Normal anatomy and variations in the confluence of sinuses using digital subtraction angiography

Intravascular ultrasound characteristics of different types of stenosis in idiopathic intracranial hypertension with venous sinus stenosis

BACKGROUND

In this study, we analyzed the characteristics of different stenosis types in idiopathic intracranial hypertension (IIH) patients with venous sinus stenosis (VSS) using intravascular ultrasound (IVUS).

METHODS

We retrospectively reviewed data from patients who underwent IVUS evaluation during venography or stenting procedures between January 2014 and February 2022.

RESULTS

Among the 80 patients with intrinsic lesions, 47 cases were identified, including 41 single lesions and 6 multiple lesions. Single lesions consisted of 36 cases of AG, 3 cases of brain herniation, and 2 cases of septation. Multiple intrinsic lesions were found in 6 patients, with AG observed in the transverse sinus and sigmoid sinus. IVUS features varied depending on the anatomical variations of intrinsic stenosis. Additionally, among the 33 cases of extrinsic stenosis, two types were observed: unilateral compression (22 cases) and bilateral compression (11 cases), primarily affecting the transverse sinus.

CONCLUSION

IVUS effectively differentiated intrinsic and extrinsic types of stenosis and identified intraluminal and mural components of intrinsic stenosis.

Absence of the torcular, review of venous sinus anatomy, and the simplified dural sinus classification

BACKGROUND

Classically, the torcular Herophili is described as the symmetric junction between the superior sagittal sinus (SSS), transverse sinuses (TSs), and straight sinus (SS). However, finding this pattern in practice is not standard. Anatomical variations are common, and different drainage patterns should be expected. Existing literature proposes highly detailed descriptions and classifications of this region. Still, a simplified and practical categorization is not available.

METHODS

We present an anatomical finding of the torcular Herophili discovered on a cadaveric dissection. Then, we conducted a retrospective study examining the 100 most recent cranial magnetic resonance venographies (MRVs) from the Mayo Clinic, labeling them with a new proposed dural sinus classification system. Images were initially classified by two authors and further validated by a board-certified neurosurgeon and a board-certified neuroradiologist from our institution. To measure consistency in image identification, two additional international neurosurgeons were asked to classify a subset of the same MRV images, and their answers were compared.

RESULTS

Of the MRV cohort, 33 patients were male and 67 were female. Their ages ranged from 18 to 86 years, with a mean of 47.35 years and a median of 49 years. Upon examination, 53 patients presented as confluent (53%), 9 as SSS divergent (9%), 25 as SS divergent (25%), 11 as circular (11%), and 2 as trifurcated (2%). The inter-rater reliability ranked very good; agreement between the two neurosurgeons was 83% (κ = 0.830, p < 0.0005).

CONCLUSION

The confluence of the venous sinuses is a highly variable anatomical area that is rarely evaluated with neuroimaging before surgery. The classic textbook configuration is not the rule. Using a simplified classification system may increase awareness and hopefully patient safety by preparing the physician for anatomical variations that they will encounter in a surgical or clinical scenario.

Cerebral Venous Outflow Implications in Idiopathic Intracranial Hypertension-From Physiopathology to Treatment

In this review, we provide an update on the pathogenesis, diagnosis, and management of adults with idiopathic intracranial hypertension (IIH) and implications of the cerebral venous system, highlighting the progress made during the past decade with regard to mechanisms of the venous outflow pathway and its connection with the cerebral glymphatic and lymphatic network in genesis of IIH. Early diagnosis and treatment are crucial for favorable visual outcomes and to avoid vision loss, but there is also a risk of overdiagnosis and misdiagnosis in many patients with IIH. We also present details about treatment of intracranial hypertension, which is possible in most cases with a combination of weight loss and drug treatments, but also in selected cases with surgical interventions such as optic nerve sheath fenestration, cerebral spinal fluid (CSF) diversion, or dural venous sinus stenting for some patients with cerebral venous sinus stenosis, after careful analysis of mechanisms of intracranial hypertension, patient clinical profile, and method risks.

Acute cerebral venous outflow obstruction during convexity meningioma resection

BACKGROUND

Cerebral venous outflow obstruction involves idiopathic intracranial hypertension, and the most common related condition is dural venous sinus stenosis or, in other words, an obstruction of the dural venous sinuses. In these cases, the pathological process is often chronic, displays only mild symptoms, and rarely requires urgent surgical intervention. In this study, we present a unique case involving an acute cerebral venous outflow obstruction that occurred during meningioma resection that ultimately had catastrophic consequences.

MATERIALS AND METHODS

The patient's preoperative imaging only revealed an unremarkable frontal convexity meningioma with an average diameter exceeding 8 cm. She was admitted for a scheduled right frontoparietal craniotomy for lesion resection.

RESULTS

The patient's unique congenital dural venous sinus structure along with a non-surgical epidural hematoma both contributed to a catastrophic outcome, causing a progressive hemispheric encephalocele, significant blood loss, and wound closure difficulties.

CONCLUSION

Neurosurgeons should place an additional focus on cerebral venous outflow patency during tumor resection, even if the tumor does not involve the transverse or sigmoid sinuses. It is well known that the tacking sutures play an essential role in preventing an epidural hematoma, but the procedure to mitigate hematomas occurring outside the surgical field of view is not fully recognized by neurosurgeons. If dural tacking sutures are placed after complete tumor resection, the prophylactic effect for preventing EDH in the non-surgical areas may not be guaranteed. Therefore, we strongly advocate for the tacking sutures to be accurately placed before dural incisions are made.

Safety and efficacy of intravascular ultrasound as an adjunct to stenting for cerebral venous sinus stenosis-induced idiopathic intracranial hypertension: a pilot study

OBJECTIVE

Symptomatic intracranial hypertension can be caused by cerebral venous sinus stenosis (CVSS) and cerebral venous sinus thrombotic (CVST) stenosis, which is usually found in some patients with idiopathic intracranial hypertension (IIH). Recently, at the authors' center, they utilized intravascular ultrasound (IVUS) as an adjunct to conventional venoplasty or stenting to facilitate diagnosis and accurate stent placement in CVSS.

METHODS

The authors designed a retrospective review of their prospective database of patients who underwent IVUS-guided venous sinus stenting between April 2016 and February 2017. Clinical, radiological, and ophthalmological information was recorded and analyzed. IVUS was performed in 12 patients with IIH (9 with nonthrombotic CVSS, 3 with secondary stenosis combined with CVST) during venoplasty through venous access. The IVUS catheter was used from a proximal location to the site of stenosis. Post-stenting follow-up, including symptomatic improvement, stent patency, and adjacent-site stenosis, was assessed at 1 year.

RESULTS

Thirteen stenotic cerebral sinuses in 12 patients were corrected using IVUS-guided stenting. No technical or neurological complications were encountered. The IVUS images were excellent for the diagnosis of the stenosis, and intraluminal thrombi were clearly visualized by using IVUS in 3 (25%) of the 12 patients. A giant arachnoid granulation was demonstrated in 1 (8.3%) of the 12 patients. Intravenous compartments or septations (2 of 12, 16.7%) and vessel wall thickening (6 of 12, 50%) were also noted. At 1-year follow-up, 10 of 12 patients were clinically symptom-free in our series.

CONCLUSIONS

IVUS is a promising tool with the potential to improve the diagnostic accuracy in IIH, aiding in identification of the types of intracranial venous stenosis, assisting in stent selection, and guiding stent placement. Further study of the utility of IVUS in venous stenting and venous stenosis pathology is warranted.