Temporary occlusion of the middle cerebral artery in intracranial aneurysm surgery: time limitation and advantage of brain protection

The clinical challenge of subarachnoid hemorrhage associated with multiple aneurysms when the bleeding source is not certainly identifiable

BACKGROUND

Multiple intracranial aneurysms (IAs) are encountered in 20-30% of the subarachnoid hemorrhages (SAH). Neuroimaging and clinical examination are usually sufficient to detect the bleeding source, but sometimes it can be misdiagnosed with catastrophic consequences.

METHODS

We reviewed our diagnostic work-up for all patients admitted from January 2016 to December 2020 for SAH with multiple IAs accounting for our rate of diagnostic failure. Then, we grouped the patients into 4 categories according to aneurysms topography and described our operative protocol in case of uncertain bleeding origin.

RESULTS

Sixty-two patients harboring 161 IAs were included. The bleeding source was identified in 56 patients (90.3%), who harbored other 81 bystander aneurysms. In 6 cases (9.7%) with a total of 24 aneurysms we failed the bleeding source identification. According to IAs topography, we grouped the IAs multiplicity in: 1) anterior plus posterior circulation IAs; 2) multiple posterior circulation IAs; 3) bilateral anterior circulation IAs; and 4) multiple ipsilateral anterior circulation IAs. In case of unidentified bleeding source, key-elements favoring the simultaneous multiple IAs treatment were their number, morphology, topography, clinicians' experience, and management modality as endovascular treatment allows a faster exclusion of multiple IAs distant one each other compared with surgery. MCA involvement represented the more frequent reason to prefer multiple clipping rather than multiple coiling.

CONCLUSIONS

In a small percentage of patients with SAH with multiple IAs, bleeding source identification can be difficult. Until the routinely availability of new tools such as vessel wall imaging or computational fluid dynamics, an experienced neurovascular team and strategies aiming to simultaneously exclude multiple IAs remain mandatory.

The Management of Intracranial Aneurysms: Current Trends and Future Directions

Intracranial aneurysms represent a major global health burden. Rupture of an intracranial aneurysm is a catastrophic event. Without access to treatment, the fatality rate is 50% in the first 30 days. Over the last three decades, treatment approaches for intracranial aneurysms have changed dramatically. There have been improvements in the medical management of aneurysmal subarachnoid haemorrhage, and there has been an evolution of treatment strategies. Endovascular therapy is now the mainstay of the treatment of ruptured intracranial aneurysms based on robust randomised controlled trial data. There is now an expansion of treatment indications for unruptured intracranial aneurysms to prevent rupture with both microsurgical clipping and endovascular treatment. Both microsurgical and endovascular treatment modalities have evolved, in particular with the introduction of innovative endovascular treatment options including flow diversion and intra-saccular flow disruption. These novel therapies allow clinicians to treat more complex and previously untreatable aneurysms. We aim to review the evolution of treatment strategies for intracranial aneurysms over time, and discuss emerging technologies that could further improve treatment safety and functional outcomes for patients with an intracranial aneurysm.

Role of temporary arterial occlusion in subarachnoid hemorrhage outcomes: a prospective cohort study

PURPOSE

Temporary arterial occlusion (TAO) is a widespread practice in the surgical treatment of intracranial aneurysms. This study aimed to investigate TAO's role during ruptured aneurysm clipping as an independent prognostic factor on short- and long-term outcomes.

METHODS

This prospective cohort included 180 patients with ruptured intracranial aneurysms and an indication of microsurgical treatment. Patients who died in the first 12 hours after admission were excluded.

RESULTS

TAO was associated with intraoperative rupture (IOR) (odds ratio - OR = 10.54; 95% confidence interval - 95%CI 4.72-23.55; p < 0.001) and surgical complications (OR = 2.14; 95%CI 1.11-4.07; p = 0.01). The group with TAO and IOR had no significant difference in clinical (p = 0.06) and surgical (p = 0.94) complications compared to the group that had TAO, but no IOR. Among the 111 patients followed six months after treatment, IOR, number of occlusions, and total time of occlusion were not associated with Glasgow Outcome Scale (GOS) in the follow-up (respectively, p = 0.18, p = 0.30, and p = 0.73). Among patients who underwent TAO, IOR was also not associated with GOS in the follow-up (p = 0.29).

CONCLUSIONS

TAO was associated with IOR and surgical complications, being the latter independent of IOR occurrence. In long-term analysis, neither TAO nor IOR were associated with poor clinical outcomes.

Has intraoperative neuromonitoring changed the surgery for unruptured middle cerebral artery aneurysms? A retrospective comparative study

Intraoperative neurophysiological monitoring (IONM) represents one of the available technologies able to assess ischemia and aimed to improve surgical outcome reducing the treatment related morbidity in surgery for intracranial aneurysms. Many studies analyzing the impact of IONM are poised by the heterogeneity bias affecting the cohorts. We report our experience with IONM for surgery of unruptured middle cerebral artery (MCA) aneurysm in order to highlight its influence on functional and radiological outcome and surgical strategy. We retrospectively reviewed all MCA unruptured aneurysms treated between January 2013 and June 2021 by our institutional neurovascular team. Patients were divided into 2 groups according to the use of IONM. A total of 153 patients were included in the study, 52 operated on without IONM and 101 with IONM. The groups did not differ preoperatively regarding clinical status and aneurysm characteristics. Patients operated with IONM had better functional outcomes at discharge as well as at follow-up (p= 0.048, p=0.041) due to lower symptomatic ischemia and better radiological outcome due to lower rate of unexpected aneurysmal remnants (p= 0.0173). The introduction of IONM changed the use of temporary clipping (TeC), increasing its average duration (p= 0.01) improving the safety of dissecting and clipping the aneurysm. IONM in surgery for unruptured MCA aneurysm could improve the efficacy and safety of clipping strategy in the way it showed a role in changing the use of TeC and was associated to the reduction of unexpected aneurysmal remnants' rate and improvement in both short- and long-term patient's outcome.

Predictive value of IOM in clipping of unruptured intracranial aneurysms - A prospective study from the surgeon's point of view

Introduction

Intraoperative neuromonitoring (IOM) of motor/somatosensory evoked potentials is a well-established approach for reducing ischemic complications after aneurysm clipping.

