Surgical treatment of unruptured aneurysms of the posterior circulation

Surgical outcomes of patients with unruptured anterior vs. inferior circulation aneurysms: A meta‑analysis

The treatment option for unruptured intracranial aneurysms (UIAs) depends on their natural history-related risk of rupture vs. the risk of surgical management. The present meta-analysis sought to assess the association between the surgical outcomes of anterior and posterior circulation UIAs. The present study investigated the comparative articles involving the surgical treatment of anterior vs. posterior circulation UIAs through electronic databases, including the Cochrane Library, PubMed (1980 to March, 2023), Medline (1980 to March, 2023) and EMBASE (1980 to March, 2023). Quoting all exclusion and inclusion criteria, nine articles finally remained for statistical analysis. The entire number of patients included in these nine articles was 3,253 (2,662 in the anterior and 591 in the posterior circulation UIAs group). The present meta-analysis proposes that the surgical treatment of anterior circulation UIAs is associated with better outcomes compared with the surgical management of posterior circulation UIAs.

Brain retraction injury: systematic literature review

Cerebral retraction is frequently required in cranial surgery to access deep areas. Brain retractors have been systematically used in the past, but they have been associated with brain injury. Nonetheless, they are still used and, even recently, new systems have been advocated. The aim of this study is to provide a systematic and critical review of brain retraction injury. A systematic literature review was performed in February 2023 according to PRISMA statement. Search terms included brain retraction and injury, with their variations and pertinent associations. Studies reporting qualitative and quantitative data on brain retraction injury were included. Out of 1689 initially retrieved articles, 90 and 26 were included in the systematic review for qualitative and quantitative data, respectively. The definition of brain retraction injury varies and its reported incidence in clinical studies is 5-10%, up to 47% if cerebral edema is considered. Some studies have hypothesized threshold values of pressures to be respected in order to prevent complications, with most data deriving from animal studies. At present, there are no instruments for brain retraction that can guarantee full safety. Some form of cerebral retraction might always be necessary for specific scenarios. Further studies are needed to collect quantitative and, ideally, clinical and comparative data on pressure thresholds to develop retraction systems that can reduce injury to a minimum.

Microsurgical Management of Posterior Circulation Aneurysms: A Retrospective Study on Epidemiology, Outcomes, and Surgical Approaches

Posterior circulation aneurysms have been regarded as the most challenging for endovascular coiling and microsurgical occlusion. The role of microsurgical treatment is gradually being overlooked and diminishing in the trend of endovascular treatment. As microsurgical occlusion of posterior circulation aneurysms is decreasing, we present our relevant experience to evaluate treatment options and surgical approaches. A retrospective study was conducted in the Department of Neurosurgery of the First Affiliated Hospital of Soochow University between 2016 and 2021. Patients with posterior circulation aneurysms treated by clipping, bypass, and trapping were enrolled and followed up for at least six months. We included 50 patients carrying 53 posterior circulation aneurysms, 43 of whom had aneurysm ruptures. The posterior cerebral artery and posterior inferior cerebellar artery were the most common aneurysm locations. Direct clipping was performed in 43 patients, while bypass and trapping was performed in six patients. The retrosigmoid, far-lateral, and midline or paramedian suboccipital approaches were performed for those aneurysms in the middle and lower thirds. Aneurysms in the upper third required the lateral supraorbital approach, pterional approach, subtemporal approach, and occipital craniotomy. The lateral supraorbital approach was utilized in seven patients for aneurysms above the posterior clinoid process. Thirty-four patients recovered well with modified Rankin score 0-3 at discharge. No patient experienced aneurysm recurrence during the mean follow-up period of 3.57 years. Microsurgery clipping and bypass should be considered in conjunction with endovascular treatment as a treatment option in posterior circulation aneurysms. The lateral supraorbital approach is a feasible, safe, and simple surgical approach for aneurysms above the posterior clinoid process.

Microsurgical Management of Posterior Circulation Aneurysms: A Retrospective Study on Epidemiology, Outcomes, and Surgical Approaches

Posterior circulation aneurysms have been regarded as the most challenging for endovascular coiling and microsurgical occlusion. The role of microsurgical treatment is gradually being overlooked and diminishing in the trend of endovascular treatment. As microsurgical occlusion of posterior circulation aneurysms is decreasing, we present our relevant experience to evaluate treatment options and surgical approaches. A retrospective study was conducted in the Department of Neurosurgery of the First Affiliated Hospital of Soochow University between 2016 and 2021. Patients with posterior circulation aneurysms treated by clipping, bypass, and trapping were enrolled and followed up for at least six months. We included 50 patients carrying 53 posterior circulation aneurysms, 43 of whom had aneurysm ruptures. The posterior cerebral artery and posterior inferior cerebellar artery were the most common aneurysm locations. Direct clipping was performed in 43 patients, while bypass and trapping was performed in six patients. The retrosigmoid, far-lateral, and midline or paramedian suboccipital approaches were performed for those aneurysms in the middle and lower thirds. Aneurysms in the upper third required the lateral supraorbital approach, pterional approach, subtemporal approach, and occipital craniotomy. The lateral supraorbital approach was utilized in seven patients for aneurysms above the posterior clinoid process. Thirty-four patients recovered well with modified Rankin score 0–3 at discharge. No patient experienced aneurysm recurrence during the mean follow-up period of 3.57 years. Microsurgery clipping and bypass should be considered in conjunction with endovascular treatment as a treatment option in posterior circulation aneurysms. The lateral supraorbital approach is a feasible, safe, and simple surgical approach for aneurysms above the posterior clinoid process.

Flow diverters for the posterior inferior cerebellar artery aneurysms: A systematic review and a single-arm meta-analysis

BACKGROUND

The treatment of posterior inferior cerebellar artery aneurysms is controversial. Recently, flow diverters have emerged as an attractive treatment option. Here, we performed a systematic review and meta-analysis of the angiographic and clinical outcomes of flow diverter-treated posterior inferior cerebellar artery aneurysms.

METHODS

We searched the PubMed, EMBASE and Web of Science databases for studies published from inception to January 2021. We included studies that described flow diverters procedures for posterior inferior cerebellar artery aneurysms with ≥2 patients. The outcomes were the complete occlusion rate and flow diverter-related complication rate. Meta-analysis was performed using a random or fixed effects model based on heterogeneity.

RESULTS

We included six studies involving 46 posterior inferior cerebellar artery aneurysms. There were 14 ruptured aneurysms. All flow diverters were successfully released and the technical success rate was 100%. The complete occlusion rate was 81% (95% confidence interval = 65-93%; I² = 0.00%; P < 0.01). The flow diverter-related complication rate was 18% (95% confidence interval = 5-36%; I² = 0.00%; P < 0.01). One patient died of rebleeding. The mortality rate was <1% (95% confidence interval = -1-1%; I² = 0.00%; P = 0.951).

