Arachnoid granulations are structures filled with cerebrospinal fluid (CSF) that extend into the venous sinuses through openings in the dura mater and allow the drainage of CSF from subarachnoid space into venous system. Usually they are asymptomatic but can be symptomatic when large enough to cause sinus occlusion.

Where do arachnoid granulations drain?

Arachnoid granulations are structures filled with cerebrospinal fluid (CSF) that extend into the venous sinuses through openings in the dura mater and allow the drainage of CSF from subarachnoid space into venous system. Usually they are asymptomatic but can be symptomatic when large enough to cause sinus occlusion.

Can arachnoid granulations calcify?

MR images show these entities as largely isointense with cerebrospinal fluid in all sequences. Linear variations of signal intensity within the granulations are thought to be fibrous septa or vessels. Calcification was present in 3 granulations and altered both CT density and MR signal intensity.

Can arachnoid granulations cause pulsatile tinnitus?

When significant to influence blood flow, it may lead to pulsatile tinnitus. One of the most common stenosis mechanisms is the enlargement of arachnoid granulations or valves found in the venous sinus walls. These valves regulate the flow of cerebrospinal fluid (CSF) into the venous sinuses.

Can tight neck muscles cause pulsatile tinnitus?

Narrowing of the arteries of the head or the neck near the ear can also cause pulsatile tinnitus. Pulsatile tinnitus can result from muscle spasm of one of the muscles within the ear, or from myoclonus of the palatial muscles.

What is arachnoid granulation?

Arachnoid granulation. Arachnoid granulations (or arachnoid villi) are small protrusions of the arachnoidthrough the dura mater. Largest granulations lie along the superior sagittal sinus. They are, however, present along other dural sinuses as well. Smaller granulations are called villi, large calcified ones are referred to as pacchionian body.

How is cerebrospinal fluid (CSF) drained from the Arachnoids?

The importance of arachnoid granulations for the drainage of CSF is controversial. By some accounts, a large portion (perhaps the majority) of CSF is drained through lymphatics associated with extracranial segments of the cranial nerves.

Are “giant” arachnoid granulations just like CSF?

Trimble CR, Harnsberger HR, Castillo M, Brant-Zawadzki M, Osborn AG. “Giant” arachnoid granulations just like CSF?: NOT!! AJNR Am J Neuroradiol. 2010 Oct;31 (9):1724-8. doi: 10.3174/ajnr.A2157. Epub 2010 Jun 25. PubMed PMID: 20581064.

Can giant arachnoid granulations cause venous hypertension?

Although usually incidental, giant arachnoid granulations that are of sufficient size to fill the lumen of a dural sinus and cause local dilation or filling defects can rarely cause symptoms due to sinus obstruction leading to venous hypertension.