Neoplasia, Inflammation, Infection, eLearning, Education, MR, Neuroradiology spine, Neuroradiology brain
S. Mghaieth1, O. Ghdes2, N. Achour2, H. Hriz2, N. Mnif2; 1Tunis, tunis/TN, 2TUNIS/TN
The dura mater is also called pachymeninx whereas arachnoid mater and the pia mater are collectively designated as the leptomeninx.
- The dura mater is the outermost layer of the meninges.
It consists of an inner meningeal layer and an outer endosteal layer.
- The outer layer is the skull’s periosteum and contains vessels and nerves.
It is adherent to the inner surface of the skull and is continuous through cranial sutures and foramina.
The deeper layer is known as the meningeal layer.
This layer is responsible for forming reflections.
The tentorium cerebelli,
falxcerebri and falx cerebelli are dural reflections dividing the intracranial compartment.Apart from when they separate to form the dural venous sinuses,
there is no distinct border between the meningeal and periosteal dura.
At the spinal level,
only the internal dura layer is present.
- The inner meningeal layer is closely applied to the arachnoid mater over the surface of the brain and is separated from it by a narrow subdural space.
- The arachnoid mater is further divided into three layers: outer arachnoid layer,
subarachnoid space and arachnoid trabecula,
and inner arachnoid layer.
- The pia mater is a delicate,
highly vascular membrane surrounding the brain and spinal cord.
It forms a continuous layer of cells closely adherent to the brain surface that dip into the sulci and fissures.
The cells are joined by desmosomes and gap junctions,
therefore providing a barrier function.
The meningeal layers are separated by spaces:
- The epidural space is a virtual space situated between the inner table and dura.
- The subdural space is a virtual space located between the dura and arachnoid.
- The subarachnoid space is located between the arachnoid and pia and contains the cerebrospinal fluid (CSF).
The subarachnoid space extends to the dural sinuses and granulations of Pacchioni where CSF is absorbed into the venous blood.
The perivascular spaces of Virchow-Robin contain CSF but are separated from the subarachnoid space by the pia and therefore do not directly communicate with the subarachnoid space.
- MRI is the best imaging modality to assess the intracranial and intraspinal meninges.
However the presence of meningeal enhancement is nonspecific and is a sign of multiple pathologies.
Correlation between distribution and characterization of meningeal abnormalities,
parenchymal signal abnormalities,
clinical and paraclinicalsetting is mandatory for appropriate differential diagnosis.