Keyhole Approach and Neuroendoscopy for Cerebral Aneurysms

Treating diseases in the field of neurosurgery has progressed concomitantly with technical advances. Here, as a surgical armamentarium for the treatment of cerebral aneurysms, the history and present status of the keyhole approach and the use of neuroendoscopy are reviewed, including our clinical data. The major significance of keyhole approach is to expose an essential space toward a target, and to minimize brain exposure and retraction. Among several kinds of keyhole approaches, representative keyhole approaches for anterior circulation aneurysms include superciliary and lateral supraorbital, frontolateral, mini-pterional and mini-interhemispheric approaches. Because only a fixed and limited approach angle toward a target is permitted via the keyhole, however, specialized surgical devices and preoperative planning are very important. Neuroendoscopy has helped to widen the indications of keyhole approaches because it can supply illumination and visualization of structures beyond the straight line of microscopic view. In addition, endoscopic indocyanine green fluorescence angiography is useful to detect and correct any compromise of the perforators and parent arteries, and incomplete clipping. The authors think that keyhole approach and neuroendoscopy are just an intermediate step and robotic neurosurgery would be realized in the near future.

Engaging in a Keyhole Concept for the Management of Ruptured and Unruptured Aneurysms

OBJECTIVE

Many new endovascular devices have been used under the guidance of the International Subarachnoid Aneurysm Trial. Clipping still offers higher occlusion rates, and its technique continues to evolve, resulting in smaller exposures and reduced manipulation to brain tissue. We sought to evaluate the routine use of the minisphenoidal approach to manage intracranial aneurysms in a high-volume institution.

METHODS

We retrospectively reviewed our database of patients with aneurysm from October 2013 to May 2016. Data were originally collected prospectively. The minisphenoidal approach has been progressively replacing the pterional approach for managing aneurysms in our department. Occlusion rates for ruptured and unruptured aneurysms were analyzed using late follow-up angiograms. Functional outcome assessment and the impact on quality of life were also measured.

RESULTS

We performed 124 minisphenoidal craniotomies in 117 patients to clip 147 aneurysms. Patient mean age was 53.9 years. Seventy patients (59.8%) presented with subarachnoid hemorrhage. Middle cerebral artery aneurysms represented 48% of the total number of aneurysms; posterior communicating artery aneurysms represented 24%. The minisphenoidal craniotomy was helpful in managing superior cerebellar artery aneurysms and 1 ruptured orbitofrontal artery aneurysm. We achieved an occlusion rate of 97.8%, with a mean follow-up of 13.2 months. Favorable outcomes were achieved for 79% of patients with subarachnoid hemorrhage and for 98% of unruptured patients.

CONCLUSIONS

Evolution of endovascular techniques has paved the way for minimizing surgical exposures. Routine use of the minisphenoidal approach for managing ruptured, unruptured, and previously coiled aneurysms is safe and provides adequate exposure with robust occlusion rates.

Frameless Stereotactic Insertion of Viewsite Brain Access System with Microscope-Mounted Tracking Device for Resection of Deep Brain Lesions: Technical Report

The surgical management of deep brain tumors is often challenging due to the limitations of stereotactic needle biopsies and the morbidity associated with transcortical approaches. We present a novel microscopic navigational technique utilizing the Viewsite Brain Access System (VBAS) (Vycor Medical, Boca Raton, FL, USA) for resection of a deep parietal periventricular high-grade glioma as well as another glioma and a cavernoma with no related morbidity. The approach utilized a navigational tracker mounted on a microscope, which was set to the desired trajectory and depth. It allowed gentle continuous insertion of the VBAS directly to a deep lesion under continuous microscopic visualization, increasing safety by obviating the need to look up from the microscope and thus avoiding loss of trajectory. This technique has broad value for the resection of a variety of deep brain lesions.

Intradural Procedural Time to Assess Technical Difficulty of Superciliary Keyhole and Pterional Approaches for Unruptured Middle Cerebral Artery Aneurysms

Objective

This study used the intradural procedural time to assess the overall technical difficulty involved in surgically clipping an unruptured middle cerebral artery (MCA) aneurysm via a pterional or superciliary approach. The clinical and radiological variables affecting the intradural procedural time were investigated, and the intradural procedural time compared between a superciliary keyhole approach and a pterional approach.

