Revascularization and aneurysm surgery: current techniques, indications, and outcome

Hemodynamic effect of bypass geometry on intracranial aneurysm: A numerical investigation

BACKGROUND AND OBJECTIVE

Hemodynamic analyzes are used in the clinical investigation and treatment of cardiovascular diseases. In the present study, the effect of bypass geometry on intracranial aneurysm hemodynamics was investigated numerically. Pressure, wall shear stress (WSS) and velocity distribution causing the aneurysm to grow and rupture were investigated and the best conditions were tried to be determined in case of bypassing between basilar (BA) and left/right posterior arteries (LPCA/RPCA) for different values of parameters.

METHODS

The finite volume method was used for numerical solutions and calculations were performed with the ANSYS-Fluent software. The SIMPLE algorithm was used to solve the discretized conservation equations. Second Order Upwind method was preferred for finding intermediate point values in the computational domain. As the blood flow velocity changes with time, the blood viscosity value also changes. For this reason, the Carreu model was used in determining the viscosity depending on the velocity.

RESULTS

Numerical study results showed that when bypassed, pressure and wall shear stresses reduced in the range of 40-70% in the aneurysm. Numerical results obtained are presented in graphs including the variation of pressure, wall shear stress and velocity streamlines in the aneurysm.

CONCLUSION

Considering the numerical results for all parameter values, it is seen that the most important factors affecting the pressure and WSS values in bypassing are the bypass position on the basilar artery (L_b) and the diameter of the bypass vessel (d). Pressure and wall shear stress reduced in the range of 40-70% in the aneurysm in the case of bypass for all parameters. This demonstrates that pressure and WSS values can be greatly reduced in aneurysm treatment by bypassing in cases where clipping or coil embolization methods can not be applied.

Graft Occlusion and Graft Size Changes in Complex Internal Carotid Artery Aneurysm Treated by Extracranial to Intracranial Bypass Using High-Flow Grafts with Therapeutic Internal Carotid Artery Occlusion

BACKGROUND

Although the extracranial-to-intracranial high-flow bypass (EC-IC HFB) continues to be indispensable for complex aneurysms, the risk factors for the graft occlusion and whether the graft size changes after the bypass have not been well established.

OBJECTIVE

To evaluate the risk factors for the graft occlusion and to confirm whether graft diameters changed over time.

METHODS

The data of 75 patients who suffered from complex internal carotid artery (ICA) aneurysms and were treated by EC-IC HFB using radial artery graft (RAG) or saphenous vein graft (SVG) with therapeutic ICA occlusion were evaluated. Clinical and radiological characteristics were compared in patients with and without the graft occlusion by the log-rank test. Graft diameters measured preoperatively, postoperatively, at 6 months, and at 1 year were compared by paired t-test.

RESULTS

During a follow-up period (median 26.2 months), graft occlusions were seen in 4 patients (5.3%), and these were the SVGs. Only SVG was related to graft occlusion (P < .001). There was a significant increase with time in RAG diameters (preoperative, 3.1 ± 0.41 mm; postoperative, 3.6 ± 0.65 mm; 6 months, 4.3 ± 1.0 mm; 1 year, 4.4 ± 1.0 mm), while there were no significant diameter changes in SVGs.

CONCLUSION

The present study showed that the SVG was related to the graft occlusion and RAGs gradually enlarged. Unless Allen test is negative, RAG may be better to be used as a graft in EC-IC HFB if therapeutic ICA occlusion is needed.

High-flow bypass with radial artery graft followed by internal carotid artery ligation for large or giant aneurysms of cavernous or cervical portion: clinical results and cognitive performance

High-flow bypass followed by ligation of the internal carotid artery (ICA) is an effective treatment, but the impact of abrupt occlusion of the ICA is unpredictable, especially on postoperative cognitive function. The present study evaluated the clinical results as well as cognitive performances after high-flow bypass using radial artery graft (RAG) with supportive superficial temporal artery (STA)-middle cerebral artery (MCA) bypass, followed by ICA ligation. Ten consecutive patients underwent high-flow bypass surgery for large or giant ICA aneurysms of cavernous or cervical portion. Demographics, clinical information, magnetic resonance (MR) imaging, computed tomography, digital subtraction angiography (DSA), intraoperative somatosensory evoked potentials, neuropsychological examinations including the Wechsler Adult Intelligence Scale-Third Edition and the Wechsler Memory Scale-Revised (WMS-R), and follow-up data were analyzed. The aneurysm was located on the cavernous segment in eight cases and cervical segment in two cases, and mean aneurysm size was 27.9 mm. Postoperative DSA demonstrated robust bypass flow from the external carotid artery to MCA via the RAG, and no anterograde flow into the aneurysm. No patient showed new symptoms after the operation. Follow-up clinical study and MR imaging were performed in nine patients and showed no additional ischemic lesion compared with preoperative imaging. Seven patients completed neuropsychological examinations before and after surgery. All postoperative scores except WMS-R composite memory score slightly improved. High-flow bypass followed by ICA ligation can achieve good clinical outcomes. Successful high-flow bypass using RAG with supportive STA-MCA bypass and ICA ligation does not adversely affect postoperative cognitive function.

Occipital Artery to Middle Cerebral Artery Bypass: Operative Nuances

BACKGROUND

Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is a common procedure for vascular neurosurgeons, and it is used in a variety of diseases. However, there are cases in which the STA is absent or is too hypoplastic to be used as a donor for revascularization. Occipital artery (OA)-MCA bypass may be a treatment option in these cases.

METHODS

We encountered 4 cases of symptomatic cerebral ischemia in which the STA was absent or unavailable. These cases were treated by revascularization from the OA to the periphery of the MCA.

RESULTS

By meticulous dissection of the OA to the level of the superior temporal line, the OA could reach the periphery of the angular artery and be anastomosed to it in the usual fashion. The patency of the donor artery was confirmed by magnetic resonance angiography soon after the operation and 3 years later.

CONCLUSIONS

OA-MCA bypass may be a surgical option for cerebral revascularization when the STA is not available.

Rescue bypass for the treatment of pseudoaneurysm on the distal anterior cerebral artery: a case report of vertical side-to-side anastomosis of the distal callosomarginal artery-pericallosal artery

Pseudoaneurysm on the distal anterior cerebral artery (ACA) is rare but potentially fatal. It usually cannot be treated with typical treatment modalities. A 47-year-old female patient was diagnosed with a ruptured aneurysm on the pericallosal artery (PerA). During surgical exploration, it was found to be a pseudoaneurysm and could not be treated with clipping. We performed surgical trapping of the involved segment of the proximal PerA followed by side-to-side anastomosis between the ipsilateral PerA and the callosomarginal artery. The patient recovered without any neurologic deficit. This new method of anastomosis could be an alternative option.

Double-Barrel Superficial Temporal Artery-Middle Cerebral Artery Bypass: Can It Be Considered “High-Flow?”

BACKGROUND

Traditionally, superficial temporal artery-middle cerebral artery (STA-MCA) bypass uses one STA branch. Its augmentation of flow has classically been described as “low flow.” In a double-barrel STA-MCA bypass, however, both branches of the STA are utilized. Here we hypothesize that this should not be considered “low flow.”

OBJECTIVE

To review quantitative flow data from our cases and investigate the impact of double-barrel STA-MCA bypass on total flow augmentation, and to assess whether double-barrel STA-MCA bypass might be useful in situations that traditionally demand more complex bypass strategies.

