Malignant brain oedema after radiosurgery of a medium-sized vestibular schwannoma.

Case report: We present a patient with an unusual malignant brain oedema occurring after gamma knife radiosurgery of a medium-sized vestibular schwannoma.

Clinical presentation: A 62-year-old female with a large vestibular schwannoma underwent partial microsurgical resection; 6 months later she underwent a second intervention with gamma knife radiosurgery for a medium-sized tumour remnant. With a latency period of 6 months after radiosurgery, she presented with progressive neurological deterioration. Serial magnetic resonance imaging revealed progression of the tumour and of the perifocal oedema which finally extended up to the ipsilateral internal capsule. The patient became comatose.

Intervention: The tumour was nearly completely removed via a standard retrosigmoid craniotomy. Histopathological examination demonstrated increased mitotic activity compared to the initial histology. The patient became conscious 10 days after surgery and recovered slowly. Surprisingly, the brain oedema resolved rapidly. The CT scan obtained 11 days after surgery showed almost complete disappearance of the oedema.

Conclusion: Although rare, radiosurgery of medium-sized vestibular schwannomas causing brainstem compression may lead to life-threatening tumour progression and malignant brain oedema. Therefore, microsurgical gross total resection should be the preferred treatment option in vestibular schwannomas causing significant brainstem compression.