Surgical Resection following Primary Radiation Treatment for Vestibular Schwannomas: Does Radiation Impact Surgical Outcomes and Extent of Resection?
Objective: With the advent of highly focused delivery of radiation, an increasing number of vestibular schwannomas are being treated this way. A minority of these patients will fail this management strategy and require subsequent treatment. Early studies have shown poor post-operative facial function pressumably due to radiation-induced fibrosis and adhesions to surrounding neurovascular structures. We present our experience with salvage surgical procedures following failed primary radiation treatment for vestibular schwannomas.
Methods: We performed a retrospective review of patients with unilateral vestibular schwannomas who underwent surgical resection following failed primary radiation treatment. No patient had prior surgery for the same lesion and NF2 patients were excluded. We present patient demographic information, pre-operative radiation treatment modality and pre-operative facial nerve function. We review operative approach, pathology, extent of resection, facial nerve function, tumor control and complications.
Results: 5 patients with vestibular schwannomas previously treated with radiation underwent surgical resection. 3 patients received prior SRS and 2 patients received prior fractionated radiotherapy. Average time between radiation treatment and surgery was 42 months. No patients had serviceable hearing prior to surgery. All patients underwent a translabyrinthine approach. A gross total resection was achieved in 4 patients (80%), and a subtotal resection in 1 patient (20%). 3 patients (60%) had a good (HBI & II) post-operative facial nerve outcome. 2 patients had a HB IV facial nerve palsy. Pathology revealed WHO I vestibular schwannoma in all patients. No patient had post-operative tumor progression with an average of 27 months follow up.
Conclusion: Vestibular schwannomas that have failed primary radiation can present a difficult treatment dilemma to the surgeon. Although radiation effects can increase the potential for post-operative cranial nerve dysfunction and decrease the likelihood of achieving a gross total resection, surgical resection with modern surgical technique is a safer and more effective treatment than what earlier data would suggest.