Comparative Assessment of Extracranial-to-Intracranial and Intracranial-to-Intracranial In Situ Bypass for Complex Intracranial Aneurysm Treatment Based on Rupture Status: A Case Series

BACKGROUND

Comparative outcomes of extracranial-to-intracranial (EC-IC) and intracranial-to-intracranial (IC-IC) bypass for complex aneurysm treatment based on rupture status are not well described in the literature. In this study, we compare outcomes of EC-IC and IC-IC bypass for complex intracranial aneurysm treatment based on rupture status.

METHODS

A prospective neurosurgical patient database was retrospectively reviewed. Sixty-three consecutive patients with aneurysm managed with revascularization were identified between July 2014 and December 2018.

RESULTS

During the study period, 41 patients with aneurysm underwent EC-IC bypass (65%; 24 [58.5%] ruptured, 17 [41.5%] unruptured) and 22 patients with aneurysm underwent IC-IC bypass (34.9%; 13 [59.1%] ruptured, 9 [40.9%] unruptured). Graft spasm occurred in 4 patients (9.8%) in the EC-IC group (all ruptured aneurysms) and all anastomoses were patent on immediate postoperative imaging. Perioperative mortality occurred in 5 patients who underwent EC-IC bypass (12.2%; 3 ruptured, 2 unruptured) EC-IC and 2 patients who underwent IC-IC bypass (9.1%; both ruptured); (P = 0.709). Bypass-related complications occurred only in patients with ruptured aneurysm (2 [8.3%] in the EC-IC group and 0 [0%] in the IC-IC group; P = 0.285). For unruptured aneurysms, the overall complication rate was lower in IC-IC compared with the EC-IC group (P = 0.006). Modified Rankin Scale scores on discharge were significantly lower in IC-IC compared with EC-IC bypass for unruptured aneurysms (P = 0.008). There was a trend for shorter temporary occlusion and hospitalization times and overall better outcomes with IC-IC compared with EC-IC bypass.

CONCLUSIONS

Although often considered riskier than EC-IC bypass, IC-IC in situ bypass showd a favorable technical and safety profile for the treatment of complex, unruptured aneurysms.

A3-A3 Anastomosis in the Management of Complex Anterior Cerebral Artery Aneurysms: Experience With in Situ Bypass and Lessons Learned From Pseudoaneurysm Cases

BACKGROUND

A3-A3 side-to-side bypass is an intracranial-to-intracranial (IC-IC) revascularization option when aneurysm treatment involves occlusion of one anterior cerebral artery (ACA).

OBJECTIVE

To describe applications of A3-A3 side-to-side bypass in the management of ACA true and pseudoaneurysms along with a review of pertinent literature.

METHODS

Six consecutive patients undergoing an A3-A3 bypass as part of their aneurysm management, representing a single-surgeon experience in a 2-yr period, were included in this retrospective review of a prospectively collected database.

RESULTS

Three male and three female patients with a median (range) age of 41.5 (11-69) years representing four ruptured and two unruptured aneurysms were included. Two of the aneurysms were communicating while four were postcommunicating from which three were pseudoaneurysms. Complete aneurysm obliteration was achieved in 5/6 cases. Bypass patency was evaluated in all cases intra- and postoperatively. Good outcomes (modified Rankin Scale score ≤ 2) at follow-up were observed in 4/6 patients. An improvement in mRS scores at the most recent follow-up as compared to preoperative status was achieved in three while scores remained the same in two patients. Ischemic complications related to aneurysm treatment were observed in two patients, both of which achieved good functional recovery upon follow-up. One patient deceased postoperatively due to progression of vasospasm-related infarcts.

CONCLUSION

A3-A3 bypass in the management of true as well as pseudoaneurysms of the ACA can achieve good postoperative outcomes in selected patients. Prompt diagnosis and aggressive surgical treatment needs to be pursued if a vessel injury with pseudoaneurysm formation is suspected.

