The Retrolabyrinthine Presigmoid Approach: An Underutilized Approach for Safe Resection of Expansive CP Angle Tumors

Purpose: We present our outcomes for patients undergoing a retrolabyrinthine presigmoid approach for tumor resection, and its benefit over retrosigmoid versus more lateral approaches.

Background: Pathologies of the CP angle amenable to the retrolabyrinthine presigmoid approach include vestibular schwannomas and meningiomas, amongst others. MRI remains the gold standard for assessing mass effect on adjacent brainstem and cranial nerves, invasion of bony foramina, as well as location of vascular structures. CT is helpful for understanding petrous bone anatomy. Intra-operative navigation and neuromonitoring is helpful for identifying cranial nerves which may be encased or displaced within a tumor mass.

Methods: A retrospective review of illustrative patients presenting between July 2015 and January 2019 was performed. Clinical data and radiographic parameters were reviewed using electronic medical records.

Results: A total of 20 illustrative patients were reviewed. Fifteen (75%) patients were women and the average age was 46 years (16–74). Pathologies included vestibular schwannoma (n = 8), meningioma (n = 6), epidermoid (n = 3), chordoma (n = 1), cranial nerve 4 schwannoma (n = 1), and cranial nerve 5 schwannoma (n = 1). The average tumor size was 18.9 ± 14.1 cm³. Gross total resection was accomplished in 14 (70%) of cases with an average estimated blood loss of 264 ± 161 cc. Average surgical time was 13:47. Complications associated with the approach included cranial neuropathies that were temporary in 4 patients (20%) and permanent in 4 patients (20%), CSF leak (n = 2, 10%), pseudomeningocele (n = 2, 10%), and wound dehiscence (n = 1, 5%). Need for permanent CSF diversion was required in two patients (10%).

Conclusion: As compared with the retrosigmoid and more lateral approaches, the retrolabyrinthine presigmoid approach allows for ample exposure and freedom of surgical manipulation of the sigmoid sinus, tentorium, and tumor mass without the morbidity associated with significant retraction or violating middle ear structures.

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