Transvenous retrograde nidus sclerotherapy under controlled hypotension (TRENSH): a newly proposed treatment for brain arteriovenous malformations--concepts and rationale.

PURPOSE: An alternative endovascular treatment to conventional transarterial embolization of cerebral arteriovenous malformations (AVMs) is proposed. CONCEPT: According to this proposed treatment, selected AVMs could undergo transvenous retrograde nidus sclerotherapy under controlled hypotensive anesthesia (TRENSH). RATIONALE: It is hypothesized that TRENSH may provide the means of avoiding delivery of embolic agents via arterial feeders (thus preventing ischemic complications), in addition to a possible more complete permeation of an AVM nidus with a sclerosant than can otherwise be obtained with current agents via arterial feeders. DISCUSSION: Instead of relying on access to an AVM nidus from the arterial side (with its usual complexity), TRENSH would require retrograde access to the lesion via much larger and anatomically simpler draining veins. Retrograde permeation of the AVM nidus may then be possible with a liquid sclerosant (to effect a "chemical embolization") provided that the arterial inflow is reduced sufficiently by temporary controlled systemic hypotension, with or without the aid of temporary balloon occlusion of the main arterial feeder(s). Retrograde spread of sclerosant within the nidus that falls short of filling arterial feeders and their branches to normal brain tissue may then be possible. Angioarchitectural and hemodynamic considerations are addressed, as are the potential role and limitations of TRENSH in the management of cerebral pial AVMs. Future implementation of this new technique in some specific selected cases in which the anatomic configuration of the AVM and its draining veins might be favorable could prove to be a potentially useful addition to the armamentarium of AVM therapies, which currently includes microsurgery, radiosurgery, and transarterial embolotherapy. Experimental studies directed at assessing the feasibility of TRENSH before potential future clinical application seem justified.