S. Tanoue

Dural Arteriovenous Fistula Involving the Posterior Condylar Canal

SUMMARY: Although dural arteriovenous fistulas (DAVFs) occur in any structure that is covered by the dura mater, DAVFs at the posterior condylar canal have not been reported. We present a DAVF that involves the posterior condylar canal and drains into the posterior condylar vein and the occipital sinus, which was treated by selective transvenous embolization. Knowledge of venous anatomy of the craniocervical junction and careful assessment of the location of the arteriovenous fistula can contribute to successful treatment.

Selective Transvenous Embolization of Dural Arteriovenous Fistulas Involving the Hypoglossal Canal

The hypoglossal canal contains a venous plexus that connects the inferior petrous sinus, condylar vein, jugular vein and paravertebral plexus. The venous plexus is one of the venous drainage routes of the posterior skull base. Only a few cases of dural arteriovenous fistulas (AVFs) involving the hypoglossal canal have been reported. We describe three cases (a 62-year-old female, a 52-year-old male, and an 83-year-old male) of dural AVFs involving the hypoglossal canal. Symptoms were pulse-synchronous bruit in two cases and proptosis/chemosis in one. All dural AVFs were mainly fed by the ipsilateral ascending pharyngeal artery. Two of three dural AVFs involving the hypoglossal canal mainly drained through the anterior condylar confluence into the inferior petrosal sinus retrogradely with antegrade drainage through the lateral condylar vein. The other one drained through the lateral and posterior condylar veins into the suboccipital cavernous sinus. All dural AVFs were completely occluded by selective transvenous embolization without any complications, and the symptoms disappeared within one week in all cases. Dural AVFs involving the hypoglossal canal can be successfully treated by selective transvenous embolization with critical evaluation of venous anatomy in each case.

Superior Petrosal Sinus: Hemodynamic Features in Normal and Cavernous Sinus Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE: Normal hemodynamic features of the superior petrosal sinus and their relationships to the SPS drainage from cavernous sinus dural arteriovenous fistulas are not well known. We investigated normal hemodynamic features of the SPS on cerebral angiography as well as the frequency and types of the SPS drainage from CSDAVFs. MATERIALS AND METHODS: We evaluated 119 patients who underwent cerebral angiography by focusing on visualization and hemodynamic status of the SPS. We also reviewed selective angiography in 25 consecutive patients with CSDAVFs; we were especially interested in the presence of drainage routes through the SPS from CSDAVFs. RESULTS: In 119 patients (238 sides), the SPS was segmentally (anterior segment, 37 sides; posterior segment, 82 sides) or totally (116 sides) demonstrated. It was demonstrated on carotid angiography in 11 sides (4.6%), receiving blood from the basal vein of Rosenthal or sphenopetrosal sinus, and on vertebral angiography in 235 sides (98.7%), receiving blood from the petrosal vein. No SPSs were demonstrated with venous drainage from the cavernous sinus. SPS drainage was found in 7 of 25 patients (28%) with CSDAVFs. CSDAVFs drained through the anterior segment of SPS into the petrosal vein without draining to the posterior segment in 3 of 7 patients (12%). CONCLUSIONS: The SPS normally works as the drainage route receiving blood from the anterior cerebellar and brain stem venous systems. The variation of hemodynamic features would be related to the relatively lower frequency and 2 different types of SPS drainage from CSDAVFs.

Artery of the Superior Orbital Fissure: An Undescribed Branch from the Pterygopalatine Segment of the Maxillary Artery to the Orbital Apex Connecting with the Anteromedial Branch of the Inferolateral Trunk.

BACKGROUND AND PURPOSE: Some branches of the internal maxillary artery have anastomoses with the inferolateral trunk that are important as intracranial-extracranial collateral pathways and as dangerous anastomoses for transarterial embolization of these branches. We present here an undescribed branch potentially anastomosing with the anteromedial branch of the inferolateral trunk, which is provisionally named the artery of the superior orbital fissure, defined as an arterial branch from the pterygopalatine segment of the maxillary artery to the orbital apex at the superior orbital fissure. MATERIALS AND METHODS: Two neuroradiologists reviewed 3D and MPR images of the external and/or common carotid artery with particular interest paid to the artery of the superior orbital fissure in 54 patients who underwent 3D angiography with a field of view covering the pterygopalatine fossa and the cavernous sinus. The underlying diseases in these patients were 17 parasellar hypervascular lesions (including 13 cavernous sinus dural arteriovenous fistulas and 4 meningiomas), 18 internal carotid artery stenoses/occlusions, and 19 other diseases. RESULTS: The artery of the superior orbital fissure was identified in 20 of 54 patients; it arose at the pterygopalatine segment of the maxillary artery, either singly or from a common trunk with the artery of the foramen rotundum, and ran upward to reach the superior orbital fissure. It anastomosed with the anteromedial branch of the inferolateral trunk at the superior orbital fissure with blood flow toward the cavernous sinus (n = 14) and/or the ophthalmic artery (n = 2). It was more prominent in parasellar hypervascular lesions and internal carotid artery stenoses/occlusions than in other diseases. CONCLUSIONS: The artery of the superior orbital fissure, a remnant of the anastomotic artery, was often identified, especially in patients with parasellar hypervascular lesions.

Turn-Back Embolization Technique for Effective Transvenous Embolization of Dural Arteriovenous Fistulas

SUMMARY: For effective transvenous embolization of DAVFs, it is important to place coils at the shunting venous pouch in the initial step of the procedure. When it was difficult to navigate a microcatheter to the shunting venous pouch due to the anatomic relationship of approach routes with targeted pouches, we navigated the microcatheters by a “turn-back technique” within the involved sinuses into the target pouches. Complete occlusion or regression of the DAVF was obtained in all cases.