Research question

To determine the predictive validity of IOM for postoperative functional outcome and its perceived added value for intraoperative real-time feedback of functional impairment in the surgical treatment of unruptured intracranial aneurysms (UIAs).

Material and methods

Prospective study of patients scheduled for elective clipping of UIAs between 02/2019-02/2021. Transcranial motor evoked potentials (tcMEP) were used in all cases, a significant decline was defined as loss of ≥50% in amplitude or 50% latency increase. Clinical data were correlated to postoperative deficits. A surgeon's questionnaire was conceived.

Results

47 patients were included, median age 57 years (range 26-76). IOM was successful in all cases. In 87.2%, IOM was stable throughout surgery, although 1 patient (2.4%) demonstrated a permanent postoperative neurological deficit. All patients with an intraoperatively reversible tcMEP-decline (12.7%) showed no surgery-related deficit, regardless of the decline duration (range 0.5-40.0 ​min; mean: 13.8). Temporary clipping (TC) was performed in 12 cases (25.5%), with a decline in amplitude in 4 patients. After clip-removal, all amplitudes returned to baseline. IOM provided the surgeon with a higher sense of security in 63.8%.

Discussion and conclusion

IOM remains invaluable during elective microsurgical clipping, particularly during TC of MCA and AcomA-aneurysms. It alerts the surgeon of impending ischemic injury and offers a way of maximizing the time frame for TC. IOM has highly increased surgeons' subjective feeling of security during the procedure.

An Analysis of Landmark Articles Regarding Aneurysms of the Middle Cerebral Artery

OBJECTIVE

Aneurysms located on the middle cerebral artery (MCA) range from 22% to 31.5% in prevalence of all aneurysms in the anterior cerebral circulation. This bibliometric analysis summarizes the most cited articles on MCA aneurysms and highlights the landmark publications that contributed to evidence-based practice.

METHODS

In the execution of this bibliometric-based review article, the Scopus database was used to perform a title-specific, keyword-based search for all publications until August 2022. The keyword "(middle cerebral artery OR MCA) AND aneurysm" was used. Our results were arranged in descending order based on the citation count of the article. The 100 most cited articles were selected for analysis. Parameters included the following: title, citation count, citations per year, authors, specialty of first author, institution, country of origin, publishing journal, Source Normalized Impact per Paper, and Hirsch index.

RESULTS

The keyword-based search showed that 1206 articles on MCA aneurysms were published up to August 2022. The top 100 articles were published between 1940 and 2019. The top 100 most cited articles collected a total of 6232 citations with an average of 62.3 citations per article. The rate of self-citations accounted for an average of 5.75% of the total number of citations.

CONCLUSIONS

The bibliometric analysis provides a quantitative overview of how medical literature and interventions are analyzed in academic medicine. In the present study, we evaluated the global trends in research regarding MCA aneurysms by finding the top 100 most cited articles.

Association of Preoperative Vascular Wall Imaging Patterns and Surgical Outcomes in Patients With Unruptured Intracranial Saccular Aneurysms

BACKGROUND

MR vascular wall imaging (VWI) may have prognostic value in patients with unruptured intracranial aneurysms (UIAs).

OBJECTIVE

To evaluate the value of VWI as a predictor of surgical outcome in patients with UIAs.

METHODS

This prospective cohort study evaluated surgical outcomes in consecutive patients with UIAs who underwent surgical clipping at a single center. All participants underwent high-resolution VWI and were followed for at least 6 months. The primary clinical outcome was modified Rankin scale (mRS) score 6 months after surgery.

RESULTS

The number of patients in the no wall enhancement, uniform wall enhancement (UWE), and focal wall enhancement (FWE) groups was 37, 145, and 154, respectively. Incidence of postoperative complications was 15.5% in the FWE group, 12.4% in the UWE group, and 5.4% in the no wall enhancement group. The proportion of patients with mRS score >2 at the 6-month follow-up was significantly higher in the FWE group than in the UWE group (14.3% vs 6.9%; P = .0389). In the multivariate analysis, FWE (odds ratio, 2.573; 95% CI 1.001-6.612) and positive proximal artery remodeling (odds ratio, 10.56; 95% CI 2.237-49.83) were independent predictors of mRS score >2 at the 6-month follow-up.

CONCLUSION

Preoperative VWI can improve the surgeon's understanding of aneurysm pathological structure. Type of aneurysmal wall enhancement on VWI is associated with clinical outcome and incidence of salvage anastomosis and surgical complications.

Enhance Safety in Aneurysm Surgery: Strategies for Prevention of Intraoperative Vascular Complications

Complications during surgery for intracranial aneurysms can be devastating. Notorious pitfalls include premature rupture, parent vessel occlusion, local cerebral injury and brain contusion, and incomplete neck obliteration. These unfavorable intraoperative events can result in major neurological deficits with permanent morbidity and even mortality. Herein, the author highlights the relevant surgical strategies used in his daily practice of aneurysm surgery (e.g., aneurysm clipping with adenosine-induced temporary cardiac arrest), application of which may help prevent vascular complications and enhance surgical safety through reduction of the associated risks, thus allowing improvement of postoperative outcomes. Overall, all described methods and techniques should be considered as small pieces in the complex puzzle of prevention of vascular complications during aneurysm surgery.

Robotic Arm-Protected Microsurgical Pericallosal and Middle Cerebral Artery Aneurysm Clipping: A Technical Note and Case Series

BACKGROUND

Managing intraoperative aneurysm rupture (IAR) during intracranial aneurysm clipping can be challenging given the excessive hemorrhage and limited field of view under the microscope for visualizing the proximal artery and safe temporary clipping.

OBJECTIVE

To describe the first known use of robotic arm for safeguarding IAR in microsurgical aneurysm clipping.

METHODS

A robotic arm was used to safeguard 3 microsurgical clipping cases (1 pericallosal and 2 middle cerebral artery) performed by a single surgeon. The device was installed onto the side rail of the operating table along with the clip applier attachment. After dissecting the cerebral artery segment proximal to the aneurysm, a temporary aneurysm clip was loaded and established at the appropriate segment before dissecting distally toward the aneurysm.

RESULTS

Setup for the robotic arm and temporary clip was simple, quick, precise, and without any unforeseen accommodations needed in all 3 instances. The temporary clip acted as an emergency gate and could be deployed either manually or remotely through a controller. IAR occurred in case 1, and the robotic-assisted temporary clip deployment achieved immediate hemostasis without complications. This method bypassed the need for significant suctioning, packing, and further exploration for safe temporary clipping. Case 2 and 3 demonstrated the feasibility for middle cerebral artery protection and ease of intraoperative readjustment.