Intraoperative Assessment of Cortical Perfusion After Intracranial-To-Intracranial and Extracranial-To-Intracranial Bypass for Complex Cerebral Aneurysms Using Flow 800

BACKGROUND

Revascularization strategies for complex cerebral aneurysms are largely based on subjective interpretation of flow demands, or indirect measures of perfusion in at-risk territories. Indocyanine Green -based flow analyses ((ICG-BFA); Flow 800, Carl Zeiss, Oberkochen, Germany) provide a real-time, semiquantitative measure of intraoperative cortical perfusion during cerebral bypass surgery for complex aneurysms.

OBJECTIVE

To determine the utility of intraoperative ICG-BFA for assessing cortical perfusion in at-risk territories during cerebral bypass for complex aneurysms requiring vessel sacrifice.

METHODS

Retrospective analysis of consecutive patients from a prospective, single-institution open cerebrovascular database.

RESULTS

Intraoperative ICG-BFA confirmed adequate cortical perfusion in 2 patients with fusiform posterior circulation aneurysms, treated with a posterior inferior cerebellar artery (PICA)-PICA and occipital artery (OA)-to-third segment of the posterior cerebral artery (P3) bypass with proximal vessel sacrifice, respectively. ICG-BFA was used in a third patient that underwent clip reconstruction/ intracranial-to-intracranial bypass for a large middle cerebral artery (MCA) bifurcation aneurysm requiring sacrifice of the temporal M2 branch. In this case, a frontal M3 to temporal M3 side-to-side anastomosis was created to arborize the MCA tree and allow filling of both M2 territories through a single M2 branch. After aneurysm reconstruction, ICG-BFA identified an inadvertent occlusion of the frontal M2 that left the entire MCA distribution reliant on collateral flow but did not cause a neuromonitoring change. Repeat ICG-BFA after clip re-arrangement demonstrated aneurysm occlusion and equal flow in both frontal and temporal MCA cortical distributions from the arborization.

CONCLUSION

ICG-BFA is a useful adjunct for intraoperative cortical flow assessment during cerebral revascularization for complex aneurysms requiring vessel sacrifice.

Bypass and Deconstructive Technique for Hunt and Hess Grade 3-5 Aneurysmal Subarachnoid Hemorrhage Deemed Unfavorable for Endovascular Treatment: Case Series of Outcomes and Comparison with Clipping

BACKGROUND

Intracranial bypass to treat ruptured aneurysms has been well described in the literature but is largely deferred in patients with higher Hunt and Hess (H & H) grades due to complexity and length of surgery, risk of inducing vasospasm, and poor prognosis. However, there is a paucity of data and no direct comparison with more traditional open surgical techniques. This study investigated outcomes in patients with H & H grade 3-5 aneurysmal subarachnoid hemorrhage (aSAH) unfavorable for stand-alone endovascular treatment managed with bypass compared with direct surgical clipping.

METHODS

A prospective database of patients treated for aSAH with H & H grade 3-5 between 2013 and 2018 was retrospectively analyzed. Complications and functional status at discharge and latest follow-up were compared between patients who underwent bypass surgery versus direct clipping.

RESULTS

Twenty-three patients underwent revascularization, and 60 underwent clipping alone. There were no significant differences in all-cause 30-day mortality (15% vs. 16%; P = 0.97) or Glasgow Outcome Scale and modified Rankin Scale at discharge or median 8-month follow-up (P > 0.67). There was a higher overall stroke rate with revascularization (P = 0.004), specifically endovascular treatment-related stroke (P = 0.049), with no difference in surgical (P = 0.47) or vasospasm-related stroke (P = 0.53). There were no differences in overall complications, medical complications, seizures, reruptures, hydrocephalus, or perioperative death (P > 0.05).

CONCLUSIONS

Bypass is a viable option for patients presenting with higher H & H grade aSAH deemed unfavorable for stand-alone endovascular therapy. Despite obvious differences in aneurysm complexity and a higher risk of stroke, functional outcomes with revascularization can be comparable with clipping in this high-risk patient cohort.

