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

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.

Internal Maxillary Artery-Radial Artery-Middle Cerebral Artery Bypass and STA-MCA Bypass for the Treatment of Complex Middle Cerebral Artery Bifurcation Aneurysm: A Case Report

Background

Children's complex middle cerebral artery (MCA) aneurysm is a relatively rare occurrence. When the huge aneurysm is located in the MCA bifurcation with an inconspicuous neck and involving numerous arteries, intravascular interventional surgery or aneurysm clipping are often difficult treatment options. At this point, high flow bypass revascularization is necessary as a treatment to preserve cerebral blood flow. In recent years, the internal maxillary artery (IMA) has gradually become the mainstream donor artery of thw high flow bypass. We performed internal maxillary artery -radial artery-middle cerebral artery (IMA-RA-MCA) and superficial temporal artery-middle cerebral artery (STA-MCA) bypass as the treatment of a complex MCA bifurcation aneurysm in consideration of the patient's condition and the advantage of the IMA. According to the author, this case is the youngest reported case of IMA-RA-MCA bypass at present.

Case Description

A male child, 7 years and 8 months, was admitted to the hospital due to “recurrent headache for more than 9 months,” DSA indicated that there was a large wide-necked aneurysm at the bifurcation of the right MCA M1 segment, with a size of about 1.16*1.58*1.32 cm. The inflow path of the aneurysm was in front of M1 bifurcation, and one outflow path originated from the aneurysm body, and another small outflow path attached to the aneurysm body. After completing the preoperative evaluation, an extended pterional approach with zygomatic osteotomy was performed to fully expose the aneurysm and IMA, harvesting the left radial artery at the same time, then a STA-MCA bypass, IMA-RA-MCA bypass, and aneurysm trapping were performed. postoperative re-examination showed that bypass vessels and the distal middle artery vessels were patent and the aneurysm disappeared, the child has no neurological dysfunction.

Conclusions

IMA-RA-MCA bypass is an effective high-flow cerebral blood reconstruct scheme in the treatment of complex middle cerebral artery bifurcation aneurysms. This case can provide a reference for the surgical treatment of complex middle cerebral artery bifurcation aneurysms in children.

Imaging features of internal maxillary artery and extracranial middle meningeal artery and their relationships on head CTA

BACKGROUND

The internal maxillary artery and extracranial middle meningeal artery are vitally important. Anatomical studies of the relationship of between them using computed tomography angiography are rare.

MATERIAL AND METHODS

This study assessed 75 cases involving 150 sides. And the vascular diameters and lengths of the internal maxillary artery and middle meningeal artery were measured using a GE workstation. The distance between the zygomatic arch midpoint and the internal maxillary artery, the angle between the internal maxillary artery and middle meningeal artery were measured, and the middle meningeal artery branch and internal maxillary artery aneurysm were recorded. The internal maxillary artery course classifications were recorded. All of these parameters were statistically analysed.

RESULTS

Ages ranged from 18 to 72 (average 40.2) years, and there were 30 women (40%, 30/75) and 45 men (60%, 45/75). Internal maxillary artery length from its origin to middle meningeal artery origin was 1.37 ± 0.59 cm. The extracranial middle meningeal artery length was 1.79 ± 0.48 cm. The vessel diameters of internal maxillary artery origin, middle meningeal artery origin, and middle meningeal artery at the skull base were 2.93 ± 0.52 mm, 1.58 ± 0.43 mm, and 1.33 ± 0.43 mm, respectively. Among the 150 sides of internal maxillary artery course type, there were 138 superficial (92%, 138/150) and 12 (8%, 12/150) deep course cases. The angle between the internal maxillary artery and middle meningeal artery was 116.2 ± 35.76°.

CONCLUSIONS

The findings of this study elucidate the imaging features of the internal maxillary artery and extracranial middle meningeal artery and their relationships, which are helpful for the extracranial-intracranial bypass and endovascular treatment via the internal maxillary artery and middle meningeal artery.

Angio-anatomical study of the pterygovaginal artery based on cone-beam computed tomography

PURPOSE

To investigate the anatomical characteristics and clinical implications of the pterygovaginal artery (PtVA), a recurrent branch from the distal internal maxillary artery (IMA), which courses through the pterygovaginal canal that connects the pterygopalatine fossa and nasopharynx.

METHODS

Eighty-two patients with 90 sides of cone-beam computed tomography (CBCT) reconstructed from rotational angiography of the external or common carotid artery with a field of view covering the pterygopalatine fossa were retrospectively reviewed. The origin from the IMA, branching type, distribution, and anastomoses was evaluated. The underlying lesions were 36 hypervascular lesions with possible supply from PtVA (17 cavernous sinus arteriovenous fistulas (AVFs), 6 anterior condylar AVFs, and 13 nasopharyngeal, parasellar, or paraclival tumors) and 46 other diseases.

RESULTS

PtVA was identified in 75 sides (83%). It originated from the pterygopalatine segment of the IMA in 45 sides (60%) and from the pterygoid segment in 30 sides (40%). It arose independently (77%), sharing the common trunk with the Vidian artery (15%) or with other branches. It ran posteromedially through the pterygovaginal canal to supply the mucosa over the nasopharyngeal roof, the choanae, and the pharyngeal ostium of the eustachian tube. It anastomosed with the ascending pharyngeal artery (n=37), the accessory meningeal artery (n=7), and the mandibular artery from the petrous internal carotid artery (n=2). It served as a feeder of osseous AVFs and skull base tumors.

