1-Occipital craniectomy, C1 posterior arch removal, and duraplasty
2- Posterior fossa decompression (PFD)
3- PFD + cervical laminectomy if the ventricular shunt is patent
4-Occipital craniectomy, C1 posterior arch removal, and duraplasty
5-Occipital craniectomy and duraplasty
6-Occipital craniectomy, C1 posterior arch removal, and duraplastysuboccipital craniectomy + cervical laminectomy in all pts
(i) durotomy + duraplasty: 4
(ii) resection of cerebellar tonsils + lysis of abhesions + duraplasty