People who have acoustic neuromas, now more accurately called vestibular schwannomas, very rarely have facial weakness as their first symptom. Instead, because this tumor occurs on the hearing and balance nerve, a persons initial symptoms can be related to hearing loss, dizziness and balance impairment. Treating the tumor can frequently result in transient or even permanent loss of facial function simply because the facial nerve runs through the exact same tight space, and can be bruised or otherwise traumatized, when the tumor is being removed. Most often, the facial nerve is able to be left anatomically intact during the surgery to remove this type of tumor, and patients awaken with normal facial function. If patients awaken with facial weakness, but the surgeon feels the nerve is anatomically intact, usually a waiting period is established during which the patient should start to experience some positive changes. If after six months there is absolutely no change in facial function, then we do start considering facial reanimation options that will not eliminate the possibility of spontaneous recovery through the facial nerve, but will enhance the overall smile in the long run. There are also situations where the facial nerve requires intraoperative sacrifice, therefore no spontaneous recovery will be expected to occur, and in those cases re-innervation techniques with other nerves routed into the distal stump of the facial nerve are usually performed very soon after the acoustic neuroma surgery. Every case of acoustic neuroma/vestibular schwannoma is different, and care is extremely individualized. For example, patients who wake up with poor sensation of the side of the face might need more aggressive management of their eye than people who wake up with normal sensation in their face. The most contemporary thinking is that when patients have no movement after six months, then the timing is right to intervene rather than waiting 12 to 18 months to do so. This shift has occurred because the maneuvers that we can now do will not prevent spontaneous recovery, so both neurosurgeons and neurotologists are more comfortable letting patients undergo these procedures before the full 12 to 18 month waiting period.
Sometimes people undergo radiation therapy for acoustic neuroma/vestibular schwannoma, rather than surgery. In these cases, sometimes the acute insult of radiation can result in what looks like a Bell’s palsy type of picture, and patients experience rapid loss of function, and then significant recovery. In other cases, radiation therapy can lead to very slow onset facial weakness, in which case spontaneous recovery is normally not possible.