Posterior fossa decompression (PFD)

What it is

Posterior fossa decompression (PFD) is the main surgical treatment for Chiari malformation. It creates more space at the back of the skull and the foramen magnum to relieve crowding of the cerebellar tonsils and restore the normal flow of cerebrospinal fluid.

Understanding Posterior fossa decompression (PFD)

The core of PFD involves removing a small portion of the occipital bone at the back of the skull (a suboccipital craniectomy) and often the back arch of the first vertebra (a C1 laminectomy), enlarging the space at the foramen magnum. This relieves the crowding caused by the descending tonsils and aims to restore CSF flow at the craniocervical junction — which can improve symptoms and, when a syrinx is present, lead it to shrink. PFD can be performed with or without opening the dura and adding a patch (duraplasty); the choice involves a trade-off between effectiveness and complication risk. PFD is the foundation of surgical treatment for Chiari. Understanding posterior fossa decompression clarifies the main surgery and what it aims to accomplish.

Why it matters

Understanding posterior fossa decompression helps families see the main Chiari surgery — creating space to relieve crowding and restore CSF flow — which can improve symptoms and shrink a syrinx.