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

The optimal temporary occlusion time for the treatment of internal carotid artery aneurysms

Post-operative silent DWI hyperintensities are potential risk factors for cognitive dysfunction. Microsurgical clipping offers high occlusion rates and low recurrence, and temporary occlusion is often essential to safely dissect aneurysms. However, addressing these DWI changes is crucial for improving outcomes and minimizing complications. This study aimed to determine the optimal temporary occlusion time for ICA aneurysm treatment. A retrospective analysis was performed on 267 cases of ICA aneurysms. Clinical outcomes and factors associated with post-operative DWI hyperintensities were analyzed. The post-operative DWI hyperintensities were classified as either perforating artery infarction or 'other' infarction. Of 267 cases, post-operative DWI hyperintensity signals were observed in 38 cases (14.2%), including two symptomatic cases. Temporary occlusion was performed in 239 cases (89.5%), and retrograde suction and decompression (RSD) in 65 cases (24.3%). Multi-variate analysis revealed a significant association between maximum temporary occlusion duration (per 1-min increment) and perforator infarction (OR: 1.29, 95% CI [1.07-1.54]). Temporary occlusion under 5 min presented the lowest risk of DWI changes, while risks significantly increased beyond 12.5 min. Poor outcomes (mRS ≥ 2) were noted in 6 patients (2.2%). Adjunct techniques such as temporary occlusion or RSD used in microsurgical clipping, allow for safer manipulation of ICA aneurysms and dissection of surrounding structures, enabling complete aneurysmal neck clipping. However, post-operative DWI hyperintensities particularly in the perforator infarction may be observed in cases with prolonged temporary occlusion. This study highlights the safety of temporary occlusion when performed for less than 5 min intervals for the treatment of ICA aneurysms.

Transcarotid flow reversal for proximal control during cerebral aneurysm clip reconstruction: illustrative case

BACKGROUND

Paraclinoid aneurysms can pose an operative challenge during clip reconstruction, given the complex surrounding anatomy and the aneurysmal tendency to maintain turgor despite standard approaches to proximal control. This report demonstrates the use of intraoperative retrograde arteriovenous shunting with the transcarotid artery revascularization (TCAR) system to assist in the safe clip reconstruction of an irregular paraclinoid aneurysm.

OBSERVATIONS

A 33-year-old woman presented with perimesencephalic subarachnoid hemorrhage and was found to have an incidental 9-mm ophthalmic aneurysm. Coil embolization was not successful. During microsurgical clip reconstruction, the left common carotid artery was exposed to allow for proximal control as well as transcarotid arterial sheath placement. Flow reversal was instituted throughout the aneurysm dissection and clipping, with a visible softening of the aneurysm. Intraoperative angiography confirming successful clip reconstruction was performed utilizing the TCAR sheath. The case was complicated by the development of cerebrospinal fluid rhinorrhea postoperatively, requiring surgical repair. The patient has since made a complete recovery.

LESSONS

Transcarotid flow reversal utilizing the TCAR system has potential for use in the surgical treatment of paraclinoid aneurysms, as it may aid in softening the aneurysm for safer dissection and clip reconstruction, protect against aneurysm-associated emboli, and provide an avenue for intraoperative angiography. https://thejns.org/doi/10.3171/CASE24330.

Clinical Characteristics and Outcome of Patients With Intraoperative Aneurysm Rupture: A Retrospective Cohort Study From Nepal

BACKGROUND AND OBJECTIVES

Intraoperative aneurysm rupture (IAR) is a significant complication during microsurgical clipping of cerebral aneurysms. The timing of rupture during surgery, morphology of the aneurysm, and strategies to mitigate risk are the key factors that influence the outcome.

METHODS

Consecutive patients with the diagnosis of ruptured cerebral aneurysms were retrospectively reviewed at a single University Hospital in Kathmandu, Nepal. Variables analyzed included age, sex, presenting symptoms, Hunt and Hess grades, the location of aneurysms, the timing of surgery, and intraoperative rupture status. Outcomes were assessed at 6 months after surgery.

