Faculty Bibliography

BACKGROUND:Cerebral bypass operation is a technically challenging operation that requires excellent surgical visibility and efficient ergonomics to minimize complications and maximize successful revascularization. Despite the operative microscope's utilization for the past two generations, there remains a need for continued improvement in operative visualization and surgical ergonomics. OBJECTIVE:To report the positives and negatives of our initial experience using a novel 4 K high-definition (4K-HD) 3-dimensional (3D) exoscope (EX) for cranial bypass surgery. METHODS:A retrospective review over 6 mo was performed of all patients who have undergone cerebral bypass surgery at a single institution using the 4K-HD 3D EX. Advantages and disadvantages of the EX and clinical outcome of the patients were assessed. RESULTS:A total of 5 patients underwent cerebral EC-IC bypass surgery with no EX-related complications and successful revascularization. The lightweight design of the EX allowed for easy instrument maneuverability as well as uncomplicated surgical set up in the operating room. The assistance of the cosurgeon was significantly more efficient compared to that of the operating microscope. The large monitor allowed for an immersive, collaborative, and valuable educational surgical experience. CONCLUSION/CONCLUSIONS:Using the EX for cerebral bypass surgery, with 3D ultra-high-definition optics, enhancements of ergonomics, and improved training, we believe that the 3D 4K-HD EX may represent the next generation of operative scopes in microneurosurgery.

BACKGROUND:Colloid cysts (CC) have been associated with neurocognitive function (NCF) decline, both preoperatively and following resection. Factors such as local pressure on the fornix and hydrocephalus are thought to contribute to preoperative NCF decline. Potential cause of post-operative decline is thought to be forniceal injury during surgery. In the current series, we describe NCF outcomes amongst patients with CC, both non-operated and operated. METHODS:36 patients (23 operated, 13 non-operated) were included in this retrospective study. All patients underwent at least one NCF evaluation battery. Five of the 13 non-operated cases had follow up tests too. Of the 23 operated, 14 had both pre-and post-operative tests, 8 had early and late postoperative tests. RESULTS:There was no significant difference in baseline NCF between non-operated and operated cases (as evaluated preoperatively). Non-operated patients had a stable NCF test over time. Patients that were operated showed a significant improvement after surgery in several NCF variables. There was no significant change in NCF between early and late postoperative evaluation. None of the operated patients had a postoperative NCF decline. CONCLUSIONS:Patients with CC should undergo routine NCF testing with a standardized protocol, whether they are operated or followed. Surgery has a positive impact on NCF; however, it remains to be determined if the improvement is solely secondary to treatment of hydrocephalus, or to a reduction of local pressure on the fornices. It remains to be determined whether the surgical technique - i.e. endoscopic, interhemispheric, or transcortical, has an impact on NCF outcome.

PURPOSE OF REVIEW/OBJECTIVE:Cerebral aneurysms are commonly diagnosed incidentally with non-invasive neuro-imaging modalities (i.e., brain MRA and/or head CTA). The first decision to be made in the management of patients with unruptured cerebral aneurysms is to determine if the aneurysm should undergo treatment as any intervention carries a risk of morbidity and mortality. RECENT FINDINGS/RESULTS:The multiple risk factors that are associated with increased risk of aneurysm rupture should be evaluated (size, shape, and location of aneurysm; history of hypertension and cigarette smoking and family history of cerebral aneurysms). With the advent and rapid evolution of less traumatic neuro-endovascular surgery techniques in the past two decades, many more patients are undergoing treatment of cerebral aneurysms. The neuro-endovascular surgeon has multiple options for the treatment of aneurysms including coiling, with or without balloon/stent assistance, and flow diversion. A number of intrasaccular devices for the neuro-endovascular treatment of cerebral aneurysms are being evaluated. The percentage of patients with cerebral aneurysms treated with craniotomy and clip ligation is decreasing. This is controversial as it has direct impact in neurosurgical training and the aneurysms that are usually recommended for microsurgical clipping are the ones with challenging anatomy that cannot be treated safely with endovascular approaches. The best outcomes are achieved with management by experienced, high-volume practitioners at specialized cerebrovascular treatment centers that consist of individuals with dedicated training in neuro-endovascular surgery as well as individuals trained in open cerebrovascular neurosurgery.

OBJECTIVE:To clarify the reported experience with keyhole approaches for the treatment of intracranial aneurysms. METHODS:The PubMed and Embase databases were searched up to December 2017 for full-text publications that report the treatment of aneurysms with the eyebrow variant of the supraorbital craniotomy (SOC), the minipterional craniotomy, or the eyelid variant of the SOC. The anatomical distribution of aneurysms, the postoperative aneurysm occlusion rate, and the type and rate of complications were examined using univariate analysis. RESULTS:Sixty-seven publications covering treatment of 5770 aneurysms met the eligibility criteria. The reported experience was the largest for the eyebrow variant of the SOC (69.4% of aneurysms), followed by the minipterional approach (28.2%), and the eyelid variant of the SOC (2.4%). The anterior communicating artery (ACoA) was the most frequent aneurysm location for the SOC (eyebrow variant: 33.2%; eyelid variant: 31.2%). The middle cerebral artery (MCA) was the most frequent aneurysm location in the minipterional cohort (55.2%). In the eyelid variant of the SOC cohort, the rate of complete aneurysm occlusion was the lowest (eyelid variant: 90.8%; eyebrow variant: 97.8%, p < 0.001; minipterional approach: 97.9%, p < 0.001), and the postoperative infarction rate was the highest (eyelid variant: 7.2%; eyebrow variant: 3.5%, p = 0.025; minipterional approach: 2.6%, p = 0.003). CONCLUSION/CONCLUSIONS:Each approach has a specific safety and efficacy profile. Surgeons selected the eyebrow variant of the SOC for many aneurysm locations including in particular the ACoA. There is a recent tendency however to opt for the minipterional approach above all for MCA aneurysms. ABBREVIATIONS/BACKGROUND:SOC: Supraorbital Craniotomy; MPT: Minipterional; MCA: Middle Cerebral Artery; ACoA: Anterior Communicating Artery; PCoA: Posterior Communicating Artery; aSAH: Aneurysmal Subarachnoid Hemorrhage; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; MINORS: Methodological Index For Non-Randomized Studies.

