[Fat inside the dural sheath of lumbar nerve roots in humans]

Epidural fat deposition, which varies at different levels of the vertebral column, generates a reservoir from which retained lipophilic substances could be redistributed. The aim of the study was to determine whether fat is deposited within or underneath the dural sheath or whether it is only found within the epidural space, outside the sheath.

Samples of dural sheath from the lumbar spine of human cadavers aged 65 to 72 years were analyzed by scanning electron microscopy.

The dural sheaths were made up of an arachnoid layer and a dura mater with a thickness of 100 to 150 microm. A large number of adipocytes were observed between the layers of the dura mater as well as beneath it.

Fat similar to that found in the peripheral nerves is present within and underneath the dural sheaths. The fat found in the dural sheaths would be in close contact with the axons of the nerve roots, unlike the fat contained in the epidural space. The release of lipophilic substances from the fat in the dural sheath could have a greater effect on the nerve roots due to the limited distance that separates the fat from the axons as well as to the poor vascular clearance.