CONCLUSION

This technical note highlights the feasibility and relative ease of using a robotic arm as a safeguard device, and it enables on-demand control of proximal blood flow and may enhance the safety of microsurgical aneurysm procedures.

Temporary vessel occlusion in cerebral aneurysm surgery guided by direct cortical motor evoked potentials

BACKGROUND

Temporary clipping is an important tool in the vascular neurosurgeon's armamentarium. We routinely utilize intraoperative neurophysiological monitoring (IONM) for complex brain aneurysm surgery cases, relying on direct cortical motor evoked potential (DCMEP) alerts to guide the duration of temporary clipping. Previous studies have argued for relatively short and intermittent temporary clipping strategies. In this study, we sought to assess the maximal permissive temporary clipping time during complex aneurysm surgery. To do this, we assessed patient outcome in relation to temporary clip duration guided by DCMEP.

METHODS

We queried our prospectively collected neuromonitoring database for anterior circulation aneurysm cases where temporary clipping was utilized by a single cerebrovascular surgeon between 2018 and 2021. Operative and IONM reports were reviewed. Patients in whom the duration of temporary clipping could not be determined were excluded. The operative strategy permissively allowed continuous temporary clipping as long as no neuromonitoring alerts were encountered. Maximal permissive parent artery occlusion time (Clip_max) was recorded as the longest duration of tolerated temporary vessel clipping without decrement in DCMEP.

RESULTS

A total of 41 complex anterior circulation aneurysm clipping cases met criteria for this study. The mean Clip_max for all cases was just over 19 min and did not differ between ruptured and unruptured aneurysms. Initial alert times were not found to be predictive of final permissive temporary clip duration after re-perfusion. In 100% (41/41) of cases, the aneurysm was completely clip occluded without residual on catheter angiogram. Stable or improved modified Rankin Score was achieved in 98% (40/41) of cases at 3-month follow-up.

CONCLUSIONS

This study demonstrates that using DCMEP can facilitate relatively long but safe temporary clipping durations in complex anterior circulation aneurysm surgery. In the endovascular era with only a limited subset of technically challenging aneurysms needing open surgical treatment, extended permissive temporary clipping guided by DCMEPs can significantly enhance a surgeon's ability to achieve excellent technical and clinical outcomes.

Evaluation of multimodal intraoperative neurophysiologic monitoring during supratentorial aneurysm surgery: a comparative study

The objective of this study is to determine the role of multimodal intraoperative neurophysiologic monitoring (IONM) in the overall outcome of intracranial aneurysms surgery, and the risk factors associated with ischemic complications. We grouped 268 ruptured and unruptured intracranial aneurysms surgically treated at our institution into 2 cohorts, based on the use of IONM (180; 67.16%) or non-use of IONM (88; 32.84%). The IONM technique used was multimodal: electroencephalogram (EEG), somatosensory evoked potentials (SSEPs), transcranial (TES), and direct cortical (DCS) stimulation motor evoked potentials (MEPs). There was a significant difference, with a reduction in perioperative strokes (p = 0.011) and better motor surgery-related outcome in the IONM group (p = 0.016). Independent risk factors identified for surgery ischemic complications were temporary clipping time ≥ 6'05″ (odds ratio [OR]: 3.03; 95% CI: 1.068-8.601; p = 0.037), aneurysm size ≥ 7.5 mm (OR: 2.65; 95% CI: 1.127-6.235; p = 0.026), and non-use of IONM (OR: 2.79; 95% CI: 1.171-6.636; p = 0.021). Conversely, aneurysm rupture was not detected as an independent risk factor (OR: 2.5; 95% CI: 0.55-4.55; p = 0.4). Longer temporary clipping time, larger aneurysm size, and the non-use of IONM could be considered as risk factors for ischemic complications during microsurgical clipping. A standardized designed protocol including multimodal IONM with DCS provides continuous information about blood supply and allows reduction of treatment-related morbidity. Multimodal IONM is a valuable technique in intracranial aneurysm surgery.

Electroencephalographic Burst-Suppression, Perioperative Neuroprotection, Postoperative Cognitive Function, and Mortality: A Focused Narrative Review of the Literature

Burst-suppression is an electroencephalographic pattern that results from a diverse array of pathophysiological causes and/or metabolic neuronal suppression secondary to the administration of anesthetic medications. The purpose of this review is to provide an overview of the physiological mechanisms that underlie the burst-suppression pattern and to present in a comprehensive way the available evidence both supporting and in opposition to the clinical use of this electroencephalographic pattern as a therapeutic measure in various perioperative settings.

Optimal Use of Temporary Clip Application during Aneurysm Surgery - In Search of the Holy Grail

Temporary clips are invaluable safety tools during the clipping of an aneurysm. Controversies regarding maximum permissible duration and safety, however, remain unanswered. This descriptive narrative attempts to review the literature to provide valuable insights on controversies clouding the use of temporary clips among neurosurgeons. Popular databases, including Pub Med, Medline/Medscape, Scopus, Cochrane, Embase, Google Scholar, were searched to find available literature on temporary clips. The searched MeSH terms were "Temporary Clip," "Temporary Clipping," "Cerebral Aneurysm," and "Aneurysm." Temporary clips have been in use since 1928 and have undergone considerable structural and technical modifications. A temporary clip's optimal safety limit is not yet defined with literature evidence ranging from immediate to 93 min. It is not yet definite whether temporary clips application aggravates vasospasm, but emergency temporary clips application, especially in poor-grade aneurysmal subarachnoid hemorrhage patients, is associated with poor outcomes. A temporary clip needs to be applied with caution in patients treated earlier by endovascular technique and having indwelling stents. Nitinol Stent is feasible, while a Cobalt-Chromium alloy stent does not get occluded and gets deformed under the closing pressure of a temporary clip. Although a temporary clip application is a fundamental strategy during the clipping of an aneurysm; the exact safe duration remains to be decided in randomized control trials. Their utility for the shorter duration is beneficial under un-conclusive evidence of neuroprotective agents and intraoperative monitoring. Neurosurgeons need to consider all aspects of their pros and cons for optimal use.

