Case report We report a 57-year-old male who presented with a posterior fossa subarachnoid hemorrhage secondary to an AVM supplied by the right posterior inferior cerebellar artery (PICA) and anterior inferior cerebellar artery (AICA). Multiple aneurysms were present on feeding arteries. Due to the proximal location of several aneurysms, and the amount of vascular displacement that occurs with removing the microcatheter after Onyx, there was concern for increased risk of hemorrhage. Under a compassionate use exemption application from the FDA and institutional IRB acknowledgment, permission to use the new APOLLO microcatheter was granted. The APOLLO is a DMSO compatible microatheter with a very soft, detachable distal tip, allowing for prolonged Onyx injection times. The soft tip allows the microcather to perform very similar to the Marathon microcatheter and is recommended with the Mirage 0.008 wire (eV3); although, we tend to use the Synchro 10 wire (Stryker; Fremont, CA). The APOLLO microcatheter was developed with detachable distal tip lengths of 15, 20 and 30 millimeters (mm). The distance between the optimal microcather embolization location and the feeding pedicle aneurysms was approximately 1 cm. Therefore, the 15 mm detachable tip APOLLO microcather was felt to be the best option. The APOLLO was navigated distally into one of the hemispheric branches of PICA over a Synchro 10 microwire and the detachment point kept proximal to the most proximal aneurysm so that reflux would occlude this aneurysm without affecting the ability to detach the tip. This pedicle was then embolized with Onyx 34 to completion. The microcatheter tip was safely detached on pullback at the expected location. A second 15 mm detachable tip APOLLO microcatheter was advanced into the other hemispheric branch using the same methodology. This pedicle was also embolized in a similar fashion. The microcatheter tip was safely detached at the expected location upon pullback. A final DSA showed near complete embolization of the AVM. The patient did not suffer any neurologic complications. The AVM was subsequently surgically resected with minimal blood loss.

Conclusion Higher rates of curative embolization and more extensive amounts of embolization are possible for the treatment of AVM's due to improvements in liquid embolic agents. Onyx, however, often requires prolonged injection times to achieve these improved results. This report describes the first US case utilizing the APOLLO detachable tip microcather allowing prolonged microcatheter injections and subsequent safe and predictable detachment of the tip during microcatheter removal.

Competing interests A Turk: EV3. M Chaudry: None. R Turner: None.