Enlargement of the Inferior Intercavernous Sinus: A New Sign for the Diagnosis of Craniospinal Hypotension

Abstract

We read with interest the recent article entitled "MR Imaging of the Optic Nerve Sheath in Patients with Craniospinal Hypotension" by Rohr et al. 1 In patients with craniospinal hypotension, apart from engorged venous sinuses, enlarged pituitary gland, subdural effusions, and sagging of the brain, the authors have observed a partially or fully collapsed intersheath space of the optic nerves. Such a demonstration is particularly clear in their Fig 3. We would like to draw more attention to changes in the pituitary gland. As shown in Fig 3C (arrow), enlargement of the sellar content is also due partially to dilation of the inferior intercavernous sinus (IICS), which has collapsed after treatment. Such a dilation is not mentioned in the legend. In our experience, the IICS, which is visible in roughly 30% of children on MR imaging, is never quite visible in the healthy adult.In a personal series of 12 adult patients with intracranial hypotension syndrome studied by MR imaging, the IICS was visualized in 11 cases 2 : The IICS was very thin in 2 cases, prominent in 6 cases, and very thick (Ͼ3 mm) in 3 cases (Fig 1). The differential diagnosis includes a pituitary gland with increased height on one hand, corresponding to physiologic (hyperplasia, pregnancy, small sella) or pathologic conditions (a holosellar pituitary adenoma, hypophysitis, and so forth), and focal intrasellar lesions such as pituitary microadenoma on the other hand. Recognition of the presence of the IICS allows exclusion of these pituitary abnormalities. In 3 of 12 cases of our series, MR imaging follow-up after blood patch or spontaneous resolution of intracranial hypotension demonstrated a significant decrease in the height of the IICS (Fig 2). In our experience, dilation of the IICS constitutes a useful adjunctive sign for the diagnosis of intracranial hypotension. Moreover, enlargement of the IICS should be added to the other causes of enlargement of the sellar content.

Brain Spontaneous Intracranial Hypotension Score for Treatment Monitoring After Surgical Closure of the Underlying Spinal Dural Leak

“…Most studies reporting on the change in brain MRI after treatment focus on single imaging findings. [15][16][17] This may be inadequate, since none of the signs is pathognomonic, and, in our experience, some signs are subject to poor interobserver agreement. [8] As previously reported, the bSIH score is a reliable and objective tool to assess 13 the likelihood of spinal CSF loss in patients with orthostatic headache at baseline.…”

An Anatomic Assessment of the Intercavernous Sinuses and Review of the Literature

“…3 Enlargement of the IIS on MRI is associated with intracranial hypotension, and a change in size may be detected with treatment of the underlying pathology. 18,19 The basilar sinus. Although not part of the circular sinus, the basilar sinus (BS), which lies posterior to the clivus and connects the posterior aspect of both cavernous sinuses, is the largest and most constant of all the intercavernous sinuses.…”

“…3 Enlargement of the IIS on magnetic resonance imaging (MRI) is associated with intracranial hypotension, and a change in size may be detected with the treatment of the underlying pathology. 18,19 The Basilar Sinus…”

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

“…A dilated inferior intercavernous sinus has been found on MR venography in several studies in which patients experienced intracranial hypotension [1,3,5]. Although some masses of the sella can compress the intercavernous sinuses making them smaller [9,11,22,33], certain pathologies such as carotid-cavernous fistulas can enlarge these structures [4,11,31,32].…”

“…Encounters with the inferior intercavernous sinus mainly occur during transsphenoidal surgery for pituitary tumors [2]. Several studies have shown that dilated inferior intercavernous sinuses are found in patients with intracranial hypotension [1][2][3][4][5][6]. Mizutani et al suggest that the literature regarding this structure is because of its deep location within the skull base and its infrequent visualisation in open craniotomies [5,7].…”