·From March 2016 to November 2019, the patients with sporadic acoustic neuroma who had visit and follow-up in the Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine were analyzed retrospectively. The patients included in the study were required to have at least two digital data of enhanced MRI, and the interval between the first and the last time was more than 60 d. Their radiological DICOM data (enhanced MRI), audiological reports (pure tone average threshold and speech discrimination score), and clinical manifestations (hearing loss, tinnitus, vertigo, and facial pain or numbness) were collected. Image data were loaded by Horos^TM software to measure tumor size and calculate tumor growth rate. Then the relationship between tumor growth rate and clinical manifestations was analyzed.

·A total of 56 patients were included, 28 males and 28 females, with the average age of (48.6±12.0) years old. Their initial tumor size was (15.9±9.6) mm in the maximum diameter, and the mean interval between the two times of MRI was (266.3±313.5) d. The average growth rate was (4.4±4.7) mm/a. Eight cystic tumors grew more rapidly than non-cystic ones [(9.4±3.8) mm/a vs (3.6±4.4) mm/a, P=0.003). Among the 48 non-cystic acoustic neuromas, 22 internal auditory canal type and small (≤10 mm) tumors grew more slowly than other tumors [(2.1±3.6) mm/a vs (4.8±4.7) mm/a, P=0.031]; the tumors grew more slowly in the patients with the ages of 60 years or above than those in the patients younger than 60 years old [(1.7±3.1) mm/a vs (4.2±4.6) mm/a, P=0.040]. 58.8% of the patients undergoing active “wait and scan” strategy had stable tumors, and 81.8% patients with measurable hearing did not show hearing deterioration during their follow-up. Other factors like sudden deafness, tinnitus, vertigo, initial hearing level, sex, and tumor side had no correlations with tumor growth rate (all P>0.05).

·Cystic sporadic acoustic neuroma is confirmed as a rapid growth tumor, which needs active treatment. The tumors grow slowly in the non-cystic acoustic neuromas which are internal auditory canal type, not bigger than 10 mm or in the patients aged 60 years and above. The cases that are suitable for “wait and scan” policy can basically maintain their original hearing level during one year.