Tonsillar reduction (coagulation/shrinkage)

What it is

Tonsillar reduction is a surgical step in which the cerebellar tonsils are shrunk — often by coagulation (using controlled heat) — to open the space at the craniocervical junction and improve CSF flow. It is used in selected cases during Chiari decompression.

Understanding Tonsillar reduction (coagulation/shrinkage)

When the tonsils significantly crowd the foramen magnum or obstruct CSF flow even after bony and dural decompression, the surgeon may reduce them — gently shrinking the lower portions using coagulation — to open the space and restore CSF flow, particularly the outflow from the fourth ventricle. This is done as part of intradural work (opening into the CSF space). Tonsillar reduction can be helpful in cases with significant crowding or a syrinx, but because it involves working directly on the tonsils within the CSF space, it carries more risk than less invasive approaches. The decision to reduce the tonsils is individualized based on the anatomy and the goals of surgery. Understanding tonsillar reduction clarifies a step used to open the space by shrinking the tonsils in selected cases.

Why it matters

Understanding tonsillar reduction helps families see how, in selected cases, gently shrinking the tonsils opens the space and improves CSF flow — a more involved step weighed against its added risk.