Transblepharo-Preseptal Modified Orbitozygomatic Approach for Resection of Giant Frontal Cavernous Malformation: 3-Dimensional Operative Video

A previously healthy 44-year-old woman presented with a first-time seizure. Magnetic resonance imaging (MRI) revealed a right frontal intraaxial mass extending from the orbitofrontal gyri and gyrus rectus to the head of the caudate (Video 1). The mass demonstrated heterogeneous signal intensity on precontrast T1-weighted MRI, minimal contrast enhancement, and mixed intensity on gradient echo MRI sequence consistent with a likely cavernous malformation. Given the location above the orbital roof with cranial-caudal extension to the level of the caudate, a transblepharo-preseptal modified orbitozygomatic craniotomy was recommended. With the assistance of plastic surgery, the lesion was approached through an eyelid incision that extended laterally to expose the keyhole. A McCarty burr hole was made, followed by a tailored orbitozygomatic craniotomy with osteotomies extending through the superolateral orbit and greater sphenoid wing to expose the proximal sylvian fissure. Dura was opened in a C-shaped fashion over the periorbital fat to allow for mild downward retraction of the globe, exposing the subfrontal trajectory. The opticocarotid cistern was opened to allow for cerebrospinal fluid egress and relaxation, and the lesion was readily identified through the use of stereotactic neuronavigation and presence of a faint hemosiderin blush within the underlying parenchyma. The standard microsurgical technique was used to perform a gross total resection of the pathologically confirmed cavernous malformation. The orbitozygomatic bone flap was replaced and plated, and the wound was closed in multiple layers. The patient was seen at a 3-month follow-up without further seizures.

Three-Vessel Anastomosis for Direct Bihemispheric Cerebral Revascularization

BACKGROUND

In rare, complex cerebrovascular pathologies, patients may benefit from simultaneous revascularization of multiple arterial territories. Traditional strategies for these situations include the use of more than 1 interposition graft, multiple microvascular anastomoses, vessel reimplantations, and staged procedures.

OBJECTIVE

To improve upon traditional revascularization strategies by describing a novel 3-vessel microvascular anastomosis. This technique combines a side-to-side and an end-to-side anastomoses to facilitate simultaneous direct revascularization of 2 arterial territories in a single procedure, with a single donor vessel.

METHODS

We present an illustrative case of moyamoya angiopathy in which a 3-vessel anastomosis was performed in the interhemispheric fissure to simultaneously directly revascularize bilateral anterior cerebral artery (ACA) territories. A detailed step-by-step depiction of the anastomosis technique is provided. In the presented case, 3-vessel anastomosis was combined with a radial artery fascial flow-through free flap, allowing for an additional indirect revascularization.

RESULTS

Technical execution of the 3-vessel anastomosis was uncomplicated. The patency of the anastomosis providing direct bilateral ACA territory revascularization was demonstrated intra- and postoperatively.

CONCLUSION

With this report, we demonstrate technical feasibility of a novel 3-vessel anastomosis for direct 2 arterial territory revascularization This single-stage approach combines side-to-side and end-to-side techniques and has benefits over traditional revascularization techniques, as it is not deconstructive, requires only a single craniotomy and a single interposition graft, and does not require lengthy recipient artery dissection.

Lessons Learned from the Initial Experience with Pedicled Temporoparietal Fascial Flap for Combined Revascularization In Moyamoya Angiopathy: A Case Series

BACKGROUND

The pedicled temporoparietal fascial flap (TPFF) with a direct superficial temporal (STA) artery to middle cerebral artery (MCA) bypass is a novel combined revascularization approach for moyamoya angiopathy (MMA). With this case series, we aim to report the initial experience with pedicled TPFF combined revascularization for MMA treatment.

METHODS

Data from 14 consecutive patients undergoing pedicled TPFF combined revascularization for MMA between May 2016 and December 2018 were retrospectively reviewed. Patients admitted with acute ischemia or a modified Rankin Scale (mRS) score >3 were considered high risk.

RESULTS

Mean ± standard deviation age on surgery was 41.9 ± 15.4 years. Three of 14 patients (21.4%) presented with an mRS score >3. Nine of 14 patients (64.3%) presented with ischemic stroke, 4 of whom (44.4%) had acute ischemia. Direct anastomosis patency was confirmed in all cases postoperatively. Mean hospitalization time was 13 ± 9.3 days and mean follow-up time was 14.1 ± 9.3 months. From admission to follow-up, neurologic status improved in 8 patients (57.1%) and stabilized in 6 patients (42.9%). Overall, 11/14 patients (78.6%) achieved good functional outcome (mRS score ≤2). All patients achieved some radiographic collateral development, with 5 (71.5%) graded as Matsushima A and B. Three patients developed new radiographic ischemia and 3 experienced wound complications, all in the high-risk group.

