gms | German Medical Science

Objective: Vestibular schwannomas (VS) in children below 16 years are very rare and usually confined to NF2 patients. We treated children with unusually large unilateral VS, not related to classical NF2, which seem to comprise a distinct subgroup of VS.

Method: Three children age 15, 14 and 7 years, presented with functionally complete hearing loss and vestibular dysfunction. Pre-operative facial nerve function according to House and Brackman was grade 2, 2 and 4, respectively. MRI showed large VS Type T4a with severe brain stem compression. CT bone scan confirmed bony destruction of the petrous bone, far beyond usual widening of internal auditory canal. The 14 year old had previous surgery with subtotal resection at an outside institution, with facial nerve palsy grade 4 postoperatively. He presented to us at age 16 with growth of residual tumour and underwent repeat surgery

Results: All children had surgery using the retrosigmoid suboccipital route. In the 15-year-old, a subtotal resection was performed leaving small tumour remnants alongside the facial nerve in the petrous bone. Postoperative facial nerve palsy deteriorated from grade 2 to 3, but recovered to normal within 3 months. In the initially 14 years old boy, who had repeat surgery, all tumour was removed without deterioration of facial nerve palsy grade. In the 7 year old with severe facial nerve palsy, the tumour was totally removed and facial nerve reconstructed with sural nerve graft. His paresis had improved to grade 3 nine months later. On follow-up (mean duration 9 months) none had tumour recurrence or growth of residual tumour. In all, genetic screening for NF2 in the blood, was negative, in one it was positive in tumour tissue, thus opening the possibility of mosaic type of NF2.

Conclusions: There is a distinct variant of VS with early manifestation down to 7 years, Children present with severe hearing loss, large T4a tumours, severe erosion of petrous bone and some degree of facial nerve palsy. Children should be managed in units with large skull base experience also regarding intraoperative facial nerve reconstruction Main aim of surgery beyond brain stem compression is preservation of facial nerve function. Tumours are not related to classical NF2 despite early manifestation, aggressive behaviour and tumours larger than usually found in NF2 cases of the same age. Long-term follow-up results will teach about recurrence rates and the necessity to perform either repeat surgery or stereotactic radiosurgery for tumour control.