CONCLUSION

PtVA was often identified by CBCT even in normal anatomy. Its detailed angio-anatomy could be evaluated in the presence of parasellar or paraclival hypervascular lesions.

Pterygo-Maxillary Fissure as a Landmark for Localization of Internal Maxillary Artery for Use in Extracranial-Intracranial Bypass

BACKGROUND

Internal maxillary artery (IMax) is a relatively new donor vessel used in the extracranial-intracranial bypass surgery. However, unfamiliarity and relatively elaborate techniques of its harvest precluded its widespread use.

OBJECTIVE

To present a simplified technique of IMax harvest based on constant anatomical landmarks without the need of extensive skull-base drilling while providing adequate space for proximal anastomosis.

METHODS

Cadaveric dissection on 4 cadaveric heads (8 sides) was performed. Zygomatic osteotomy was performed and temporal muscle was dissected off the zygomatic process of the frontal bone and the frontal process of the zygomatic bone and reflected inferiorly into the bony gap created by the zygomatic osteotomy. Posterior wall of the maxilla (PWoM) was palpated. Following PWoM inferiorly leads to pterygo-maxillary fissure (PMF), which is a constant landmark IMax passes through.

RESULTS

IMax was localized following this technique before its entrance into PMF in every specimen. Proximal dissection was carried on to the exposed adequate length of the vessel. Depending on the relationship with the lateral pterygoid muscle, this might need to be incised to allow for identification of the IMax. After its transection, proximal stump is mobilized superiorly into the surgical field. Clinical application of this technique was demonstrated on an aneurysm case.

CONCLUSION

Using the palpation of the PWoM as a landmark for localization of PMF facilitates harvesting of IMax without need for extensive skull-base drilling and shortens the time of the surgery.

Microsurgical Techniques for Exposing the Internal Maxillary Artery in Cerebral Revascularization Surgery: A Comparative Cadaver Study

BACKGROUND

The internal maxillary artery (IMAX) is currently considered one of the main donor vessels in extracranial-to-intracranial bypass surgeries. Four main techniques for harvesting the IMAX have been described: via the anterior medial infratemporal fossa (AMITF), the middle infratemporal fossa (MITF), the anterior lateral middle fossa (ALMF), and the lateral middle fossa (LMF). The advantages and limitations of these techniques have not yet been systematically evaluated and compared.

METHODS

Twenty-five cadaver specimens were used to evaluate the harvesting technique. The length and the caliber of the targeted IMAX segments, as well as the depth from the operating plane to the IMAX, surgical time, and surgical area of exposure, were analyzed.

RESULTS

The MITF technique provided the greatest operating area of exposure (mean, 3.88 ± 0.97 cm²). The LMF and MITF techniques provided the largest IMAX caliber (mean, 3.1 ± 0.4 mm and 3.0 ± 0.3 mm, respectively). The ALMF technique provided the shallowest operative depth as well as the least time of exposure (21.8 minutes). The MITF technique exposed the longest IMAX segment (mean, 18.8 ± 3.5 mm).

CONCLUSIONS

Advantages of the AMITF and MITF techniques include anatomic simplicity, absence of skull base drilling, and greater discretion in muscle dissection. These properties can simplify the anastomosis procedure compared with the ALMF and LMF techniques. Identification of the IMAX pattern is important before selecting the approach for this bypass operation.

Internal maxillary artery bypass for the treatment of complex middle cerebral artery aneurysms

OBJECTIVEThe rapid innovation of the endovascular armamentarium results in a decreased number of indications for a classic surgical approach. However, a middle cerebral artery (MCA) aneurysm remains the best example of one for which results have favored microsurgery over endovascular intervention. In this study, the authors aimed to evaluate the experience and efficacy regarding surgical outcomes after applying internal maxillary artery (IMA) bypass for complex MCA aneurysms (CMCAAs).METHODSAll IMA bypasses performed between January 2010 and July 2018 in a single-center, single-surgeon practice were screened.RESULTSIn total, 12 patients (9 males, 3 females) with CMCAAs managed by high-flow IMA bypass were identified. The mean size of CMCAAs was 23.7 mm (range 10-37 mm), and the patients had a mean age of 31.7 years (range 14-56 years). The aneurysms were proximally occluded in 8 cases, completely trapped in 3 cases, and completely resected in 1 case. The radial artery was used as the graft vessel in all cases. At discharge, the graft patency rate was 83.3% (n = 10), and all aneurysms were completely eliminated (83.3%, n = 10) or greatly diminished (16.7%, n = 2) from the circulation. Postoperative ischemia was detected in 2 patients as a result of graft occlusion, and 1 patient presenting with subarachnoid hemorrhage achieved improved modified Rankin Scale scores compared to the preoperative status but retained some neurological deficits. Therefore, neurological assessment at discharge showed that 9 of the 12 patients experienced unremarkable outcomes. The mean interval time from bypass to angiographic and clinical follow-up was 28.7 months (range 2-74 months) and 53.1 months (range 19-82 months), respectively. Although 2 grafts remained occluded, all aneurysms were isolated from the circulation, and no patient had an unfavorable outcome.CONCLUSIONSThe satisfactory result in the present study demonstrated that IMA bypass is a promising method for the treatment of CMCAAs and should be maintained in the neurosurgical armamentarium. However, cases with intraoperative radical resection or inappropriate bypass recipient selection such as aneurysmal wall should be meticulously chosen with respect to the subtype of MCA aneurysm.

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.