Exposing Vertebral Artery from Lateral to Medial under the Guide of Peri-Vertebral Artery Fat Pad in Far Lateral Approach
The far lateral approach (FLA) and its modified techniques are fundamental surgical methods for addressing lesions located at the ventral or ventrolateral side of the foramen magnum. A critical step in this procedure is the exposure of the vertebral artery (VA), particularly the V3 segment. Traditionally, neurosurgeons have relied on the suboccipital triangle—formed by the rectus capitis posterior major, the superior oblique, and the inferior oblique muscles—as a key anatomical landmark to locate and expose the VA. However, this method presents several challenges. The suboccipital triangle varies in depth, morphology, and location among patients, increasing the risk of VA injury. Additionally, the overlying layers of muscles and blood vessels can obstruct the exposure, prolonging the craniotomy time. Variations in the VA’s course, such as looping backward or bulging posteriorly, further complicate the procedure, making it difficult to predict its exact location within the suboccipital triangle. These factors collectively heighten the risk of VA injury and extend the time required for successful exposure.
To address these challenges, this study introduces a novel surgical technique for identifying and exposing the V3 segment of the VA from lateral to medial in FLA. This method leverages the transverse process of the atlas (C1) and the peri-vertebral artery fat pad (PVAFP) as anatomical landmarks, eliminating the need to expose the suboccipital triangle. The PVAFP is a loose sheath, approximately 2 to 3 mm thick, that encases the VA along its course. Its presence has been previously described, and some studies have suggested using it as a guide for VA separation from medial to lateral. However, this approach can be problematic because the PVAFP is thin and difficult to recognize when dissecting from medial to lateral. In contrast, the proposed technique involves exposing the VA from lateral to medial, which is both safer and more efficient.
The study retrospectively analyzed patients who underwent FLA for ventral lesions of the foramen magnum between January 2014 and June 2020. Patients were divided into two groups: Group A, where the VA was exposed using the transverse process of C1 and PVAFP from lateral to medial, and Group B, where the VA was exposed through the suboccipital triangle from medial to lateral. The key clinical features, treatment, and outcomes were reviewed, with a focus on VA exposure duration, estimated blood loss (EBL), and VA injury.
The surgical procedure for Group A involved positioning the patient supine with the head tilted 45 to 60 degrees to the healthy side. For lesions extending to the axis plane, a lateral position was used, with the head bent 10 to 15 degrees to the healthy side on the coronal plane. The head was fixed using a Mayfield head holder. A C-shaped incision was made for supine patients, while an inverse U-shaped incision was used for lateral cases. After cutting and opening the skin flap, the muscles were transected horizontally along the linea nuchae superior and vertically along the extension line of the mastoid tip. The muscles were separated using a unipolar electrosurgical unit to reveal the PVAFP. The transverse process of C1 was palpated and located, and the course of the V3 segment was confirmed based on the PVAFP distribution. The attachment points of the superior and inferior oblique muscles to the atlas process were cut, and the PVAFP was stripped away using meningeal scissors along the V3 segment from lateral to medial. Any venous hemorrhage was controlled using bipolar coagulation. The periosteum was cut along the posterior side of the lamina of the atlas, and the VA was stripped in a subperiosteal manner from lateral to medial. The lamina of the atlas or axis was removed, and the bone flap was formed. The occipital condyle was drilled when necessary. The dura was opened in a rectilinear fashion, and the VA dural cuff was mobilized if needed.
In Group B, the VA was exposed using the traditional suboccipital triangle method. The results showed that Group A had a significantly shorter VA exposure duration (25.6 ± 3.1 minutes) compared to Group B (55.2 ± 6.2 minutes). The mean EBL was also significantly lower in Group A (50.6 ± 18.7 mL) than in Group B (248.3 ± 217.5 mL). There were no instances of VA injury in Group A, whereas two patients in Group B experienced VA injury. The pathological diagnoses in the study included meningioma, schwannoma, and vertebral aneurysm, with no significant differences in age, gender, or lesion size between the two groups. After a mean follow-up of 38.3 ± 19.4 months, all patients were alive, and recurrence was detected in two patients, both of whom received gamma-knife radiosurgery.
The study highlights several advantages of the novel technique. First, it eliminates the need to expose the suboccipital triangle, which can be time-consuming and risky due to its variability. Second, the PVAFP serves as an ideal anatomical gap for separating and exposing the VA, as it is easy to recognize and strip away, with minimal blood supply. Third, the transverse process of C1 provides a reliable bony landmark for locating the V3 segment. By cutting off all layers of muscles together from the occipital attachment point, including the inferior oblique and rectus capitis posterior major muscles, the procedure simplifies the exposure of the PVAFP and VA. This approach also reduces the risk of VA injury and minimizes blood loss, making it a safer and more efficient alternative to traditional methods.
The proposed technique is not only applicable to FLA but also to other surgical procedures involving the posterior craniocervical junction, such as C1–C2 hemilaminectomy, posterior cervical fusion, occipitocervical fusion, and VA cessation. The limitations of the study include its retrospective nature and the potential for selection bias. However, the results demonstrate that using the transverse process of C1 and PVAFP as anatomical landmarks and exposing the VA from lateral to medial is a clear, safe, fast, and non-bleeding technique in FLA.
In conclusion, this study presents a novel surgical technique for exposing the VA in FLA that addresses the limitations of traditional methods. By leveraging the transverse process of C1 and the PVAFP, neurosurgeons can achieve a safer and more efficient exposure of the VA, reducing the risk of injury and minimizing blood loss. This technique represents a significant advancement in the field of neurosurgery and has the potential to improve outcomes for patients undergoing FLA and related procedures.
doi.org/10.1097/CM9.0000000000001947
Was this helpful?
0 / 0