PMC8422446_01
Preoperative magnetic resonance images. (a) A vascular lesion is suspected on magnetic resonance angiography (white arrow heads). (b) The vascular lesion is located beneath the cerebellar tentorium (white arrow heads).
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However, magnetic resonance angiography revealed a vascular lesion [Figure 1a]. Vascular lesions were also found below the cerebellar tentorium on constructive interference in steady-state images [Figure 1b].
Preoperative angiographic findings. Selective angiogram of the right mastoid branch of the occipital artery demonstrating an arteriovenous shunt fed by the right PMA. The shunt shows two drainage pathways, running through the superior vermian vein to the petrosal vein terminating to the transvers sinus and through the superior vermian vein to the inferior vermian vein terminating to the tentorial sinus (a: anteroposterior projection and b: lateral projection). A left occipital angiogram reveals that the arteriovenous shunt is also supplied by the left PMA (c: anteroposterior projection and d: lateral projection). The shunting point is located beneath the cerebellar tentorium (white arrows: caliber change) (e). A left vertebral angiogram does not reveal any apparent feeding arteries. Venous congestion of the left vermian hemisphere is observed. The venous circulation is antegrade but stagnated. (f) Arterial phase of anteroposterior projection. (g) Venous phase of anteroposterior projection (h) arterial phase of lateral projection. (i) Venous phase of lateral projection. PMA: Posterior meningeal artery.
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The arteriovenous shunt showed two draining patterns, travelling through the superior vermian vein to the petrosal vein and superior petrosal sinus and through the inferior hemispheric vein, inferior hemispheric vein, and tentorial sinus [Figure 2a and b]. The left occipital angiogram showed an arteriovenous shunt fed by the left PMA [Figure 2c and d]. On maximum intensity projection images, the shunting point was located beneath the cerebellar tentorium, and the drainer ran through the tentorial sinus into the transverse sinus [Figure 2e]. No retrograde flow of the basal vein of Rosenthal was observed [Figure 2f-i].
Intraoperative angiographic findings. Endovascular devices were introduced near to the shunting point (single black arrowhead: Envoy 5F 90 cm MPD, double black arrow heads: Masters HF 2.8-Fr/3.2-Fr 125 cm and triple black arrow heads: Carnelian MARVEL  1.6/1.8-Fr 155 cm) (a: lateral projection). The shunting point was embolized with 20% of NBCA. NBCA was partially migrated (b: anteroposterior injection and c: lateral projection). After the injection of 20% NBCA, the arteriovenous shunt was not seen. (d) Anteroposterior projection of the right occipital angiogram. (e) Lateral projection of the right occipital angiogram. (f) Anteroposterior projection of the left occipital angiogram. (g) Lateral projection of the left occipital angiogram. The left vertebral angiogram shows the residual arteriovenous shunt (white arrowhead). Venous congestion remained (h: arterial phase of anteroposterior projection, i: venous phase of anteroposterior projection, and j: arterial phase of lateral projection). The residual shunting point is located beneath the cerebellar tentorium (white arrow). The shunting point embolized with 20% of NBCA is also recognized (white arrow heads) (k: a sagittal image of maximum intensity projection). The residual arteriovenous shunt is supplied by the AWW (white arrow heads). The AWW branched near the bifurcation of the basilar artery and superior cerebellar artery (l and m: three-dimensional images). AWW: The artery of Wollschlaeger and Wollschlaeger, NBCA: n-butyl-2-cyanoacrylate.
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Tokyo, Japan) [Figure 3a]. NBCA reached the drainer with an injection volume of 0.3 mL, the right Carnelian MARVEL  1.6/1.8-Fr 155 cm was removed. NBCA migrated partially to the left transverse sinus, left inferior hemispheric vein, and left petrosal vein [Figure 3b and c]. The right and left occipital angiogram revealed the disappearance of the shunt [Figure 3d-g], which was also confirmed by cone beam computed tomography using a half-diluted contrast agent. Venous congestion also remained in the left cerebellar hemisphere [Figure 3h-j]. On 3-dimensional reconstructed maximum intensity projection (3D-MIP) images, the residual arteriovenous shunt beneath the cerebellar tentorium was identified above the location of the NBCA along the cerebellar tentorium [Figure 3k]. AWW [Figure 3l and m]. As the embolization of the main shunting point with NBCA was successfully achieved and the shunting flow was not remarkably strong, we considered that the residual arteriovenous shunt could be monitored under observation.
Postoperative angiography and schemas of the TDAVF in this case. (a and b) Left vertebral angiogram performed 1 week after the endovascular surgery reveals no residual arteriovenous shunt. (c and d) Schemas of the arterial supply and shunting point of the TDAVF. Preoperatively, the arterial feeding by AWW was not visualized (c). Postoperatively, the arterial feeding by AWW is observed (arrow). The shunting point was embolized with NBCA (the region margined with arrow heads). AWW: The artery of Wollschlaeger and Wollschlaeger, BA: The basilar artery, NBCA: n-butyl-2-cyanoacrylate, PMA: The posterior meningeal artery, SCA: The superior cerebellar artery.
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The residual arteriovenous fistula fed by the AWW disappeared spontaneously, as seen on follow-up vertebral angiography 1 week after the procedure [Figure 4a and b].