CONCLUSIONS

Treatment of posterior inferior cerebellar artery aneurysms with flow diverters is feasible and carries a high degree of technical success. However, this treatment is underutilized in patients with posterior inferior cerebellar artery aneurysms due to a higher complication rate and lower occlusion rate compared with clipping and traditional endovascular treatment. Further well-designed prospective and randomized studies are required to fully understand the effects of flow diverters especially in posterior inferior cerebellar artery aneurysms patients requiring endovascular treatment.

Thrombectomy and Clip Occlusion of a Giant, Stent-Coiled Basilar Bifurcation Aneurysm: 3-Dimensional Operative Video

Giant basilar apex aneurysms are associated with significant therapeutic challenges.1-6 Multiple techniques exist to treat giant basilar apex aneurysms, including direct clipping, stent-assisted coil embolization, and proximal occlusion with bypass revascularization.7-9 Hypothermic circulatory arrest was a useful adjunct for surgical repair of these aneurysms but has been abandoned because of associated risks.10,11 Rapid ventricular pacing can achieve similar aneurysm softening with minimal risks and assist in clip occlusion. This case illustrates clip occlusion of a giant, partially thrombosed, previously stent-coiled basilar apex aneurysm in a 15-yr-old boy with progressive cranial neuropathies and sensorimotor impairment. Although a wire was placed preoperatively for ventricular pacing, it was not needed during the procedure. Patient consent was obtained. A right-sided orbitozygomatic craniotomy transcavernous approach with anterior and posterior clinoidectomies was performed. The basilar quadrification was dissected, and proximal control was obtained. After aneurysm trapping, the aneurysm was incised and thrombectomized using an ultrasonic aspirator. Back-bleeding from the aneurysm was anticipated, and ventricular pacing was ready, but back-bleeding was minimal. With the coil mass left in place, stacked, fenestrated clips were applied in a tandem fashion to occlude the aneurysm neck. Indocyanine green videoangiography confirmed occlusion of the aneurysm and patency of parent and branch arteries. The patient was at a neurological baseline after the operation, with improvement in motor skills and cognition at 3-mo follow-up. This case demonstrates the use of trans-sylvian-transcavernous exposure, rapid ventricular pacing, and thrombectomy amid previous coils and stents to clip a giant, thrombotic basilar apex aneurysm. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Surgical Approaches to Basilar Apex Aneurysms: An Illustrative Review

Surgical management of basilar apex aneurysms remains one of the most challenging areas in neurovascular surgery. Technical demands of treating these aneurysms have inspired several generations of neurosurgeons to push the limitations of technical achievement. Advances in neuroanesthesia, cerebral protection paradigms, and critical care management have enhanced surgical outcomes of these lesions. Several approaches have been described to reach these lesions from anterolateral or lateral corridors. Each surgical approach has its own advantages and limitations and should be chosen for each patient according to the aneurysm's position, projection, parent arteries, and perforators. In this review, we will discuss pros and cons of the common approaches to these aneurysms with description of the important steps of each surgical procedure.

Saccular or dissecting aneurysms involving the basilar trunk: Endovascular treatment and clinical outcome

Objectives: Basilar artery trunk aneurysms (BTAs) are a rare pathology and difficult to treat. We present our experience regarding angiographic results and clinical outcomes for 16 BTAs treated by reconstructive endovascular treatment (EVT) using stent or balloon. Methods: Between January 2003 and December 2014, 15 patients (mean age, 58.6 years; 11 males) with 16 BTAs were enrolled. Clinical manifestation, outcomes and procedural complications were evaluated retrospectively, and follow-up angiography was performed 12 and 24 months after procedure. Results: Subarachnoid hemorrhage (SAH) developed in seven aneurysms and nine were found incidentally. In one case, SAH followed by acute infarction on pons. The location of the aneurysms was the pure basilar artery (BA) trunk in 13 and the junction of the BA and the superior cerebellar artery in 3. Reconstructive EVT was technically successful in 15 aneurysms (93.8%) and failed in one due to the difficulty of vascular access. Stent/balloon-assisted coiling was performed in 13 aneurysms and sole stent therapy in two aneurysms. One patient had periprocedural complication of acute in-stent thrombosis. All treated patients had no symptoms with the usual activities except three patients, who died from myocardial infarction, aneurysmal rebleeding, and cerebellar infarction. Angiographic follow-up was performed in nine aneurysms; three aneurysms were recanalized (33.3%) and six aneurysms had no interval change (66.7%). There was no significant event during the follow-up period (mean, 23.5 months). Conclusion: In the treatment of BTAs, reconstructive EVT may provide a feasible and safe option to microsurgery.

Simple Lateral Suboccipital Approach and Modification for Vertebral Artery Aneurysms: A Study of 52 Cases Over 10 Years

INTRODUCTION

Complex skull base approaches are frequently used to treat intracranial vertebral artery (VA) and proximal posterior inferior cerebellar artery (PICA) aneurysms. These complex procedures are associated with higher risk of neurovascular injury. Hence, a less-invasive surgical approach is needed to improve the efficacy and safety of treatment.

METHODS

A retrospective analysis was conducted on clinical and radiologic data from surgeries in which simple lateral suboccipital and "lateral-enough" approaches were used to clip VA aneurysms in the Department of Neurosurgery at Helsinki University Central Hospital from 2000 to 2009.

RESULTS

Fifty-two VA or PICA aneurysms were treated using the simple lateral suboccipital approach. Sixteen patients (31%) presented with an unruptured aneurysm, 21 patients (40%) with World Federation of Neurosurgical Societies (WFNS) grade 1-3, and 15 patients (29%) with World Federation of Neurosurgical Societies grade 4-5. The aneurysms were saccular in 48 cases (92%), dissecting in 3 cases (6%), and fusiform in 1 case (2%). The most common aneurysm location was the VA-PICA junction (81%). The mean final modified Rankin Scale score was 2, and in unruptured cases, all patients had favorable clinical outcomes. The main causes of unfavorable outcome were poor preoperative clinical grade (P = 0.002), preoperative intraventricular hemorrhage (P = 0.008), postoperative hydrocephalus (P = 0.003), brain infarction (P = 0.005), and postoperative pneumonia (P < 0.001).

CONCLUSIONS

We describe a 10-year experience using a simple lateral suboccipital approach and its modification by the senior author (J.H.) to treat VA and proximal PICA aneurysms. Unfavorable outcome was related to the poor preoperative clinical grade, preoperative intraventricular hemorrhage, and postoperative pneumonia.

Surgical treatment of unruptured distal basilar artery aneurysm: durability and risk factors for neurological worsening

BACKGROUND

Distal basilar artery aneurysms (DBAs) consist of basilar apex and basilar artery-superior cerebellar artery bifurcation (BA-SCA) aneurysms. The authors aimed to investigate clinical and radiological differences between two locations and to evaluate the 12-month surgical outcome in unruptured DBAs.

