Occipital Artery and Its Segments in Vertebral Artery Revascularization Surgery: A Microsurgical Anatomic Study

Use of Occipital Vessels in Head and Neck Microvascular Reconstruction: A Comprehensive Preclinical Evaluation

OBJECTIVES

To assess the use of occipital vessels for microvascular anastomosis in head and neck free tissue transfer reconstruction.

METHODS

A literature search was undertaken to identify studies utilizing the occipital vessels for microvascular anastomosis in free tissue transfer. Following literature review, 30 anatomic cadaveric dissections on 15 fresh unfixed cadavers were performed to evaluate the occipital artery and identify a reliable vein within reasonable proximity. In addition, vessel caliber pre- and post-dilation was recorded, along with vessel geometry.

RESULTS

The mean (SD) artery diameter was 2.0 (0.4) mm pre-dilation and 2.8 (0.56) mm post-dilation. An accompanying occipital vein was identified in 20% of dissections (n = 6), with a mean (SD) vein diameter of 1.85 (0.85) mm pre-dilation and 3.5 (0.93) mm post-dilation. When an accompanying occipital vein was not present, the external jugular vein was identified as a suitable vessel for venous outflow. This vessel was identified from 1.0 to 5.0 cm from the mastoid tip, with a mean of 3.3 cm.

CONCLUSIONS

The occipital artery may be reliably identified using a limited post-auricular incision. An accompanying occipital vein may be present in a minority of cases; however, the external jugular vein may be easily identified by extending this incision. The occipital vessels may be useful in reconstruction of posterior scalp defects or for use in vessel-depleted necks.

LEVEL OF EVIDENCE

N/a Laryngoscope, 2025.

Indications, operative techniques, and outcomes of occipital artery-vertebral artery bypass: an institutional series

PURPOSE

Posterior circulation cerebral bypasses often show higher risks and lower patency. Only few reports discussed occipital artery (OA)-vertebral artery (VA) bypasses. We present our illustrative cases to address current gaps in the literature on OA-VA bypass.

METHODS

A single-center retrospective review was conducted to include all institutional cases of OA-VA bypass, discussing the technique and outcomes.

RESULTS

Four institutional cases undergoing a total of 5 bypasses were evaluated, including 3 males and 1 female, with median age of 65 years (range, 62-73). All patients had vertebrobasilar insufficiency (VBI) with recurrent strokes/TIAs due to intracranial atherosclerosis, leading to unilateral VA stenosis with contralateral occlusion (1, 25%), bilateral VA stenosis (1, 25%) or occlusion (1, 25%). Medical management included aspirin for all cases (100%), with clopidogrel in 3 (75%). Surgery was performed through a far lateral approach, connecting the OA to the VA-3 segment, with no inter-positional graft. One patient underwent contralateral OA-VA bypass 6 months after the prior surgery due to worsening of the contralateral VA stenosis. Bypass patency was confirmed in all cases with post-operative angiography. All patients had clinical improvement, with one case of wound dehiscence managed conservatively. All patients were alive at last follow-up (median 7.0 months; range: 1.5-18).

CONCLUSION

OA-VA bypass is a challenging yet effective strategy in selected patients with VBI. Current literature lacks unique definitions of surgical indications and techniques, which we addressed in our series. Surgical education should focus on expanding the microsurgery anatomy knowledge.

The Vascularized Occipital Fascial Flap (OFF): A Novel Reconstructive Technique for Posterior Fossa Surgery

BACKGROUND

Posterior fossa surgery is particularly prone to cerebrospinal fluid (CSF) leakage. Several methods have been introduced to address and/or prevent this complication. However, to the best of our knowledge, the use of a vascularized fascial flap based on the occipital artery for the purpose of reconstruction has not been reported. We introduce the occipital fascial flap (OFF) for reconstruction of a craniectomy defect after the retrosigmoid approach.

METHODS

A 57-year-old woman with a large cerebellar metastasis underwent gross total resection of the mass followed by reconstruction of the craniectomy defect using OFF.

RESULTS

Postoperative imaging showed flap viability and no CSF leak occurred during follow-up.

CONCLUSIONS

We report the first use of OFF for reconstruction of a craniectomy defect in a retrosigmoid approach. The vascularized fascial flap in posterior fossa surgery is a potentially helpful technique to reduce the risk of CSF leak in high-risk patients.

Challenges in Using the Posterior Inferior Cerebellar Artery for Revascularization of the Anterior Inferior Cerebellar Artery: A Microsurgical Anatomic Study

BACKGROUND

A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis.

METHODS

Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured.

RESULTS

PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm.

CONCLUSIONS

The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.

Retromastoid-transmuscular identification and harvest of the occipital artery during retrosigmoid craniotomy

OBJECTIVE

Harvesting the occipital artery (OA) is challenging. The subcutaneous OA is usually found near the superior nuchal line and followed proximally, requiring a large incision and risking damage to the superficially located OA. The authors assessed the anatomical feasibility and safety of exposing the OA through a retromastoid-transmuscular approach.

METHODS

Using 10 cadaveric heads, 20 OAs were harvested though a 5-cm retroauricular incision placed 5 cm posterior to the external auditory meatus. The underlying muscle layers were sequentially cut and recorded before exposing the OA. Changes in the orientation of muscle fibers were used as a roadmap to expose the OA without damaging it.

