Therapy of Sporadic and NF2-Related Vestibular Schwannoma

Abstract

Vestibular schwannoma (VS) is a benign primary brain tumor that occurs sporadic or as part of a genetic syndrome. The most common cause is the mutation of the NF2 tumor suppressor gene that is involved in the production of the protein merlin. Merlin plays a role in cell growth and cell adhesion. In patients with NF2, the VSs arise bilaterally and coincide with other brain tumors. In sporadic VS, the tumor is typically unilateral and does not coincide in combination with other tumors. MRI is the standard imaging technique and can be used to assess the size and aspect of the tumor as well as the progression of disease. The preferred management of large VS in both VS types is surgery with or without adjuvant radiation. The management for the medium- or small-sized VS includes wait and scan, radiotherapy and/or surgery. This choice depends on the preference of the patient and institutional protocols. The outcomes of surgical and radiotherapy treatments are improving due to progress in surgical equipment/approaches, advances in radiation delivery techniques and dose optimizations protocols. The main purpose of the management of VS is preserving function as long as possible in combination with tumor control.

Surgical Outcome of Trigeminal Schwannomas

“…Nowadays, we know that each treatment decision in NF2 disease requires a complete evaluation of all cranial and spinal locations of the disease in order to establish surgical priorities and strategies. Yao et al already stated in case of vestibular schwannomas, that preferred management is surgery followed by radiation, depending on institutional protocols [ 34 ]. They also reported that management for medium- or small-sized vestibular schwannomas may include wait and watch, radiotherapy and/or surgery regarding to the patients’ preference or also the institutional standards.…”

“…Stereotactic radiotherapy was associated with better facial nerve function, hearing preservation and quality of life. A cohort study compared the outcomes of stereotactic radiotherapy and surgery in vestibular schwannomas with a tumor diameter ≤ 2.8 cm with no differences observed in terms of functional outcomes, tumor control and mortality [ 34 , 35 , 36 ].…”

“…Despite of wide acceptance that radiotherapy is less effective in controlling NF2 vestibular schwannomas than sporadic ones, radiotherapy as a management option should still be discussed [ 34 , 37 ], but outcomes are varying in the literature so far. For example, Mathieu et al have treated 62 of NF2 patients using radiosurgery.…”

“…In another analysis, Phi et al reported about 36 NF2 patients treated with radiosurgery with a mean tumor volume of 3.2 cm 3 . Five patients developed tumor recurrence and calculated control rates were 81%, 74% and 66% in the first, second and fifth year, respectively [ 34 , 39 ].…”

Neurofibromatosis

“…This Special Issue is completed with two reviews. Our group gives an up to date overview with modern day treatment strategies for sporadic and NF2 related VS. One clear point we tried to make is that the management strategy has shifted towards preserving function as longs as possible in combination with tumor control [ 9 ]. The other review by Lee et al focuses on the loss of Merlin/NF2 in meningioma biology.…”