METHODS

Fifty-six consecutive patients who underwent surgical treatment (37 basilar apex and 19 BA-SCA aneurysms) between April 2012 and February 2016 were retrospectively evaluated. In patients with a preoperative modified Rankin Scale score (mRS) of more than 1, neurological worsening (NW) was defined as an increase in one or more mRS. In patients without symptoms, NW was defined as mRS ≥2.

RESULTS

The mean age of the patient population was 64 ± 9.6 years, and 48 (86%) were female. Mean follow-up period was 2.6 ± 0.94 years. An excellent (mRS 0 to 1) outcome was archived in 31 (55%), 45 (82%), and 48 (87%) patients at 30 days, 6 months, and 12 months, respectively. Clinical and radiological characteristics showed no differences between two locations. One early death (1.8%) and one severe morbidity (1.8%) due to rupture were observed. The postoperative annual rupture rate was 1.4% overall (145 patient-years). After adjustment for age and location, large or giant DBA was related to 30-day and 12-month NW [n = 22 (39%) and n = 6 (11%); p = 0.009 and 0.002, respectively], aneurysm localization in the interpeduncular cistern (LIC) and perforator territory infarction were related to 30-day NW (p = 0.002 and 0.002), and DBA that needed bypass surgery and previously treated recurrent DBA were related to NW at 12 months (p = 0.017 and 0.001). Multivariate analysis showed that LIC was significantly related to perforator territory infarction (p = 0.003).

CONCLUSIONS

Clinical and radiological characteristics were not different between basilar apex and BA-SCA aneurysms; therefore, they should not be discussed separately. To avoid neurological worsening, results of surgical treatment for unruptured DBAs should be improved.

The Risk of Seizure After Surgery for Unruptured Intracranial Aneurysms

BACKGROUND:

We aimed to identify a group of patients with a low risk of seizure after surgery for unruptured intracranial aneurysms (UIA).

OBJECTIVE:

To determine the risk of seizure after discharge from surgery for UIA.

METHODS:

A consecutive prospectively collected cohort database was interrogated for all surgical UIA cases. There were 726 cases of UIA (excluding cases proximal to the superior cerebellar artery on the vertebrobasilar system) identified and analyzed. Cox proportional hazards regression models and Kaplan-Meier life table analyses were generated assessing risk factors.

RESULTS:

Preoperative seizure history and complication of aneurysm repair were the only risk factors found to be significant. The risk of first seizure after discharge from hospital following surgery for patients with neither preoperative seizure, treated middle cerebral artery aneurysm, nor postoperative complications (leading to a modified Rankin Scale score &gt;1) was &lt;0.1% and 1.1% at 12 months and 7 years, respectively. The risk for those with preoperative seizures was 17.3% and 66% at 12 months and 7 years, respectively. The risk for seizures with either complications (leading to a modified Rankin Scale score &gt;1) from surgery or treated middle cerebral artery aneurysm was 1.4% and 6.8% at 12 months and 7 years, respectively. These differences in the 3 Kaplan-Meier curves were significant (log-rank P &lt;.001).

CONCLUSION:

The risk of seizures after discharge from hospital following surgery for UIA is very low when there is no preexisting history of seizures. If this result can be supported by other series, guidelines that restrict returning to driving because of the risk of postoperative seizures should be reconsidered.

Microsurgical management of aneurysms of the superior cerebellar artery - lessons learnt: An experience of 14 consecutive cases and review of the literature

Objective:

This is a retrospective study from January 2002 to December 2012 analyzing the results of microsurgical clipping for aneurysms arising from the superior cerebellar artery (SCA).

Materials and Methods:

All patients with SCA were evaluated with computerized tomography angiography and/or digital subtraction angiography (DSA) prior to surgery. All patients in our series underwent microsurgical clipping and postoperative DSA to assess the extent of aneurysm occlusion. The Glasgow outcome scale (GOS) and the modified Rankin's scale (mRS) were used to grade their postoperative neurological status at discharge and 6 months, respectively.

Results:

Fourteen patients had SCA aneurysms (ruptured-9, unruptured-5). There were 10 females and 4 males with the mean age of 47.2 years (median - 46 years, range = 24–66 years). Subarachnoid hemorrhage (SAH) was seen in 11 patients. The mean duration of symptoms was 2.5 days (range = 1–7 days). The WFNS score at presentation was as follows: Grade 1 in 10 cases, II in 2 cases, III in 1 case and IV in 1 case. In the 9 cases with ruptured SCA aneurysm, average size of the ruptured aneurysms was 7.3 mm (range = 2.5–27 mm, median = 4.9 mm). The subtemporal approach was used in the first 7 cases. The extradural temporopolar (EDTP) approach was used in the last 5 cases. Complications include vasospasm (n = 6), third nerve palsy (n = 5) and hydrocephalus (n = 3). Two patients died following surgery. At mean follow-up 33.8 months (median - 25 months, range = 19–96 months), no patient had a rebleed. At discharge 9 (64%), had a GOS of 4 or 5 and 3 (21%) had a GOS of 3. At 6 months follow-up, 10/14 (71%) patients had mRS of 0–2, and 2 (14%) had mRS of 5.

Conclusions:

Aneurysms of the SCA are uncommon and tend to rupture even when the aneurysm size is small (<7 mm). They commonly present with SAH. The EDTP approach avoids complication caused by temporal lobe retraction and injury to the vein of Labbe.

Extended subtemporal transtentorial approach to the anterior incisural space and upper clival region: experience with posterior circulation aneurysms

BACKGROUND

Although most posterior circulation aneurysms are currently treated by endovascular means, some are not amenable to this treatment modality. The narrow working window afforded by the anterolateral and lateral surgical approaches often translates into suboptimal visualization and limited maneuverability.

OBJECTIVE

We present a modified technique of tentorial incision and reflection that optimizes the exposure achieved with the traditional subtemporal approach and report our clinical experience in a series of posterior circulation aneurysms.

METHODS

Retrospective review of patients operated via an extended subtemporal transtentorial approach for posterior circulation aneurysms. The modified tentorial incision implies dissection of the trochlear nerve along its dural canal up to its entrance into the cavernous sinus and incision of a tentorial flap that extends up to Meckel cave, which is then reflected far anterolaterally. Clinical and radiological data were reviewed.

RESULTS

This series comprises 18 patients (21 procedures). Ten patients presented (56%) with a subarachnoid hemorrhage. Aneurysms most frequently arose from the basilar tip (61%) and were of small size (50%) and saccular morphology (72%). Two patients underwent surgery following unsuccessful endovascular treatment. Aneurysm treatment was successful on the first attempt in 90% (19/21) and after a second attempt in 10% (2/21). Documented postoperative palsies of the oculomotor (n = 3) and trochlear (n = 1) nerves were all transient. No procedure-related mortality occurred.

CONCLUSION

This modified technique of tentorial incision and reflection optimizes visibility, anatomic orientation, and maneuverability by increasing the rostrocaudal and anterolateral exposure obtained via the extended subtemporal transtentorial route without permanent postoperative trochlear nerve deficit.