METHODS

Intraoperative flow probe measurements from STA-MCA bypass cases were retrospectively tabulated and compared. Cut flow and bypass flow measurements were, respectively, taken before and after completion of anastomoses. The higher value was labeled best observed flow (BOF).

RESULTS

We identified 21 STA-MCA bypass cases with available intraoperative flow probe measurements, of which 17 utilized double-barrel technique. Only 1 STA branch was available in 4 cases. Significantly higher average BOF was seen when utilizing 2 STA branches (69 vs 39 cc/min, P &lt; .001). A majority (9/17) of double-barrel bypasses provided BOF ≥ 65 cc/min (120 cc/min maximum). The single branch bypass maximum BOF was 40 cc/min.

CONCLUSION

Double-barrel bypass technique significantly enhances STA-MCA flow capacity and may be useful in situations in which a high-flow bypass is needed. The 2 efferent limbs allow flexibility in distributing flow across separate at-risk territories. The method compares favorably to other descriptions of high-flow bypass without the morbidity of graft harvest or an additional cervical incision.

Bypass Surgery for Complex Intracranial Aneurysms: 15 Years of Experience at a Single Institution and Review of Pertinent Literature

BACKGROUND

Bypass surgery is a treatment option for complex intracranial aneurysms.

OBJECTIVE

To determine the utility of bypass surgery for the treatment of complex intracranial aneurysms and to review the literature on this topic.

METHODS

Sixty-two patients were included in this retrospective study. Unruptured aneurysms were dominant (80.6%), and the internal carotid artery was the most common location of the aneurysm (56.4%), followed by the middle cerebral artery (21.0%). The mean maximal diameter of the aneurysms was 20.5 ± 11.4 mm. The clinical and angiographic states were evaluated preoperatively, immediately after surgery (within 3 days) and at the last follow-up. The mean angiographic and clinical follow-up duration was 34.2 ± 38.9 and 46.5 ± 42.5 months, respectively.

RESULTS

Sixty-one patients (98.3%) underwent extracranial–intracranial bypass, and 1 underwent intracranial–intracranial bypass. At the last follow-up angiography, 58 aneurysms (93.5%) were completely obliterated and 4 were incompletely obliterated, with a graft patency of 90.3%. Surgical mortality was 0 and permanent morbidity was 8.1%. A good clinical outcome (Karnofsky Performance Scale ≥ 70 and modified Rankin Scale score ≤ 2) was achieved in 91.9% of patients (n = 57).

CONCLUSION

With a proper selection of bypass type, bypass-associated treatment can be a good alternative for patients with complex intracranial aneurysms when conventional microsurgical clipping or endovascular intervention is not feasible.

Rationale for graft selection in patients with complex internal carotid artery aneurysms treated with extracranial to intracranial high-flow bypass and therapeutic internal carotid artery occlusion

OBJECTIVE After internal carotid artery (ICA) sacrifice without revascularization for complex aneurysms, ischemic complications can occur. In addition, hemodynamic alterations in the circle of Willis create conditions conducive to the formation of de novo aneurysms or the enlargement of existing untreated aneurysms. Therefore, the revascularization technique remains indispensable. Because vessel sizes and the development of collateral circulation are different in each patient, the ideal graft size to prevent low flow-related ischemic complications (LRICs) in external carotid artery (ECA)-middle cerebral artery (MCA) bypass with therapeutic ICA occlusion (ICAO) has not been well established. Authors of this study hypothesized that the adequate graft size could be calculated from the size of the sacrificed ICA and the values of MCA pressure (MCAP) and undertook an investigation in patients with complex ICA aneurysms treated with ECA-graft-MCA bypass and therapeutic ICAO. METHODS In the period between July 2006 and January 2016, 80 patients with complex ICA aneurysms were treated with ECA-MCA bypass and therapeutic ICAO. Preoperative balloon test occlusion (BTO) was performed, and the BTO pressure ratio was defined as the mean stump pressure/mean preocclusion pressure. Low flow-related ischemic complications were defined as new postoperative neurological deficits and ipsilateral cerebral blood flow reduction. Initial MCAP (iMCAP), MCAP after clamping the ICA (cMCAP), and MCAP after releasing the graft (gMCAP) were intraoperatively monitored. The MCAP ratio was defined as gMCAP/iMCAP. Based on the Hagen-Poiseuille law, the expected MCAP ratio ([expected gMCAP]/iMCAP) was hypothesized as follows: (1 - cMCAP/iMCAP)(graft radius/ICA radius)² + (cMCAP/iMCAP). Correlations between the BTO pressure ratio and cMCAP/iMCAP, and between the actual and expected MCAP ratios, were evaluated. Risk factors for LRICs were also evaluated. RESULTS The mean BTO pressure ratio was significantly correlated with the mean cMCAP/iMCAP (r = 0.68, p < 0.0001). The actual MCAP ratio correlated with the expected MCAP ratio (r = 0.43, p < 0.0001). If the expected MCAP ratio was set up using the BTO pressure ratio instead of cMCAP/iMCAP (BTO-expected MCAP ratio), the mean BTO-expected MCAP ratio significantly correlated with the expected MCAP ratio (r = 0.95, p < 0.0001). During a median follow-up period of 26.1 months, LRICs were observed in 9 patients (11%). An actual MCAP ratio < 0.80 (p = 0.003), expected MCAP ratio < 0.80 (p = 0.001), and (M₂ radius/graft radius)² < 0.49 (p = 0.002) were related to LRICs according to the Cox proportional-hazards model. CONCLUSIONS Data in the present study indicated that it was important to use an adequate graft to achieve a sufficient MCAP ratio in order to avoid LRICs and that the adequate graft size could be evaluated based on a formula in patients with complex ICA aneurysms treated with ICAO.

Clipping in Awake Surgery as End-Stage in a Complex Internal Carotid Artery Aneurysm After Failure of Multimodal Endovascular and Extracranial-Intracranial Bypass Treatment

BACKGROUND

Intracranial carotid artery aneurysm can be treated via microsurgical or endovascular techniques. The optimal planning is the result of the careful patient selection through clinical, anatomic, and angiographic analysis.

CLINICAL PRESENTATION

We present a case of ruptured internal carotid artery (ICA) aneurysm that became a complex aneurysm after failure of multi-endovascular and surgery treatment. We describe complete trapping in awake craniotomy after failure of coiling, stenting, and bypassing.

CONCLUSIONS

ICA aneurysms could become complex aneurysms following multi-treatment failure. Endovascular approaches to treat ICA aneurysms include coiling, stenting, flow diverter stenting, and stenting-assisted coiling technique. The role of surgery remains relevant. To avoid severe neurologic deficits, recurrence, and the need of retreatment, a multidisciplinary discussion with experienced endovascular and vascular neurosurgeons is mandatory in such complex cases.

Cerebral Revascularization for Aneurysms in the Flow-Diverter Era

BACKGROUND: Cerebral bypass has been an important tool in the treatment of complex intracranial aneurysms. The recent advent of flow-diverting stents (FDS) has expanded the capacity for endovascular arterial reconstruction.

OBJECTIVE: We investigated how the advent of FDS has impacted the application and outcomes of cerebral bypass in the treatment of intracranial aneurysms.