CONCLUSIONS

The TPFF combined approach is a viable strategy for revascularization in MMA. This technique may be suboptimal in patients presenting with acute ischemia and/or mRS score >3.

Assessment of ischemic risk following intracranial-to-intracranial and extracranial-to-intracranial bypass for complex aneurysms using intraoperative Indocyanine Green-based flow analysis

Cerebral bypass is often needed for complex aneurysms requiring vessel sacrifice, yet intraoperative predictors of ischemic risk in bypass-dependent territories are limited. Indocyanine Green (ICG)-based flow analyses (ICG-BFAs; Flow 800, Carl Zeiss, Oberkochen, Germany) semi-quantitatively assess cortical perfusion, and in this work we determine the efficacy of ICG-BFA for assessing post-operative ischemic risk during cerebral bypass surgery for complex aneurysms. Retrospective clinical and pre/post-bypass intra-operative ICG-BFA data (delay and blood flow index [BFI]) on ten patients undergoing cerebral bypass for complex cerebral aneurysms requiring vessel sacrifice were collected from a single-institution prospective database and analyzed via non-parametric testing and logistic regression. Mean age was 55.9 ± 14.8 years. Pre/post-bypass delay (median 35.6 [5.1-51.3] vs. 26.0 [17.1-59.9]; p = 0.2) and BFI (median 56.1 [8.1-120.4] vs. 32.2 [3.0-147.4]; p = 0.2) did not significantly differ. Two patients (20%) developed post-operative ischemia in bypass dependent territories. Delay ratio did not differ between patients with and without post-operative ischemia (median 1.15 [0.67-1.64] vs. 0.83 [0.36-3.56]; p = 0.6), nor predict stroke risk (odds ratio = 1.1, p = 0.9). Conversely, BFI ratio was significantly lower for patients experiencing post-operative ischemia than those without ischemia (median 0.11 [0.06-0.17] vs. 0.99 [0.28-1.42]; p = 0.03). A BFI ratio <0.21 predicted the occurrence of post-operative ischemia (odds ratio = 0.02, p = 0.05). These data suggest that intraoperative ICG-BFA may help assess post-operative ischemic risk during cerebral bypass surgery for complex aneurysms requiring vessel sacrifice.

Radial Artery Fascial Flow-Through Free Flap for Complex Cerebral Revascularization: Technical Notes and Long-Term Neurologic and Radiographic Outcomes

BACKGROUND

Surgical innovation is critical for the management of challenging cerebrovascular pathology. Flow-through free flaps are versatile composite grafts that combine viable tissue with a revascularization source. Neurosurgical experience with these flaps is limited.

OBJECTIVE

To provide an in-depth technical description of the radial artery fascial (and fasciocutaneous) flow-through free flap (RAFF and RAFCF, respectively) for complex cerebral revascularizations.

METHODS

An Institutional Review Board-approved, prospective database was retrospectively reviewed to identify patients that underwent extracranial-to-intracranial cerebral bypass with a RAFF or RAFCF. Patient demographics, underlying pathology, surgical treatment, complications, and outcomes were recorded.

RESULTS

A total of 4 patients were treated with RAFFs or RAFCFs (average age 40 ± 8.8 yr). Two patients with progressive moyamoya disease involving multiple vascular territories with predominantly anterior cerebral artery (ACA) symptoms and flow alterations underwent combined direct ACA and indirect middle cerebral artery (MCA) bypass with a RAFF. The third patient with moyamoya disease and concomitant proximal fusiform aneurysms requiring internal carotid artery sacrifice underwent dual direct ACA and MCA bypass and indirect MCA revascularization with posterior tibial artery and RAFF grafts. The fourth patient with a large MCA bifurcation aneurysm and recurrent wound complications underwent a direct MCA bypass and complex wound reconstruction using a RAFCF. Good neurologic outcomes (Glasgow Outcomes Scale score ≥4 at discharge) were achieved in all patients. There were no perioperative surgical complications, and graft patency was confirmed on long-term follow-up.