Mobilization of the transcavernous oculomotor nerve during basilar aneurysm surgery: biomechanical bases for better outcome

BACKGROUND

The transcavernous approach adds a significant exposure advantage in basilar aneurysm surgery. However, one of its frequently reported side effects is postoperative oculomotor nerve palsy.

OBJECTIVE

To present the technique of mobilizing the oculomotor nerve throughout its intracranial course and to analyze its consequences on the nerve tension and clinical outcome.

METHODS

The oculomotor nerve is mobilized from its mesencephalic origin to the superior orbital fissure. Its degree of mobility, related to the imposed pulling force, was measured in 11 cadaveric nerves. Tension was mathematically deduced and compared before and after mobilizing of the cavernous segment. One hundred four patients treated for basilar aneurysms with the orbitozygomatic pretemporal transcavernous approach were followed up for a 1-year period and evaluated for postoperative oculomotor nerve palsy.

RESULTS

Releasing the transcavernous segment compared to cisternal mobilization alone resulted in a significant increase in freedom of mobility from 4 to 7.9 mm (P < .001) and in a significant decrease in tension from 0.8 to 0.5 N (P = .006). Ninety-nine percent of aneurysms treated with this technique were amenable to neck clipping, and a total of 84% of patients had a good postoperative outcome (modified Rankin Scale score, 0-2). All patients showed direct postoperative palsy; however, 97% had a complete recovery by 9 months. Only 3 patients had a persistent diplopia on medial gaze, which was corrected with prism glasses.

CONCLUSION

Mobilization of the transcavernous oculomotor nerve results in better maneuverability and less tension on the nerve, which lead to successful surgical treatment and favorable oculomotor outcome.

Re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms

BACKGROUND

Unplanned re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms (UIAs) is sometimes required, but the underlying causes and rates of these procedures are seldom reported. This study retrospectively analyzed the causes of such re-explorations to identify methods for decreasing their necessity.

METHOD

From January 2000 to December 2011, 1,720 patients with a total of 1,938 UIAs underwent surgical treatment at our institution. From this cohort, 26 patients (1.5 %) with 38 UIAs required re-exploration. Clinical data, aneurysm characteristics, treatment methods, and the incidence and causes of re-exploration of the craniotomy were analyzed for these 26 patients.

RESULTS

Several causes of re-exploration were identified: compromised distal blood flow (eight patients, 0.47 %), hemorrhagic venous infarction (four patients, 0.23 %), brain retraction injury (three patients, 0.17 %), newly identified aneurysms (three patients, 0.17 %), bleeding from an incompletely clipped aneurysm (two patients, 0.12 %), epidural hematoma (two patients, 0.12 %), failed aneurysm clipping (two patients, 0.12 %) and other causes (two patients, 0.12 %). Annual re-exploration incidence rates ranged from 0 to 3.1 %. Annual incidence rates gradually decreased following the introduction of several intraoperative monitoring systems.

CONCLUSIONS

Precise surgical planning and careful operative techniques can reduce the incidence of unplanned re-exploration of the craniotomy. The introduction of various intraoperative monitoring systems can also contribute to a reduction in this incidence.

Flow diversion radial artery bypass graft coupled with terminal basilar artery occlusion for the treatment of complex basilar apex aneurysms: operative nuances

BACKGROUND

A subset of basilar apex aneurysms are unsuitable for either primary microsurgical clipping or endovascular coiling. These complex aneurysms can be treated by terminal basilar artery occlusion, but only if collateral circulation is adequate. To circumvent these complications, a high-flow vertebral artery-posterior cerebral artery or middle cerebral artery-posterior cerebral artery bypass may be performed to create an adequate collateral circulation to allow treatment of the aneurysm by basilar artery occlusion and/or clipping.

OBJECTIVE

To discuss the operative nuances of this approach in the case of a 47-year-old man with progressive hemiparesis resulting from brainstem compression from a giant, unruptured basilar apex aneurysm with absent posterior communicating artery collaterals and incorporation of bilateral superior cerebellar arteries and posterior cerebral arteries within the aneurysm neck.

METHODS

The patient underwent a staged bypass from V3 to P2 coupled with terminal basilar artery occlusion.

RESULTS

The patient initially presented as modified Rankin Scale score 2 with right hemiparesis. The aneurysm ruptured after the first stage of the operation, and the patient underwent a V3 to P2 bypass the next day. His postprocedural neurologic decline improved at the 14-month follow-up to modified Rankin Scale score 2, with substantial reduction in aneurysm size observed at 9 months. The outcomes for 3 other bypass cases for basilar apex aneurysms are also summarized.

CONCLUSION

: We discuss the indications, preoperative diagnostic workup, operative management, and postoperative outcomes in managing challenging basilar apex aneurysms. In our experience, high-flow bypass procedures with or without hunterian ligation in the treatment of these aneurysms are well tolerated with good long-term results.

Brain retraction injury

This paper reviews the literature of the brain retraction injury during the last century. The review focused on the instrument characteristic as well as the physiopathological and histopathological damage of the brain induced by brain retraction. It was found that lesions were induced by cerebral ischemia. We conclude that a better monitoring system needs to be developed to avoid brain injury.

Clip ligation of unruptured intracranial aneurysms: a prospective midterm outcome study

BACKGROUND

We conducted a prospective study to investigate the clinical and radiological outcome in a surgical case series of 176 patients with 203 unruptured intracranial aneurysms (UIA).

METHODS

The success of aneurysm obliteration was assessed within 2 weeks after surgery by digital subtraction angiography (DSA). Patients also underwent angiography 5 years after surgery. Clinical outcomes were assessed using the modified Rankin Scale (mRS). All predictors of poor surgical outcomes were assessed using an exact logistic regression.

RESULTS

Overall, 83 % of the patients had a good outcome (mRS score 0 or 1); 10.8 % of the patients had a slight disability (mRS score 2), and 6.2 % of the patients had a moderate or moderate-severe disability (mRS score 3 or 4). The mortality rate was 0 % overall. The most important predictors of outcome were presence of history of ischemic cerebrovascular disease and postoperative stroke. Complete aneurysm occlusion was achieved in 93.5 % of all aneurysms. Sixty percent of treated aneurysms were checked with late follow-up DSA. No cases of hemorrhage from a surgically obliterated UIA were documented in this series during the 7.3 ± 1.4 (SD)-year follow-up period.

CONCLUSIONS

If patients are carefully selected and individually assigned to their optimum treatment modality, IUAs can be obliterated by surgery with a low percentage of unfavorable outcomes.

Testing the boundaries of neurosurgical innovation … twice: an account of one patient's unique intracranial aneurysm treatment

BACKGROUND

The treatment of intracranial aneurysms has evolved over the past several decades and has profited by the ingenuity and expertise of generations of innovative neurosurgeons.

