Internal maxillary artery to intracranial artery bypass: a case series of 31 patients with chronic internal carotid/middle cerebral arterial-sclerotic steno-occlusive disease

Enhanced Benefit of STA-MCA Bypass Surgery in Chronic Terminal Internal Carotid and/or Middle Cerebral Artery Occlusion Patients With Impaired Collateral Circulation: Introducing a Novel Assessment Approach for Collateral Compensation

Background: Ischemic stroke is one of the major emergency diseases leading to death and disability worldwide, characterized by its acute onset and the urgent need for prompt medical intervention to reduce mortality and long-term disability. Chronic terminal internal carotid artery and/or middle cerebral artery occlusion (CTI/MCAO) is an important subtype of intracranial artery occlusive disease. The superficial temporal artery-to-MCA (STA-MCA) bypass has been proposed to improve cerebral blood flow (CBF) and cerebrovascular reserve (CVR), potentially enhancing neurological outcomes. However, its safety and efficacy in CTI/MCAO patients remain controversial. Methods: A total of 107 CTI/MCAO patients from Nanjing Brain Hospital, enrolled between July 2019 and June 2022, were divided into surgical and medical treatment groups. Cerebral perfusion and collateral formation were evaluated using pseudocontinuous arterial spin labeling (pCASL) and digital subtraction angiography (DSA). Modified Rankin scale (mRS) score and complication rates were compared between the two groups. In addition, correlations between Matsushima grades, early-arriving flow proportion (EFP), and lesion-side cerebrovascular (LCBV) scores were analyzed. Results: The surgical group showed significantly lower mRS scores than the medical group (p=0.018), with no significant differences in complication rates at the 6-month follow-up (p=0.861). CBF differed significantly among affected MCA segments (p < 0.001), particularly in the insular and opercular regions (M2-M3) (p=0.006). Matsushima grades in unilateral CTI/MCAO patients were negatively correlated with preoperative LCBV scores (γ s = -0.468, p=0.005) and EFP (γ s = -0.648, p=0.007). EFP demonstrated high accuracy in predicting LCBV scores in CTI/MCAO patients (AUC = 0.902, p=0.004). Conclusion: STA-MCA bypass surgery improved neurological outcomes in CTI/MCAO patients, particularly those with poor preoperative collateral compensation. EFP may serve as a reliable, noninvasive tool for assessing collateral circulation status in this population.

Localization of Maxillary Artery for Cerebral Revascularization: L-Shaped Perpendicular Two-Step Drilling Technique Stretching from the Foramen Ovale to Rotundum

BACKGROUND

The use of the maxillary artery (MA) as a donor has increasingly become an alternative method for cerebral revascularization. Localization difficulties emerge due to rich infratemporal anatomical variations and the complicated relationships of the MA with neuromuscular structures. We propose an alternative localization method via the interforaminal route along the middle fossa floor.

METHODS

Five silicone-injected adult cadaver heads (10 sides) were dissected. Safe and effective localization of the MA was evaluated.

RESULTS

The MA displayed anatomical variations in relation to the lateral pterygoid muscle (LPM) and the mandibular nerve branches. The proposed L-shaped perpendicular 2-step drilling technique revealed a long MA segment that allowed generous rotation to the intracranial area for an end-to-end anastomosis. The first step of drilling involved medial-to-lateral expansion of foramen ovale up to the lateral border of the superior head of the LPM. The second step of drilling extended at an angle approximately 90° to the initial path and reached anteriorly to the foramen rotundum. The MA was localized by gently retracting the upper head of the LPM medially in a posterior-to-anterior direction.

CONCLUSIONS

Considering all anatomical variations, the L-shaped perpendicular 2-step drilling technique through the interforaminal space is an attainable method to release an adequate length of MA. The advantages of this technique include the early identification of precise landmarks for the areas to be drilled, preserving all mandibular nerve branches, the deep temporal arteries, and maintaining the continuity of the LPM.

Internal maxillary artery (IMax) - middle cerebral artery bypass in a patient with bilateral atherosclerotic carotid occlusion: A technical case report

Since the first description of the possible utilization of the internal maxillary artery for bypass surgery, there are some reports of its use in aneurysm cases; however, there is no information about the possible advantages of this type of bypass for cerebral ischemic disease. We present a 77-year-old man with a history of diabetes, hypertension, systemic atherosclerosis, and two acute myocardial infarctions with left hemiparesis. Imaging studies reported total occlusion of the right internal carotid artery and 75% occlusion on the left side, with an old opercular infarction and repeated transient ischemic attacks in the right middle cerebral artery territory despite medical treatment. After a consensus, we decided to perform a bypass from the internal maxillary artery to the M2 segment of the middle cerebral artery using a radial artery graft. After performing the proximal anastomosis, the calculated graft's free flow was 216 ml/min. Subsequently, after completing the bypass, the patency was confirmed with fluorescein videoangiography and intraoperative Doppler. Postoperatively, imaging studies showed improvement in the perfusion values and the hemiparesis from 3/5 to 4+/5. The patient was discharged one week after the operation, with a modified Rankin scale of 1, without added deficits. The use of revascularization techniques in steno-occlusive disease indicates a select group of patients that may benefit from this procedure. In addition, internal maxillary artery bypass has provided a safe option for large areas of ischemia that cannot be supplied with a superficial temporal artery - middle cerebral artery bypass.