Anesthetic management of unruptured intracranial aneurysms: a qualitative systematic review

Intracranial aneurysms (IA) occur in 3-5% of the general population and may require surgical or endovascular obliteration if the patient is symptomatic or has an increased risk of rupture. These procedures carry an inherent risk of neurological complications, and the outcome can be influenced by the physiological and pharmacological effects of the administered anesthetics. Despite the critical role of anesthetic agents, however, there are no current studies to systematically assess the intraoperative anesthetic risks, benefits, and outcome effects in this population. In this systematic review of the literature, we carefully examine the existing evidence on the risks and benefits of common anesthetic agents during IA obliteration, their physiological and clinical characteristics, and effects on neurological outcome. The initial search strategy captured a total of 287 published studies. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 28 studies were included in the final report. Our data showed that both volatile and intravenous anesthetics are commonly employed, without evidence that either is superior. Although no specific anesthetic regimens are promoted, their unique neurological, cardiovascular, and physiological properties may be critical to the outcome in vulnerable patients. In particular, patients at risk for perioperative ischemia may benefit from timely administration of anesthetic agents with neuroprotective properties and optimization of their physiological parameters. Further studies are warranted to examine if these anesthetic regimens can reduce the risk of neurological injury and improve the overall outcome in these patients.

Does electroencephalographic burst suppression still play a role in the perioperative setting?

With the widespread use of electroencephalogram [EEG] monitoring during surgery or in the Intensive Care Unit [ICU], clinicians can sometimes face the pattern of burst suppression [BS]. The BS pattern corresponds to the continuous quasi-periodic alternation between high-voltage slow waves [the bursts] and periods of low voltage or even isoelectricity of the EEG signal [the suppression] and is extremely rare outside ICU and the operative room. BS can be secondary to increased anesthetic depth or a marker of cerebral damage, as a therapeutic endpoint [i.e., refractory status epilepticus or refractory intracranial hypertension]. In this review, we report the neurophysiological features of BS to better define its role during intraoperative and critical care settings.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Review Cerebral Ischemic Tolerance and Preconditioning: Methods, Mechanisms, Clinical Applications, and Challenges

Stroke is one of the leading causes of morbidity and mortality worldwide, and it is increasing in prevalence. The limited therapeutic window and potential severe side effects prevent the widespread clinical application of the venous injection of thrombolytic tissue plasminogen activator and thrombectomy, which are regarded as the only approved treatments for acute ischemic stroke. Triggered by various types of mild stressors or stimuli, ischemic preconditioning (IPreC) induces adaptive endogenous tolerance to ischemia/reperfusion (I/R) injury by activating a multitude cascade of biomolecules, for example, proteins, enzymes, receptors, transcription factors, and others, which eventually lead to transcriptional regulation and epigenetic and genomic reprogramming. During the past 30 years, IPreC has been widely studied to confirm its neuroprotection against subsequent I/R injury, mainly including local ischemic preconditioning (LIPreC), remote ischemic preconditioning (RIPreC), and cross preconditioning. Although LIPreC has a strong neuroprotective effect, the clinical application of IPreC for subsequent cerebral ischemia is difficult. There are two main reasons for the above result: Cerebral ischemia is unpredictable, and LIPreC is also capable of inducing unexpected injury with only minor differences to durations or intensity. RIPreC and pharmacological preconditioning, an easy-to-use and non-invasive therapy, can be performed in a variety of clinical settings and appear to be more suitable for the clinical management of ischemic stroke. Hoping to advance our understanding of IPreC, this review mainly focuses on recent advances in IPreC in stroke management, its challenges, and the potential study directions.

An endovascular assisted, nonocclusive cerebral bypass: a technical feasibility study in a rabbit model

OBJECTIVE

Temporary parent vessel occlusion performed to establish a high-flow interpositional bypass carries the risk of infarcts. The authors investigated the feasibility of a novel technique to establish a high-flow bypass without temporary parent vessel occlusion in order to lower the risk of ischemic complications.

METHODS

In 10 New Zealand white rabbits, a carotid artery side-to-end anastomosis was performed under parent artery patency with a novel endovascular balloon device. Intraoperative angiography, postoperative neurological assessments, and postoperative MRI/MRA were performed to evaluate the feasibility and safety of the novel technique.

RESULTS

A patent anastomosis was established in 10 of 10 animals; 3 procedure-related complications occurred. No postoperative focal neurological deficits were observed. The MRI/MRA findings include no infarcts and bypass patency in 50% of the animals.

CONCLUSIONS

The authors demonstrated the feasibility of an endovascular assisted, nonocclusive high-flow bypass. Future refinement of the device and technique in an animal model is necessary to lower the complication rate and increase patency rates.

The Morphology of Somatosensory Evoked Potentials During Middle Cerebral Artery Aneurysm Clipping (MoSAC): A Pilot Study

Somatosensory evoked potential (SEP) monitoring is a standard tool during clipping of aneurysms of the middle cerebral artery (MCA), and the parameter used to detect a state of cortical ischemia is amplitude. We think that the sensitivity of SEP can however be improved by using other parameters. Our study moves in this direction via SEP morphology. In this pilot preliminary study, involving a small sample without postoperative neurological deficit, we aimed at investigating the value of SEP morphology (in the 15- to 35-ms time frame), in comparison with SEP amplitude (N20 peak-to-peak), as a measure of sensitivity to blood flow reduction. The changes in the SEP morphology of 16 patients undergoing clipping of an unruptured MCA aneurysm was studied. We applied the Morph-Fréchet index for each recorded SEP (at 30-second intervals), quantifying the pattern shape change with regard to the average SEP recorded after dura opening (baseline). We also compared 3 measurements of the SEP morphology, without and with GARCH-derived filter. Filtered Morph-Fréchet never exceeded the individual's "normality" range in baseline but did so in 81% of the risk phase on average across the 16 subjects, which is more than that for amplitude (36%, P = .002). This pilot study indicates that a measurement derived from the networking nature of the brain was sensitive to blood flow reduction. The SEP morphology approach promises to improve SEP monitoring sensitivity during clipping of unruptured MCA aneurysms. New and Noteworthy. The higher sensitivity to blood flow reduction of SEP morphology than amplitude promises to improve the effectiveness of intraoperative monitoring during MCA aneurysm clipping procedures.

