Modified Sridhar classification of benign nerve sheath tumors.5
| Original types | |
|---|---|
| Type I | Intraspinal tumor <2 vertebral segments in length; a: intradural; b: extradural |
| Type II | Intraspinal tumor >2 vertebral segments in length (giant tumor) |
| Type III | Intraspinal tumor with extension into nerve root foramen |
| Type IV | Intraspinal tumor with extraspinal extension (dumbbell tumors); a: extraspinal component <2.5 cm; b: extraspinal component >2.5 cm (giant tumor) |
| Type V | Tumor with erosion into vertebral bodies (giant invasive tumor), lateral and posterior extensions into myofascial planes |
| Additional types for spinal intraosseous schwannoma | |
| Type VI | Tumor in entirely intravertebral location without intraspinal portion |
| Type VII | Intraspinal tumor with erosion into vertebral bodies (invasive tumor) and extension into nerve root foramen |