Surgical management of vestibular schwannomas after failed radiation treatment

Abstract

Increasing numbers of patients with vestibular schwannoma (VS) have been treated with focused-beam stereotactic radiation treatment (SRT) including Gamma knife, CyberKnife, X-knife, Novalis, or proton beam therapy. The purpose of this study was to document the incidence of tumor regrowth or symptoms that worsened or first developed following SRT and to discuss surgical strategies for patients who have failed SRT for VS. A consecutive series of 39 patients with SRT failed VS were surgically treated. Clinical symptoms, tumor regrowth at follow-up, intraoperative findings, and surgical outcome were evaluated. There were 15 males and 24 females with a mean age of 51.8 years. Thirty-six patients (92.3%) demonstrated steady tumor growth after SRT. Two (5.1%) patients with slight increase of the mass underwent surgical resection because of development of unbearable facial pain. Symptoms that worsened or newly developed following SRT in this series were deafness (41%), dizziness (35.9%), facial numbness (25.6%), tinnitus (20.5%), facial nerve palsy (7.7%), and facial pain (7.7%). Intraoperative findings demonstrated fibrous changes of the tumor mass, cyst formation, and brownish-yellow or purple discoloration of the tumor capsule. Severe adhesions between the tumor capsule and cranial nerves, vessels, and the brainstem were observed in 69.2%. Additionally, the facial nerve was more fragile and irritable in all cases. Gross total resection (GTR) was achieved in 33.3% of patients, near-total resection (NTR) in 35.9%, and subtotal resection (STR) in 30.8% of patients. New facial nerve palsy was seen in seven patients (19.4%) postoperatively. Our findings suggest that patients with VS who fail SRT with either tumor progression or worsening of clinical symptoms will have an increased rate of adhesions to the neurovascular structures and may have radiation-influenced neuromalacia. Salvage surgery of radiation-failed tumors is more difficult and will have a higher risk of postoperative complications. Radical total resection may not be feasible, and conservative modality of subtotal resection needs to be considered to avoid new neurologic deficits.

Surgical management for large vestibular schwannomas: a systematic review, meta-analysis, and consensus statement on behalf of the EANS skull base section

“…In their recent literature review, Husseini et al [68] reported a worsened FN function in rescue surgery in up to 83% of cases, difficult dissection between 43 and 100%, and rates of GTR between 0 and 89%. These results are in line with data published in the largest series [40,68,120,141,179], which agree that salvage surgery is associated with increased risk of nerve damage and greater difficulty in dissection. Caution should be exercised in interpreting this data as most series include a small number of cases, a heterogenous group of patients operated by surgeons of varying experiences [48].…”

Facial nerve outcome and extent of resection in cystic versus solid vestibular schwannomas in radiosurgery era

“…The reported rates of GTR after CVS surgery range between 44% and 94.6%, 22,28,35,37 depending on the size and extension of the tumor, history of previous treatment, and the surgeon's experience. 26,28,31 In the present study, the rate of GTR was not significantly different between CVSs and SVSs (p = 0.08). Although residual CVSs have been reported to be associated with rapid regrowth requiring reoperation, 18,35 we have not observed regrowth in any of our patients with residual CVSs.…”

“…Moreover, surgery after failed radiosurgery may result in decreased rates of GTR as well as increased morbidity due to adhesions and thickening and increased hypervascularity of the tumor capsule. 26 We believe that, in cases of large cystic tumors with brainstem compression, microsurgical resection remains the treatment of choice whenever GTR or NTR is possible. 2,11 Nonetheless, multicenter comparative studies with large numbers of patients and longer follow-up periods are warranted to compare the efficacy of radiosurgery versus microsurgery in the management of large CVSs.…”

Predictive factors of acoustic neuroma growth

“…Moreover several studies, about surgical excision after radiotherapy report technical difficulties, adhesion of the facial nerve to the tumor remnant, scarring and fibrosis, were increasing complications potential. 31,32 Hearing preservation potential could be an important treatment choice factor. Elliot et al did not find statistically significant differences in hearing assessment between conservatively managed patients and patients who underwent stereotactic radiosurgery, in a 132 case series.…”