Findings:
There is cerebellar tonsillar ectopia measured at approximately 12mm with stenosis at the foramen magnum.
There is a mucus retention cyst in the right maxillary sinus. There are postsurgical changes of a left sided mastoidectomy.

Impression:
Chiari I malformation. Post-surgical changes from left-sided mastoidectomy.

Recommendations:
For your training purposes, recommendations are not included in this report.