A Cautionary Tale: Persistent Trigeminal Artery and Wada Test

Introduction Epilepsy surgery workup may include Wada-test/Etomidate speech test (EST). Presence of intracranial arterial variants like persistent trigeminal artery (PTA) contraindicate EST. PTA is an embryonic remnant between proximal cavernous segment internal carotid artery (ICA) and mid-distal basilar artery. Methods We report a 14-year-old boy with drug-resistant myoclonic epilepsy presenting initially with infantile spasms and neuro-regression at 1.5 years old. Following complete electroclinical response to vigabatrin, he progressed to focal impaired-awareness seizures four years later. Comorbidities included mild intellectual disability and attention-deficit hyperactivity disorder. MRI-brain showed left temporoparietal encephalomalacia due to presumed perinatal ischemic stroke with PET concordance. Ictal and inter-ictal EEG were predominantly generalized, frequent spike/poly-spike waves mixed with polymorphic delta activity in the left temporal region. Magnetic-source imaging showed dipole cluster in left temporo-occipital and temporal operculum regions. Functional MRI for language showed bilateral language representation. Results Catheter angiography demonstrated PTA connecting to mid-basilar artery and EST was aborted. Stereo-EEG evaluation was then used for delineation of epileptogenic zone and language mapping. Primitive intracranial embryonic anastomoses persist in 0.1-1.25% of the population, PTA being the most common. PTA may be prone to aneurysms and associated with posterior ischemic strokes. PTA may be seen in vasculopathy syndromes such as PHACEs*. Thrombosis of the PTA is rare; may occur in ICA dissections. If associated with vertebrobasilar hypoplasia ischemia and steal phenomenon may be seen. Conclusion Given the serious risk of anaesthetizing the brainstem, it is pertinent to identify a PTA prior to EST and consider alternative epilepsy-surgery workup.