P90. Super selective amytal injection (Wada-Test) in a 14 year old with left sided parieto-insular epilepsy due to Focal cortical dysplasia

Introduction The classical Wada-test is performed by injecting a narcotic (usually amobarbital) into the left internal carotid artery (ICA) in order to establish language dominance. In the presurgical workup of epilepsy, it has largely been replaced by less invasive methods such as functional MRI and functional Transcranial Doppler Ultrasound. In exceptional cases, the Wada-test can be performed superselectively: the narcotic is injected into a branch of the middle cerebral artery (MCA). This allows proving or excluding language function in a small brain volume. We document the utility of a superselective Wada test in a 14-year-old girl with a dysplastic lesion in the left supramarginal cortex and dorsal insula. Methods A 14 year old girl presented with pharmacoresistant epilepsy. 3 T MRI revealed a left dorsal insular/supramaginal gyrus FLAIR hyperintensity suspicious of focal cortical dysplasia as the likely epileptogenic lesion. Multimodal presurgical work-up confirmed this. Yet, it was questionable if an extended lesionectomy would harm language function. Left ACI Wada-Test was inconclusive. Therefore, a superselective Wada-Test of an M3 branch of the left MCA/perirolandic artery was performed. Results Following the application of 70 mg Amobarbital, both EEG-slowing in electrodes C3, P3, and T5 and repeat angiography confirmed the correct localization of barbiturate action. During the superselective Wada-test, the patient was able to complete a comprehensive test battery of language functions (counting, naming, reading, calculating, spontaneous speech) without evident dysfunction. Neuronavigation and intraoperative electrophysiological monitoring supported an extended lesionectomy, preserving the white matter adjacent to the pyramidal tract. Early after surgery, the patient suffered from a Gerstmann’s syndrome and slight amnestic aphasia. However, this resolved within the first postoperative weeks. Histopathology confirmed focal cortical dysplasia type IIb. Following surgery, the patient is now seizure free for 18 months under reduced antiepileptic drugs. Her academic performance has improved compared to the preoperative status. Conclusion The Wada-test simulates the effect of resective or disconnective surgery on language functions by temporarily inactivating brain areas. Technical advances in catheter angiography allow injecting the narcotic into single MCA-branches or other arteries of similar diameter, thus simulating the effect of small cortical resections. In selected patients, this method can be a valuable supplement of multimodal presurgical workup, and may obviate the need for intra- or extraoperative cortical mapping.