Localizing value of epileptic visual auras

It is difficult to differentiate between seizures of occipital or temporal lobe origin in patients with focal epileptic seizures associated with visua l aura. These are often suspected to originate from the visual cortex, whic h causes reluctance to propose resection as treatment for the affected pati ent, To determine the value of localizing different types of visual auras, we report on 20 patients experiencing visual aura from a series of 878 surg ically treated patients suffering from intractable focal seizures. In all o f these patients, a morphological abnormality was identified on MRI (n = 18 ) or cranial CT (n = 2), These abnormalities were shown to represent the mo rphological correlate of the epileptogenic zone in each case, as demonstrat ed by intracranial ictal EEG recordings and/or seizure freedom after focal resective surgery. Elementary hallucinations, illusions and visual loss wer e reported not only by all patients with occipital lobe epilepsy, but also by patients with occipitotemporal and anteromedial temporal seizure onset. Complex hallucinations never occurred in occipital lobe seizures but were p resent in the two other groups. The same correlation was found for concentr ic changes of visual field (tunnel vision), a newly described ictal phenome non. We conclude that elementary hallucinations, illusions and visual loss, although typical for occipital lobe epilepsy, can also occur in anteromedi al temporal or occipitotemporal seizures and are therefore not a discordant feature in presurgical evaluation of patients with suspected temporal lobe epilepsy. Complex hallucinations and tunnel vision, however, should be con sidered concordant only with the assumption of an anteromedial temporal or occipitotemporal seizure onset.