Further Study of Craniotomy in Suboccipital Retrosigmoid Keyhole Approach.

BACKGROUND

The suboccipital retrosigmoid approach represents a classic and mainstream surgical corridor for the management of cerebellopontine angle lesions. Our team has previously proposed a novel, precise keypoint localization strategy termed the "one point, two lines, two distances" theory. Nevertheless, the standardized procedural techniques for craniotomy based on this localization system remain undefined and unspecified.

OBJECTIVE

On the basis of the aforementioned landmark localization system, this study aimed to elaborate on the standardized surgical techniques for retrosigmoid craniotomy and summarize the clinical efficacy and safety of this modified approach in clinical practice.

METHODS

Anatomic correlations between the defined cranial landmarks were systematically analyzed to establish a precise, safe, and standardized protocol for keyhole suboccipital retrosigmoid craniotomy. Cadaveric skull dissection was performed to verify the feasibility and reproducibility of the proposed technique. In addition, a retrospective clinical analysis was conducted on 122 consecutive patients who underwent surgery using this approach. Intraoperative localization accuracy, surgical safety, and lesion exposure quality were comprehensively evaluated.

RESULTS

Craniotomy simulation was performed on 12 cadaveric skull specimens. Following keypoint burr hole drilling, the cranial bone flap was elevated and dissected sequentially in a posterior-inferior-anterior direction. The osteotomy trajectory traversed the superior point of the digastric sulcus. The osseous tissue surrounding the mastoid emissary vein was meticulously removed using a high-speed surgical drill, and residual bony structures along the sigmoid sinus margin were subsequently resected. All cadaveric simulations and clinical operations in the 122-patient cohort achieved satisfactory craniotomy bone windows with optimal surgical field exposure. No injuries to vital neurovascular structures were observed in any case.

CONCLUSION

The craniotomy technique anchored by the superior point of the digastric sulcus is a reliable and reproducible surgical method for keyhole suboccipital retrosigmoid craniotomy, which can provide stable anatomic guidance for cerebellopontine angle lesion surgery.