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The prognosis and the recovery process of facial nerve paralysis were reviewed in 74 patients who, despite preservation of nerve continuity, showed no facial movement after acoustic neuroma resection. In 50 or 67.6% of patients, facial movement recovered sufficiently so as not to require any reanimation procedures. However, no apparent sign of remission was observed for 7–49 months in the other 24 patients (32.4%), and hypoglossal-facial nerve anastomosis was performed in 20 of these patients. When remission was seen, the first sign of muscle movement appeared most frequently after 3–4 months but, in a small number of patients, it was also seen within 1.5 months or after 5–10 months. Based upon these results, the timing of reanimation procedures for facial nerve paralysis following acoustic neuroma resection is discussed.

Facial movement following hypoglossal-facial nerve anastomosis was investigated in 29 acoustic neuroma patients. The amount of facial movement was assessed using both the grading system of House and Brackmann and the revised grading scale of Yanagihara. The data were analyzed to determine the influence of the time elapsed between tumor resection and anastomosis upon recovery of facial movement. A slightly larger number of patients with delayed anastomosis (7–23 months) showed minimally poorer results than those with early anastomosis (within 3 months). However, these differences were not statistically significant. Moreover, there was no apparent relationship between the duration of facial nerve paralysis and the recovery of facial movement within either of these two groups. These results showed that hypoglossal-facial nerve anastomosis can be delayed up to 2 years following tumor resection with only minimal effect on the recovery of facial movement.

The aim of our retrospective study was to determine whether electromyographic findings (motor unit action potentials, MUAPs) can be used in long-term prognosis for profound facial nerve paralysis in patients whose nerve continuity is preserved during surgery for acoustic neuroma. The orbicularis oris, frontal, and orbicularis oculi muscles were examined for the occurrence of MUAPs in 48 such patients. In 30 patients who recovered from complete paralysis within 10 months after surgery, MUAPs in the first two muscles tended to precede the first sign of facial movement. MUAPs appeared in the orbicularis muscle in 80% of these patients at 1 month and in all at 5 months. In the frontal and orbicularis oculi muscles, MUAPs occurred in only 0–20% of these patients in the first month; within 3–5 months the number increased rapidly, and MUAPs were present in 95% of these patients at 10 months. In the remaining 18 patients with long-term complete paralysis (at least 1 year), MUAPs appeared solely in the orbicularis oris muscle: in 20% of these patients in the first month after surgery. While this number slowly rose, there was no period of rapid increase later. We conclude that the occurrence of MUAPs in the orbicularis oris and frontal muscles within 3 months of surgery indicates a good prognosis for reversal of facial nerve paralysis.

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