RESULTS

A total of 199 patients with 231 ruptured cerebral aneurysms from July 2014 to December 2022 were reviewed. Surgery was performed within 3 days in 60 (30.1%) patients. Twenty aneurysms ruptured intraoperatively in 20 patients (10% per patient and 8.6% per aneurysm). Patients with IAR were significantly younger (mean age 52 years) than those without IAR (mean age 58 years) (P < .001, 95% CI: 3.72-8.28). There was no difference in IAR rate in early vs late surgery. Anterior communicating artery complex aneurysms were noted as the most common. However, posterior inferior cerebellar and posterior cerebral artery aneurysms had the highest IAR rate, albeit with the smallest total number. Rupture during dissection was noted in 10 (50%) and during clipping in 9 (45%) procedures. Strategies for handling IAR included direct definitive clip application in 9, temporary clip-aided permanent clipping in 8, and trapping of the parent vessel in 1 patient. Although postoperative complications were significantly higher in the IAR group (P < .000129), the neurological outcomes using the modified Rankin scale in 6 months were similar (P = .877).

CONCLUSION

The demographic and clinical characteristics and rates of IAR in our patient population are similar to those in the contemporary literature. In patients with IAR, the outcome is not worse than those without IAR.

A Step-by-Step Dissection of Cerebral Pathologies for Neurosurgical Trainees: The Middle Cerebral Artery Bifurcation Aneurysm

BACKGROUND

 Aneurysmal subarachnoid hemorrhage remains one of the most prevalent causes of strokes in the young causing a high socioeconomic damage. Both emergent and elective treatments of intracranial aneurysms remain essential challenges for neurovascular centers. We aim to present conceptual education on clip ligation of middle cerebral artery bifurcation aneurysms in an accessible and structured way to maximize the educational takeaway of residents from aneurysm cases.

METHODS

 After 30 years of experience of the senior author in cerebrovascular surgery in three centers, we closely reviewed an exemplary case of elective right middle cerebral artery bifurcation aneurysm clipping and contrasted it to an alternative microneurosurgical approach to illustrate key principles of microneurosurgical clip ligation for neurosurgical trainees.

RESULTS

 Dissection of the sylvian fissure, subfrontal approach to the optic-carotid complex, proximal control, aneurysm dissection, dissection of kissing branches, dissection of aneurysm fundus, temporary and permanent clipping, as well as aneurysm inspection and resection are highlighted as key steps of clip ligation. This proximal-to-distal approach is contrasted to the distal-to-proximal approach. Additionally, general principles of intracranial surgery such as use of retraction, arachnoid dissection, and draining of cerebrospinal fluid are addressed.

CONCLUSION

 Due to a constantly decreasing case load in the era of neurointerventionalism, the paradox of facing increased complexity with decreased experience must be met with a sophisticated practical and theoretical education of neurosurgical trainees early on and with a low threshold.

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.

Deliberate Parent Artery Sacrifice Guided by Intraoperative Neurophysiological Monitoring During Complex Surgical Clipping of a Ruptured Anterior Communicating Artery Aneurysm

Aneurysms arising from the anterior communicating artery (ACOA) are the most common intracranial aneurysms encountered. Most aneurysms can be treated with surgical clipping or endovascular coiling; however, there are times when parent vessel sacrifice (PVS) is necessary such as aneurysms with fragile necks or large/giant aneurysms. Application of intraoperative neurophysiological monitoring (IONM) can assist in guiding permissive temporary vessel occlusion during complex aneurysm clippings. However, to-date there is no literature that describes how IONM can be used as a predictor of post-operative neurological status when PVS is employed or as a guide to determine whether PVS is safe. We present a case where IONM guided the sacrifice of the A1 and anterior communicating arteries after 2 hours and 25 min of temporary vessel occlusion. No attenuation was noted in the IONM at any point during the procedure, and the IONM predicted the patient would awake neurologically intact.

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.