METHODS: We reviewed a consecutive series of cerebral bypasses during aneurysm surgery over the course of 10 years. FDS were in active use during the last 5 years of this series. We compared the clinical characteristics, surgical technique, and outcomes of patients who required cerebral bypass for aneurysm treatment during the preflow diversion era (PreFD) with those of the postflow diversion era (PostFD).

RESULTS: We treated 1061 aneurysms in the PreFD era (from July 2005 through June 2010) and 1348 in the PostFD era (from July 2010 through June 2015). Eighty-five PreFD patients (8%) and 45 PostFD patients (3%) were treated with cerebral bypass. PreFD patients had better baseline functional status compared to PostFD patients with average preoperative modified Rankin Scale score of 0.55 in PreFD and 1.18 in PostFD.

CONCLUSION: After the introduction of FDS, cerebral bypass was performed in a lower proportion of patients with aneurysms. Patients selected for bypass in the flow-diverter era had worse preoperative modified Rankin Scale scores indicating a greater complexity of the patients. Cerebral bypass in well-selected patients and revascularization remains an important technique in vascular neurosurgery. It is also useful as a rescue technique after failed FDS treatment of aneurysms.

Surgical Technique for High-Flow Internal Maxillary Artery to Middle Cerebral Artery Bypass Using a Superficial Temporal Artery Interposition Graft

BACKGROUND: Extracranial-to-intracranial high-flow bypass often requires cranial, cervical, and graft site incisions. The internal maxillary artery (IMA) has been proposed as a donor to decrease invasiveness, but its length is insufficient for direct intracranial bypass. We report interposition of a superficial temporal artery (STA) graft for high-flow IMA to middle cerebral artery (MCA) bypass using a middle fossa approach.

OBJECTIVE: To assess the feasibility of an IMA–STA graft-MCA bypass using a new middle fossa approach.

METHODS: Twelve specimens were studied. A 7.5-cm STA graft was obtained starting 1.5 cm below the zygomatic arch. The calibers of STA were measured. After a pterional craniotomy, the IMA was isolated inside the infratemporal fossa through a craniectomy within the lateral triangle (lateral to the posterolateral triangle) in the middle fossa and transposed for proximal end-to-end anastomosis to the STA. The Sylvian fissure was split exposing the insular segment of the MCA, and an STA-M2 end-to-side anastomosis was completed. Finally, the length of graft vessel was measured.

RESULTS: Average diameters of the proximal and distal STA ends were 2.3 ± 0.2 and 2.0 ± 0.1 mm, respectively. At the anastomosis site, the diameter of the IMA was 2.4 ± 0.6 mm, and the MCA diameter was 2.3 ± 0.3 mm. The length of STA graft required was 56.0 ± 5.9 mm.

CONCLUSION: The STA can be used as an interposition graft for high-flow IMA–MCA bypass if the STA is obtained 1.5 cm below the zygomatic arch and the IMA is harvested through the proposed approach. This procedure may provide an efficient and less invasive alternative for high-flow EC–IC bypass.

Surgical treatment of large and giant cavernous carotid aneurysms

Cavernous carotid aneurysms (CCAs) are uncommon pathologic entities. Extradural place and the skull base location make this type of an aneurysm different in clinical features and treatment techniques. Direct aneurysm clipping is technically difficult and results in a significant postoperative neurological deficit. Therefore, several techniques of indirect surgical treatment were developed with different surgical outcomes, such as proximal occlusion of internal carotid artery (ICA) or trapping with or without bypass (superficial temporal artery-middle cerebral artery bypass or high-flow bypass). High-flow bypass with proximal ICA occlusion seems to be the most appropriate surgical treatment for CCA because of the high rate of symptom improvement, aneurysm thrombosis, and minimal postoperative complications. However, in cases of CCA presented with direct carotid-cavernous fistula, the appropriate surgical treatment is high-flow bypass with aneurysm trapping, which the fistula can be obliterated immediately after surgery.

Bypass surgery for complex middle cerebral artery aneurysms: an algorithmic approach to revascularization

OBJECT Management of complex aneurysms of the middle cerebral artery (MCA) can be challenging. Lesions not amenable to endovascular techniques or direct clipping might require a bypass procedure with aneurysm obliteration. Various bypass techniques are available, but an algorithmic approach to classifying these lesions and determining the optimal bypass strategy has not been developed. The objective of this study was to propose a comprehensive and flexible algorithm based on MCA aneurysm location for selecting the best of multiple bypass options. METHODS Aneurysms of the MCA that required bypass as part of treatment were identified from a large prospectively maintained database of vascular neurosurgeries. According to its location relative to the bifurcation, each aneurysm was classified as a prebifurcation, bifurcation, or postbifurcation aneurysm. RESULTS Between 1998 and 2015, 30 patients were treated for 30 complex MCA aneurysms in 8 (27%) prebifurcation, 5 (17%) bifurcation, and 17 (56%) postbifurcation locations. Bypasses included 8 superficial temporal artery-MCA bypasses, 4 high-flow extracranial-to-intracranial (EC-IC) bypasses, 13 IC-IC bypasses (6 reanastomoses, 3 reimplantations, 3 interpositional grafts, and 1 in situ bypass), and 5 combination bypasses. The bypass strategy for prebifurcation aneurysms was determined by the involvement of lenticulostriate arteries, whereas the bypass strategy for bifurcation aneurysms was determined by rupture status. The location of the MCA aneurysm in the candelabra (Sylvian, insular, or opercular) determined the bypass strategy for postbifurcation aneurysms. No deaths that resulted from surgery were found, bypass patency was 90%, and the condition of 90% of the patients was improved or unchanged at the most recent follow-up. CONCLUSIONS The bypass strategy used for an MCA aneurysm depends on the aneurysm location, lenticulostriate anatomy, and rupture status. A uniform bypass strategy for all MCA aneurysms does not exist, but the algorithm proposed here might guide selection of the optimal EC-IC or IC-IC bypass technique.

A rare but morbid neurosurgical target: petrous aneurysms and their endovascular management in the stent/flow diverter era

Background/objective

The rarity of petrous internal carotid artery (ICA) aneurysms has largely precluded analyses of their presentation and management in case series format.

Methods

We performed a retrospective analysis of our endovascular database of patients treated from January 2001 to May 2016 to identify patients with petrous ICA aneurysms. We evaluated the treatment approach and results for patients managed in the era of dedicated intracranial stents and flow diverters, noting clinical and angiographic results.

Results

Our database search identified 10 patients with petrous ICA aneurysms. Six aneurysms were managed in the era of dedicated intracranial stents and flow diverters. Two patients presented with cranial nerve palsies, two with incidental but enlarging aneurysms that had completely eroded through the petrous bone, one with transient ischemic attacks, and one with pulsatile tinnitus. Five aneurysms were large and one was small but symptomatic. In three cases the aneurysm was treated by flow diversion with adjunctive coiling; two patients with at least 4-month follow-up had complete occlusion of their aneurysm and significant improvement of mass effect symptoms. In one case the aneurysm was treated with balloon-assisted coiling with resultant near-complete occlusion. In two cases, prior to the introduction of flow diverters, the aneurysm was treated via stent-assisted coiling with resultant near-complete obliteration; one patient had resolution of pretreatment pulsatile tinnitus. There were no intraprocedural or postprocedural complications; no patients underwent retreatment.

Conclusions

Endovascular treatment of large or symptomatic petrous ICA aneurysms, in the era of flow diversion, is associated with excellent angiographic and clinical outcomes.

