Factors Associated with Acute Obstructive Hydrocephalus After Retrosigmoid Approach for Extra-Axial Cerebellopontine Angle Tumors.

Background: This study aimed to identify the risk factors for acute obstructive hydrocephalus (AOHCP) after extra-axial cerebellopontine angle (CPA) tumor surgery using the retrosigmoid (RS) approach.

Methods: This retrospective study assessed 154 patients (100 vestibular schwannomas, 34 CPA meningiomas [MNGs], 9 trigeminal schwannomas, and 11 petroclival MNGs) who underwent surgical resection using the RS approach by a single surgeon between August 2010 and September 2019. AOHCP was defined as postoperative ventricular enlargement due to cerebrospinal fluid flow obstruction caused by surgery-related cerebellar injury within 1 week. The radiological characteristics of the tumors were classified, and the surgical outcomes were reviewed. We analyzed the impact of different factors on the development of AOHCP after surgery.

Results: AOHCP developed in 17 (11%) patients, all of whom were treated with external ventricular drain insertion. Multivariate analysis showed that CPA MNGs (odds ratio [OR], 37.98), grade of tumor extension beyond the petroclival junction (grade 1: OR, 16.42; grade 2: OR, 17.47), major fourth ventricle compression (OR, 17.77), and surgery-related hemorrhage (OR, 7.64) were associated with AOHCP. Surgery-related hemorrhage was observed in 17 (11%) patients. 9 (6%) patients underwent ventriculoperitoneal shunt surgery because of persistent HCP.

Conclusions: An increased risk of AOHCP after the RS approach was observed in patients with extra-axial CPA tumors with clival extension and major fourth ventricle compression. Compulsive and meticulous hemostasis must be achieved because postoperative hemorrhage is associated with AOHCP.