Precise MEP monitoring with a reduced interval is safe and useful for detecting permissive duration for temporary clipping

Although temporary clipping of the parent artery is an indispensable technique in clipping surgery for intracranial aneurysms, the permissive duration of temporary clipping is still not well known. The aim of this study is to confirm the safety of precise motor evoked potential (MEP) monitoring and to estimate the permissive duration of temporary clipping for middle cerebral artery (MCA) aneurysm based on precise MEP monitoring results. Under precise MEP monitoring via direct cortical stimulation every 30 seconds to 1 minute, surgeons released a temporary clip and waited for MEP amplitude to recover following severe (>50%) reduction of MEP amplitude during temporary clipping. Precise MEP monitoring was safely performed. Twenty-eight instances of temporary clipping were performed in 42 MCA aneurysm clipping surgeries. Because precise MEP monitoring could be used to determine when to release a temporary clip even with a severe reduction in MEP amplitude due to lengthy temporary clipping, no patients experienced permanent postoperative hemiparesis. Based on logistic regression analysis, if a temporary clip is applied for 312 seconds or more, there is a higher probability of a severe reduction in MEP amplitude. We should therefore release temporary clips after 5 minutes in order to avoid permanent postoperative hemiparesis.

Effects of propofol on ischemia-reperfusion and traumatic brain injury

Oxidative stress exacerbates brain damage following ischemia-reperfusion and traumatic brain injury (TBI). Management of TBI and critically ill patients commonly involves use of propofol, a sedation medication that acts as a general anesthetic with inherent antioxidant properties. Here we review available evidence from animal model systems and clinical studies that propofol protects against ischemia-reperfusion injury. However, evidence of propofol toxicity in humans exists and manifests as a rare complication, "propofol infusion syndrome" (PRIS). Evidence in animal models suggests that brain injury induces expression of the p75 neurotrophin receptor (p75NTR), which is associated with proapoptotic signaling. p75NTR-mediated apoptosis of neurons is further exacerbated by propofol's superinduction of p75NTR and concomitant inhibition of neurotrophin processing. Propofol is toxic to neurons but not astrocytes, a type of glial cell. Evidence suggests that propofol protects astrocytes from oxidative stress and stimulates astroglial-mediated protection of neurons. One may speculate that in brain injury patients under sedation/anesthesia, propofol provides brain tissue protection or aids in recovery by enhancing astrocyte function. Nevertheless, our understanding of neurologic recovery versus long-term neurological sequelae leading to neurodegeneration is poor, and it is also conceivable that propofol plays a partial as yet unrecognized role in long-term impairment of the injured brain.

Adenosine-induced cardiac arrest as an alternative to temporary clipping during intracranial aneurysm surgery

OBJECTIVE

The purpose of this study was to analyze the impact of adenosine-induced cardiac arrest (AiCA) on temporary clipping (TC) and the postoperative cerebral infarction rate among patients undergoing intracranial aneurysm surgery.

METHODS

In this retrospective matched-cohort study, 65 patients who received adenosine for decompression of aneurysms during microsurgical clipping were identified (Group A) and randomly matched with 65 selected patients who underwent clipping but did not receive adenosine during surgery (Group B). The matching criteria included age, Fisher grade, aneurysm size, rupture status, and location of aneurysms. The primary outcomes were TC time and the postoperative infarction rate. The secondary outcome was the incidence of intraoperative aneurysm rupture (IAR).

RESULTS

In Group A, 40 patients underwent clipping with AiCA alone and 25 patients (38%) received AiCA combined with TC, and in Group B, 60 patients (92%) underwent aneurysm clipping under the protection of TC (OR 0.052; 95% CI 0.018–0.147; p < 0.001). Group A required less TC time (2.04 minutes vs 4.46 minutes; p < 0.001). The incidence of postoperative lacunar infarction was equal in both groups (6.2%). There was an insignificant between-group difference in the incidence of IAR (1.5% in Group A vs 6.1% in Group B; OR 0.238; 95% CI 0.026–2.192; p = 0.171).

CONCLUSIONS

AiCA is a useful technique for microneurosurgical treatment of cerebral aneurysms. AiCA can minimize the use of TC and does not increase the risk of IAR and postoperative infarction.

Central retinal artery occlusion - rethinking retinal survival time

Background

The critical time from onset of complete occlusion of the central retinal artery (CRA) to functionally significant inner retinal infarction represents a window of opportunity for treatment and also has medical-legal implications, particularly when central retinal artery occlusion (CRAO) complicates therapeutic interventions. Here, we review the evidence for time to infarction from complete CRAO and discuss the implications of our findings.

Methods

A Medline search was performed using each of the terms “central retinal artery occlusion”, “retinal infarction”, “retinal ischemia”, and “cherry red spot” from 1970 to the present including articles in French and German. All retrieved references as well as their reference lists were screened for relevance. An Internet search using these terms was also performed to look for additional references.

Results

We find that the experimental evidence showing that inner retinal infarction occurs after 90–240 min of total CRAO, which is the interval generally accepted in the medical literature and practice guidelines, is flawed in important ways. Moreover, the retinal ganglion cells, supplied by the CRA, are part of the central nervous system which undergoes infarction after non-perfusion of 12–15 min or less.

Conclusions

Retinal infarction is most likely to occur after only 12–15 min of complete CRAO. This helps to explain why therapeutic maneuvers for CRAO are often ineffective. Nevertheless, many CRAOs are incomplete and may benefit from therapy after longer intervals. To try to avoid retinal infarcton from inadvertent ocular compression by a headrest during prone anesthesia, the eyes should be checked at intervals of less than 15′.

