Posterior cerebral artery P1 segment at the stoma during endoscopic third ventriculostomy in adults.

[hydrocephalus with stenosis of the aqueduct of sylvius]

A serious catastrophic complication of endoscopic third ventriculostomy (ETV ) is basilar artery (BA ) damage . Although the BA has been discussed as the cause of haemorrhage and even pseudoaneurysm , variations of the posterior cerebral artery proximal segment (P 1 ) and its protrusion into the third ventricle floor have not been emphasised . A series of cases are reported in which the P 1 segment was located at the stoma during an ETV and was at risk of perforation . Precautionary techniques for complication avoidance are described .A retrospective review was performed of all ETVs performed in adults at our institution between 2004 and 2008 . Cases were identified in which the P 1 segment was noted to herniate into the stoma at the time of third ventricular floor fenestration .Among 65 cases reviewed , six were identified in which the P 1 segment significantly herniated into an area of the stoma at the time of third ventricular floor fenestration . In no case was the P 1 segment injured by the ETV procedure . Each of the six patients had opaque third ventricle floors . A 'cookie cut ' technique was used in which the opaque third ventricle floor was abraded to reveal the underlying translucent membrane , offering an improved view of arteries in the basilar cisterns . In four of six patients , ETV resulted in clinical improvement .The posterior cerebral artery P 1 segment is potentially at risk during ETV in adults as well as in children . Awareness and proper precautions may help reduce injuries to either the P 1 or the basilar apex during an ETV .