Distal outflow occlusion with bypass revascularization: last resort measure in managing complex MCA and PICA aneurysms

BACKGROUND

Partial trapping with or without bypass revascularization is a well-established strategy in the surgical management of complex aneurysms. Distal outflow occlusion is performed by occluding the efferent artery downstream of the aneurysm and represents an alternative to proximal inflow occlusion in partial trapping treatment. With this article we report a case series employing distal outflow occlusion for managing posterior-inferior cerebellar artery (PICA) and middle cerebral artery (MCA) complex aneurysms and discuss the rationale of this treatment strategy.

METHODS

A case series of eight patients who underwent surgery for complex PICA (n = 3) and MCA (n = 5) aneurysms by means of distal outflow occlusion and flow-replacement bypass is presented. Two out of the eight patients presented with subarachnoid hemorrhage (SAH) (1 PICA and 1 MCA aneurysm).

RESULTS

In seven out of eight patients (87.5 %), total aneurysmal thrombosis was obtained; in one patient, postoperative neuroimaging showed a partial aneurysmal thrombosis. Aneurysm growth or delayed rupture was not observed. All the bypasses were patent at the end of the procedure and all but one at follow-up (asymptomatic occlusion). One patient had postoperative worsening, unrelated to bypass patency. All other patients improved. Three patients maintained an mRS score of 1, four patients had improved mRS scores by ≥1, and 1 patient had a worsened mRS score compared to preoperatively.

CONCLUSIONS

We believe that partial trapping with distal outflow occlusion for treating complex intracranial aneurysms represents a useful strategy as a last resort measure. To avoid cerebral ischemia, flow-replacement bypass is key to success.

Treatment of a Giant Serpentine Aneurysm in the Anterior Cerebral Artery

A giant serpentine aneurysm (GSA) in the anterior cerebral artery (ACA) poses a technical challenge in treatment given its large size, unique neck, and dependent distal vessels. Here we report the case of a GSA in the ACA successfully treated with a combined surgical and endovascular approach. A 54-year-old woman presented with dull headache. On brain computed tomography (CT), a large mass (7 cm × 5 cm × 5 cm) was identified in the left frontal lobe. Cerebral angiography revealed a GSA in the left ACA. Bypass surgery of the distal ACA was performed, followed byocclusion of the entry channel via an endovascular approach. Follow-up CT performed 5 days after treatment revealed disappearance of the vascular channel and peripheral rim enhancement. Follow-up imaging studies performed 7 months after treatment revealed gradual reduction of the mass effect and patency of bypass flow. No complications were noted over a period of 1 year after surgery.

The use of combined revascularization surgery for successful elimination of a middle cerebral artery aneurysm

OBJECTIVE

The study objective is to present a clinical case of successful surgical treatment of a complex middle cerebral artery (MCA) aneurysm using various types of bypasses.

MATERIAL AND METHODS

A 59-year-old female patient presented with nontraumatic intracranial hemorrhage caused by rupture of a complex right MCA aneurysm. The anatomical features of the MCA aneurysm were identified using computed tomography (CT) in angiographic and 3D modes. The surgical intervention included aneurysmectomy and an end-to-end reanastomosis between the M1 and M2 segments of the MCA followed by an extra-intracranial microvascular anastomosis (EICMA) between the frontal branch of the right superficial temporal artery (STA) and the cortical branch of the right MCA located on the frontal lobe surface.

RESULTS

The intraoperative blood flow via an intra-intracranial bypass (IC-IC bypass) was 30 mL/min, and the linear velocity of blood flow (LVBF) was 50 cm/s; the blood flow and LVBF via the STA-MCA bypass were 7-8 mL/min and 15 cm/s, respectively. CT angiography performed on the 1st postoperative day revealed the patency of the IC-IC and STA-MCA bypasses. The patient was discharged in satisfactory condition (Glasgow Outcome Scale -V) 1 month after surgery.

CONCLUSION

Revascularization surgery is the sought-after surgical technique for complex intracranial aneurysms that enables efficient exclusion of the aneurysm from blood flow and prevention of ischemic brain injuries in the carrying artery territory.

Surgical Flow Alteration for the Treatment of Intracranial Aneurysms That Are Unclippable, Untrappable, and Uncoilable

OBJECTIVE

The treatment of complex intracranial aneurysms remains challenging. One approach is the application of surgical flow alteration to treat aneurysms that are neither clippable, trappable, or coilable. The efficacy and limitations of surgical flow alteration have not yet been established.

METHODS

Cases of complex aneurysms treated with surgical flow alteration (proximal occlusion with or without bypass, distal occlusion with or without bypass and bypass only) were included in this retrospective study.

RESULTS

Among a total of 16 cases, there were 7 giant aneurysms (≥25 mm diameter) and 9 large aneurysms (>10 mm diameter); 15 of 16 aneurysms were unruptured. There were 8 aneurysms located in the anterior circulation, while the other 8 were in the posterior circulation. Aneurysms were treated with proximal occlusion in 10 cases and distal occlusion in 5 cases; in 1 case, the aneurysm occluded spontaneously after bypass without parent artery occlusion. All but 2 cases underwent prior or concurrent bypass surgery. Complete obliteration of the aneurysm at the latest imaging follow-up was shown in 12 of 16 cases (75.0%). Bypass patency was confirmed in 13 of 15 cases (86.7%). Surgery-related morbidity developed in 3 cases (18.8%, Glasgow outcome scale of 4) and all were perforator infarctions. There were no mortalities.

CONCLUSION

Surgical flow alteration resulted in a high rate of aneurysmal obliteration with acceptable morbidity. Although several limitations remained, it could represent an alternative method for treating complex aneurysms.

Donor Selection in Flow Replacement Bypass Surgery for Cerebral Aneurysms: Quantitative Analysis of Long-term Native Donor Flow Sufficiency

BACKGROUND:

Graft selection in extracranial-intracranial bypass surgery for cerebral aneurysms has traditionally been based on clinical impression and operator preference. However, decision making can be optimized with a donor selection algorithm based on intraoperative flow data.

OBJECTIVE:

To present long-term follow-up and quantitative assessment of flow sufficiency for native donors selected in this manner.

METHODS:

Patients with bypass for anterior circulation intracranial aneurysms using only a native donor (superficial temporal artery) selected on the basis of an intraoperative flow algorithm over a 10-year period were retrospectively studied. Intracranial hemispheric and bypass flows were assessed preoperatively and postoperatively when available with quantitative magnetic resonance angiography.

RESULTS:

Twenty-two patients with flow data were included (median aneurysm size, 22 mm). The intraoperative flow offer (cut flow) of the superficial temporal artery was sufficient in these cases relative to the flow demand in the sacrificed vessel (59 vs 28 mL/min) to warrant its use. Bypass flow averaged 81 mL/min postoperatively (n = 19). Bypass flows were highest in the immediate postoperative period but remained stable between the intermediate and final follow-up (40 vs 52 mL/min; P = .39; n = 8). Mean ipsilateral hemisphere flows were maintained after bypass (299 vs 335 mL/min; P = .42; n = 7), and remained stable over intermediate and long-term follow-up. Ipsilateral hemispheric flows remained similar to contralateral flows at all time points.

CONCLUSION:

Despite a relative reduction in bypass flow over time, hemispheric flows were maintained, indicating that simple native donors can carry sufficient flow for territory demand long term when an intraoperative flow-based algorithm is used for donor selection.