The impact of temporary clipping during aneurysm surgery on the incidence of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

OBJECTIVE Clipping of a ruptured intracranial aneurysm requires some degree of vessel manipulation, which in turn is believed to contribute to vasoconstriction. One of the techniques used during surgery is temporary clipping of the parent vessel. Temporary clipping may either be mandatory in cases of premature rupture (rescue) or represent a precautionary or facilitating surgical step (elective). The aim of this study was to study the association between temporary clipping during aneurysm surgery and the incidence of vasospasm and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (aSAH) in a large clinical series. METHODS Seven hundred seventy-eight patients who underwent surgical aneurysm treatment after aSAH were retrospectively included in the study. In addition to surgical parameters, the authors recorded transcranial Doppler (TCD) sonography-documented vasospasm (TCD-vasospasm, blood flow acceleration > 120 cm/sec), delayed ischemic neurological deficits (DINDs), and delayed cerebral infarction (DCI). Multivariate binary logistic regression analysis was applied to assess the association between temporary clipping, vasospasm, DIND, and DCI. RESULTS Temporary clipping was performed in 338 (43.4%) of 778 patients during aneurysm surgery. TCD sonographic flow acceleration developed in 370 (47.6%), DINDs in 123 (15.8%), and DCI in 97 (12.5%). Patients with temporary clipping showed no significant increase in the incidence of TCD-vasospasm compared with patients without temporary clipping (49% vs 48%, respectively; p = 0.60). DINDs developed in 12% of patients with temporary clipping and 18% of those without temporary clipping (p = 0.01). DCI occurred in 9% of patients with temporary clipping and 15% of those without temporary clipping (p = 0.02). The need for rescue temporary clipping was a predictor for DCI; 19.5% of patients in the rescue temporary clipping group but only 11.3% in the elective temporary clipping group had infarcts (p = 0.02). Elective temporary clipping was not associated with TCD-vasospasm (p = 0.31), DIND (p = 0.18), or DCI (p = 0.06). CONCLUSIONS Temporary clipping did not contribute to a higher rate of TCD-vasospasm, DIND, or DCI in comparison with rates in patients without temporary clipping. In contrast, there was an association between temporary clipping and a lower incidence of DINDs and DCI. There is no reason to be hesitant in using elective temporary clipping if deemed appropriate.

Simulating Internal Carotid Artery Injury during Transsphenoidal Transclival Endoscopic Surgery in a Perfused Cadaver Model

Introduction  Managing internal carotid artery (ICA) injury during extended endoscopic transsphenoidal surgery is an extreme challenge. We aimed to find a possible surgical treatment strategy. Methods  We operated seven fresh, perfused cadaver heads with a transsphenoidal endoscopic approach of the ICA using a three-dimensional-high definition (3D-HD) endoscope. We made a paraclival ICA leak, which we tried to manage with clips and microsutures. Results  Accurate transsphenoidal clip application on the ICA was impossible with standard aneurysm clips and applier. It was only feasible with a 9 mm slightly bended clip that could be opened from the inside and be applied with a dedicated flexible thin applier. Transsphenoidal suturing of an ICA leak was impossible from the ipsilateral nostril or with standard microinstruments. Suturing was only feasible from the contralateral nostril using flexible microinstruments with a thin 90-mm shaft. This was technically very challenging and involved a steep learning curve. Conclusion  Tamponade with muscle or fat and a quick transfer to the angiography suite for endovascular control remains the preferable option in case of an ICA leak during endoscopic transsphenoidal surgery. If tamponade gives insufficient initial control, ICA clipping could be possible with dedicated instruments, with risk of increasing the defect, stenosis, or occlusion of the vessel. Transsphenoidal ICA suturing remains extremely difficult, and laboratory practice seems essential.

Safe time duration for temporary middle cerebral artery occlusion in aneurysm surgery based on motor-evoked potential monitoring

BACKGROUND

Temporary vessel occlusion of the parent artery is an essential technique for aneurysm surgery. Our aim was to clarify the safe time for temporary occlusion for aneurysm surgery, that is the "safe time duration" (STD), in which brain tissue exposed to ischemia will almost never fall into even the ischemic penumbra during temporary occlusion of the middle cerebral artery (MCA), and even transient postoperative motor impairment will be rare using intraoperative motor-evoked potentials (MEP).

METHODS

Twenty-four patients underwent MCA aneurysm clipping surgery with MEP monitoring for 13 ruptured aneurysms and 11 unruptured aneurysms. The duration of vessel occlusion in patients without MEP changes was measured as the STD. Average STD was calculated as 95% confidence interval for the population mean using sample data from patients with MEP changes and patients without changes.

RESULTS

All 24 patients received proximal flow control only. Five patients (20.8%) developed significant intraoperative MEP changes. Time to MEP change (i.e., STD) in these patients was 4.6 ± 2.1 min. In patients without MEP changes, STD was 2.7 ± 1.4 min. Average STD was thus 3.1 ± 0.7 min.

CONCLUSIONS

The 95% lower confidence limit for average STD was 2.4 min when applying temporary occlusion on the proximal side of the MCA. This STD resembled that previously reported for temporary proximal occlusion of the internal carotid artery.

The arborization bypass: Sequential intracranial-intracranial bypasses for an unruptured fusiform MCA aneurysm

Revascularization techniques are being featured more prominently as endovascular treatments continue to select out complex cerebrovascular pathologies for open surgical management. The current healthcare environment requires decreased hospital stays and improved clinical outcomes despite the growing complexity of open surgical cases. Recent efforts to reduce operative room time and decrease risk for bypass surgery have focused on avoiding graft harvest and maintaining the entire bypass intracranial. The presented technique features an arborization bypass to serially anastomose the middle cerebral artery vessels allowing for proximal trapping of a complex aneurysm without graft harvest. The arborization technique has several advantages to traditional techniques and serves to supplement the revascularization surgeon's armamentarium.

Reversal of intraoperative arterial thrombosis with a fibrinolytic agent when treating large and giant partially thrombosed aneurysms of the middle cerebral artery

OBJECT

Thrombosis of the cerebral arteries is one of the complications of microsurgical operations for partially thrombosed intracranial aneurysms. The object of this study was to assess the frequency of intraoperative arterial thrombosis (IAT) during microsurgical treatment of large and giant partially thrombosed aneurysms of the middle cerebral artery (MCA) and also to assess the efficacy of the treatment of this complication.

MATERIALS

The authors analyzed a consecutive series of 53 patients who underwent surgery for partially thrombosed aneurysms of the MCA at the Burdenko Neurosurgical Institute between January 2005 and September 2014. Thirty-two patients had large aneurysms (15–25 mm) and 21 had giant aneurysms (> 25 mm). Clipping of aneurysms was performed in 47 patients, trapping was performed in 3, and wrapping was performed in 3.

RESULTS

IAT was diagnosed in 10 patients (18.9%). The authors describe a technique for IAT reversal involving the injection of modified human recombinant prourokinase (mr-proUK). Of the 7 patients who underwent injection of mr-proUK in the thrombosed artery, 5 (71.4%) were discharged without any change in neurological status, 1 (14.3%) experienced moderate deterioration (modified Rankin Scale [mRS] score of 2), and 1 (14.3%) experienced severe deterioration (mRS score of 4). Among the 3 patients who had complications and did not receive an injection of mr-proUK, 2 experienced severe deterioration (mRS score of 3 and 4) and 1 had moderate deterioration (mRS score of 2).

