The brain is encased and protected by three layers of covering called meninges.
The layer directly covering the brain, including every folding of the brain is named pia, the next layer is the arachnoid, and these two layers are called the leptomeninges.
The outer meningeal layer is the dura, which is like a sleeve around the brain.
Immune cells are present in healthy meninges and contribute to healthy immune surveillance of these structures.
Several studies suggest that inflammation can occur in the meninges of MS patients.
This meningeal inflammation has been found in biopsies of patients with different stages and types of MS.
Recent work has demonstrated that special MRI sequences can detect leptomeningeal enhancement, which has been associated with above-described meningeal inflammation.
This leptomeningeal enhancement can be seen in early-stage MS but has been described more frequently in progressive disease and has been identified in a wide range (15-81%) of MS patients.
The detection of leptomeningeal enhancement is an important MRI finding in MS, especially as it has been associated with measures of disability, however it needs to be determined whether and how leptomeningeal enhancement contributes to the disease course of MS and confirmatory studies are warranted.
Ulrike Kauzner MD, PhD