Torcular dural arteriovenous fistula treated via stent placement and angioplasty in the affected straight and transverse sinuses: case report

The successful obliteration of torcular dural arteriovenous fistula (DAVF) with a diffuse shunt in the affected sinus may require complex treatment strategies. Therapeutic goals include the preservation of normal venous drainage and complete obliteration of shunt flow. The authors report the case of a torcular DAVF. The treatment of this type of AVF may require a combined approach with transarterial and transvenous embolization, open surgery, or radiosurgery and is associated with many problems. Stent placement and angioplasty in the affected sinus result in compression of the fistulous dural wall of the sinus and decrease shunt flow. In cases in which there is a diffuse shunt in the affected sinus and no evident shunt point, such as in AVFs involving venous pouches and parasinuses, sealing the fistula orifice with self-expandable stents and angioplasty (balloon inflation) is considered the best treatment option to preserve normal cerebral venous sinus drainage and obliterate shunt flow. In such cases, the authors recommend using one or more self-expandable and closed-cell stents and using angioplasty to avoid endoleakage into the gap between the stent graft and the vessel wall.

Is There an Identifiable Intact Medial Wall of the Cavernous Sinus? Macro- and Microscopic Anatomical Study Using Sheet Plastination

BACKGROUND: The medial wall of the cavernous sinus is believed to play a significant role in determining the direction of growth of pituitary adenomas and in planning pituitary surgery. However, it remains unclear whether there is a dural wall between the pituitary gland and the cavernous sinus. OBJECTIVE: To identify and trace the membranelike structures medial to the cavernous sinus and around the pituitary gland and their relationships with surrounding structures. METHODS: Sixteen cadavers (7 females and 9 males; age range, 54-89 years; mean age, 77 years) were used in this study and prepared as 16 sets of transverse (5 sets), coronal (2 sets), and sagittal (9 sets) plastinated sections that were examined at both macro- and microscopic levels. RESULTS: The pituitary gland was fully enclosed in a fibrous capsule, but the components between the anterosuperior aspect of the gland capsule and the cavernous sinus. Posteroinferiorly, however, this dural layer disappeared as it fused with the capsule. A weblike loose fibrous network connected the capsule, carotid artery, venous plexus, and the dura of the middle cranial fossa. CONCLUSION: The medial wall of the cavernous sinus consists of both the meningeal dura and weblike loose fibrous network, which are located at the anterosuperior and posteroinferior aspects, respectively.

Dural relationships of Meckel cave and lateral wall of the cavernous sinus

Object The purpose of this study was to elucidate the anatomy of the trigeminal nerve (cranial nerve [CN] V), Meckel cave (MC), and lateral wall of the cavernous sinus (CS). Methods Ten fresh cadaver heads (20 sides) and 2 middle fossa embalmed specimens were removed, decalcified, sectioned, stained, and studied microscopically. Results In the MC, the posterior fossa meningeal dura extended into the middle fossa surrounding CN V. The average medial length of the MC was 16.7 mm and the lateral length was 13.5 mm. The dural roof of MC was thicker than its floor and was covered by a paw-shaped fibrous tissue extending from the tentorium to the ganglion (in 100% of specimens). Between the dural sleeve of the MC and venous space of the CS, a separate fibrous wall could be identified in 45% (9 of 20) extending between the tentorium and the floor of the CS. The mean length of CN V in the MC proximal to the posterior margin of the Gasserian ganglion was 11.8 mm. The mean length of CN V1 was 19.4 mm; V2, 12.3 mm; and V3, 7.4 mm distal to the anterior margin of the ganglion. The periosteal dura followed the bone of the middle fossa and was continuous with the extracranial periosteum. The lateral dural wall of the CS consisted of a medial (membranous) and a lateral wall. The latter was separated into a thin outer layer and a thicker fibrous inner layer that became thinner as it extended posterolaterally. Conclusions The MC is an extension of the posterior fossa dura with intricate relationships with the surrounding dural layers.

Magnetic resonance imaging of cavernous sinus invasion by pituitary adenoma diagnostic criteria and surgical findings

This study used MRI to define preoperative imaging criteria for cavernous sinus invasion (CSI) by pituitary adenoma (PA). MR images of 103 patients with PA submitted to surgery (48 with CSI) were retrospectively reviewed. The following MR signs were studied and compared to intraoperative findings (the latter were considered the gold standard for CSI detection): presence of normal pituitary gland between the adenoma and CS, status of the CS venous compartments, CS size, CS lateral wall bulging, displacement of the intracavernous internal carotid artery (ICA) by adenoma, grade of parasellar extension (Knosp-Steiner classification) and percentage of intracavernous ICA encased by the tumor. Statistical analysis was performed using qui-square testing and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were obtained for each MR finding. The following signs have been found to represent accurate criteria for non-invasion of the CS: 1- normal pituitary gland interposed between the adenoma and the CS (PPV, 100%); 2- intact medial venous compartment (PPV, 100%); 3- percentage of encasement of the intracavernous ICA lower than 25% (NPV, 100%) and 4- medial intercarotid line not crossed by the tumor (NPV, 100%). Criteria for CSI were: 1- percentage of encasement of the intracavernous ICA higher than 45%; 2- occlusion of three or more CS venous compartments and 3- occlusion of the CS lateral venous compartment. The CS was very likely to be invaded if the inferior venous compartment was not detected (PPV. 92,8%), if the lateral intercarotid line was crossed (PPV. 96,1%) or if a bulging lateral dural wall of the CS was seen (PPV, 92,3%). The preoperative diagnosis of CSI by PA is extremely important since endocrinological remission is rarely obtained after microsurgery alone in patients with invasive tumors. The above mentioned MR imaging criteria may be useful in advising most of the patients preoperatively on the potential need for complimentary therapy after surgery.

Tumors of the lateral wall of the cavernous sinus

✓ The lateral dural wall of the cavernous sinus is composed of two layers, the outer dural layer (dura propria) and the inner membranous layer. Tumors arising from the contents of the lateral dural wall are located between these two layers and are classified as interdural. They are in essence extradural/extracavernous. The inner membranous layer separates these tumors from the venous channels of the cavernous sinus. Preoperative recognition of tumors in this location is critical for selecting an appropriate microsurgical approach. Characteristics displayed by magnetic resonance imaging show an oval-shaped, smooth-bordered mass with medial displacement but not encasement of the cavernous internal carotid artery. Tumors in this location can be resected safely without entering the cavernous sinus proper by using techniques that permit reflection of the dura propria of the lateral wall (methods of Hakuba or Dolenc). During the last 5 years, the authors have identified and treated five patients with interdural cavernous sinus tumors, which included two trigeminal neurinomas arising from the first division of the fifth cranial nerve, two epidermoid tumors, and one malignant melanoma presumed to be primary. The pathoanatomical features that make this group of tumors unique are discussed, as well as the clinical and radiological findings, and selection of the microsurgical approach. A more favorable prognosis for tumor resection and cranial nerve preservation is predicted for interdural tumors when compared with other cavernous sinus tumors.