Generalised tonic clonic to absence?

[huang.hin]

I have a patient. He is seizure patient, He has 13 seizures in total since age 15 till Jan 2011. Every seizure attack occurred 2 years apart. However, the last 3 episodes happened in the matter of 3 months' time. We have explored all the various causes namely family background(genetic), history of head trauma, occupational hazards, alcohol abuse or medications. No positive findings noted. There were various investigations done on Jan 2011 namely EEG, CT brain and MRA. None of these investigations showed significant findings. Hence he was diagnosed with idiopathic seizures and prescribed with sodium valproate 200mg BD. He took the medications regularly and has no seizure attack ever since. It has been 8 months seizure free.

But, of late, he complained of having several episodes of 'black-outs'. On one occasions, he was about to go to the toilet. He stood up and walked down the stairs. Suddenly, he totally went 'blank' for 10-15 sec. His wife claimed that he urinated during the ‘black-out’ period. He didn’t know he urinated until he ‘regain’ his senses. He just stood up and paused for 10-15 secs. When his wife called out for him, he ‘wanted’ to respond but just could not do so. Then he will ask ‘What had happen?
Is is possible for a patient to have generalized tonic clonic and develop absence seizure???