Despite all the information you provided, I don't think anyone here would be able to make an educated guess without further test on your patient, including EEG recording too locate a possible focus for the seizure and its type and response to medication (list available here: http://www.webmd.com/epilepsy/medications-treat-seizures).

Nail hypoplasia might also be a results of medications (anti convulsant), here again the history of the patient is needed. I just hope you are not planning to do the surgery yourself.

These are the tough cases. . . .planning a surgery would start with a detailed evaluation of these children. The surgeries could very from focused resections and disconnections to palliative surgeries such as callosotomy and modified hemispherotomy. Clinically if drop attacks and falls with severe injuries, we could consider palliative surgeries. But if its multifocal epilepsy with one type of semiology being predominant and disabling to the patient, with adequate  localization on EEG, MRI, VEEG and PET/SPECT then a more focussed surgery can be considered. 

These are complicated cases and usually depend on a tailored surgery as per the treating consultant and parents of the patient.

First seizure semiology is one of the key points. Additionaly with techniques like EEG (invazive EEG if required), MRI (fMRI is required especially in temporal lobe epilepsies), vEEG (i think the most important diagnostic technique for pre-operative evaluation. It helps you studying seizure semiology with EEG) and PET (necessary when there is any temporal hypometabolizm).

If we talk about your patient you must consider if it a rasmussen encephalytis or not. If so functional hemispherotomy will be effective.

But there are some pitfalls in such cases. There are some spastic tetraplegic patients such as hallowerden sp. syndrome, which is hard to diagnose and make a good diff. diagnosis. good luck with your patient.

I think it is difficult to answer this question without proper history semiology of seizure developmental History anti epileptic drug used whether the drug itself duration dose compliance

also epilpsy protocol MRI

prpoer EEG