The Importance of the Temporary Clip Removal Phase on Exposure to Hypoxia: On-Line Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms

BACKGROUND

Most studies concerning intraoperative temporary arterial occlusion overlook the period between and after clip placement.

OBJECTIVE

To analyze the brain tissue oxygen tension through the process by which anterograde arterial blood flow is re-established after temporary clipping (TR).

METHODS

In this prospective observational study, patients who presented to surgery for middle cerebral artery aneurysms were continuously monitored with ICM+, to obtain temporal (downstream) PbtO2 levels while M1 segment temporary clips were applied and removed. PbtO2 changes were analyzed and compared with the clipping phase, and measures of exposure to hypoxia were defined and assessed during both phases and used in a model to test the impact of extending them.

RESULTS

Eighty-six TRs (20 patients) were recorded. The mean acquired amount of time per clip release (CR) event was 336.7 seconds. Temporary clip removal produced specifically shaped, highly individual PbtO2 curves that correlated with their corresponding clipping phase events but developing slower and less consistently. The CR phase was responsible for greater cumulative exposure to hypoxia than the clip application phase through the first and second minutes of each. In our model, the duration of the TR phase was mostly responsible for the total exposure to hypoxia, and longer CR phases reduced the mean exposure to hypoxia.

CONCLUSION

During the clip removal phase, the brain tissue is still exposed to oxygen levels that are significantly below the baseline, reverting through a singular, dynamic process. Therefore, it must be regarded by surgeons with the same degree of attention as its counterpart.

ROC Curve Analysis of Electrophysiological Monitoring and Early Warning During Intracranial Aneurysm Clipping

OBJECTIVE

To explore the safe duration of temporary clipping of the parent artery under intraoperative electrophysiological monitoring.

METHODS

The clinical data of 97 patients who underwent intracranial aneurysm clipping under electrophysiological monitoring in the Department of Neurology, Affiliated Hospital of Qingdao University from June 2019 to June 2020 were retrospectively analyzed. The safety duration of temporary clipping was analyzed using receiver operating characteristic (ROC) curves, and the results were validated in clinical data.

RESULTS

Temporary clipping during operation (P < 0.05) and electrophysiological warning during operation (P < 0.05) were related risk factors of a cerebral ischemia event after operation. The ROC curve was drawn for the duration of temporary clipping and the occurrence of intraoperative electrophysiological warning, and the area under the curve was 0.78 (P < 0.05). The optimal cutoff value was 372.5 seconds, the sensitivity was 0.818, and the specificity was 0.762. After reviewing the clinical data, P < 0.05 was statistically significant after a χ² test with 372.5 seconds equal to approximately 6 minutes. The ROC curve was drawn for the duration of temporary clipping and the time of postoperative ischemia, and the area under the curve was 0.667 (P < 0.05). The optimal cutoff value was 430.5 seconds, the sensitivity was 0.592, and the specificity was 0.842.

CONCLUSION

Temporary intraoperative block is the risk factor for cerebral ischemia after operation. In this study, the temporary clipping time of the parent artery should not be longer than 6 minutes, and there is approximately 1 minute to adjust the current procedure after the electrophysiological warning to restore the baseline of intraoperative electrophysiological monitoring.

Effects of Temporary Clipping as an Expression of Circulatory Individuality: Online Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms

OBJECTIVE

Despite its widespread use, much is left to understand about the repercussions of parent artery temporary clipping in neurosurgery. This study seeks a better comprehension of the subject by aiming at the online measurement of brain tissue oxygen pressure (P_btO₂) during such events.

METHODS

This was a prospective observational study. Patients submitted to surgery for middle cerebral artery aneurysms (both ruptured and unruptured) were continuously monitored under Intensive Care Monitoring+ software, in order to obtain temporal (downstream) P_btO₂ levels while temporary clips were applied. Separate P_btO₂ curve events were identified, extracted, and processed. These were studied for assessing intraindividual and interindividual variability and the potential impact of repeated clipping and previous aneurysmal rupture.

