Rapid enlargement of a vestibular schwannoma following gamma knife treatment.

Stereotactic radiosurgery has been proposed as the first line treatment for acoustic tumours and has been particularly advocated in cases of Type 2 Neurofibromatosis (NF2) with bilateral acoustic nerve tumours. We present the case of a 22-year-old male with NF2 and bilateral acoustic nerve tumours. He underwent an uncomplicated excision of the larger, left sided lesion. Histology showed a benign acoustic schwannoma with no atypical features. One year later he underwent stereotactic radiosurgery (Gamma Knife 1500 cGy) to the right sided lesion. After initial swelling, within 12 months the tumour had reduced in size and undergone central necrosis. However, 2 years later MRI of the brain revealed a dramatic increase in the size of the right sided tumour, with considerable brain stem compression. The patient subsequently died. This highly unusual case highlights the need for careful clinical and radiological follow up. in patients with acoustic tumours, regardless of the treatment method employed.