CONCLUSIONS

The primary risk factor of thrombectomy with temporary trapping is thrombosis in the MCA branches. The injection of a fibrinolytic agent into thrombosed MCA branches is an effective method for the treatment of IAT.

"Clip first" policy in management of intracranial MCA aneurysms: Single-centre experience with a systematic review of literature

BACKGROUND

The results of microsurgical treatment for middle cerebral artery (MCA) aneurysms (ANs) have been highly satisfying for decades, notoriously posing a challenge for interventional neuroradiologists. Following the International Subarachnoid Aneurysm Trial (ISAT) study results, most centres across Europe and the USA switched to a "coil first" policy. The purpose of this study is to evaluate and critically review the substantiation of this change.

METHODS

The authors conducted a single-institution retrospective study of MCA AN treatment between January 2000 and December 2013 maintaining a "clip first" policy. The results are supplied with a literature review.

RESULTS

A total of 315 MCA ANs were treated in 288 consecutive patients (209 females, 79 males). Microsurgical treatment was performed for 238 AN patients (116 ruptured, 122 unruptured) and 77 AN patients (46 ruptured, 31 unruptured) who underwent a coiling procedure. Treatment-related morbidity and mortality (MM) for unruptured ANs was 2.8 % in the microsurgical group and 10.3 % in the endovascular group. The percentage of patients with no/minor permanent neurological deficits after SAH in a good initial clinical state (HH 1-2) was 93 % in the microsurgical and 76 % in the endovascular group. A literature review identified 21 studies concerning MCA AN treatment with a specified decision-making algorithm. Microsurgery seemed superior to endovascular management regarding both clinical and radiological outcomes, although several aspects of the analysed reports might appear questionable.

CONCLUSION

Although this study has its inherent limitations, the effect brought about by microsurgical clipping of MCA ANs remains superior to that of endovascular embolisation and it should be sustained as the first treatment choice. The decision about the treatment strategy should be made by a multi-disciplinary team consisting of specialists from both teams, bearing in mind the higher occlusion rate and longevity of the surgical treatment.

Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a worldwide health burden with high fatality and permanent disability rates. The overall prognosis depends on the volume of the initial bleed, rebleeding, and degree of delayed cerebral ischemia (DCI). Cardiac manifestations and neurogenic pulmonary edema indicate the severity of SAH. The International Subarachnoid Aneurysm Trial (ISAT) reported a favorable neurological outcome with the endovascular coiling procedure compared with surgical clipping at the end of 1 year. The ISAT trial recruits were primarily neurologically good grade patients with smaller anterior circulation aneurysms, and therefore the results cannot be reliably extrapolated to larger aneurysms, posterior circulation aneurysms, patients presenting with complex aneurysm morphology, and poor neurological grades. The role of hypothermia is not proven to be neuroprotective according to a large randomized controlled trial, Intraoperative Hypothermia for Aneurysms Surgery Trial (IHAST II), which recruited patients with good neurological grades. Patients in this trial were subjected to slow cooling and inadequate cooling time and were rewarmed rapidly. This methodology would have reduced the beneficial effects of hypothermia. Adenosine is found to be beneficial for transient induced hypotension in 2 retrospective analyses, without increasing the risk for cardiac and neurological morbidity. The neurological benefit of pharmacological neuroprotection and neuromonitoring is not proven in patients undergoing clipping of aneurysms. DCI is an important cause of morbidity and mortality following SAH, and the pathophysiology is likely multifactorial and not yet understood. At present, oral nimodipine has an established role in the management of DCI, along with maintenance of euvolemia and induced hypertension. Following SAH, hypernatremia, although less common than hyponatremia, is a predictor of poor neurological outcome.

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.

Local O2 Balance in Cerebral Ischemia-Reperfusion Improved during Pentobarbital Compared with Isoflurane Anesthesia

BACKGROUND

Most anesthetics affect cerebral blood flow and metabolism. We compared microregional O2 balance in cerebral ischemia-reperfusion during pentobarbital and isoflurane anesthesia.

METHODS

After 1 hour of middle cerebral artery occlusion and a 2-hour reperfusion under isoflurane (1.4%, n = 14) or pentobarbital (50 mg/kg, n = 14) anesthesia in rats, regional cerebral blood flow using (14)C-iodoantipyrine autoradiography, microregional arterial and venous O2 saturation (20-60 μm in diameter) using cryomicrospectrophotometry, and the size of cortical infarct were determined.

RESULTS

Ischemia-reperfusion decreased the average cortical venous O2 saturation in both pentobarbital and isoflurane groups (P < .0001), which was higher (P < .05) with pentobarbital despite a similar average regional cerebral blood flow and O2 consumption. The heterogeneity of venous O2 saturation reported as a coefficient of variation (100 × standard deviation/mean) was smaller (P < .005) with pentobarbital than that with isoflurane (7.5 versus 16.1). The number of veins with low venous O2 saturation (<50%) was smaller (P < .005) with pentobarbital (5 of 80 versus 24 of 80). The percentage of cortical infarct in total cortex was smaller with pentobarbital (5.2 ± 2.5% versus 12.3 ± 2.6%, P < .001).

CONCLUSIONS

In the cerebral ischemic-reperfused cortex, the average venous O2 saturation was higher, and its heterogeneity and the number of veins with low O2 saturation were smaller under pentobarbital than isoflurane anesthesia. This improvement in microregional O2 balance with pentobarbital was accompanied by the reduced cortical infarct. Our data suggest that the neurologic outcome could vary during cerebral ischemia-reperfusion depending on the anesthetics used.

Efficacy and outcomes of perioperative anesthetic management of extracranial to intracranial bypass for complex intracranial aneurysm in the absence of advanced neurological monitoring

Background and Aims:

Anesthetic management of extracranial to intracranial (EC-IC) bypass for complex intracranial aneurysms is challenging as the goals involve balancing the cerebral perfusion during parent artery clamping and avoiding factors that predispose to rupture of the unsecured aneurysm. There is very sparse literature available on anesthetic management for this procedure.