Forearm Cephalic Vein Graft for Short, “Middle”-Flow, Internal Maxillary Artery to Middle Cerebral Artery Bypass

BACKGROUND

The cervical carotid system has been used as a source of donor vessels for radial artery or saphenous vein grafts in cerebral bypass. Recently, internal maxillary artery to middle cerebral artery bypass has been described as an alternative, with reduction of graft length potentially correlating with improved patency.

OBJECTIVE

To describe our experience using the forearm cephalic vein grafts for short segment internal maxillary artery to middle cerebral artery bypasses.

METHODS

All vein grafts were harvested from the volar forearm between the proximal cubital fossa where the median cubital vein is confluent with the cephalic vein and the distal wrist.

RESULTS

Six patients were treated with internal maxillary artery to middle cerebral artery bypass. In 4, the cephalic vein was used. Postoperative angiography demonstrated good filling of the grafts with robust distal flow. There were no upper extremity vascular complications. All but 1 patient (mortality) tolerated the procedure well. The other 3 patients returned to their neurological baseline with no new neurological deficit during follow-up.

CONCLUSION

The internal maxillary artery to middle cerebral artery “middle” flow bypass allows for shorter graft length with both the proximal and distal anastomoses within the same microsurgical field. These unique variable flow grafts represent an ideal opportunity for use of the cephalic vein of the forearm, which is more easily harvested than the wider saphenous vein graft and which has good match size to the M1/M2 segments of the middle cerebral artery. The vessel wall is supple, which facilitates handling during anastomosis. There is lower morbidity potential than utilization of the radial artery. Going forward, the cephalic vein will be our preferred choice for external carotid-internal carotid transplanted conduit bypass.

Current Management of Aneurysmal Subarachnoid Hemorrhage Guidelines from the Canadian Neurosurgical Society

Published medical evidence pertaining to the management of aneurysmal subarachnoid hemorrhage (SAH) was critically reviewed in order to prepare practice guidelines for this condition. SAH should be considered as a possible cause of all sudden and/or unusual headaches, and every attempt should be made to recognize mild SAHs, as they are still frequently misdiagnosed. The first test for SAH is computed tomography (CT), followed by lumbar puncture when the CT is negative for intracranial bleeding (the case in only several per cent of patients within 24 hours of aneurysm bleeding). Urgent cerebral angiography is necessary to detect the underlying cerebral aneurysm. The advantage of rapid diagnosis of SAH followed by early aneurysm repair is minimizing the risk of catastrophic aneurysm rebleeding. Early surgery for aneurysm repair is often possible and is recommended, unless the aneurysm location or size renders it technically difficult to expose in clot-laden subarachnoid cisterns beneath an acutely swollen brain. Aneurysm ablation is optimally accomplished with open microsurgery and clipping of the aneurysm neck, although other options include proximal parent artery occlusion, “trapping” of the aneurysmal segment of the artery, and embolization of thrombogenic materials (e.g., platinum “microcoils”) directly into the aneurysm dome using endovascular techniques. Neurological outcome following SAH is also optimized through the prevention of secondary SAH complications, and further management specific for ruptured cerebral aneurysms can include anticonvulsants, neuroprotectants, and various agents and techniques to prevent or reverse delayed-onset cerebral vasospasm. All patients with aneurysmal SAH should be treated with the calcium antagonist nimodipine, and in certain circumstances patients should receive anticonvulsants. Induced arterial hypertension, hypervolemia and in some instances percutaneous balloon angioplasty are recommended to reverse vasospasm causing symptomatic cerebral ischemia prior to cerebral infarction.

Cerebral Blood Flow after Acute Bypass with Parent Artery Trapping in Patients with Ruptured Supraclinoid Internal Carotid Artery Aneurysms

BACKGROUND

Bypass with parent artery trapping is an alternative treatment method for ruptured internal carotid artery (ICA) aneurysms when clipping or coiling is contraindicated. However, the efficacy and safety of this strategy during the acute stage of subarachnoid hemorrhage (SAH) is undetermined.

METHODS

A retrospective review of 955 consecutive patients presenting SAH between 2006 and 2014 identified 17 patients with ruptured ICA aneurysms treated by bypass with parent artery trapping within 72 hours after the bleeding (bypass group). The 26 cases with ruptured posterior communicating artery aneurysms treated with clipping during the same period were defined as a control group (clipping group). Postoperative cerebral blood flow (CBF) was evaluated by single photon emission computed tomography (SPECT). We analyzed the postoperative hemodynamic status, surgical complications, and the clinical outcomes.

RESULTS

Postoperative rebleeding did not occur in any of the cases. CBF in the first postoperative week in the bypass group was lower than that in the clipping group (P = .0165). This CBF decrease improved in the second postoperative week and did not differ from that of the clipping group. The incidence of acute ischemic complications was significantly higher in the bypass group (P = .0284), but the incidence of delayed cerebral ischemia did not differ between the 2 groups. The incidence of favorable outcomes at 6 months was 82.4% in the bypass group and 81% in the clipping group.

CONCLUSIONS

Although the transient CBF decrease with acute ischemic complications should be noted, acute bypass with parent artery trapping is safe and effective for unclippable/uncoilable ruptured ICA aneurysms.

Internal maxillary artery-middle cerebral artery bypass: infratemporal approach for subcranial-intracranial (SC-IC) bypass

BACKGROUND:

Internal maxillary artery (IMax)–middle cerebral artery (MCA) bypass has been recently described as an alternative to cervical extracranial-intracranial bypass. This technique uses a “keyhole” craniectomy in the temporal fossa that requires a technically challenging end-to-side anastomosis.

OBJECTIVE:

To describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax to facilitate bypass.

METHODS:

Orbitozygomatic osteotomy is used followed by frontotemporal craniotomy and subsequently laterotemporal fossa craniectomy, reaching its medial border at a virtual line connecting the foramen rotundum and foramen ovale. The IMax was identified by using established anatomic landmarks, neuronavigation, and micro Doppler probe (Mizuho Inc. Tokyo, Japan). Additionally, we studied the approach in a cadaveric specimen in preparation for microsurgical bypass.

RESULTS:

There were 4 cases in which the technique was used. One bypass was performed for flow augmentation in a hypoperfused hemisphere. The other 3 were performed as part of treatment paradigms for giant middle cerebral artery aneurysms. Vein grafts were used in all patients. The proximal anastomosis was performed in an end-to-side fashion in 1 patient and end-to-end in 3 patients. Intraoperative graft flow measured with the Transonic flow probe ranged from 20 to 60 mL/min. Postoperative angiography demonstrated good filling of the graft with robust distal flow in all cases. All patients tolerated the procedure well.

CONCLUSION:

IMax to middle cerebral artery subcranial-intracranial bypass is safe and efficacious. The laterotemporal fossa craniectomy technique resulted in reliable identification and wide exposure of the IMax, facilitating the proximal anastomosis.