CONCLUSION

The RAFF and RAFCF are versatile grafts for complex cerebral revascularizations.

Complex Revascularization for Idiopathic Intracranial Occlusive Disease with Unruptured, Fusiform Anterior Cerebral Artery and Middle Cerebral Artery Aneurysms: 3-Dimensional Operative Video

Revascularization is an important strategy when treating cerebrovascular occlusive disease and complex aneurysms. Radial artery fascial flow-through free flaps (RAFFs) are flexible grafts that provide direct and indirect revascularization. RAFFs can be especially useful for large territory revascularization and can be combined with other direct bypasses. Although common in plastic and reconstructive surgery, RAFF neurosurgical applications have rarely been described. The 3-dimensional video presents a 47-year-old man with watershed infarcts on imaging who presented with right-sided weakness (Video 1). Vessel imaging was significant for bilateral internal carotid artery (ICA) terminus stenosis. The left middle cerebral artery (MCA) ended in a fusiform aneurysm of the M1 segment. The left anterior cerebral artery (ACA) also had a smaller fusiform aneurysm at the A1/2 junction. A perfusion study demonstrated an increased mean transit time in the left MCA territory. Given the patient's age, his symptomatic ischemia, and enlarging MCA aneurysm, he was recommended for a combined revascularization and left ICA occlusion. A left facial artery-to-MCA bypass using the right posterior tibial artery was performed for direct MCA revascularization. A left superficial temporal artery-to-ACA bypass with a RAFF was performed for direct ACA and indirect MCA territory revascularization. Postoperative angiography demonstrated patency of both direct grafts. The patient suffered small pericallosal infarcts because of retraction and perforator sacrifice at the revascularization site. At early follow-up, the patient was at his neurologic baseline, and at 1-year follow up, the patient had no additional infarcts on imaging and was living independently.

Extracranial-to-Intracranial Bypass for Refractory Vertebrobasilar Insufficiency

BACKGROUND

Vertebrobasilar insufficiency (VBI) is associated with high rates of morbidity and mortality, especially after failure of first-line medical and/or endovascular therapies. Although the optimal therapeutic strategy for refractory VBI remains unclear, surgical bypass represents a potentially life-saving treatment in this patient subset.

METHODS

A multi-institution retrospective database review was performed to identify patients with symptomatic refractory VBI over a 4-year period (July 2014 to July 2018). Surgical treatments, as well as clinical and neurologic outcomes were recorded.

RESULTS

Five patients were identified with refractory VBI (average age 55 ± 11.0 years). All 5 patients had clinically significant posterior circulation strokes on presentation. Three patients underwent superficial temporal artery-to-superior cerebellar artery bypass based on significant acute perfusion mismatches or progressive strokes despite maximal medical therapy; 1 surgical patient (33%) experienced punctate perioperative strokes and there were no significant bypass related complications. Functional outcomes in the 3 surgical patients were correlated with preoperative stroke burden. The remaining 2 patients experienced rapid neurologic declines after presentation that precluded bypass, and died shortly thereafter.

CONCLUSIONS

Refractory VBI has high morbidity, with cerebral bypass representing a safe and potentially efficacious treatment for selected patients. Long-term post-bypass outcomes are dependent on the level of irreversible preoperative neurologic injuries.

Ruptured Mycotic Aneurysm of the Distal Circulation in a Patient with Mucormycosis Without Direct Skull Base Extension: Case Report

BACKGROUND AND IMPORTANCE

Infectious intracranial aneurysms are a rare subset of intracranial aneurysms caused by bacterial, fungal, or viral sources. Intracranial aneurysms of fungal etiology carry a high mortality risk and typically occur in immunocompromised patients via direct extension of skull base infections, or more rarely, after intracranial surgery.

