Traumatic pericallosal artery aneurysm: a rare complication of transcallosal surgery. Case report.

Traumatic intracranial aneurysms are rare in adults but account for up to 33% of all aneurysms encountered in a pediatric population. The most common location of such lesions in children is the pericallosal or adjacent branch of the anterior cerebral artery, where a head impact exerts sudden decelerating shearing forces on the arteries tethered on the brain surface against an immobile falx cerebri, weakening the arterial wall. This action can lead to dissection of the damaged vascular layers, with resultant expansion of the affected site into a fusiform aneurysm. Pericallosal aneurysms following a penetrating intracranial injury have also been described, and the resultant lesion in some cases can be a pseudoaneurysm. The incidence of iatrogenic pericallosal artery aneurysms, however, is extremely rare. The authors describe the first reported case of a traumatic pericallosal artery aneurysm following transcallosal surgery. This 6-year-old boy underwent resection of a hypothalamic pilocytic astrocytoma, which was approached via the transcallosal corridor. A follow-up magnetic resonance image obtained within 1 year of surgery disclosed a small flow void off the right pericallosal artery, which was initially interpreted as residual tumor. Serial investigations showed the lesion enlarging over time, and subsequent angiography revealed a round 7-mm pericallosal artery aneurysm with an irregularly shaped 2- to 3-mm lumen. The aneurysm was difficult to treat with clip reconstruction or suturing of the affected segment, and an excellent outcome was ultimately achieved with resection of the lesion and autogenous arterial graft interposition. The authors also discuss the likely pathophysiology of the aneurysm and the surgical procedures undertaken to treat it.