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Recurrent Basilar Tip Pseudoaneurysm Treated Successfully with Flow Diversion

Key findings

  • Neurosurgeons at Massachusetts General Hospital have reported the first case of an iatrogenic basilar aneurysm being successfully treated with a flow diverter.
  • A 13-year-old boy developed a pseudoaneurysm of the basilar tip during repeat endoscopic third ventriculostomy (ETV) for hydrocephalus
  • Although rare, basilar artery aneurysm can be a serious consequence of ETV in pediatric patients
  • The pseudoaneurysm recurred despite initial coil embolization but was successfully treated with flow diversion

Vascular injury and traumatic pseudoaneurysm are rare complications of endoscopic third ventriculostomy (ETV), a common treatment for noncommunicating hydrocephalus. In the Journal of Neurosurgery: Pediatrics, neurosurgeons at Massachusetts General Hospital report what they believe to be the first case of a basilar artery aneurysm developing during repeat ETV and of an iatrogenic basilar aneurysm being successfully treated with flow diversion.

Neurosurgeons William Butler, MD, and Aman B. Patel, MD, co-director of the Neuroendovascular Program at Mass General, along with residents Christopher J. Stapleton, MD, and Matthew J. Koch, MD, report that the 13-year-old male patient presented to the emergency department with persistent headaches. He had a history of ETV and ventriculoperitoneal shunting for hydrocephalus secondary to intraventricular hemorrhage of prematurity.

Magnetic resonance imaging of the brain revealed signs of shunt and ETV failure: enlarged lateral and third ventricles and closure of the ETV fenestration site. Dr. Patel's team decided on repeat ETV because of its potential long-term durability and lower potential complication rate.

Under stereotactic guidance, the surgeons advanced a rigid endoscope into the right lateral ventricle and third ventricle. As the balloon catheter was being prepared for introduction, though, arterial bleeding of indeterminate origin was observed from the fenestration site.

The site was irrigated for 30 minutes until hemostasis was achieved, but because of the amount of bleeding, the procedure was terminated. Intraoperative computed tomography demonstrated a 3-mm basilar tip pseudoaneurysm, subarachnoid hemorrhage and intraventricular hemorrhage.

The patient was emergently taken to the endovascular suite, where left vertebral angiography re-demonstrated an aneurysm. The surgeons performed coil embolization. The patient awoke without a neurological deficit and his shunt was reinternalized on postoperative day 14.

On postoperative day 17, angiography demonstrated recurrence and enlargement of the aneurysm. There was also evidence of coil compaction at the superior left dome. Dr. Patel's group decided that flow diversion was needed as a definitive therapy.

Flow diversion requires the use of dual antiplatelet therapy. While in the endovascular suite, the patient received loading doses of 325 mg aspirin and 30 mg prasugrel. The pseudoaneurysm was recoiled and a flow-diverter device was placed from the left P1 posterior cerebral artery to the basilar artery. The patient was discharged the following day.

One month later, angiography showed complete obliteration of the aneurysm and complete filling of the right posterior cerebral artery. These findings were again evident seven months postoperatively, at which time prasugrel was discontinued.

In a literature search, the authors found only three prior cases of basilar aneurysms as complications of ETV and no prior case of bleeding or aneurysm development in repeat ETV.

Experiences with flow diversion in children is limited, they acknowledge, but in the adult literature, they found no report of recurrence of an aneurysm treated with flow diversion. The authors believe that when treatment options are limited, as in this case, the risks associated with conservative management may outweigh the risks of flow diversion. Those include the potential for in-stent thrombosis and loss of branch vessels.

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