Regrowth of the residual tumour after acoustic neurinoma surgery.

Ideally, acoustic neurinomas should be completely removed without neurological deficit. In some cases, however, removal is subtotal in order to preserve anatomical continuity of the facial nerve. In this report we discuss the regrowth of residual tumour in these patients and the difference between regrowing and dormant tumours. Eight of 81 patients with acoustic neurinomas where the facial nerve was anatomically preserved leaving tumour overlying it were investigated and followed-up. Only one case with residual tumour along the 7th nerve from the intrameatal portion to its entry to the brainstem showed regrowth 3.5 years after the operation. In the other seven cases with residual tumour along the nerve from the porus to the brainstem, the tumour remained dormant during a follow-up period of 4.5-8.5 years. Removal of tumour in the internal auditory meatus may make regrowth unlikely.