CLINICAL PRESENTATION

We present the case of a 27-yr-old female with systemic lupus erythematous and primary pulmonary mucormycosis, who suffered a subarachnoid hemorrhage from a ruptured fusiform distal middle cerebral artery aneurysm. Despite undergoing a successful extracranial-to-intracranial bypass and aneurysm excision, the patient ultimately died following progressive disseminated infection and a secondary intracranial hemorrhage of unknown etiology. Pathological examination of the excised artery confirmed Mucor infection.

CONCLUSION

To the best of our knowledge, this case represents one of the first mycotic cerebral aneurysms from mucormycosis in a patient without an underlying skull base infection or previous intracranial surgery. Despite optimal surgical management, clinical outcomes for mycotic cerebral aneurysms are largely dependent on the success of medical therapies at controlling systemic disease.

Intentional Subtotal Resection of Vestibular Schwannoma: A Reexamination

Background  Treatment of vestibular schwannomas (VS) remains controversial. Historical surgical series prioritized gross total resections (GTR); however, near total resections (NTR) and intentional subtotal resections (STR) aiming at improving cranial nerve outcomes are becoming more popular. Objective  The main purpose of this article is to assess the tumor control and facial nerve outcomes in VS patients treated with STR or NTR. Methods  VS patients undergoing STR or NTR at our institution between 1984 and 2016 were retrospectively reviewed. Patient demographics, extent of tumor resection, facial nerve injury, tumor recurrence, and need for Gamma Knife radiosurgery were analyzed. Facial nerve outcomes were quantified using House-Brackmann (HB) scores. Tumor regrowth was defined by the San Francisco criteria. Results  Four-hundred fifty-seven VS resections were performed in a 32-year period. Sixty cases met inclusion criteria. The mean (range) follow-up duration was 30.9 (12-103) months. The STR cohort ( n  = 33) demonstrated regrowth in 12 patients (36.3%) at an average of 23.6 months. The NTR cohort ( n  = 27) did not experience tumor recurrence. Risk of tumor recurrence was positively correlated with preoperative tumor size ( p  = 0.002), size of residual tumor ( p  < 0.001), and STR ( p  < 0.001). Facial nerve outcomes of HB1-2 were observed in the majority of patients in both cohorts (74.1% NTR, 56% STR), though NTR was associated with a higher likelihood of facial nerve recovery ( p  = 0.003). Conclusion  GTR remains the gold standard as long as facial nerve outcomes remain acceptable. NTR achieved superior tumor control and higher likelihood of facial nerve recovery compared with STR.

Role of botulinum neurotoxin-A in cerebral revascularization graft vasospasm prevention: current state of knowledge

Graft stenosis and occlusion remain formidable complications in cerebral revascularization procedures, which can lead to significant morbidity and mortality. Graft vasospasm can result in early postoperative graft stenosis and occlusion and is believed to be at least partially mediated through adrenergic pathways. Despite various published treatment protocols, there is no single effective spasmolytic agent. Multiple factors, including anatomical and physiological variability in revascularization conduits, patient age, and comorbidities, have been associated with graft vasospasm pathogenesis and response to spasmolytics. The ideal spasmolytic agent thus likely needs to target multiple pathways to exert a generalizable therapeutic effect. Botulinum toxin (BTX)-A is a powerful neurotoxin widely used in clinical practice for the treatment of a variety of spastic conditions. Although its commonly described paradigm of cholinergic neural transmission blockade has been widely accepted, evidence for other mechanisms of action including inhibition of adrenergic transmission have been described in animal studies. Recently, the first pilot study demonstrating clinical use of BTX-A for cerebral revascularization graft spasm prevention has been reported. In this review, the mechanistic basis and potential future clinical role of BTX-A in graft vasospasm prevention is discussed.

Pedicled temporoparietal fascial flap for combined revascularization in adult moyamoya disease

Moyamoya disease (MMD) is a progressive, idiopathic cerebrovascular occlusive disease. Various revascularization techniques including direct, indirect, and combined microvascular bypasses have been described. This article presents a modified revascularization technique for MMD utilizing a pedicled temporoparietal fascial flap (TPFF) for combined revascularization. This technique combines a large area of coverage for indirect revascularization with the benefits of a direct bypass. The pedicled TPFF also benefits from intact venous drainage to minimize the risk of flap swelling that could result in complications from mass effect.