Small Vestibular Schwannomas: Observation, Surgery, and Gamma-Knife Treatment

Material and Results: Two hundred thirty-five patients with unilateral acoustic neuroma equal to or less than 20 mm in the CP angle are compared when surgery, observation, and Gamma-knife (GK) are used. Surgery is reported with at least a 4-year follow-up, observation with a minimum of 5 years, and GK with a minimum of 5 years of follow-up. Surgery was carried out in 104 cases and the hearing l in 5 cases. Two patients had postoperative CSF leakage, and one had to be reoperated to repair this. Ninety-three patients had HB grade I to II facial function after surgery and one had to be reoperated due to growth in residual tumor. In 53 patients, GK surgery was the primary treatment. The tumor control rate was 96%. Eight patients experienced facial paresis, 4 transient and 4 with a permanent paresis (2 HB grade II, 2 HB grade III). Hearing was preserved in 77% of the ears at pretreatment level. Trigeminal reduction was found in 6%, and 8% experienced hydrocephalus. Observation for more than 2 years was carried out in 82 patients. Growth was seen in 43% and growth more than 2 mm (2 to 7 mm) in diameter per year was seen in 28%. All tumors that did grow showed this in the first year of observation and there was no correlation between tumor size, age, hearing, vertigo, and growth rate. Treatment was suggested in 20 out of 23 patients with growth of more than 2 mm in diameter per year. Surgery was performed in 15 patients and 5 were treated with GK. Hearing deteriorated in 36% of the patients while under observation. Conclusion: It is probably wise initally to “wait and scan” small- and some medium-sized VS.