CASE DESCRIPTION

A 79-year-old man presented with symptoms related to recurrence of his previously ruptured basilar bifurcation aneurysm 35 years after undergoing the first awake hunterian ligation for the same aneurysm performed by Dr. Charles Drake.

CONCLUSIONS

This report details the treatment strategies applied in the management of the patient's aneurysm then and now, offering us a glimpse into the evolution of neurosurgical treatment for basilar bifurcation aneurysms in a patient who was able to benefit from neurosurgical innovation twice in his lifetime.

Endovascular Treatment of Basilar Trunk Saccular Aneurysms

Basilar artery (BA) trunk aneurysms are rare and still remain a formidable surgical challenge. The purpose of this retrospective study was to report the clinical entities and results of endovascular surgery of BA trunk saccular aneurysms. Between 1995 and 2009, 14 patients with 14 BA trunk saccular aneurysms underwent endovascular surgery. Six patients presented subarachnoid hemorrhage (SAH), three patients had another associated aneurysm which developed SAH, one patient presented with mass effect to the brain stem, and four patients were incidentally discovered. Five ruptured and seven unruptured aneurysms were successfully treated by endovascular surgery. Another one incompletely embolized aneurysm had grown to huge size five years later and the patient underwent a Hunterian ligation with a radial artery graft between the extracranial vertebral artery and the posterior cerebral artery. In one ruptured case, we attempted neck clipping, but this was abandoned because of concern for neck tearing by clipping. The aneurysm was embolized using detachable coils later. BA trunk aneurysms showed characteristic features such as so-called lateral aneurysm (43%), multiple aneurysms (43%) and four BA fenestrations (36%). The unusual high incidence of associated various vascular anomalies suggests that focal wall weakness must be based on the mechanism of aneurysm initiation on the BA trunk. Most patients presented with SAH. Pre-treatment neurological state was predictive for clinical outcome. Endovascular surgery is an effective therapeutic alternative that is associated with low morbidity and mortality rates, and should be considered the first choice treatment.

Experience in Using the Excimer Laser–Assisted Nonocclusive Anastomosis Nonocclusive Bypass Technique for High-Flow Revascularization

BACKGROUND

The excimer laser–assisted nonocclusive anastomosis (ELANA) technique enables large-caliber bypass revascularization without temporary occlusion of the parent artery.

OBJECTIVE

To present the surgical experience of 2 bypass centers using ELANA in the treatment of complex intracranial lesions.

METHODS

Between July 2002 and December 2007, 64 consecutive patients (37 in Germany and 27 in Finland) were selected for high-flow bypass surgery with ELANA. Modified Rankin Scale, a bypass success rate, and the success rate of the laser arteriotomy were assessed.

RESULTS

In 66 surgeries for 64 intent-to-treat patients, 58 ELANA procedures were completed successfully. A favorable outcome (postoperative modified Rankin Scale score less than or equal to preoperative modified Rankin Scale) at 3 months was achieved in 43 of 56 patients (77%) with anterior circulation lesions (37 of the 43 patients had aneurysms, 4 had ischemia, and 2 received a bypass before tumor removal) and only in 2 of 8 patients (25%) with posterior circulation aneurysms. Perioperative (&lt; 7 days) mortality for anterior and posterior circulation aneurysms was 6% and 50%, respectively. At the 3-month follow-up, 12% and 63% of patients with anterior and posterior circulation aneurysms, respectively, were dead. The success rate of the laser arteriotomy was 70%. Another 14% were retrieved manually after a nearly complete laser arteriotomy.

CONCLUSION

The ELANA procedure requires a meticulous and careful operative technique. Morbidity and especially mortality rates, usually unrelated to ELANA, are comparable to those of contemporary series of conventional high-flow revascularization operations. This underscores the overall complexity of treating neurovascular pathologies by high-flow bypasses.

The Impact of Minimizing Brain Retraction in Aneurysm Surgery: Evaluation Using Magnetic Resonance Imaging

BACKGROUND:

Recent advances in skull base and microsurgical techniques minimize the need for brain retraction.

OBJECTIVE:

We studied the impact of such techniques in 36 patients (51 aneurysms) using magnetic resonance imaging (MRI).

METHODS:

Preoperative and 24 hours postoperative MR imaging was performed in patients undergoing microsurgical clipping of intracranial aneurysms. Images were evaluated for parenchymal signal changes. During surgery, use and time of brain retraction were recorded. The degree of cortical injury was quantified using a 0 to 3 scale (grade 0 = normal surface; 1 = pial/arachnoidal damage; 2 = gray matter injury; 3 = contusion/necrosis).

RESULTS:

Brain retraction by use of a brain spatula was used in all patients. Retraction times ranged from 14 to 290 minutes (mean, 84.1). Cortical surface changes were grade 0 in 86% and grade 1 in 14%; none showed grade 2 or 3 changes. In the postoperative MRI, 4 patients presented with parenchymal alterations, 4 with edema (11.1%), and 1 patient had additional contusion (2.8%). All lesions were confined to the temporal pole. The grade of cortical surface changes was not related to lesions found on MR imaging. No patients showed retraction-related neurological deficits.

CONCLUSION:

The incidence of evident mechanical parenchymal injury (infarction or contusion) is very low when appropriate microsurgical and skull base techniques are used. Minor pia-arachnoid injury should nevertheless continue to be attended through future advances.

Evaluation of the prognostic indicators of giant intracranial aneurysms

The indicators of poor outcome in giant intracranial aneurysms have been the subject of several studies in the literature. We conducted a retrospective analysis to evaluate the predictors of poor outcome in giant intracranial aneurysms. We studied consecutive cases with aneurysms admitted over a 9-year period in our institution. All the aneurysms were treated with clipping. Patient demographics, clinical profile, and aneurysm characteristics were evaluated in a multivariate analysis as probable indicators of Glasgow Outcome Scale (GOS) score. The outcome of the aneurysms (GOS score) was compared with the remaining non-giant aneurysms. A total of 41 giant and 348 non-giant aneurysms were identified in our series. In the multivariate analysis, the indicators of poor outcome were identified as poor clinical grade (p < 0.0004), intraoperative rupture (p < 0.007), and posterior circulation of the aneurysms (p < 0.01). Non-giant aneurysms had a better outcome compared with the giant aneurysms (p < 0.01). Giant aneurysms impose a relatively higher risk of morbidity and mortality to the patients. The predictors of the postsurgical outcome of the giant aneurysms include the clinical condition of the patient, location of the aneurysm, and intraoperative rupture.

