Oldie springer - is he going senile?

ace is 11 1/2 he had a massive seizure a few months ago but has been great ever since eating well,loving his walks,drinking toileting no problems woke up today gave him his brekkie (the usual) after hes been out for toilt hes been hyper! he was crying and whining so we bought him into where the kids were hes been out for a run but since then all hes doing is pacing/walking fast up and down between the living room and conservtory! i cant get him to settle and seems extra hyper. is this a sign of going senile?

No one can diagnose him over the internet, I think it's time for a vet trip. Canine dementia can cause behaviour like you describe but so could other conditions. If it is him going senile then there are medication which can help - not a cure but I believe they increase bloodflow to the brain and can help lesson symptoms/slow down progression.

hes just been to vets had a thorough check up when he had his jabs were not sure if he has something on his brain hence the seizure but i wont put him thru the op to check as he gets agitated at vets and as the vet says no point in treating him if there is anything as he may not get thru the op so just enjoy him while hes happy . its just today that he seems hyper and wont setle

I would be tempted to get another opinion. One option could be to try medication as a diagnostic tool - basically you give medication for dementia and if he improves then there's a good chance that's the problem. There may be reasons why the vet hasn't gone down this route though - if the vet suspects the siezure to be caused by a brain tumour for example, medication that increases blood flow to the brain could speed up the growth by feeding the tumour.
However, a good vet will explain things thoroughly so you're not sent home unsure about options or your dog's behaviour. If your vet hasn't explained their opinion/decision properly, I would suggest going elsewhere.
Even if there's nothing that can be done medically for your dog, the vet should offer some advice for your next steps. Perhaps something like a DAP plug-in/spray/collar to calm him down, or a supplement like Zylkene?
The leaflet for Aktivait (one of the medications for dementia) has some tips on managing dementia-related behaviour which might be worth a try - http://www.vetplus.co.uk/PDF/LEAF/aktivait_leaflet.pdf

I have no experience with doggy dementia myself so please don't take my above comments as instructions on what to do next, just possible options to look into/discuss with a vet.