Cerebellar ptosis / slump (post-decompression)

What it is

Cerebellar ptosis (or cerebellar slump) is downward sagging of the cerebellum into the surgical defect after decompression. It is a complication that can occur if too much bone is removed (an overly large craniectomy), leaving insufficient support for the cerebellum.

Understanding Cerebellar ptosis / slump (post-decompression)

The goal of decompression is to remove enough bone to relieve crowding, but not so much that the cerebellum loses support and sags downward over time. When the craniectomy is too large, the cerebellum can slump into the defect, potentially re-crowding the foramen magnum, obstructing CSF flow again, and causing or worsening symptoms (including headaches). Cerebellar ptosis can sometimes lead to persistent or recurrent symptoms after surgery. It is avoided by removing an appropriate (not excessive) amount of bone — one reason the extent of decompression is carefully judged. If cerebellar ptosis causes significant problems, treatment (sometimes involving a procedure to support or reconstruct the area) may be considered. Understanding cerebellar ptosis clarifies a complication of over-decompression and why the extent of bone removal is balanced.

Why it matters

Understanding cerebellar ptosis helps families see why surgeons avoid removing too much bone — because the cerebellum can sag into an overly large defect, potentially causing or worsening symptoms.