperative monitoring can be considered as an essential point in the decision making in eloquent or near-eloquent AVMs. Furthermore, the hybrid operating room represents the best expression of an excellent neurovascular team where the use of the intraoperative angiography allows neurosurgeons and neurointerventional radiologists to work at the same time in a combined approach to achieve the best surgical removal.

The availability of flow diverters and new endovascular techniques has greatly reduced the need and indications for bypass surgery. Nevertheless, there are situations where a bypass is the best option for a complex cerebrovascular problem. Generally, typical indications are giant aneurysms with a wide neck and/or partially calcified aneurysms with main branches or perforating arteries arising directly from the sac or from the neck itself, or fusiform aneurysms, partially calcified aneurysms. In this paper we discuss the following issues as they apply to the modern use of bypass techniques. In case of fusiform aneurysms involving the proximal bifurcations of the media or the internal carotid artery combined and coordinated evaluations and efforts by a team which includes neurosurgeons and endovascular specialists is essential. Treatment with bypass alone may not be sufficient and the combination of one or more bypasses with an endovascular treatment of occlusion, partial aneurysm embolization or flow diversion may be the best strategy. Addressing complex and fusiform aneurysm surgery requires a problem solving attitude and in this lies both the challenging and the fun side of this surgery.

As the conclusions of the ARUBA Study are strongly oriented towards therapeutic abstention, we think it is appropriate to express the concern of the Italian Society of Neurosurgery for the impact that this study might have on the health of patients, if not properly evaluated. The vast majority of patients (76-81%) included in the study was treated with endovascular or radiotherapy treatments, alone or in combination. Only 18 patients (19%) had surgery. It is well known that a partial treatment of arteriovenous malformations (AVMs), as is often the case with endovascular therapy, may increase the risk of bleeding. The primary endpoint (death or symptomatic stroke) in the treated group was reached in 30.7%, i.e. almost one-third of the subjects. This has no comparison in the current surgical literature. Considering permanent and transient neurological deficits along with headaches and seizures all together in the same outcome evaluation parameter may be inappropriate and misleading. The graph with all results from the ARUBA Study, which claims to be the demonstration that natural history is better that treatment, clearly shows that what is assumed to be treated has not actually been treated. If death or stroke occur a few years from treatment, it only means that the disease was not cured and patients received a partial - therefore ineffective, if not dangerous - treatment. An effective treatment, as surgery is, must have a flat follow-up curve. The ARUBA Study shows that incomplete treatment leads to negative outcome, confirming that an integrated multidisciplinary strategy has to be plotted out before starting any treatment and that a complete exclusion of the AVM must be achieved.

26 patients harbouring a CSF shunt for non-tumoral aqueductal stenosis hydrocephalus underwent Brainstem Acoustic Evoked Potentials (BAEPs) recording, to evaluate brainstem function. Only 6 patients presented with normal responses both at standard and at sensitized tests. In the remaining 19 patients, BAEPs were abnormal, bilaterally in 10 cases, monolaterally in 9. Four out of the 6 normal responses belonged to the group recognized of congenital origin. As refers to ventricular size BAEPs were abnormal in 62% of patients with normal ventricle and in 92% of patients with enlarged ventricles. The most significant BAEPs abnormalities were found in patients with maximal ventricular dilation. It appears that BAEPs abnormalities are to the ascribed to both primary and secondary brainstem dysfunction: no reliable criterion to differentiate between these two possibilities is evident. In the individual patient, serial BAEPs recording may contribute to recognize the early phase of supratentorial hypertension due to shunt dysfunction.