Materials and Methods:

A retrospective review of the records of 20 patients undergoing EC-IC bypass was performed with an objective of assessing the efficacy and outcomes of anesthetic management in the absence of advanced neurological monitoring.

Results:

A total of 20 patients underwent EC-IC bypass as an adjunct cerebral revascularization in the management of complex intracranial aneurysms. Intraoperatively normotension and normocarbia were maintained. During the EC-IC bypass, when the temporary clamp was applied, mild hypertension (increase from baseline by 20%) and hypervolemia (central venous pressure increased to 12 mmHg) were maintained. Cerebral protection during temporary clipping of intracranial vessel was provided using moderate hypothermia to 34°C and intravenous thiopentone. Temporary clip time ranged from 15 min to 54 min (mean-25 min). All patients except one were extubated post-operatively (19/20 = 95%). None of the patients had rupture of aneurysm in the peri-operative period. Three patients developed neurologic events (3/20 = 15%). One patient had cerebral vasospasm and two patients developed cerebral infarction. Two patient subsequently improved and one succumbed to the neurological deterioration (mortality 1/20 = 5%).

Conclusion:

Adherence to the principal goals for the procedure, avoidance of hemodynamic fluctuations such as hypotension and hypertension, maintenance of normocarbia, and cerebral protection, result in favorable neurological outcome even in the absence of advanced neuromonitoring.

A double-edged sword: volatile anesthetic effects on the neonatal brain

The use of volatile anesthetics, a group of general anesthetics, is an exceedingly common practice. These anesthetics may have neuroprotective effects. Over the last decade, anesthetic induced neurotoxicity in pediatric populations has gained a certain notoriety based on pre-clinical cell and animal studies demonstrating that general anesthetics may induce neurotoxicity, including neuroapoptosis, neurodegeneration, and long-term neurocognitive and behavioral deficits. With hundreds of millions of people having surgery under general anesthesia worldwide, and roughly six million children annually in the U.S. alone, the importance of clearly defining toxic or protective effects of general anesthetics cannot be overstated. Yet, with our expanding body of knowledge, we have come to learn that perhaps not all volatile anesthetics have the same pharmacological profiles; certain ones may have a more favorable neurotoxic profile and may actually exhibit neuroprotection in specific populations and situations. Thus far, very few clinical studies exist, and have not yet been convincing enough to alter our practice. This review will provide an update on current data regarding volatile anesthetic induced neurotoxicity and neuroprotection in neonatal and infant populations. In addition, this paper will discuss ongoing studies and the trajectory of further research over the coming years.

Is there a place for cerebral preconditioning in the clinic?

Preconditioning (PC) describes a phenomenon whereby a sub-injury inducing stress can protect against a later injurious stress. Great strides have been made in identifying the mechanisms of PC-induced protection in animal models of brain injury. While these may help elucidate potential therapeutic targets, there are questions over the clinical utility of cerebral PC, primarily because of questions over the need to give the PC stimulus prior to the injury, narrow therapeutic windows and safety. The object of this review is to address the question of whether there may indeed be a clinical use for cerebral PC and to discuss the deficiencies in our knowledge of PC that may hamper such clinical translation.

Two indices affecting the directions of the sylvian fissure dissection in middle cerebral artery bifurcation aneurysms

OBJECTIVE

This study proposes more objective methods for deciding the appropriate direction of the sylvian fissure dissection during surgical clipping in middle cerebral artery (MCA) bifurcation aneurysms.

METHODS

We reviewed data of 36 consecutive patients with MCA bifurcation aneurysms. We measured 2 indices preoperatively on 3-dimensional computed tomography angiography (3D-CTA). Analysis of the calculated data allowed us to select the appropriate direction of sylvian fissure dissection for ease of proximal control of M1. Statistically, Mann-Whitney test was used.

RESULTS

We classified subjects into 2 groups based on the technical level of M1 exposure during surgical clipping. When it was difficult to expose M1, subjects were assigned to Group I, and Group II were subjects in whom M1 exposure was easy. The mean difference between the distances extending from the limbus sphenoidale (LS) line to the internal carotid artery bifurcation and extending from the LS line to the MCA bifurcation was 1.00 ± 0.42 mm in group I and 4.39 ± 2.14 mm in group II. The mean M1 angle was 9.36 ± 3.73° in the group I and 34.05 ± 16.71° in the group II (M1 slope gap p < 0.05, M1 angle p < 0.05).

CONCLUSION

We have found an objective method for preoperatively verifying ease of exposure of M1 artery during surgical clipping. Therefore, we suggest use of the preoperative M1 slope gap and M1 angle as indicators in 3D-CTA selecting the direction of sylvian fissure dissection for easy proximal control of M1.

Surgical Treatment of 127 Anterior Choroidal Artery Aneurysms A Cohort Study of Resultant Ischemic Complications

BACKGROUND:

The anterior choroidal artery (AChA) supplies important areas of the nervous system, particularly the posterior limb of the internal capsule and optic radiation. Treatment of AChA aneurysms poses particular challenges because of the complex anatomy of the aneurysm associated with the relatively small diameter of AChAs, making preservation of the parent vessel during clip ligation or endosaccular coiling challenging.

OBJECTIVE:

To investigate the incidence and features of ischemia in treatment of AChA aneurysms.

METHODS:

A prospectively maintained database of patients who underwent treatment of aneurysms from 1985 to 2011 was queried to find patients with AChA aneurysms. Age, sex, Hunt and Hess grade, treatment modality, and complications were analyzed by use of the unpaired Student t test and Fisher exact test.

RESULTS:

One hundred twenty-two patients harbored 127 AChA aneurysms, and 67% (82 of 122) had multiple aneurysms. Treatment included 112 microsurgical clip ligations, 8 endosaccular coil embolizations, 5 aneurysmal wrappings, and 2 surgical explorations. Complications developed in 53% (67 of 127) of AChA aneurysms. Postoperative ischemia occurred in 12% (15 of 127) of treated aneurysms. The number of temporary clip applications was most closely associated with postoperative ischemia. Glasgow Outcome Scale scores of 4 or 5 were obtained by 78% at discharge, 89% at 6 months, and 85% at 1 year.

CONCLUSION:

The ischemic complication rate from surgical treatment of AChA aneurysms is most closely associated with higher frequency of temporary clip applications for proximal control and may be lower than previously reported. Supplementary intraoperative tools and limitation of vessel manipulation should be used to improve outcomes.