Endovascular treatment of aneurysms arising from the basilar artery trunk and branches

This study reports our experience with the endovascular treatment of basilar artery (BA) trunk and branch aneurysms. Subjects included 16 patients with BA trunk and branch aneurysms who underwent endovascular treatment in our hospital from October 2000 to October 2009, including four patients with associated arteriovenous malformation (AVM), two with associated moyamoya disease, one with multiple aneurysms at adjacent sites, and one with a distant aneurysm. Endovascular coil embolization, together with stent or balloon assistance when necessary, or while occluding the parent artery was performed. Associated diseases were managed intraoperatively or in the second stage, or treated with gamma knife radiotherapy, or followed up. Two patients with unsuccessful embolization died of re-rupture at the fourth month and fifth month follow-up. The remaining 14 patients reported good outcomes and experienced no re-rupture of either the aneurysm or associated disease. Angiographic follow-ups were conducted for the 14 patients for six to 12 months. Digital subtraction angiography (DSA) examination at the last follow-up showed no recurrence of the BA trunk and branch aneurysms. Together, BA trunk and branch aneurysms should be actively managed via endovascular techniques to prevent serious consequences due to aneurysm rupture and bleeding. Favorable outcomes can be obtained by the proper selection of endovascular treatment regimens.

Preoperative factors affecting the outcome of unruptured posterior circulation aneurysm surgery

We retrospectively investigated preoperative variables contributing to adverse surgical outcome for repair of unruptured posterior circulation aneurysms on data collected prospectively between October 1989 and March 2010. Putative risk factors including age, sex, smoking status, positive family history, modified Rankin Score prior to the surgery, size of the aneurysm, specific site (basilar caput and trunk, vertebral artery and posterior inferior cerebellar artery), midline location, presence of calcium, thrombus or irregularity in the aneurysm on preoperative imaging, associated arteriovenous malformation and preoperative coiling were investigated using regression analyses. In a total of 121 operations, surgical mortality and morbidity was 16.3%. For patients with aneurysms less than 9mm this rate was 3.2%. Among the investigated variables we found that size, calcification of the aneurysm and age were each predictors of surgical outcome of unruptured posterior circulation aneurysms.

The small “surgical aneurysm” at the basilar apex

Object

Because the risks are reduced, larger basilar apex aneurysms are usually treated endovascularly instead of with surgery. However, small basilar apex aneurysms are more common and an unfavorable shape may prevent definitive endovascular treatment. The goal of this study was to reevaluate the outcome of traditional surgery for small unruptured basilar apex aneurysms as an alternative to the currently more accepted endovascular treatment.

Methods

The authors reviewed clinical data obtained in 21 patients who underwent surgery between 2000 and 2007 for unruptured basilar apex aneurysms < 7 mm.

Results

The median age of the 21 patients was 52 years (range 29–74 years). All patients experienced a good outcome. Two patients harbored a small residual aneurysm (> 95% occlusion). Eight patients (38%) suffered a temporary third nerve paresis, which resolved in all cases.

Conclusions

Surgical clip ligation remains an excellent treatment for small basilar apex aneurysms. The treatment is definitive and in experienced hands is associated with a low risk.

Results of surgical management for posterior cerebral artery aneurysms: 7-year experience in the endovascular era

PURPOSE

Unlike most posterior circulation aneurysms, posterior cerebral artery (PCA) aneurysms can be surgically approached, we believe, without significant technical difficulty or procedural morbidity. We report our recent experience to assess procedural complications and clinical outcomes for PCA aneurysms.

METHODS

In our retrospective review of 15 consecutive patients with PCA aneurysms, six patients underwent surgical treatment, six patients had endovascular coiling, (three patients from the endovascular group also underwent surgical revascularization), and three patients were treated conservatively (medical or observation) (2001-2007). Clinical records were reviewed for: patient demographics; clinical presentation; aneurysm location, size, and morphology; treatment; procedural complications; outcome (clinical and angiographic).

RESULTS

Complete aneurysm obliteration with parent vessel or bypass patency was demonstrated by intraoperative angiography in all patients. One patient died and two patients suffered procedure-related permanent neurologic injury. Considering both surgical end endovascular treatment modalities, mortality was 8.3% and permanent morbidity was 16.6%. At mean clinical follow-up of 2-96 months (15.8 +/- 10.5 months), nine of ten patients had a Glasgow Outcome Score of 4 or 5. In patients who underwent bypass procedures, computed tomographic (CT) angiography or cerebral angiography demonstrated a patent functional bypass before the PCA occlusion.

CONCLUSIONS

Our findings for these 15 patients suggest the value of a multimodality of treatments for PCA aneurysms. Revascularization of the PCA can be performed with favorable technical results and clinical outcomes when the patency of the PCA cannot be preserved.

GUIDELINES FOR THE SURGICAL TREATMENT OF UNRUPTURED INTRACRANIAL ANEURYSMS

THE MANAGEMENT OF unruptured cerebral aneurysms remains one of the most controversial topics in neurosurgery. To this end, we discuss the diagnosis and estimated prevalence of these lesions as well as review the literature regarding the rate of rupture for cerebral aneurysms and risks of operative intervention. Our interpretation of the literature concludes that aneurysms are present in approximately 1% of the adult population, varying between less than 1% in young adults to 4% in the elderly. The yearly risk of subarachnoid hemorrhage for an unruptured intracranial aneurysm is approximately 1% for lesions 7 to 10 mm in diameter. Based on these assumptions, we recommend that 1) with rare exceptions, all symptomatic unruptured aneurysms should be treated; 2) small, incidental aneurysms less than 5 mm in diameter should be managed conservatively in virtually all cases; 3) aneurysms larger than 5 mm in patients younger than 60 years of age should be seriously considered for treatment; 4) large, incidental aneurysms larger than 10 mm should be treated in nearly all patients younger than 70 years of age; and 5) microsurgical clipping rather than endovascular coiling should be the first treatment choice in low-risk cases. Critical to our guidelines is collaboration by a highly experienced cerebrovascular team of microneurosurgeons and endovascular neurosurgeons working at a tertiary medical center with a high case volume and using a decision-making paradigm designed to offer only low-risk treatments. In certain patients for whom both treatment and natural history carry high risks, such as those with giant aneurysms, nonoperative management is typically elected.

Efficacy of endovascular surgery for unruptured internal carotid artery aneurysms presenting with cranial nerve symptoms

SUMMARY

Whether endovascular surgery is able to reduce the mass effects of unruptured aneurysms is still controversial, although some reports have suggested efficacy in cases of internal carotid artery aneurysms with cranial nerve palsy. Here we assessed outcome in a series of cases. Between April 1992 and April 2005, 18 patients with unruptured internal carotid artery aneurysms presenting with cranial nerve palsy were treated by endovascular surgery. The patients were two males and 16 females aged from 19 to 84 (mean 59.6 years). Aneurysms were located in the cavernous portion in 14, at the origin of the ophthalmic artery in one and at the origin of P-com in three. The aneurysms were all embolized using Guglielmi detachable coils, Interlocking detachable coils, Cook's detachable coils or Trufill DSC and detachable Balloons were applied to occlude the proximal parent artery.We analyzed the efficacy of endovascular surgery for such aneurysms retrospectively. The mean aneurysm size was 21.4 mm and the mean follow-up period was 57.7 months. Palsy of II(nd) cranial nerve was evident in three patients, of the III(rd) in eight, of the V(th) and V(th) in one each, and of the VI(th) in nine. Post embolization occlusion was complete in nine patients and neck remnant in the other seven. Regarding complications of endovascular surgery, one case (5.6%) showed TIA after embolization. Overall 11 (46%) cranial nerve symptoms showed complete resolution, eight (33%) showed some improvement, and five (21%) were unchanged. In three cases (12.5%), the symptoms worsened after treatment. The shorter the duration of symptoms was a factor predisposing to resolution of symptoms. In complete resolution cases, the timing of treatment after symptoms appeared and the time of complete resolution were in proportion. These results showed that there is no difference in reduction of mass effects between surgical clipping and endovascular surgery for unruptured internal carotid artery aneurysms.With endovascular surgery, the rapidity of treatment after symptoms is the most important factor for successful results.