OBJECTIVE:Minimally invasive alternatives to the pterional craniotomy include the minipterional and the supraorbital craniotomy (SOC). The latter is performed via either an eyebrow or an eyelid skin incision. The purpose of this systematic review was to analyze the type and the incidence of approach-related complications of these keyhole craniotomies. METHODS:We review pertinent publications retrieved by search in the PubMed/Medline database. Inclusion criteria were all full-text publications, abstracts, and posters in English, up to 2016, reporting clinical results. RESULTS:105 publications containing data on 5837 surgeries performed via a minipterional or either of the two variants of the SOC met the eligibility criteria. Pain on mastication was the most commonly reported approach-related complication of the minipterional approach, where it occurred in 7.5% of cases. Temporary palsy of the frontal branch of the facial nerve and temporary supraorbital hypesthesia were associated with the SOC eyebrow variant, where it occurred in 6.5%, respectively in 4.6% of cases. Transient postoperative periorbital edema and transient ophthalmoparesis occurred in 36.8%, respectively in 17.4% of cases when the SOC was performed via an eyelid skin incision. The risk of occurrence of the latter two approach-related complications was related to the removal of the orbital rim, which is obligate part of the SOC through the eyelid approach but optional with the SOC eyebrow variant. CONCLUSION/CONCLUSIONS:Each of three "keyhole" approaches has a specific set and incidence of approach-related complications. It is essential to be aware of these complications to make the safest individual choice.

OBJECTIVE Resection of intraaxial tumors adjacent to the optic radiation (OR) may be associated with postoperative visual field (VF) deficits. Intraoperative navigation using MRI-based tractography and electrophysiological monitoring of the visual pathways may allow maximal resection while preserving visual function. In this study, the authors evaluated the value of visual pathway mapping in a series of patients undergoing awake craniotomy for tumor resection. METHODS A retrospective analysis of prospectively collected data was conducted in 18 patients who underwent an awake craniotomy for resection of intraaxial tumors involving or adjacent to the OR. Preoperative MRI-based tractography was used for intraoperative navigation, and intraoperative acquisition of 3D ultrasonography images was performed for real-time imaging and correction of brain shift. Goggles with light-emitting diodes were used as a standard visual stimulus. Direct cortical visual evoked potential (VEP) recording, subcortical recordings from the OR, and subcortical stimulation of the OR were used intraoperatively to assess visual function and proximity of the lesion to the OR. VFs were assessed pre- and postoperatively. RESULTS Baseline cortical VEP recordings were available for 14 patients (77.7%). No association was found between preoperative VF status and baseline presence of cortical VEPs (p = 0.27). Five of the 14 patients (35.7%) who underwent subcortical stimulation of the OR reported seeing phosphenes in the corresponding contralateral VF. There was a positive correlation (r = 0.899, p = 0.04) between the subcortical threshold stimulation intensity (3-11.5 mA) and the distance from the OR. Subcortical recordings from the OR demonstrated a typical VEP waveform in 10 of the 13 evaluated patients (76.9%). These waveforms were present only when recordings were obtained within 10 mm of the OR (p = 0.04). Seven patients (38.9%) had postoperative VF deterioration, and it was associated with a length of < 8 mm between the tumor and the OR (p = 0.05). CONCLUSIONS Intraoperative electrophysiological monitoring of the visual pathways is feasible but may be of limited value in preserving the functional integrity of the posterior visual pathways. Subcortical stimulation of the OR may identify the location of the OR when done in proximity to the pathways, but such proximity may be associated with increased risk of postoperative worsening of the VF deficit.

BACKGROUND:Mycotic aneurysms, although well recognized, are relatively rare intracranial vascular pathology. These aneurysms are typically located in distal cortical vessels. When these aneurysms are located in eloquent cerebral territories, they may become challenging to treat. Eloquent location may necessitate intraoperative angiographic evaluation to verify complete aneurysmal occlusion/obliteration and preservation of normal adjacent vasculture. Recently, ICG videoangiography has become a widely used intra-operative adjunct and is an important tool used to assess complete occlusion and vessel patency at the conclusion of clip reconstruction. In this report, we outline the comprehensive and concurrent utilization of both vascular imaging modalities to ensure safe and complete occlusion of a mycotic aneurysm. METHODS:We describe our experience with a patient with left M4, Rolandic, enlarging mycotic aneurysm that was treated in a comprehensive fashion with microsurgery and intra-operative angiography (IA). CONCLUSIONS:ICG videoangiography, in combination with concurrent intraoperative angiography in the setting of complex vascular lesions, may support intraoperative decision-making and provide demonstration of complete occlusion in an immediate fashion. A hybrid operative suite allows for high-quality imaging confirming complete resection.