Does Everyone Have Arachnoid Granulations?

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.

How common are arachnoid granulations?

Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies. Conclusion: Discrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies.

What causes arachnoid granulations?

Arachnoid granulations increase in numbers and enlarge with age in response to increased CSF pressure from the subarachnoid space and are usually quite apparent by 4 years of age.