Koos Classification (Vestibular Schwannoma)
1.0.0Assigns Koos grade I–IV for vestibular schwannoma based on intracanalicular versus cisternal extent and contact or compression of the brainstem, aiding surgical and radiosurgical planning.
Also searched as: acoustic neuroma · CPA · skull base · MRI · cerebellopontine angle · brain · ear
Information
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- Please provide: Koos grade.
How this tool works
The Koos classification (popularized from 1990s microsurgical series) stages vestibular schwannomas by extrameatal growth and mass effect on the brainstem rather than by linear diameter alone. Grade I is purely intracanalicular; II extends into the CPA cistern without brainstem contact; III fills the cistern and contacts brainstem without displacement; IV compresses/displaces brainstem and cranial nerves. Higher grades correlate with greater surgical complexity and facial-nerve risk; grade also influences candidacy for observation, SRS, or microsurgery.
References
- Radiopaedia — Koos classification of vestibular schwannomas
- Koos et al. J Neurosurg 1998 (neurotopographic considerations)
- Otoscape — Koos Classification summary
Implemented from the cited published sources. Educational use only; confirm against current guidelines before clinical use.
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