Dural arachnoid granulations and “giant” arachnoid granulations

Abstract

Although arachnoid granulations (AGs) were already described by Antonio Pacchioni more than 300 years ago, two issues draw particular attention: first, the radiological features and differential diagnosis of the so-called giant AGs (GAGs) and second, their possible association with various disease processes. In order to evaluate the frequency, size and normal distribution of GAGs, an anatomical study of the dural sinuses was carried out. It involved all the autopsies performed during the period August 2002-February 2005 and included 651 cases: 306 females and 345 males, aged 13-99 years (mean 69 years). Grossly visible GAGs were identified in 24 cases: 7 females and 17 males, aged 45-92 years (mean 69 years). This is the largest population-based anatomical study on GAGs. It shows that GAGs, in general a rare finding (3.68%), are rather common in the adult population, especially in the elderly (aged >65 years) and that they can reach remarkable size (up to 2.5 cm and more in diameter). Giant AGs should be considered in the radiological differential diagnosis of intradural lesions, particularly those occurring in the transverse sinus of the elderly.

Cranial Arachnoid Protrusions and Contiguous Diploic Veins in CSF Drainage

“…[1][2][3][4] Arachnoid granulations located adjacent to or in the cranial dural sinuses have been explored by using a variety of methods, including neuroimaging, [5][6][7][8][9][10][11][12][13][14][15] postmortem dissection, 5,16,17 investigations by using casting material, 18 and ex vivo studies. 1 However, no report has actually shown the process of CSF absorption in vivo.…”

Radiological Approach to Osteolytic Benign Calvarial Lesions

“…Sometimes hypointense areas related with fibrotic septa are observed in MRI. Multiple myeloma, metastatic lesions, EC, DC and AC should be taken into consideration for differential diagnosis [13][14][15][16][17][18] . The complaints of all patients were headache.…”

The relationship between age and arachnoid depressions in humans

“…Mapping the locations of arachnoid depressions offered a good way of verifying the accounts of previous research, which indicates that these structures occur predominantly in the lateral lacunae along the superior sagittal sinus (zones 2, 4, 5, and 7 of the vault), at the junction of the sagittal and coronal sutures (zones 4, 7, and 9 of the vault), transverse sinuses (zones 7, 8, and 9), anterior (zones 1 and 2) and middle (zones 3 and 4) cranial fossae, and posterior temporal bone, (zones 5 and 6) (le Gros Clark 1920; Haybaeck et al 2008). In this analysis, the highest frequencies of arachnoid depressions on the vault were seen along the anterior half of the sagittal sinus and at the junction of the sagittal and coronal sutures.…”

“…Haybaeck et al (2008) noted that large granulations (approx. 2.5 cm) occurred in the transverse sinuses of (mostly) individuals over the age of 65 years.…”

“…In 1704, Pacchioni documented the presence of large depressions on the vault in the region of the sagittal sinus. These structures occur predominantly at the intersecting point of the sagittal and coronal sutures in the region of the superior sagittal sinus, but they have been documented at the lateral lacunae of the sagittal sinus, along the transverse sinus, and in anterior and middle cranial fossae as well (see Figure 1; le Gros Clark 1920; Grzybowski et al 2007;Haybaeck et al 2008).…”