Demonstration of the inferior intercavernous sinus is closely linked to the extent of pneumatization of the sphenoid sinus: useful information for the pituitary surgeon.

PURPOSE: To study the utility of T2-weighted MRI sequences in the identification of the inferior intercavernous sinus (IICS), a potential source of bleeding during transsphenoidal surgery of pituitary adenomas. METHODS: Pituitary sagittal T1W and coronal T2W MRI sequences were analyzed in 237 consecutive patients, after the exclusion of postoperative MRIs and those revealing an empty sella or a pituitary macroadenoma. Sphenoid sinus pneumatization was defined as incomplete (group 1) if it did not reach the nadir of the sella turcica, as complete (group 2) if it extended beyond the nadir of the sella or asymmetric (group 3), when only one side of the sinus was completely pneumatized. RESULTS: In Group 2 (70% of the patients), the IICS was rarely visualized on coronal T2W MRI (6/167 patients-3.6%), whereas in Group 1 it was identified in nearly all patients (55/57 patients - 96.5%, p < 0.001). In Group 3, the IICS was only visible above the non-pneumatized part of the sphenoid sinus. CONCLUSIONS: The IICS can be identified on coronal T2W images in patients with an incompletely pneumatized sphenoid sinus, but very rarely in patients with a totally pneumatized sinus. This information can help to increase awareness among pituitary surgeons of the need to potentially manage IICS bleeding during transsphenoidal surgery in patients with an incompletely pneumatized sphenoid sinus.

Microsurgical anatomy of the inferior intercavernous sinus.

PURPOSE: Intercavernous sinuses (ICSs) are physiological communications between the cavernous sinuses. The ICSs run between the endosteal and meningeal layers of the dura mater of the sella turcica. Whereas the anterior and posterior ICSs have been frequently described, the inferior ICS (iICS) has been less well studied in the literature; however, poor awareness of the ICS's anatomy can lead to serious problems during transsphenoidal, transsellar surgery. The objective of the present anatomical study was to describe the iICS in detail. METHODS: The study was carried out over a 6-month period in a university hospital's anatomy laboratory, using brains extracted from human cadavers. The brains were injected with colored neoprene latex and dissected to study the iICS (presence or absence, shape, diameter, length, distance between inferior and anterior ICSs, distance between inferior and posterior ICSs, relationships, and boundaries). RESULTS: Seventeen cadaveric specimens were studied, and an iICS was found in all cases (100%). The shape was variously plexiform (47.1%), filiform (35.3%), or punctiform (17.6%). The mean ± standard deviation diameter and length of the iICS were 3.75 ± 2.90 mm and 11.92 ± 2.96 mm, respectively. The mean iICS-anterior ICS and iICS-posterior ICS distances were 5.36 ± 1.99 mm and 7.03 ± 2.28 mm, respectively. CONCLUSION: The iICS has been poorly described in the literature. However, damage to the iICS during transsphenoidal, transsellar surgery could lead to serious vascular complications. A precise radiological assessment appears to be essential for a safe surgical approach.

Ossification around intercavernous sinus: An osteological finding that can complicate trans - sphenoidal surgery.

The aim of the study was to document an anatomical variation around the sella turcica which was unique and lacked any reference in the literature. A low lying osseous bar connecting the right middle clinoid process to the midpoint of the right lateral border of the dorsum sella was observed in a human skull specimen. The osseous bar was forming a foramen close to the floor of the sella, and the structure in association with this part of sella is the inferior intercavernous sinus. Measurements of the sella turcica bridge (STB), carotico-clinoid foramen (CCF), interclinoid foramen (ICF) on both sides and that of the ossified bar and foramen formed by itself were taken with the help of ImageJ software. The values observed for the measurements of different parameters of STB and its components, for CCF and ICF were bilaterally different. While the values for the osseous bar and foramen formed by it cannot be compared because of its unilateral occurrence. The presence of foramen around the inferior intercavernous sinus may lead to difficulty in performing procedures like transsphenoidal surgery (TSS) or extended TSS (eTSS) while extracting intradural lesions, thus increasing the chances of haemorrhage.

The inferior intercavernous sinus: An anatomical study with application to trans-sphenoidal approaches to the pituitary gland.

OBJECTIVES: The inferior intercavernous sinus is located below the pituitary gland in the sella turcica. Its presence has been controversial among anatomists because it is not always found on radiological imaging or during cadaveric dissections; however, it is becoming a better-known structure in the neurosurgical and radiological fields, specifically with respect to transsphenoidal surgery. Therefore, the present study was performed to better elucidate this structure at the skull base. PATIENTS AND METHODS: Fifty adult, latex injected cadavers underwent dissection. The presence or absence of the inferior cavernous sinus was evaluated and when present, measurements of its width and length were made. Its connections with other intradural venous sinuses were also documented. RESULTS: An inferior intercavernous sinus was identified in 26 % of specimens. In all specimens, it communicated with the left and right cavernous sinus. The average width and length were 3 mm and 9.5 mm, respectively. In the sagittal plane, the inferior intercavernous sinus was positioned anteriorly in 31 %, at the nadir of the sella turcica in 38 %, and slightly posterior to the nadir of the sella turcica in 31 %. In two specimens (15.4 %), the sinus was plexiform in its shape. In one specimen a diploic vein connected the basilar venous plexus to the inferior intercavernous sinus on its deep surface. CONCLUSION: An improved understanding of the variable anatomy of the inferior intercavernous sinus is important in pathological, surgical, and radiological cases.