ABBREVIATIONS:

EC-IC, extracranial-intracranial

IMax, internal maxillary artery

MCA, middle cerebral artery

SC-IC, subcranial-intracranial

STA, superficial temporal artery

Giant and complex aneurysms treatment with preservation of flow via bypass technique

Due to their anatomical characteristics and the complexity of the procedures required to obtain their complete occlusion, the treatment of giant intracranial aneurysms is a real challenge. Direct reconstructive strategies, whether by interventional neuroradiology (coils, stents) or microsurgical (clipping) means, are not always applicable and, in patients that would not tolerate parent or collateral artery sacrifice, the adjunction of a revascularization procedure using a bypass technique might be necessary. Cerebral arterial bypasses can be classified according to their function (3 types: flow replacement, flow reversal or protective), the branching mode of the graft used (3 types: pedicled, interpositional or in situ), the sites of anastomosis (2 types: extracranial-intracranial or intracranial-intracranial) and the class of flow they are supposed to provide (3 types: low-, intermediate- or high-flow). In this article, the authors review the different aspects in the management of patients with a giant intracranial aneurysm using a bypass: preoperative work-up, types of bypass and indications, surgical techniques and results.

Prevention of Retrograde Blood Flow Into Large or Giant Internal Carotid Artery Aneurysms by Endovascular Coil Embolization with High-Flow Bypass: Surgical Technique and Long-Term Results

BACKGROUND

Recanalization has been reported in large or giant aneurysms of the internal carotid artery (ICA) addressed by high-flow bypass and endovascular treatment. Aneurysmal recanalization may be attributable to retrograde blood flow into the aneurysm through the ICA branches, such as the ophthalmic artery or the meningohypophyseal trunk, or through the surgically created bypass. We modified the endovascular treatment of aneurysms to prevent retrograde flow and evaluated the long-term efficacy of our method.

METHODS

We used a hybrid operative/endovascular technique to treat 5 patients with large or giant aneurysms arising from the C2-C4 segment of the ICA who presented with visual symptoms due to the mass effect of the aneurysm. To prevent retrograde flow into the aneurysm our modified endovascular treatment involves coil embolization of the aneurysmal orifice and the ICA, including the origin of the ophthalmic artery and meningohypophyseal trunk, and placement of a high-flow bypass using a radial artery graft.

RESULTS

During the 5- to 12-year follow-up period, 4 aneurysms disappeared, and the other decreased in size. There were no subarachnoid hemorrhages. All bypass grafts remained patent. Visual preservation was achieved in 2 patients; 1 patient manifested visual improvement. Although 2 patients experienced transient neurological deficits we encountered no permanent complications in this series. The final modified Rankin scale of the 5 patients was 0 or 1.

CONCLUSIONS

Prevention of retrograde flow into the aneurysm by coil embolization with high-flow bypass is a safe and effective method. It prevents the recanalization of large or giant ICA aneurysms.

Resolution of cranial neuropathies following treatment of intracranial aneurysms with the Pipeline Embolization Device

Object

Intracranial aneurysms, especially those of the cavernous segment of the internal carotid artery (ICA), can present with cranial nerve (CN) palsies. The Pipeline Embolization Device (PED) has demonstrated safety and efficacy in the treatment of cerebral aneurysms by flow diversion, but little data exist reporting the outcomes of cranial neuropathies following treatment with the device.

Methods

The prospectively maintained Barrow Neurological Institute's endovascular database was reviewed for all patients treated with the PED after presenting with one or more CN palsies secondary to a cerebral aneurysm since May 2011. Patient charts and digital subtraction angiograms were reviewed to report clinical and angiographic outcomes. Only patients with clinical follow-up were included in the analysis.

Results

A total of 127 patients were treated with the PED at the authors' institution after FDA approval. Twentytwo patients presented with cranial neuropathies, for initial inclusion in this study. Of these, 20 had sufficient followup for analysis. Cranial neuropathies included those of CN II, III, V, and VI, with presenting symptoms of diplopia, decreased visual acuity, and facial numbness and/or pain. Thirteen lesions were cavernous segment ICA aneurysms, whereas the remainder included supraclinoid and petrous segment ICA, posterior communicating artery, and basilar trunk aneurysms. At an average clinical follow-up of 9.55 months, 15 patients (75%) had resolution or significant improvement of their cranial neuropathies, and the remaining 5 had stable symptoms. Of the 18 patients with angiographic follow-up, 12 (66.7%) demonstrated complete obliteration or small neck residual, whereas 6 (33.3%) had residual lesion. Patients with complete or near-complete obliteration of their lesion were significantly more likely to demonstrate symptomatic improvement at follow-up (p = 0.009). Two patients with persistent symptoms were eventually treated with microsurgical bypass. Transient complications in this series included 6 (30%) extracranial hemorrhagic complications related to dual-antiplatelet therapy, all of which were managed medically. There was 1 delayed right ICA occlusion following retreatment that led to microsurgical bypass.

Conclusions

Intracranial aneurysms presenting with one or more CN palsies show a high rate of clinical improvement after treatment with the PED. Clinical outcomes must be weighed against the risks and challenges faced with flow diverters. Further research is warranted for patients whose symptoms do not respond optimally to device placement.

Use of superior thyroid artery as a donor vessel in extracranial-intracranial revascularization procedures: a novel technique

Objective To describe the use of the superior thyroid artery as a donor vessel in extracranial-intracranial (EC-IC) revascularization when a "low-flow" bypass is required and the superficial temporal artery is not available. Design Case report. Setting University hospital. Participants Four cases. Main Outcome Measures Postoperative course after EC-IC bypass surgery. Results In case 1, the parent vessel was occluded postoperatively. The radial bypass was sufficient to replace the internal carotid artery (ICA) flow, and a prophylactic was turned into a definitive bypass. In case 2, the superior thyroid artery was used because the radial artery was not long enough to reach the external carotid artery. The recipient vessel was modified from the middle cerebral artery to the ophthalmic segment of the ICA. In case 3, the graft was occluded after surgery because of carotid artery reconstruction. In case 4, after surgery/radiotherapy for meningioma, the patient developed wound dehiscence and was reoperated for bypass occlusion. The graft was weak and bled intraoperatively, without infarction. The three first patients are intact, and the fourth remains disabled (Glasgow Outcome Scale: 3; Rankin Scale: 5). Conclusion The superior thyroid artery was adequate for proximal anastomosis in EC-IC procedures in the situations described.

Anterior cerebral artery bypass for complex aneurysms: an experience with intracranial-intracranial reconstruction and review of bypass options

Object

The authors describe their experience with intracranial-to-intracranial (IC-IC) bypasses for complex anterior cerebral artery (ACA) aneurysms with giant size, dolichoectatic morphology, or intraluminal thrombus; they determine how others have addressed the limitations of ACA bypass; and they discuss clinical indications and microsurgical technique.

Methods

A consecutive, single-surgeon experience with ACA aneurysms and bypasses over a 16-year period was retrospectively reviewed. Bypasses for ACA aneurysms reported in the literature were also reviewed.

Results

Ten patients had aneurysms that were treated with ACA bypass as part of their surgical intervention. Four patients presented with subarachnoid hemorrhage and 3 patients with mass effect symptoms from giant aneurysms; 1 patient with bacterial endocarditis had a mycotic aneurysm, and 1 patient's meningioma resection was complicated by an iatrogenic pseudoaneurysm. One patient had his aneurysm discovered incidentally. There were 2 precommunicating aneurysms (A1 segment of the ACA), 5 communicating aneurysms (ACoA), and 3 postcommunicating (A2–A3 segments of the ACA). In situ bypasses were used in 4 patients (A3-A3 bypass), interposition bypasses in 4 patients, reimplantation in 1 patient (pericallosal artery-to-callosomarginal artery), and reanastomosis in 1 patient (pericallosal artery). Complete aneurysm obliteration was demonstrated in 8 patients, and bypass patency was demonstrated in 8 patients. One bypass thrombosed, but 4 years later. There were no operative deaths, and permanent neurological morbidity was observed in 2 patients. At last follow-up, 8 patients (80%) were improved or unchanged. In a review of the 29 relevant reports, the A3-A3 in situ bypass was used most commonly, extracranial (EC)–IC interpositional bypasses were the second most common, and reanastomosis and reimplantation were used the least.