RESULTS

Eighty-six temporary clippings (from 20 patients) were recorded with a mean duration of 140.8 (41 - 238) seconds. Temporary arterial occlusion at the M1 segment of the middle cerebral artery produced specifically shaped trajectories, characterized by a preclipping P_btO₂ level, rapid downward sigmoid-shaped curve, succession of progressively angled slopes, and lower plateau. The steepest slope of the curve correlated strongly with P_btO₂ range (P < 0.001, r = 0.944). These features were highly reproducible only intraindividually and did not vary significantly with repeated clippings.

CONCLUSIONS

The effects of temporary arterial occlusion on temporal lobe oxygenation demonstrate a high degree of singularity, highlighting the potential benefits of assessing individual available collateral circulation intraoperatively. The "P_btO₂ steepest slope" predicted the severity of P_btO₂ decrease and was available within the first minute.

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.

The evolution of intracranial aneurysm treatment techniques and future directions

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator’s experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Adenosine-induced transient asystole to control intraoperative rupture of intracranial aneurysms: institutional experience and systematic review of the literature

BACKGROUND

Intraoperative rupture of an intracranial aneurysm is a life-threatening situation that carries a high risk of morbidity and mortality. Since 2000, adenosine has been used successfully to induce transient hypotension and/or asystole to control bleeding and facilitate surgical clipping of aneurysms that rupture intraoperatively. Given the paucity of reports describing this method in a limited number of patients, we performed a systematic review of the literature detailing the use and outcomes of this technique.

METHODS

The authors performed a systematic review and identified all studies in which adenosine was used in the setting of an intracranial aneurysm that ruptured intraoperatively. We then determined overall morbidity and mortality rates, adding an additional six of our own patients.

RESULTS

Data was analyzed for a total of 29 patients, including 23 previously reported patients from the literature and 6 additional cases from our own experience (mean age 54.8 years, 58.6% female). Most patients (82.8%, 24/29) presented with subarachnoid hemorrhage (SAH). Overall mean dose of adenosine was 51.8 mg. Successful clipping was achieved in 100% of patients. Transient or permanent morbidity was reported in 5/29 (17.2%) and the overall mortality rate was 31% (9/29), which occurred primarily due to an initial severe SAH and its resultant complications.

CONCLUSIONS

Adenosine-induced circulatory arrest appears to safely control intraoperative bleeding and facilitate the clipping of ruptured intracranial aneurysms based on the limited published literature available. Further studies comparing patient outcomes using this technique to traditional approaches are required to validate the safety and efficacy of adenosine in this high-risk setting.

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.

Monitoring Corticocortical Evoked Potentials During Intracranial Vascular Surgery

BACKGROUND

Monitoring of corticocortical evoked potentials (CCEPs) during brain tumor surgery of patients under anesthesia was recently reported to be effective in assisting in preservation of speech function. The aim of this study was to investigate whether CCEPs can be reproducibly measured between the frontal and temporal lobes during standard intracranial vascular surgery under general anesthesia; whether dynamic changes in CCEPs caused by reduced focal cerebral blood flow can be measured; and whether CCEPs can be used to monitor speech function, particularly associated with the left side of the brain.

METHODS

We monitored CCEPs during 58 vascular surgeries (42 clipping procedures; 15 bypasses, 1 of which overlapped with clipping; and 2 hematoma removals from the left frontal and temporal lobe) at Kashiwaba Neurosurgical Hospital from October 2016 to January 2018.

RESULTS

CCEPs could be reproducibly and routinely monitored in bilateral vascular surgeries. None of the patients experienced any postoperative symptoms or showed any ischemic lesions on postoperative magnetic resonance imaging; however, 5 patients temporarily demonstrated reduced CCEPs intraoperatively that were caused by transient obstructions of blood flow. Motor evoked potentials and somatosensory evoked potentials were simultaneously monitored intraoperatively and did not show any changes.

CONCLUSIONS

The results of our pilot study show that CCEPs can be routinely monitored during bilateral intracranial vascular surgery and that they are sensitive to ischemia. CCEPs on the left side could serve as unique intraoperative monitoring of speech function under anesthesia.