Methods

During a 5.5-year period, patients with a single MCA aneurysm were enrolled in this retrospective study. The selection criteria for a superciliary keyhole approach included : 1) maximum diameter of the unruptured MCA aneurysm <15 mm, 2) neck diameter of the MCA aneurysm <10 mm, and 3) aneurysm location involving the sphenoidal or horizontal segment of MCA (M1) segment and MCA bifurcation, excluding aneurysms distal to the MCA genu. Meanwhile, the control comparison group included patients with the same selection criteria as for a superciliary approach, yet who preferred a pterional approach to avoid a postoperative facial wound or due to preoperative skin trouble in the supraorbital area. To determine the variables affecting the intradural procedural time, a multiple regression analysis was performed using such data as the patient age and gender, maximum aneurysm diameter, aneurysm neck diameter, and length of the pre-aneurysm M1 segment. In addition, the intradural procedural times were compared between the superciliary and pterional patient groups, along with the other variables.

Results

A total of 160 patients underwent a superciliary (n=124) or pterional (n=36) approach for an unruptured MCA aneurysm. In the multiple regression analysis, an increase in the diameter of the aneurysm neck (p<0.001) was identified as a statistically significant factor increasing the intradural procedural time. A Pearson correlation analysis also showed a positive correlation (r=0.340) between the neck diameter and the intradural procedural time. When comparing the superciliary and pterional groups, no statistically significant between-group difference was found in terms of the intradural procedural time reflecting the technical difficulty (mean±standard deviation : 29.8±13.0 min versus 27.7±9.6 min).

Conclusion

A superciliary keyhole approach can be a useful alternative to a pterional approach for an unruptured MCA aneurysm with a maximum diameter <15 mm and neck diameter <10 mm, representing no more of a technical challenge. For both surgical approaches, the technical difficulty increases along with the neck diameter of the MCA aneurysm.

Open Surgery for Recurrent Intracranial Aneurysms: Techniques and Long-Term Outcomes

BACKGROUND

After occlusion of an aneurysm, a patient may experience aneurysm regrowth at the same site or develop de novo aneurysms. We present our experience in microsurgery of recurrent aneurysms with analysis of long-term results.

METHODS

The senior authors (R. T. and H. K.) performed recurrent aneurysm clipping on 44 patients at Teishinkai Hospital and Asahikawa Red Cross Hospital in Sapporo, Japan. Operative techniques included clipping only, clipping and protective bypass, trapping of aneurysm with bypass, proximal occlusion, and bypass. Postoperative outcome was analyzed retrospectively using the modified Rankin Scale.

RESULTS

Our series included 10 men (23%) and 34 women (77%), with a mean patient age of 63 years (range, 7-82 years). Before primary treatment, 11 patients (25%) had a ruptured aneurysm, while 33 patients (75%) had an unruptured aneurysm. The mean follow-up time after primary surgery was 7.6 years (range, 0.8-25 years). At our department the treatment of recurrent aneurysm included the clipping in 19 patients (43%), clipping with bypass in 6 patients (14%), aneurysm trapping with bypass in 10 patients (23%), and proximal occlusion and bypass in 9 patients (20%). The mean follow-up time after surgical treatment of recurrent aneurysms stood at 3.5 years (range 0.1-9 years). Altogether, 37 patients (84%) experienced favorable outcomes at last follow-up examination (modified Rankin Scale scores 0 and 1).

CONCLUSIONS

Microsurgery of recurrent aneurysms may be performed safely and effectively, as shown by our study, in which 84% of patients experienced favorable results.

Incidence, Timing, and Predictors of Delayed Shunting for Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Although hydrocephalus is often treated with permanent cerebrospinal fluid (CSF) shunting during hospitalization for acute aneurysmal subarachnoid hemorrhage (SAH), little is known about the development of delayed hydrocephalus.

METHODS

Using administrative data on all visits to nonfederal emergency departments and acute care hospitals across California from 2005 to 2010, we identified patients with SAH and discharged without placement of a CSF shunt. Patients were followed for up to 7 years to determine whether they subsequently developed delayed hydrocephalus, as indicated by hospitalization for a permanent CSF diversion procedure.

