Transvenous Approach for the Treatment of Cerebral Arteriovenous Malformations

Transvenous Approach for the Treatment of Cerebral Arteriovenous Malformations (TATAM): A Randomized Controlled Trial and Registry

A new endovascular route for the treatment of brain AVMs may be possible in some cases: Trans-Venous Embolization (TVE). The technique uses microcatheters to navigate to the draining veins of AVM, to reach and then fill the AVM nidus retrogradely with liquid embolic agents until the lesion is occluded. This technique has the potential to improve on some of the problems with the arterial approach to AVM embolization, such as a low overall occlusion rate. However, by occluding the vein first, and filling the lesion with the embolic agent in a retrograde fashion, the method transgresses a widely held dogma in the surgical or endovascular treatment of AVMs: to preserve the draining vein until all afferent vessels have been occluded. Nevertheless, the initial case series have shown promising results, with high occlusion rates, and few technical complications.

The method is increasingly used in an increasing number of centers, but there is currently no research protocol to guide the use of this promising but still experimental treatment in a prudent fashion. Care trials can be designed to offer such an experimental treatment, taking into account the best medical interests of patients, in the presence of rapidly evolving indications and techniques.

Inclusion Criteria:

• Any patient harboring a brain AVM (ruptured or unruptured) in whom TVE is considered a promising but yet unproven therapeutic option by the participating clinicians can be submitted to the Case Selection Committee.
• Patients must be in stable, non-urgent clinical condition, with the acute phase of the AVM rupture resolved (where applicable).
• Case must be approved by the CSC.

Notes on potentially suitable cases:

1. Current indications may include (but are NOT restricted to) brain AVMs with a small <3 cm nidus (or small residual nidus), with a single draining vein, and for which curative treatment can be attained with one or at most two treatment sessions.
2. Physicians are not required to submit cases prior to any or all treatment; a case can be submitted to the CSC for consideration after previous treatments (including previous arterial embolization sessions) have been performed. The timing of the submission of the case will be left to individual operators. Previously treated AVMs (by any other modality: embolization/surgical resection/radiosurgery) are not excluded from TATAM.

Exclusion Criteria:

• Absolute contra-indication to endovascular treatment or anesthesia.
• Inability to obtain informed consent.