Surgical Approaches for Acoustic Neuroma

The choice of surgical approach depends upon the size of the tumor and the level of residual hearing detected on the audiogram. Again, the larger the tumor the lower the chances of saving hearing. The three most common surgical approaches for acoustic neuromas are the translabyrinthine, middle fossa and retrosigmoid approach. All of these procedures are performed under general anesthesia. Patients in general spend 5 days in the hospital, including the day of surgery.

Translabyrinthine Approach

This approach was refined and popularized by surgeons at the House Clinic in Los Angeles. The House Clinic group has the largest experience in the world with this surgical approach for acoustic neuromas and other skull base tumors. The translabyrinthine approach involves an incision that is made behind the ear. The mastoid bone and the balance canal structures of the inner ear are removed in order to expose the tumor. This approach results in complete tumor removal in nearly every case. One of the main advantages in this approach is that there is little or no retraction of the brain required to provide excellent exposure of the tumor. Another advantage is early and direct localization of the facial nerve which facilitates separation of the nerve from tumor, optimizing facial nerve outcome. After completion of tumor removal, the opening in the mastoid bone is closed with a fat graft which is taken from the abdomen.

This approach sacrifices the hearing and balance mechanism of the inner ear. As a consequence, the ear is made permanently deaf. Although the balance mechanism is removed on the operated ear, the balance mechanism in the opposite ear provides stabilization for the patient. Rarely patients experience transient vertigo immediately after surgery. This generally improves within the first five days following surgery and the patient has no further problems. In cases of larger tumors, the compensation for loss of the balance nerves on the tumor side has naturally occurred over time while the tumor has slowly grown to its large size. The patients rarely experience any vertigo in the early postoperative period.

Middle Fossa Approach

The middle fossa approach is another treatment that House Clinic surgeons developed and currently utilize more than any other center in the world. This approach is used for small tumors and is utilized in cases when hearing is to be conserved. An incision is made beginning just in front of the ear and extends upward in a curved fashion. A small opening in the bone is made above the ear, and the membrane that covers the brain is elevated away from the bone and gently held away from the bony floor of the skull. Bone is then removed over the top of the internal auditory canal to expose the tumor. Tumor removal is complete in the vast majority of cases. Every effort is made to preserve hearing and still completely remove the tumor. In these cases of small tumors, hearing is preserved in the majority of cases in our experience at the House Clinic.

Retrosigmoid Approach

An incision is made behind the ear and an opening in the skull is made behind the mastoid bone. The portion of the brain called the cerebellum is retracted away in order to expose the tumor. In most cases the tumor can be completely removed. Every effort is made in this approach to preserve hearing and still completely remove the acoustic neuroma. In some cases, because of invasion of the auditory nerve by the tumor, it is necessary to sacrifice hearing in order to completely remove the neuroma. The success of hearing preservation in these cases is largely dependent upon the size of the tumor and the condition of the auditory nerve in relation to the tumor.