RESULTS

In 8,889 patients discharged with SAH, 116 (1.3 %) went on to develop delayed hydrocephalus. Most (>90 %) diagnoses of delayed hydrocephalus occurred within the first year after discharge. Cox proportional hazards analysis identified microsurgical clipping (hazard ratio 2.0; 95 % confidence interval 1.2-3.3), temporary ventriculostomy placement (2.5; 1.6-4.1), mechanical ventilation (1.7; 1.1-2.8), and discharge to a skilled nursing facility (2.9; 1.8-4.6) as being significantly associated with the development of delayed hydrocephalus. At 1 year after discharge, the cumulative rate of delayed hydrocephalus was 0.9 % (95 % CI, 0.7-1.1 %) for those without temporary ventriculostomy placement during the initial hospitalization, versus 5.7 % (95 % CI, 3.9-8.1 %) in those who had received a temporary ventriculostomy.

CONCLUSION

Delayed hydrocephalus after SAH occurs rarely overall, but in a substantial proportion of patients who required temporary ventriculostomy during the initial hospitalization. These results support vigilant surveillance of patients after removal of a temporary ventriculostomy, given the potential of delayed hydrocephalus to impair recovery or even result in clinical deterioration following SAH.

Factors for Achieving Safe and Complete Treatment for Unruptured Saccular Aneurysm Smaller Than 10 mm by Simple Clipping or Simple Coil Embolization

OBJECTIVE

Reducing complications from unruptured aneurysms (UAs) treatment is important. We clarify the criteria for achieving safe and complete treatment for UAs ≤10 mm by clipping or coil embolization.

METHODS

This study included 59 newly treated UAs in the past 2 years. We prospectively decided on criteria to recommend active treatment. UAs ≤10 mm and in ≤75 year-olds, located at in the internal carotid artery at the paraclinoid portion and the posterior circulation aneurysms except for a vertebral artery-inferior posterior cerebellar artery aneurysm were mainly treated by coil embolization, and those in the internal carotid artery except at the paraclinoid portion, in the anterior or middle cerebral artery, and in the vertebral artery-inferior posterior cerebellar artery were treated preferably by clipping. UAs with a height/neck ratio or a dome/neck ratio ≤1.4 were treated preferentially by clipping. Specific preoperative imaging and careful manipulation were adopted for clipping.

RESULTS

Fifty-seven (96.6%) achieved modified Rankin scale (mRS) 0-1, 2 (3.4%) mRS 2-5, and 0 had mRS 6. Fifty-three UAs (89.8%) achieved complete occlusion (CO) and 7 (10.1%) had neck remnants (NR). Forty-one UAs (100%) within the criteria achieved mRS 0-1, 40 (98%) achieved CO, and 1 (2%) NR. The odds ratio of NR for those outside the criteria was 18.5 (95% confidence interval, 1.83-186.6) (P < 0.05). CO treated within the criteria was 39 and NR was 1. CO treated outside the criteria was 14 and NR was 5 (P < 0.05). The mRS 0-1 with age ≤75 years was 55 and the mRS 2-6 was 0. The mRS 0-1 with age ≥76 years was 2 and the mRS 2-6 was 2 (P < 0.01).

CONCLUSIONS

The treatment for UAs within the criteria, with the most recent points of concern, can lead to safe and complete results.

The Impact of Surgical Experience on Major Intraoperative Aneurysm Rupture and Their Consequences on Outcome: A Multivariate Analysis of 538 Microsurgical Clipping Cases

