Retrosigmoid approach for acoustic tumor removal.

The retrosigmoid technique has evolved from the traditional suboccipital operation and, when combined with removal of the posterior wall of the internal auditory canal, affords a wide exposure of the cerebellopontine angle. This approach may be used for acoustic neuromas of all sizes, from intracanalicular to more than 4 cm from the porus acusticus. Hearing preservation may be attempted and is generally successful in a substantial minority of cases. The facial nerve is readily visualized at the lateral end of the internal auditory canal and is at no greater risk than in the translabyrinthine operation. We use this approach for all hearing preservation surgery as well as for tumors of more than 3 cm, regardless of hearing.