Basilar Invagination and Atlantoaxial instability - Occipitocervical fusion a 49 year old male from bhopal presented to us with weakness in both hands, imbalance while walking for last few years. his problem was gradually increasing. His nek was tilted to one side with restricted Neck movements. His MRI showed Basilar invagination with atlantoaxial instability. Xrays showed complete reduction in extension. He underwent Occipitocervical fusion and foramen Magnum decompression. Patient started showing improvement after surgery. He was mobilised from next day and discharge after 3 days.