The incidence and associated mortality of major intraoperative rupture (MIOR) in intracranial aneurysm surgery is diverse. One possible reason is that many studies failed to consider and properly adjust the factor of surgical experience in the context. We conducted this study to clarify the role of surgical experience on MIOR and associated outcome. 538 consecutive intracranial aneurysm surgeries performed on 501 patients were enrolled in this study. Various potential predictors of MIOR were evaluated with stratified analysis and multivariate logistic regression. The impact of surgical experience and MIOR on outcome was further studied in a logistic regression model with adjustment of each other. The outcome was evaluated using the Glasgow Outcome Scale one year after the surgery. Surgical experience and preoperative Glasgow Coma Scale (GCS) were identified as independent predictors of MIOR. Experienced neurovascular surgeons encountered fewer cases of MIOR compared to novice neurosurgeons (MIOR, 18/225, 8.0% vs. 50/313, 16.0%, P = 0.009). Inexperience and MIOR were both associated with a worse outcome. Compared to experienced neurovascular surgeons, inexperienced neurosurgeons had a 1.90-fold risk of poor outcome. On the other hand, MIOR resulted in a 3.21-fold risk of unfavorable outcome compared to those without it. Those MIOR cases managed by experienced neurovascular surgeons had a better prognosis compared with those managed by inexperienced neurosurgeons (poor outcome, 4/18, 22% vs. 30/50, 60%, P = 0.013).

Detection of wall and neck calcification of unruptured intracranial aneurysms with flat-detector computed tomography

OBJECT

Microsurgical clipping is a widely used surgical technique in intracranial aneurysm treatment. It can be difficult in large sized aneurysms, and those with wide necks, thick walls and calcification located in the vicinity of the neck. This study reviewed calcification of the intracranial aneurysm wall and its relation to patient age, gender, location and size of the aneurysm. A possible cut-off value after which the aneurysm calcification rate increases was also investigated to classify patients' risk factors for microclipping.

METHODS

A retrospective review of all unruptured intracranial aneurysms that underwent digital subtraction angiography at a single centre was performed. Flat-detector computed tomography images of the aneurysm were reviewed for aneurysm location, size and calcification. The independent samples t test and χ(2) test were used to show the relation between aneurysm wall calcification and patient age, gender, aneurysm localisation and size.

RESULTS

None of the reviewed factors were statistically significantly related to aneurysm calcification except aneurysm size (P < 0.01). Receiver operating characteristic curves showed aneurysms greater than 10.5 mm could be predicted to be calcified with a sensitivity of 80% and specificity of 63%.

CONCLUSION

In this study, the presence of calcification was related to aneurysm size. Larger aneurysms were more likely to be calcified. Aneurysms greater than 10.5 mm should be further investigated with a modality such as flat-detector computed tomography to show the calcification in detail, especially if microclipping is considered.

Surgical management of ruptured small cerebral aneurysm: Outcome and surgical notes

Background:

Management of small aneurysms often poses a therapeutic dilemma and surgical treatment or coiling can be considered as therapeutic choices. In the present study, we reviewed our series of ruptured small cerebral aneurysm treated surgically.

Methods:

A total of 53 consecutive patients with ruptured small aneurysm were surgically treated between January 2008 and July 2014. Data were retrospectively collected. Procedure-related death and complications were systematically reviewed. Clinical outcomes were assessed using the Modified Ranking Scale. Neuroradiological follow-up was performed to assess aneurysmal occlusion and recanalization rate.

Results:

The mean aneurysm size was 2 mm ± 0.8 mm. All the patients were operated and the aneurysm clipped. Clinical outcomes were as expected on the basis of the presenting Hunt and Hess grade. Overall, major and minor neurological deficit related to clipping were 5.2% and 2.2%, respectively. At the time of discharge, 84.9% of the patients presented with a favorable outcome, while 15.1% had poor clinical outcome. Aneurysm occlusion was achieved in all the cases. Neither recanalization nor re-aneurysmal rupture was observed in the clinical follow-up.

Conclusion:

Aneurysms, 3 mm in diameter or smaller, represent a therapeutic challenge. Given the proven role of microsurgery in small aneurysms and the perceived challenges with endovascular therapy, surgical clipping still can be considered an effective treatment modality in this setting.