Conclusions

Anterior cerebral artery aneurysms requiring bypass are rare and can be revascularized in a variety of ways. Anterior cerebral artery aneurysms, more than any other aneurysms, require a thorough survey of patient-specific anatomy and microsurgical options before deciding on an individualized management strategy. The authors' experience demonstrates a preference for IC-IC reconstruction, but EC-IC bypasses are reported frequently in the literature. The authors conclude that ACA bypass with indirect aneurysm occlusion is a good alternative to direct clip reconstruction for complex ACA aneurysms.

Surgical decision-making for managing complex intracranial aneurysms

The treatment of complex intracranial aneurysms remains a therapeutic challenge. These lesions are frequently not amenable to selective clipping or coiling or other endovascular procedures and surgery still has a predominant role.We illustrate our "surgical decision making" for managing complex intracranial aneurysmal lesions. The best strategy is decided on the basis of pre-operative neuroradiological and intra-operative main determinants such as anatomical location, peri-aneurysmal angioanatomy (branch vessels, critical perforators), broad neck, intraluminal thrombosis, aneurysmal wall atherosclerotic plaques and calcifications, absence of collateral circulation, and previous treatment. The surgical strategy encompasses one of the following treatment possibilities: (1) Direct clip reconstruction; (2) Complete trapping ("classic" or "variant"); (3) Partial trapping (proximal "inflow" or distal "outflow" occlusion). Because the goal of any aneurysm treatment is both (1) aneurysm exclusion and (2) blood flow replacement, cerebral revascularization represents a major management option whenever definitive or temporary vessel occlusion is needed.Cerebral revascularization can therefore be used temporarily as a "protective" bypass, or definitively as a "flow replacement" bypass.Complete and partial trapping strategies are associated with flow "replacement" bypass surgery, to preserve blood flow into the territory supplied by the permanently trapped vessel. The construction of the "ideal" bypass depends on several factors, the most important of which are amount of flow needed, recipient vessel, donor vessel, and microanastomosis technique.The choice between "complete" or "partial" trapping depends on angioanatomical criteria as well. A complete trapping is always favored, as it has the advantage of immediate aneurysm exclusion. When perforating vessels arise from the aneurysmal segment or when the inspection of all the angioanatomy of the aneurysm is considered inadvisable and risky, "partial trapping" strategies are of interest. Partial trapping may consist either of proximal or distal occlusion. We discuss the rationale behind these treatment modalities and illustrate it with a case series of seven patients successfully treated for complex intracranial aneurysmal lesions (location: 1 ICA, 1 ACom, 3 MCA, 2 PICA).

Impact of cervical internal carotid clamping and radial artery graft bypass on cortical arterial perfusion pressure during craniotomy

Strategic cervical internal carotid occlusion is employed either temporarily or permanently in various neurosurgical procedures. The aim of the present study was to assess changes in cortical arterial pressure during cervical internal carotid cross-clamping before and after the placement of radial artery (RA) graft bypass in the treatment of complex carotid artery aneurysms. Perfusion pressure of the middle cerebral artery (MCA) was assessed in 22 patients with complex carotid aneurysm treated with RA graft bypass. Regional cerebral blood flow was assessed postoperatively using single-photon computed tomography. Mean cortical blood pressure (mcBP) was found to be 48.2 ± 24.2 and 97.0 ± 24.0 % of baseline after clamping the cervical internal carotid artery and opening the RA graft bypass, respectively. Cerebral perfusion pressure estimated by the mcBP failed to sustain a critical limit of greater than 70 mmHg under craniotomy in 16 out of 20 (80 %) patients. There was an inverse correlation in mcBP between the baseline and after the placement of the RA graft bypass (r = 0.66, P < 0.005). Postoperative regional cerebral blood flow in the MCA territory on the ipsilateral side of the aneurysm was 97 ± 7 % of that of the contralateral side after internal carotid artery (ICA) ligation combined with RA graft bypass. Substantial pressure reductions in cerebral cortical arteries were observed during the cervical internal carotid cross-clamping. Perfusion pressure in peripheral cortical arteries after the placement of the RA graft bypass was comparable to the state before ICA clamping.

EC-IC bypass for cavernous carotid aneurysms: An initial experience with twelve patients

AIMS

Need for performing a bypass procedure prior to parent artery occlusion in patients with good cerebral vascular reserve is controversial. We analyze our experience of 12 giant internal carotid artery aneurysms treated with extracranial-intracranial (EC-IC) bypass and proximal artery occlusion.

MATERIALS AND METHODS

Retrospective analysis of the case records of all complex carotid aneurysms operated in our institute since January 2009.

RESULTS

The study included eleven cavernous carotid aneurysms and one large fusiform cervical carotid aneurysm reaching the skull base. Preoperative assessment of cerebral vascular reserve was limited to Balloon test occlusion with hypotensive challenge. Eleven patients who successfully completed a Balloon test occlusion (BTO) underwent low flow superficial temporal artery to middle cerebral artery (STA-MCA) bypass, while one patient with a failed BTO underwent a high flow bypass using a saphenous vein graft. Parent artery ligation was performed in all patients following the bypass procedure. Check angiogram revealed thrombosis of the aneurysm in all patients with a graft patency rate of 81.8%. We had one operative mortality, probably related to a leak from the anastomotic site. The only patient who had a high flow bypass developed contralateral hemispheric infarcts and remained vegetative. All the other patients had a good recovery and with a Glasgow outcome score of 5 at last follow-up.

CONCLUSION

We feel that combining EC-IC bypass prior to parent vessel occlusion helps in reducing the risk of post operative ischemic complications especially in situations where a complete mandated cerebral blood flow studies are not feasible.

Treatment for giant fusiform aneurysm located in the cavernous segment of the internal carotid artery using the pipeline embolization device

The pipeline embolization device (PED) is a new endovascular device for treatment of complex, fusiform and wide-neck intracranial aneurysms. The main mechanism of this stent is to divert the flow in the parent artery with reduction of inflow in the aneurysm leading to thrombosis. We treated a 40-year-old woman who had left facial pain and orbit discomfort. Angiography showed a giant fusiform aneurysm located in the cavernous segment of the left internal carotid artery. A PED was successfully deployed across the aneurysm. The procedure and post-procedural course were uneventful. After 3 months, angiography showed complete obliteration of the aneurysm with good patency of the branching vessels originating from the deployed segment. The patient's symptoms improved completely without complications.

Revascularization and Aneurysm Surgery

BACKGROUND:

Given advances in endovascular technique, the indications for revascularization in aneurysm surgery have declined.

OBJECTIVE:

We sought to define indications, outline technical strategies, and evaluate the outcomes of patients treated with bypass in the endovascular era.

METHODS:

We retrospectively reviewed all aneurysms treated between September 2006 and February 2013.