RESULTS OF MICROSURGICAL CLIPPING OF 50 HIGH COMPLEXITY BASILARAPEX ANEURYSMS

OBJECTIVE

Complex basilar aneurysms (large size, wide base, low bifurcation, and dysmorphic posteriorly projecting domes) frequently fail endovascular treatment. We report our experience using the pretemporal transzygomatic transcavernous approach with 50 complex basilar aneurysms.

METHODS

Using the pretemporal transcavernous route, opening the occulomotor trigone, and removing the anterior clinoid and the posterior clinoid when necessary, a wide exposure of the interpeduncular fossa is achieved. Temporary clips are applied to a perforator-free zone of the basilar trunk, proximal to the superior cerebellar artery. Complexity criteria in the 50 aneurysms included large or giant size in 27 patients, wide dysmorphic base in 18 patients, low bifurcation in 21 patients, posteriorly projecting dome in 11 patients, and dolichoectasia of the apex in three patients.

RESULTS

Twenty-five patients presented with subarachnoid hemorrhage. There were 14 men and 36 women between the ages of 32 and 76 years (mean, 52.2 yr). Forty-nine aneurysms (98%) were successfully clipped. There was no procedure-related mortality. Two patients died (one from delayed bowel ischemia and one from a vasospasm-related complication). There were three ischemia-related events, two of which were procedure-related (medial thalamic lacunar infarct, superior cerebellar distribution ischemia) and one which was a third distal middle cerebral cardiac embolus after stopping Coumadin (DuPont Pharmaceuticals, Wilmington, DE) for atrial fibrillation. Transient partial or complete occulomotor palsies occurred in all patients with full recovery as the rule, except in one patient. At discharge, Glascow Outcome Scale scores were 4 or 5 in 88% of the patients. At the 6-month follow-up examination, Rankin Outcome Scale scores were 0 to 2 in 92% of the patients.

CONCLUSION

Our experience reintroduces microsurgery as a safe and more durable treatment option for the management of complex basilar apex aneurysms that tend to have a higher rate of failure with endovascular therapy.

Reprint of: SYMPOSIUM ON CEREBROVASCULAR DISEASES. Pathogenesis, Natural History, and Treatment of Unruptured Intracranial Aneurysms

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Expression of structural proteins and angiogenic factors in normal arterial and unruptured and ruptured aneurysm walls

OBJECTIVE

To identify differences in the expression of certain structural proteins and angiogenic growth factors in vessel tissues that represent different phases of the process of intracranial aneurysm formation and rupture: normal vessel wall, intact (unruptured) aneurysm wall, and ruptured vessel wall.

METHODS

The novel study design involved 10 pairs of specimens (ruptured and unruptured aneurysm wall) obtained perioperatively during clipping operations in 10 patients with multiple aneurysms. All surgeries were performed within 5 days of subarachnoid hemorrhage. As controls, five circle of Willis specimens were obtained from five cadavers. Sections of each of the 25 specimens were separately immunostained for five structural proteins (collagen Types III and IV, alpha-smooth muscle actin, fibronectin, and laminin) and three angiogenic factors (vascular endothelial growth factor, basic fibroblast growth factor, and transforming growth factor-alpha). Levels of expression for each protein and factor were graded, and the average grades for each tissue group were recorded and compared.

RESULTS

Among the structural proteins studied, fibronectin specifically is densely expressed in ruptured aneurysms, which is graded as 2.0. However, its expression is less prominent both in nonaneurysmal vessel wall (Grade 1.0) and unruptured aneurysm vessel wall (Grade 1.1). Contrary to fibronectin, laminin is more intensely and regularly expressed in normal vessel wall (Grade 2.7) than in ruptured (Grade 1.1) and unruptured (Grade 1.0) aneurysmal specimens. Among the angiogenic growth factors studied, transforming growth factor-alpha shows a peculiar grading of staining, different from the other two angiogenic factors examined, so that it is more highly expressed in normal circle of Willis specimens (Grade 2.1) than in unruptured and ruptured aneurysm walls, graded as 0.5 and 0.6, respectively.

CONCLUSION

Normal vessel wall, unruptured aneurysm wall, and ruptured aneurysm wall exhibit different levels and patterns of expression for the structural proteins and regulator growth factors investigated. If one accepts the premise that immunohistochemical study has its inherent methodological problems, these results suggest that the biological mediators of aneurysm formation in a vessel wall differ from those of the biological mediators of aneurysm rupture. There was a novel finding related to fibronectin and laminin: the results indicated that a rise in the fibronectin-to-laminin ratio in an unruptured aneurysm wall may contribute to rupture. A drop in transforming growth factor-alpha expression in a vessel wall may also contribute to aneurysm formation.

Outcome of Surgical Clipping of Unruptured Aneurysms as it Compares with a 10-Year Nonclipping Survival Period

OBJECTIVE

Recent studies on the natural history of unruptured intracranial aneurysms dictate that we reevaluate the risks and benefits of surgical intervention as it compares with the natural course. We analyzed the outcome of surgical clipping of a patient cohort with unruptured aneurysms as it compares with a 10 year nonclipping survival period on the basis of two previously published studies (International Study on Unruptured Intracranial Aneurysms and a study by Juvela et al. [36] from Helsinki).

METHODS

Data on 148 unruptured aneurysms in 116 consecutive surgically treated patients were prospectively recorded and retrospectively analyzed. The overall majority were diagnosed with cerebral angiography. Data analyzed included aneurysmal properties and clinical outcomes including surgical related mortalities and morbidities. The observed outcomes were compared with the expected outcome of a 10 year nonclipping survival period if the patient cohort was included in recently reported studies on unruptured aneurysms. More than 1 year follow-up was available in 93.1% (108) of patients and follow-up cerebral angiography was performed in 80% (93) of patients.