Surgical Treatment of Middle Cerebral Artery Aneurysms Without Using Indocyanine Green Videoangiography Assistance: Retrospective Monocentric Study of 263 Clipped Aneurysms

INTRODUCTION

Middle cerebral artery (MCA) aneurysms represent 20% of intracranial aneurysms. Most (80%) of them are located on the sylvian bifurcation, the seat of hemodynamic turbulence flow. Morbidity and mortality related to surgery of MCA aneurysms are not negligible. MCA vascularization areas are important eloquence functional territorial of Brain tissue. Indocyanine green videoangiography assistance (ICG-VA) is an emergent tool for intraoperative assessment of aneurysmal occlusion and for checking a possible stenosant clip in vascular area. The purposes of this study were to evaluate the safety of clipping procedure in terms of morbidity, mortality, and efficiency of aneurysm occlusion without using ICG-VA, recurrence and bleeding/rebleeding at short and long terms, and angiographic and clinical follow-ups.

MATERIAL AND METHODS

This study is a monocentric retrospective study performed at Pitié-Salpêtrière-Charles Foix Hospital Center, reporting clinical and angiographic follow-up of consecutive patients treated for MCA aneurysms (ruptured and unruptured) by clipping procedures. From 2002-2012, 251 consecutive patients were admitted at the author's institution for treatment of 263 MCA aneurysms (163 ruptured and 100 unruptured). Procedure-related death and complications were systematically assessed without video-angiography availability. The degree of aneurysms exclusion was evaluated according to the Raymond-Roy scale after the procedure and at long-term angiographic follow-up (mean delay = 36 months).

RESULTS

The death rate related to aneurysmal exclusion procedure was 1.2%. The major complication rate related to surgery was 5.3%. Postprocedure, an aneurysm occlusion rate Raymond-Roy grade A or B was 95.6%. Neither recanalization controlled clipped aneurysms nor re-aneurysmal rupture was observed in the long-term clinical follow-up (mean time = 83.5 months). The institution's series of surgical outcomes reported 95.6% of complete exclusion and 4.5% incomplete procedures without ICG-VA. A clip of repositioning rate was estimated at 15% when ICG-VA was used.

CONCLUSION

Surgical management is relatively safe for patients, with an acceptable complication rate in the era when ICG-VA was not yet available. Indeed, the main source of procedural ischemia microsurgery is stenosant clip. To limit the occurrence of malposition, the author's center began using ICG-VA a few months ago and expects to reduce its rate of incomplete occlusion.

Augmented reality-assisted bypass surgery: embracing minimal invasiveness

OBJECTIVE

The overlay of virtual images on the surgical field, defined as augmented reality, has been used for image guidance during various neurosurgical procedures. Although this technology could conceivably address certain inherent problems of extracranial-to-intracranial bypass procedures, this potential has not been explored to date. We evaluate the usefulness of an augmented reality-based setup, which could help in harvesting donor vessels through their precise localization in real-time, in performing tailored craniotomies, and in identifying preoperatively selected recipient vessels for the purpose of anastomosis.

METHODS

Our method was applied to 3 patients with Moya-Moya disease who underwent superficial temporal artery-to-middle cerebral artery anastomoses and 1 patient who underwent an occipital artery-to-posteroinferior cerebellar artery bypass because of a dissecting aneurysm of the vertebral artery. Patients' heads, skulls, and extracranial and intracranial vessels were segmented preoperatively from 3-dimensional image data sets (3-dimensional digital subtraction angiography, angio-magnetic resonance imaging, angio-computed tomography), and injected intraoperatively into the operating microscope's eyepiece for image guidance.

RESULTS

In each case, the described setup helped in precisely localizing donor and recipient vessels and in tailoring craniotomies to the injected images.

CONCLUSIONS

The presented system based on augmented reality can optimize the workflow of extracranial-to-intracranial bypass procedures by providing essential anatomical information, entirely integrated to the surgical field, and help to perform minimally invasive procedures.

Endovascular and surgical options for ruptured middle cerebral artery aneurysms: review of the literature

Middle cerebral artery (MCA) aneurysms are common entities, and those of the bifurcation are the most frequently encountered sublocation of MCA aneurysm. MCA bifurcation (MBIF) aneurysms commonly present with subarachnoid hemorrhage (SAH), are devastating, and are often lethal. At the present time, the treatment of ruptured MBIF aneurysms entails either endovascular or open microneurosurgical methods to permanently secure the aneurysm(s). The purpose of this report is to review the current available data regarding the relative superiority of endovascular versus open microneurosurgical clipping for the treatment of ruptured middle cerebral artery bifurcation aneurysms.