Maxillary artery utilization in subcranial-intracranial bypass procedures: a comprehensive systematic review and pooled analysis

The utilization of the internal maxillary artery (IMAX) in subcranial-intracranial bypass for revascularization in complex aneurysms, tumors, or refractory ischemia shows promise. However, robust evidence concerning its outcomes is lacking. Hence, the authors embarked on a systematic review with pooled analysis to elucidate the efficacy of this approach. We systematically searched PubMed, Embase, and Web of Science databases following PRISMA guidelines. Included articles used the IMAX as a donor vessel for revascularizing an intracranial area and reported at least one of the following outcomes: patency, complications, or clinical data. Favorable outcomes were defined as the absence of neurologic deficits or improvement in the baseline condition. Complications were considered any adverse event directly related to the procedure. Out of 418 retrieved articles, 26 were included, involving 183 patients. Among them, 119 had aneurysms, 41 experienced ischemic strokes (transient or not), 2 had arterial occlusions, and 3 had neoplasia. Furthermore, 91.8% of bypasses used radial artery grafts, and 87.9% revascularized the middle cerebral artery territory. The median average follow-up period was 12 months (0.3-53.1). The post-operation patency rate was 99% (95% CI: 97-100%; I2=0%), while the patency rate at follow-up was 82% (95% CI: 68-96%; I2=77%). Complications occurred in 21% of cases (95% CI: 9-32%; I2=58%), with no significant procedure-related mortality in 0% (95% CI: 0-2%; I2=0%). Favorable outcomes were observed in 88% of patients (95% CI: 81-96%; I2=0%), and only 3% experienced ischemia (95% CI: 0-6%; I2=0%). The subcranial-intracranial bypass with the IMAX shows excellent postoperative patency and considerable favorable clinical outcomes. While complications exist, the procedure carries a minimal risk of mortality. However, long-term patency presents heterogeneous findings, warranting additional research.

Maxillary Nerve as Landmark for Exposure of the Internal Maxillary Artery in Extracranial-Intracranial Bypass Surgery

OBJECTIVE

To establish a new method for fast exposure of the internal maxillary artery (IMA) during extracranial-intracranial bypass surgery.

METHODS

To explore the positional relationship between the IMA and the maxillary nerve and pterygomaxillary fissure, 11 formalin-fixed cadaveric specimens were dissected. Three bone windows of the middle fossa were created for further analysis. Then the IMA length that could be pulled up above the middle fossa was measured after different degrees of removal of bony structure. The IMA branches under each bone window were also explored in detail.

RESULTS

The top of the pterygomaxillary fissure was located 11.50 mm anterolateral to the foramen rotundum. The IMA could be identified just inferior to the infratemporal segment maxillary nerve in all specimens. After drilling of the first bone window, the IMA length that could be pulled above the middle fossa bone was 6.85 mm. After drilling of the second bone window and further mobilization, the IMA length that could be harvested was significantly longer (9.04 mm vs. 6.85 mm; P < 0.001). Removal of the third bone window did not significantly improve the IMA length that could be harvested.

CONCLUSIONS

The maxillary nerve could be used as a reliable landmark for the exposure of the IMA in the pterygopalatine fossa. With our technique, the IMA could be easily exposed and sufficiently dissected without zygomatic osteotomy and extensive middle fossa floor removal.

Double-barreled IMA-M2 and STA-MCA bypass in severe stenosis of terminal internal carotid artery: three case reports

EC-IC bypasses have been performed to treat complex aneurysms or moyamoya disease or atherosclerotic steno-occlusive disease. We report the three cases that underwent EC-IC revascularization of the IMA-M2 bypass using the radial artery graft concurrently after the STA-MCA anastomosis to prevent potential ischemic damage during the operation and augment more flow in terminal internal carotid artery stenosis. All patients experienced neither perioperative complications nor further events for a 3-month follow-up. The double-barreled IMA-M2 and STA-MCA bypass is a good option for substantial amount of EC-IC revascularization with minimizing ischemic injury and maximizing flow amount in patients with severe hemodynamic compromise.

