Subtotal resection of vestibular schwannoma with subsequent Gamma Knife irradiation – tumor growth control, facial and cochlear nerve outcome – preliminary results

Introduction: The choice of treatment of vestibular schwannoma (VS) depends on several factors, including the tumor size, the patient’s age and overall health, and the presence and severity of symptoms.Aim: The aim of the study was to assess the effectiveness of intentional subtotal resection (STR) of tumor followed by Gamma Knife surgery (GKS) in patients with larger VS (Koos 3 and 4).Materials and methods: The retrospective analysis was performed on 18 patients. Data of VS volumes measured in MRI, the facial nerve function assessed in the House-Brackmann scoring system (HB), and the results of audiological examination expressed on the Gardner-Robertson scale (GR) were collected preoperatively, postoperatively, and post-GKS.Results: Preoperatively, the main symptom was hearing loss observed in 13 out of 18 patients. The facial nerve function was assessed as HB 1 in 16, whereas HB 2 in 2 patients. The mean volume of the tumor in the initial MRI amounted to 16.81 cm3 . Postoperatively, the facial nerve was assessed as HB 1 or 2 in 16, whereas HB 3 in 2 patients. Serviceable hearing was presented by only 4 persons. The Mean diameter of the tumor after subtotal surgery amounted to 3.16 cm3 , 1.83 cm3 after GKS, and 1.58 cm3 at the last follow-up. The facial nerve function and hearing level remained the same as before GKS in all patients.Conclusions: STR followed by GKS can be a safe and effective method of treatment of large VS concerning the functional outcome of the facial nerve and the tumor volume growth control.