Which disease can be categorized using the Koos grading system?
['The patients had Koos Grade I or II tumors and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Class D hearing status preoperatively. ', 'METHODS: This is a retrospective review of 22 patients with VS Koos grade III and IV who were treated with STR followed by SRS. ', ' VS was characterized by its size (Koos classification) and the presence or not of a cystic component.', 'MAIN OUTCOME MEASURES: All data recorded were reviewed to access age, sex, tumor type, and tumor size according to the Koos classification and presenting symptoms. ', 'Facial nerve preservation surgery for koos grade 3 and 4 vestibular schwannomas.', 'Safety and Efficacy of Gamma Knife Radiosurgery for the Management of Koos Grade 4 Vestibular Schwannomas.', 'In all 333 patients microsurgical vestibular schwannoma (Koos grade 1: 12, grade 2: 34, grade 3: 62, and grade 4: 225) removal was performed.', 'Facial nerve preservation surgery for koos grade 3 and 4 vestibular schwannomas.', 'To report, in a retrospective study, outcomes for large Koos grade 3 and 4 vestibular schwannomas.', 'Safety and Efficacy of Gamma Knife Radiosurgery for the Management of Koos Grade 4 Vestibular Schwannomas.']
['Koos grading system is used for vestibular schwannoma.']
['vestibular schwannoma']