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Subarachnoid Dissection

Last Updated: September 28, 2018

Figure 1:  Sylvian fissure split unveils the world of subarachnoid dissection that defines aneurysm surgery.

The Subarachnoid Space

The subarachnoid space contains cerebrospinal fluid (CSF) and is positioned between an outer membrane, the arachnoid mater, and an inner membrane, the pia mater. The pia mater rests on the parenchymal surface of the brain and remains in contact with the brain throughout its gyral folds and sulci. The meningeal layer of the dura mater encloses the arachnoid mater with a small potential subdural space situated between these two membranes.

The subarachnoid anatomy is such that the relationship between the arachnoid mater and pia mater is highly dependent on cortical topography. Anatomic sections where the gyri encroach upon the arachnoid mater demonstrate me...