Cha, "Giant arachnoid granulation misdiagnosed as transverse sinus thrombosis," Journal of Korean Neurosurgical Society, vol.
Poon, "Focal brain herniation into giant arachnoid granulation: a rare occurrence," European Journal of Radiology Extra, vol.
Arachnoid granulations represent growths of arachnoid membrane into the dural sinuses through which CSF enters the venous system  and are macroscopically visible .
The presence of preexisting arachnoid granulations facilitates the formation of brain herniation into the dural venous sinus (DVS) or adjacent calvarium.
Arachnoid granulations (AG) were first described by Antonio Pacchioni in 1705 .
 reported that approximately 80% of giant arachnoid granulations contain CSF-incongruent fluid on at least one MR image and nearly half contain fluid that does not parallel CSF on at least two sequences.
However, it is possible that venous structures and/or connective tissues into the arachnoid granulations maybe tamponed by mass effect from the herniated parenchyma, thereby making them invisible .
Battal and Castillo  concluded that herniations of brain parenchyma into arachnoid granulations can occur spontaneously or as a result of increased intracranial pressure.
Balko, "Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease," American Journal of Neuroradiology, vol.
Potts, "Arachnoid granulations: radiology and anatomy," Radiology, vol.
Tomsick, "Large arachnoid granulations involving the dorsal superior sagittal sinus: findings on MR imaging and MR venography," American Journal of Neuroradiology, vol.