Everyone reacts differently to all aed's.  I was on Lamictal for just
under 1 year some time ago.  It caused the frequency & severity of my
seizures to increase & eventually landed me in the local A&E department
with a dose of status.

On the other hand, I've been on keppra for almost a year now.  You'll
see other posts here from people who regard keppra as the most evil
thing on the planet.  In my case, after I got over the initial side
effects, it's been great.  Now seizure free since I started taking it.

Over the last 9 years, I've changed meds several times as nothing
seemed to control me.  Lamictal, neurontin, high doses of tegretol,
topomax, epilim & now keppra.  

The only way to find out whether or not Lamictal's going to be any use
to your wife is for her to try it & see.

Best wishes & good luck.