A neuromodulation system for treating epilepsy provides therapeutic elements for modulating nerve activity to prevent or diminish (e.g. through reduced intensity or shortened duration) epileptic seizures. The therapeutic elements may be positioned in the vasculature of the patient and are energized to modulate nerve fibers positioned outside the vascular walls. Electrode positions may include the maxillary vein, inferior alveolar vein, lingual vein, retromandibular or facial vein, or the emissary vein of the foramen ovale. Target nerves include the mandibular branch (V3) of the trigeminal nerve, or a branch of the mandibular branch (e.g. the inferior alveolar nerve).