RESULTS

The suboccipital segment of the OA was exposed without damage after incising two consecutive layers of muscles and their investing fasciae. These muscles displayed different fiber directions: the superficially located sternocleidomastoid muscle with vertically oriented fibers, and the underlying splenius capitis with anteroposteriorly (and mediolaterally) oriented fibers. The OA could be harvested along the entire length of the skin incision in all specimens. If needed, the incision can be extended proximally and/or distally to follow the OA and harvest greater lengths.

CONCLUSIONS

This transmuscular technique for identification of the OA is a reliable method and may facilitate exposure and protection of the OA during a retrosigmoid approach. This technique may obviate the need for larger incisions when planning a bypass to nearby arteries in the posterior circulation via a retrosigmoid craniotomy. Additionally, the small skin incision can be enlarged when a different craniotomy and/or bypass is planned or when a greater length of the OA is needed to be harvested.

Carotid-vertebral artery bypass with saphenous vein graft for symptomatic vertebrobasilar insufficiency

OBJECTIVESymptomatic steno-occlusion of the proximal vertebral artery (VA) or subclavian artery (ScA) heralds a poor prognosis and high risk of stroke recurrence despite medical therapy, including antiplatelet or anticoagulant drugs. In some cases, the V2 segment of the cervical VA is patent and perfused via collateral vessels. The authors describe 7 patients who were successfully treated by external carotid artery (ECA)-saphenous vein (SV)-VA bypass.METHODSSeven cases involving symptomatic patients were retrospectively studied: 3 cases of V1 segment occlusion, 2 cases of severe in-stent restenosis in the V1 segment, and 2 cases of occlusion of the proximal ScA. All patients underwent ECA-SV-VA bypass. The ECA was isolated and retracted, and the anterior wall of the transverse foramen was unroofed. The VA was exposed, and then the 2 ends of the SV were anastomosed to the VA and ECA in an end-to-side fashion.RESULTSSurgical procedures were all performed as planned, with no intraoperative complications. There were 2 postoperative complications (severe laryngeal edema in one case and shoulder weakness in another), but both patients recovered fully and measures were taken to minimize laryngeal edema and its effects in subsequent cases. All patients experienced improvement of their symptoms. No new neurological deficits were reported. Postoperative angiography demonstrated that the anastomoses were all patent, and analysis of follow-up data (range of follow-up 12-78 months) revealed no further ischemic events in the vertebrobasilar territory.CONCLUSIONSThe ECA-SV-VA bypass is a useful treatment for patients who suffer medically refractory ischemic events in the vertebrobasilar territory when the proximal part of the VA or ScA is severely stenosed or occluded but the V2 segment of the cervical VA is patent.

A Microanatomical Study of the Far Lateral Approach

OBJECTIVE

The far-lateral approach (FLA) remains a challenge for neurosurgeons due to the complex anatomy of this region, especially in patients with anatomical variations. There is therefore an urgent need for better quantitative knowledge of the microsurgical anatomy of the FLA.

METHODS

The study was performed using the dried skulls and atlas vertebrae of 50 Chinese adults, in which significant clinical parameters were measured. We further used 12 cadaveric heads to simulate the FLA to explore the step-by-step anatomy entailed by this procedure, enabling us to obtain key images and related information.

RESULTS

Limited to hypoglossal canal, the occipital condyle posterior was abraded by roughly 10 mm, which provided good exposure to the ventral front of the foramen magnum. When occipital artery exits the occipital groove, the mean diameter was 2.20 mm. The average occipital artery suboccipital segment length was 65.26 mm. The posterior spinal artery (PSA) and posterior inferior cerebellar artery (PICA) generally originated from the fourth vertebral artery segment intradurally, and the mean distances from the PSA and PICA to the dural entry point of the vertebral artery were 2.62 mm and 8.71 mm, respectively. The incidence of PSA and PICA arising from the third vertebral artery segment was 16.67% and 4.17%, respectively.

CONCLUSIONS

Understanding the important anatomic structures of the CVJ region and developing improved knowledge of the microsurgical anatomy of the FLA offer an opportunity to ensure safe exposure and treatment of lesions in the ventral and ventrolateral regions of the CVJ.

Posterior Cerebral Artery Reconstruction by In-Situ Bypass with Superior Cerebellar Artery via Occipital Transtentorial Approach

BACKGROUND

Posterior cerebral artery (PCA) aneurysms are relatively rare, and neck clipping is often difficult due to their fusiform shape. We report a case of a thrombosed aneurysm of the distal PCA for which curative trapping and parent artery reconstruction by in situ bypass were performed through an occipital transtentorial approach (OTA).

CASE DESCRIPTION

A 67-year-old woman had been suffering from numbness in the right face and limbs for 4 months. Radiologic imaging demonstrated a thrombosed aneurysm on a distal portion of the left PCA. Curative trapping of the aneurysm and in-situ bypass between the distal PCA and superior cerebellar artery were performed through the OTA. Before surgery, we had evaluated access to the PCA and feasibility of the bypass in a cadaveric simulation. The PCA was well exposed in the posterior half of the ambient cistern, and the proximity of the distal PCA to the superior cerebellar artery through a tentorial incision was confirmed.

CONCLUSIONS

This OTA could represent a useful option for definitive treatment of distal PCA aneurysms.