What you are describing is a
stroke, not a TIA. A TIA means a
transient ischemic attack, meaning that symptoms disappear within an hour and that doesn't seem to be the case.
There is no surgical procedure to help him. As for what else could, well it depends, some more details about this shaking would've been helpful, if by shaking which has improved you mean weakness of his hand as a consequence of the stroke then there is no specific treatment apart
physiotherapy. Medical therapy serves only to try to prevent a second stroke from happening, not much can be done now about the old stroke. If he hasn't recovered in two years I believe the weakness will remain forever.
On the other hand if these shaking episodes come in the form of short lasting seizures (
fits), especially if accompanied by
loss of consciousness, they could be epileptic seizures, a known complication of stroke. In that case he should undergo evaluation with EEG and start anti-epileptics.