RESULTS

Mean age was 53.57 years. There were 25 (16.8%) small aneurysms (less than 7 mm), 70 (47.2%) aneurysms 7 to 12 mm in size, 41 (27.70%) large (13-24 mm), and 12 (8.10%) giant (>25 mm) aneurysms. Posterior circulation aneurysm comprised 13.51%. One hundred forty-three (96.62%) aneurysms were successfully clipped, and 3.37% were either wrapped or later coiled. Surgical-related mortality was 0.82% (1 patient because of air embolism). Surgical related permanent morbidity was 3.44% (4 patients) and transient surgical-related mild morbidities was 7.7% (9 patients). Immediate postsurgical good outcome (Glasgow Outcome Score = 4-5) was 87.93% (102 patients) and 95.68% in 3 months (111 patients). At 1 year, the modified Rankin scale scores were 0 to I = 102, II = 3, III = 2, IV = 1, and V = 0. Residual aneurysms were seen in none of the postoperative angiograms (93 patients). Using the chi method, the comparison of the expected to the observed mortality and morbidity revealed a statistically significant difference in the mortality in favor of surgical clipping (P = 0.034 when compared with the International Study on Unruptured Intracranial Aneurysms and P = 0.05 when compared with the Juvela et al. [36] study). There was no statistically significant difference in the permanent morbidity.

CONCLUSION

Studies on natural history of unruptured intracranial aneurysms suggest 10 year cumulative bleeding-related mortality and severe morbidity of no less than 7.5%. In our study, surgical clipping resulted in an 0.8% rate of mortality and 3.4% permanent morbidity. This suggests that surgical clipping has the potential of a superior outcome to the natural history of patients who have an estimated life expectancy of no less than 10 years.

Anévrismes intracrâniens non rompus : que proposer ?

Intracranial unruptured aneurysm (ICUA) has become a common condition for patient consultation. The mortality rate after fissuration is estimated to be between 52% and 85.7%. The final therapeutic decision results from a balance between the risk of rupture and risks related to the aneurysmal exclusion. Analysis of the risk of rupture risk enables a classification of risk factors. Depending on the circumstances of diagnosis, we considered the ICUA at high risk of rupture for incidental ICUA larger than 7 mm and in the event of associated aneurysms. Classifying by morphologic features, high-risk ICUA were located in the vertebrobasilar system (RR: 4.4; 95%CI: 2.7-6.8), those with a size between 7 and 12 mm (RR: 3.3; 95%CO: 1.3-8.2), larger than 12 mm (RR: 17; 95%CI: 8-36.1), those that were multilobular or a larger size and those ones with a index P/L superior to 3.4 (risk x20). Familial ICUA would expose to a major rupture risk (2 to 7 times sporadic ICUA). Some systemic factors were related to ICUA rupture: arterial hypertension (RR: 1.46; 95%CI: 1.01-2.11) and smoking addiction (RR: 3.04; 95%CI: 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were 10% and 2% respectively. Some microsurgical morbidity factors were identified: age (32%>65 years), size (14%>15 mm), vertebrobasilar location and temporary occlusion. The rupture incidence after microsurgical exclusion was estimated 0.26%/year. After endovascular exclusion, the morbidity and mortality rates were 8% and 1% respectively. The complete exclusion rate varied between 47% and 67%. The rupture risk was estimated at 0.9%/year. Treatment recommendations were classified into 3 categories.

Surgical Clipping of Complex Basilar Apex Aneurysms: A Strategy for Successful Outcome Using the Pretemporal Transzygomatic Transcavernous Approach

OBJECTIVE:

Complex basilar apex aneurysms (large size, wide and complex neck, tortuous parent vessels) continue to pose a challenge in treatment. Endovascular treatment has a high risk of recanalization, and surgical treatment is limited by the space and time necessary to achieve safe clipping. To overcome these obstacles, a modification of previously reported approaches was developed. The pretemporal transzygomatic transcavernous approach and a clipping strategy were used in the treatment of 21 high-complexity basilar apex aneurysms.

METHODS:

By use of the pretemporal route, the zygomatic notch was widened, the anterior clinoid was removed, the cavernous sinus was partially exposed, and the oculomotor nerve was mobilized. The depth of the field was widened by further cavernous exposure and the removal of the posterior clinoid. Temporary clips were applied to the basilar trunk perforator-free zone to preserve visualization of the aneurysm neck and perforators and to maintain collateral flow to the brainstem.

RESULTS:

Twenty-one high-complexity basilar apex aneurysms, 11 of which caused subarachnoid hemorrhage, were treated. Twenty (95%) were successfully clipped (Glasgow Outcome Scale scores, 4 or 5 in 90.5% at discharge; Rankin Disability Score, 1 in 90.5% at 1-yr follow-up). Complications were transient oculomotor palsy in all patients, small thalamic infarct in one patient, and cerebrospinal fluid leak in another. There was no surgical mortality. Delayed follow-up angiography in 19 of the 21 patients showed no residual aneurysm.

CONCLUSION:

We report the largest series of a unique, challenging group of complex basilar apex aneurysms treated with the pretemporal transzygomatic transcavernous approach, which provided improved safety of clipping by 1) increased visualization of the basilar apex and perforator arteries, 2) improved maneuverability of clip application, 3) a safer perforator-free location, and 4) preservation of brainstem collateral flow.

Upper basilar artery aneurysms: oculomotor outcomes in 163 cases

Object. The purpose of this study was to identify factors predictive of postoperative oculomotor nerve palsy among patients who undergo surgery for distal basilar artery (BA) aneurysms. The data can be used to estimate preoperative risk in this population. The natural history of oculomotor nerve palsy in patients with good outcomes is also defined.

Methods. The cases of 163 patients with distal BA aneurysms, who were treated surgically between 1996 and 2002, were retrospectively studied to identify factors contributing to oculomotor nerve palsy. After the data had been collected, stepwise logistic regression procedures were used to determine the predictive effects of each variable on the development of oculomotor nerve palsy and to create a scoring system. Factors that interfered with resolution of oculomotor dysfunction in patients with good outcomes were also studied.

Postoperative oculomotor nerve palsy occurred in 86 patients (52.8%) with distal BA aneurysms. The following factors were associated with postoperative oculomotor dysfunction, as determined by a categorical data analysis: 1) younger patient age (p < 0.001); 2) poor admission Hunt and Hess grade (p < 0.001); 3) use of temporary arterial occlusion (p < 0.001); 4) poor Glasgow Outcome Scale score (p < 0.001); and 5) the presence of a BA apex aneurysm that projected posteriorly (p < 0.001). For patients with good outcomes, postoperative oculomotor nerve palsy resolved completely within 3 months in 31 patients (52%) and within 6 months in 47 patients (80%). The projection of the BA aneurysm was associated with incomplete oculomotor recovery at 6 months postoperatively (p = 0.019).

Conclusions. The results of this study can help identify patients with a high risk for the development of oculomotor nerve palsy. This may help neurosurgeons in preoperative planning and discussions.

Pathogenesis, natural history, and treatment of unruptured intracranial aneurysms

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.