Sequential approach of internal maxillary-to-middle cerebral artery bypass and endovascular occlusion for giant middle cerebral artery aneurysm: a case report

Background

The combined approach to complex brain МСА aneurysm seems to be generally considered viable. Although it is fairly common, the combinations of modalities, which are suggested in different case reports, vary significantly. This case discusses a sequential approach of reconstructive microsurgery with internal maxillary-to-middle cerebral artery bypass followed by the balloon test occlusion and endovascular embolization of the aneurysm and the MCA. The combined approach together with use of maxillary artery helped minimize the intraoperative and postoperative complications.

Case presentation

A 62-year-old female with rare episodes of headache and depression revealed giant middle cerebral artery aneurysm. The patient underwent a combined operation in a hybrid operating room with no serious neurologic deficit after surgery.

Conclusions

Multimodality management in a hybrid operating room should be considered in case of complex fusiform aneurysm of MCA, which is associated with high risks of clipping. Thus, the sequential procedures will improve patient outcomes in treatment of complex МСА aneurysms.

Surgical therapy for chronic internal carotid artery occlusion: a systematic review and meta-analysis

Chronic internal carotid artery occlusion (CICAO) significantly increases the risk of recurrent stroke. Given unfavorable outcomes, revascularization procedures are not generally recommended for CICAO. In the last several years, loads of studies reported successful surgical revascularization for CICAO with promising success rate and favorable short-term outcomes. Meanwhile, due to the lack of high-quality evidence, the safety and efficacy of revascularization procedures remain debatable. This systematic review aims to scrutinize current evidence for the applicability of revascularization for CICAO. We also investigated potential predictors of postoperative prognosis. We searched clinical studies on surgical treatment of CICAO on the Medline, Cochrane library, and Embase databases, published from Jan 1990 to Jan 2021. Surgical operation was restricted to bypass surgery, endarterectomy, endovascular therapy, and hybrid surgery. Controlled clinical studies were included for clinical outcomes. Large-sample single-arm studies were supplemented to assess complications and success rate. Co-primary endpoints were technical success rate and neurological function; secondary endpoints were recurrent stroke/cerebrovascular events, complications, and deaths within follow-up. This systematic review has been registered in PROSPERO (CRD42020181250). One RCT and 5 cohort studies with a total of 465 patients were included in this review. Seven single-arm studies were supplemented for assessing success rate and complications. Bypass surgery presented the highest graft patency of 96% and a low incidence of complications, but no benefits on neurological function, recurrent stroke, or deaths. Endovascular therapy (carotid stenting) was characterized by a relatively lower technical success rate, significant neurological function recovery, and nonsignificant reduction of cerebrovascular events and deaths. Hybrid surgery was considered as a potential treatment for CICAO because of a high technical success rate and significant neurological improvement. Endarterectomy is only suitable for short-segment occlusion. Prospective clinical trials should focus on carotid stenting and hybrid surgery for their significant capacity of improving neurologic function and potential capacity of reducing deaths and cerebrovascular events.

Simultaneous PET-MRI imaging of cerebral blood flow and glucose metabolism in the symptomatic unilateral internal carotid artery/middle cerebral artery steno-occlusive disease

Purpose

Cerebral blood flow (CBF) and glucose metabolism are important and significant factors in ischaemic cerebrovascular disease. The objective of this study was to use quantitative hybrid PET/MR to evaluate the effects of surgery treatment on the symptomatic unilateral internal carotid artery/middle cerebral artery steno-occlusive disease.

Methods

Fifteen patients diagnosed with ischaemic cerebrovascular disease were evaluated using a hybrid TOF PET/MR system (Signa, GE Healthcare). The CBF value measured by arterial spin labelling (ASL) and the standardized uptake value ratio (SUVR) measured by ¹⁸F-FDG PET were obtained, except for the infarct area and its contralateral side, before and after bypass surgery. The asymmetry index (AI) was calculated from the CBF and SUVR of the ipsilateral and contralateral cerebral hemispheres, respectively. The ΔCBF and ΔSUVR were calculated as the percent changes of CBF and SUVR between before and after surgery, and paired t tests were used to determine whether a significant change occurred. Spearman’s rank correlation was also used to compare CBF with glucose metabolism in the same region.

Results

The analysis primarily revealed that after bypass surgery, a statistically significant increase occurred in the CBF on the affected side (P < 0.01). The postprocedural SUVR was not significantly higher than the preprocedural SUVR (P > 0.05). However, the postprocedural AI values for CBF and SUVR were significantly lower after surgery than before surgery (P < 0.01). A significant correlation was found between the AI values for preoperative CBF and SUVR on the ipsilateral hemisphere (P < 0.01).

