Intradural exploration / arachnoid dissection

What it is

Intradural exploration (with arachnoid dissection) is an approach in which the surgeon opens into the CSF space — through both the dura and the arachnoid — to directly address structures such as the cerebellar tonsils, scar tissue (adhesions), or the outlets of CSF flow during Chiari decompression.

Understanding Intradural exploration / arachnoid dissection

While some decompressions preserve the arachnoid, in other cases the surgeon opens into the CSF space to do more — for example, freeing adhesions (scar tissue) that obstruct CSF flow, reducing or coagulating the tonsils to open the space, or ensuring CSF flows freely from the fourth ventricle's outlet. This intradural work can improve CSF flow in situations where bony and dural decompression alone may be insufficient, such as significant scarring or certain syrinx cases. However, opening into the CSF space carries more risk of CSF-related complications (leak, pseudomeningocele, meningitis) than arachnoid-sparing approaches. The surgeon weighs the benefits and risks for each case. Understanding intradural exploration clarifies a more extensive approach used when directly addressing structures is needed.

Why it matters

Understanding intradural exploration helps families see why a surgeon might open into the CSF space — to directly address the tonsils, scar tissue, or a syrinx — and that this more extensive approach carries more risk.