subaracnoide

The subarachnoid space, sometimes referred to as the subaracnoide in some languages, is the fluid-filled interval between the arachnoid mater and the pia mater that surrounds the brain and spinal cord. It contains cerebrospinal fluid (CSF) and extends through the cranial and spinal subarachnoid compartments.

In the brain, CSF is produced mainly by the choroid plexus and circulates from the ventricles into the subarachnoid space via the foramina of Magendie and Luschka. The CSF then bathes the surface of the brain and spinal cord, and is absorbed into the venous system through arachnoid granulations (villi) into the dural venous sinuses.

Functions of the subarachnoid space include cushioning the brain to reduce mechanical injury, providing buoyancy to offset brain weight, and helping maintain stable chemical and metabolic conditions for neural tissue. The space also contains major cerebral vessels that run within its confines.

Pathologies involving the subarachnoid space include subarachnoid hemorrhage, typically due to rupture of a cerebral aneurysm or trauma, presenting with a sudden, severe headache and possible neck stiffness. Diagnosis often begins with non-contrast CT imaging; if CT is inconclusive but suspicion remains, lumbar puncture may reveal xanthochromia or blood breakdown products. Other conditions, such as meningitis, can also involve the subarachnoid space and require prompt evaluation and treatment. Treatment focuses on stabilizing the patient, addressing the underlying cause, and preventing complications.