Skip to main content

Table 1 Koos classification system

From: Early magnetic resonance image volumetric changes of vestibular schwannoma after Gamma Knife radiosurgery: a prospective study of 18 cases

Grade

Definition

1

Intracanalicular

2

Tumor in the cerebellopontine angle but not reaching the pons

3

Tumor reaching the pons, perhaps deforming it but not shifting it

4

Tumor deforming the pons and shifting the fourth ventricle