Conclusions

The present study demonstrates that a combination of ASL and ¹⁸F-FDG PET could be used to simultaneously analyse changes in patients’ cerebral haemodynamic patterns and metabolism between before and after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery. This therefore represents an essential tool for the evaluation of critical haemodynamic and metabolic status in patients with symptomatic unilateral ischaemic cerebrovascular disease.

Minimally Invasive Exposure of the Maxillary Artery at the Anteromedial Infratemporal Fossa

BACKGROUND

The maxillary artery (MA) has been described as a reliable donor for extracranial-intracranial high-flow bypass. Existing techniques to harvest MA require brain retraction and drilling of the middle fossa (with or without a zygomatic osteotomy), carrying the potential risks of venous bleeding, injury to the branches of the maxillary or mandibular nerves, muscular transection, or temporomandibular junction disorders.

OBJECTIVE

To describe a novel technique to expose the MA without bony drilling and with minimal impact to surrounding structures.

METHODS

A conventional curvilinear incision was performed in 10 cadaveric specimens, prior to elevating the scalp to expose the zygomatic root and lateral orbital rim. The sphenozygomatic suture was followed to the anterolateral edge of the inferior orbital fissure (IOF) to locate and harvest the pterygoid segment of the MA. Topographic anatomy was assessed using surrounding landmarks and 3D Cartesian coordinates to define the surgical area. The number of visible MA branches and their lengths were recorded.

RESULTS

The MA was successfully exposed in all specimens. This approach allowed 6 branches of MA to be exposed. The average length of exposure was 23.3 ± 8.3 mm and the average surgical area was 2.8 ± 0.9 cm2. The IOF was 11.5 ± 4.2 mm from the MA.

CONCLUSION

Our technique provides landmarks to identify the distal pterygoid segment of MA as a donor for extracranial-intracranial bypasses without the need for additional craniectomies. Clear anatomical landmarks, including the sphenozygomatic suture, anterolateral edge of IOF, infraorbital artery, and the pterygomaxillary fissure defined a trajectory to efficiently localize the MA with minimal risk to surrounding structures.

Internal Maxillary Artery to Anterior Circulation Bypass with Local Interposition Grafts Using a Minimally Invasive Approach: Surgical Anatomy and Technical Feasibility

BACKGROUND

The internal maxillary artery (IMA) is a reliable donor for extracranial-intracranial high-flow bypasses. However, previously described landmarks and techniques to harvest the IMA are complex and confusing and require extensive bone drilling, carrying significant neurovascular risk. The objective of our study was to describe a minimally invasive technique for exposing the IMA and to assess the feasibility of using the IMA as a donor for anterior-circulation recipient vessels using 2 different local interposition vessels.

METHODS

Via a minimally invasive technique, the IMA was harvested in 10 cadaveric specimens and a pterional craniotomy was performed. Two interposition grafts-the superficial temporal artery (STA) and middle temporal artery-were evaluated individually. Transsylvian exposure of the second segment of middle cerebral artery (M2), the supraclinoid internal carotid artery, and the proximal postcommunicating anterior cerebral artery segment was completed. Relevant vessel calibers and graft lengths were measured for each bypass model.

RESULTS

The mean caliber of the IMA was 2.7 ± 0.5 mm. Of all 3 recipients, the shortest graft length was seen in the IMA-STA-M2 bypass, measuring 42.0 ± 8.4 mm. There was a good caliber match between the M2 (2.4 ± 0.4 mm) and STA (2.3 ± 0.4 mm) at the anastomotic site. The harvested middle temporal artery was sufficient in length in only 30% cases, with a mean distal caliber of 2.0 ± 0.7 mm.

CONCLUSIONS

This study confirmed the technical feasibility of IMA as a donor for an extracranial-intracranial bypass to the second segment of the anterior cerebral artery, M2, and the supraclinoid internal carotid artery. However, IMA-STA-M2 was observed to be the most suitable bypass model.

The History and Evolution of Internal Maxillary Artery Bypass

Internal maxillary artery (IMA) bypass has gained momentum in the last 5 years for the treatment of complex cerebrovascular disorders and skull base tumors. However, some issues regarding this treatment modality have been proposed. As one of the most experienced neurosurgical teams to perform internal maxillary artery bypass in the world (>100 clinical cases), we reviewed the literature in aspects of basic anatomy of maxillary artery with its variations to the lateral pterygoid muscle, initial anastomosis modalities, and subsequent exposure techniques in cadaver studies, preoperative arterial evaluation methods, optimal interposed graft selections, and surgical outcome in the management of complex aneurysms, skull base tumors, and steno-occlusive disorders.