Is unilateral intracranial EEG monitoring ever appropriate in the pre-surgical workup for presumed non-lesional epilepsy?  

The thought being, if no clearly defined lesion exists on available neuroimaging, how do we balance the benefits, risks, and uncertainty in choosing whether or not to monitor the hemisphere contralateral to the proposed epileptogenic focus?

And if it can be appropriate, under what circumstances? (i.e. how much and what kinds of objective data need to be fully in agreement to forego contralateral monitoring?)