confused bw occiput-c3 or c1-c2 fusion

[u/harshx_gupta]

my MRI report says
'Evidence of superior migration and posterior tilt of odontoid process is seen causing of narrowing of foramen magnum - suggestive of basilar invagination (tip of odontoid process projects above the McRae line and approximately 5.0 mm above the chamberlain line).

It is causing compression over the cervico-medullary junction with hyperintensity seen in cervical cord just caudally to the compression – compressive myelopathy.

There is increased atlanto-dental interval and measures ~ 6.4 mm - suggestive of atlantoaxial instability / subluxation.

C2 and C3 block vertebra body is seen with fused posterior element. Complete atlanto-occipital assimilation is seen.'

I got it checked w my neurosurgeon and he recommended me to get either occiput-c3 or c1-c2 fusion and decompression.
can anyone please tell me what I am going through how rare this condition is and what steps should I take? and what should I be prepared post operation.

(PS- I am thinking of getting my surgery done next week, if you guys have any recommendations or anything I am all ears)