Malignant Transformation of Previously Radiated Vestibular Schwannoma: Two-Dimensional Operative Video.

Malignant transformation of vestibular schwannomas (VSs), though rare, demands a comprehensive, multidisciplinary treatment approach to optimize patient outcomes. We present a rare case of malignant transformation in a VS after radiation treatment in a 58-year-old woman (Video 1). Initially diagnosed with a right cerebellopontine angle VS, the patient underwent CyberKnife (Accuray, Madison, Wisconsin, USA) treatment 16 years ago, receiving 18 Gy across 3 fractions. Despite initial stability, the patient experienced progressive hearing loss, ultimately requiring a bone-anchored hearing aid implant. Years later, she presented with rapid-onset facial weakness, dizziness, nausea, and vomiting, leading to a wheelchair-bound state and nutritional support upon admission. Advanced imaging revealed a significantly enlarged tumor, characterized by brain edema and suspicious hemorrhage, prompting urgent surgical intervention. Our multidisciplinary approach, including otolaryngology collaboration, led to the decision for a right retrosigmoid craniotomy and meatotomy. This strategy aimed at maximal tumor resection while preparing for potential facial nerve sacrifice due to the suspected malignancy. Intraoperative findings confirmed the malignant nature of the tumor, necessitating facial nerve resection. Postoperatively, the patient demonstrated clinical improvement and was discharged with plans for physical therapy and adjuvant radiation therapy, considering the malignant peripheral nerve sheath transformation of the tumor. This case underscores the importance of vigilant monitoring for patients with VS, particularly patients with rapid symptom progression and tumor growth, highlighting the crucial role of adjuvant radiotherapy in treatment regimens. This study received institutional review board approval. The patient provided informed consent for the use of their image and information.