RESULTS:

We identified 54 consecutive patients (16 males and 39 females) with 56 aneurysms. Aneurysms were located along the cervical internal carotid artery (ICA) (n = 1), petrous/cavernous ICA (n = 1), cavernous ICA (n = 16), supraclinoid ICA (n = 7), posterior communicating artery (n = 2), anterior cerebral artery (n = 4), middle cerebral artery (MCA) (n = 13), posterior cerebral artery (PCA) (n = 3), posterior inferior cerebellar artery (n = 4), and vertebrobasilar arteries (n = 5). Revascularization was performed with superficial temporal artery (STA) to MCA bypass (n = 25), STA to superior cerebellar artery (SCA) (n = 3), STA to PCA (n = 1), STA-SCA/STA-PCA (n = 1), occipital artery (OA) to PCA (n = 2), external carotid artery/ICA to MCA (n = 15), OA to MCA (n = 1), OA to posterior inferior cerebellar artery (n = 1), and in situ bypasses (n = 8). At a mean clinical follow-up of 18.5 months, 45 patients (81.8%) had a good outcome (Glasgow Outcome Scale 4 or 5). There were 7 cases of mortality (12.7%) and an additional 9 cases of morbidity (15.8%). At a mean angiographic follow-up of 17.8 months, 14 bypasses were occluded. Excluding the 7 cases of mortality, the majority of aneurysms (n = 42) were obliterated. We identified 7 cases of residual aneurysm and recurrence in 6 patients at follow-up.

CONCLUSION:

Given current limitations with existing treatments, cerebral revascularization remains an essential technique for aneurysm surgery.

Bypass surgery for complex middle cerebral artery aneurysms: impact of the exact location in the MCA tree

Object

The object of this study was to describe the authors' institutional experience in the treatment of complex middle cerebral artery (MCA) aneurysms necessitating bypass and vessel sacrifice.

Methods

Cases in which patients with MCA aneurysms were treated with a combination of bypass and parent artery sacrifice were reviewed retrospectively.

Results

The authors identified 24 patients (mean age 46 years) who were treated with bypass and parent artery sacrifice. The aneurysms were located in the M1 segment in 7 patients, MCA bifurcation in 8, and more distally in 9. The mean aneurysm diameter was 30 mm (range 7–60 mm, median 26 mm). There were 8 saccular and 16 fusiform aneurysms.

Twenty-one extracranial-intracranial and 4 intracranial-intracranial bypasses were performed. Partial or total trapping (only) of the parent artery was performed in 17 cases, trapping with resection of aneurysm in 3, and aneurysm clipping with sacrifice of an M2 branch in 4.

The mean follow-up period was 27 months. The aneurysm obliteration rate was 100%. No recanalization of the aneurysms was detected during follow-up.

There was 1 perioperative death (4% mortality rate) and 6 cerebrovascular accidents, causing permanent morbidity in 5 patients. The median modified Rankin Scale score of patients with an M1 aneurysm increased from 0 preoperatively to 2 at latest follow-up, while the score was unchanged in other patients. Most of the permanent deficits were associated with M1 aneurysms. Twenty-one patients (88%) had good outcome as defined by a Glasgow Outcome Scale score of 4 or 5.

Conclusions

Bypass in combination with parent vessel occlusion is a useful technique with acceptable frequencies of morbidity and mortality for complex MCA aneurysms when conventional surgical or endovascular techniques are not feasible. The location of the aneurysm should be considered when planning the type of bypass and the site of vessel occlusion. Flow alteration by partial trapping may be preferable to total trapping for the M1 aneurysms.

Advances in Open Microsurgery for Cerebral Aneurysms

BACKGROUND:

Endovascular techniques introduced strong extrinsic forces that provoked reactive changes in aneurysm surgery. Microsurgery has become less invasive, more appealing to patients, lower risk, and efficacious for complex aneurysms, particularly those unfavorable for or failing endovascular therapy.

OBJECTIVE:

To review specific advances in open microsurgery for aneurysms.

METHODS:

A university-based, single-surgeon practice was examined for the use of minimally invasive craniotomies, surgical management of recurrence after coiling, the use of intracranial-intracranial bypass techniques, and cerebrovascular volume-outcome relationships.

RESULTS:

The mini-pterional, lateral supraorbital, and orbital-pterional craniotomies are minimally invasive alternatives to standard craniotomies. Mini-pterional and lateral supraorbital craniotomies were used in one-fourth of unruptured patients, increasing from 22% to 28%, whereas 15% of patients underwent orbital-pterional craniotomies and trended upward from 11% to 20%. Seventy-four patients were treated for coil recurrences (2.3% of all aneurysms) with direct clip occlusion (77%), clip occlusion after coil extraction (7%), or parent artery occlusion with bypass (16%). Intracranial-intracranial bypass (in situ bypass, reimplantation, reanastomosis, and intracranial grafts) transformed the management of giant aneurysms and made the surgical treatment of posterior inferior cerebellar artery aneurysms competitive with endovascular therapy. Centralization maximized the volume-outcome relationships observed with clipping.

CONCLUSION:

Aneurysm microsurgery has embraced minimalism, tailoring the exposure to the patient's anatomy with the smallest possible craniotomy that provides adequate exposure. The development of intracranial-intracranial bypasses is an important advancement that makes microsurgery a competitive option for complex and recurrent aneurysms. Trends toward centralizing aneurysm surgery in tertiary centers optimize results achievable with open microsurgery.

Selective Targeted Cerebral Revascularization via Microscope Integrated Indocyanine Green Videoangiography Technology

Protective or flow replacement bypass surgery has an important role in the management of complex middle cerebral artery (MCA) aneurysms. Protective bypass is useful when prolonged temporary arterial occlusion is needed for clip reconstruction. Flow replacement bypass is instead important when aneurysmal trapping is the treatment of choice in order to supply permanent collateral blood flow to the brain distal to the "trapped" vessel. In both cases, the identification of the correct recipient artery is an essential surgical step. When a superficial (cortical) artery is chosen as recipient, it indeed has to represent a distal branch of the involved (temporarily or permanently occluded) vessel.Here we describe a technique for selective-targeted revascularization based on the use of indocyanine green video angiography (ICG-VA), a microscope-integrated intraoperative tool nowadays known to provide real-time assessment of the cerebral circulation with distinct visualization of arterial, capillary and venous angiographic phases. The technique is founded on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. It enables reliable identification of the cortical recipient and eliminates the risk of erroneous revascularization of non-involved territories. The surgical decision-making of two patients treated for complex MCA aneurysms with selective-targeted bypass is presented.

Distal posterior cerebral artery revascularization for a fusiform PCA aneurysm: A lesson learned

The need for revascularization with proximal posterior cerebral artery occlusion in the treatment of giant and fusiform aneurysms is unclear. While early series demonstrated only about a 10% chance of infarction following posterior cerebral artery occlusion, recently several authors have advocated a bypass prior to parent vessel sacrifice in all cases. We present the case of an adult man with a fusiform aneurysm of the right posterior cerebral artery at the P2-P3 junction. He clinically failed a balloon test occlusion preoperatively and therefore underwent an occipital artery to distal posterior cerebral artery bypass with subsequent endovascular occlusion of the parent vessel and aneurysm. Despite the fact that the immediate and 6 month follow up cerebral angiography confirmed a patent bypass, the patient still developed a posterior cerebral artery territory stroke. We believe this case demonstrates that successful distal revascularization in the setting of proximal posterior cerebral artery occlusion does not guarantee against cerebral ischemia and infarction even in those patients that fail a test occlusion.