Like RJam said, a normal full battery NeuroPsych Assessment (NPA) takes from a few hours to 8 to even 16 hours, depending on which subtests are done. The report should be available about a month later.

The ImPACT test is a very abbreviated NPA with very limited value, especially if there was not a baseline done before the head injury.

An NPA report will indicate the various brain functioning levels compared to the rest of the population. Visual and auditory immediate and short term memory, executive functioning, motor response time, verbal processing, and many more functions can be tested and scored.

An NPA can get very expensive, $4000 is not uncommon. And, insurance will usually want an strong reason for the referral for the NPA.

An NPA can be a two headed monster, one good, one not so good. It can put a diagnosis to our struggles making them real. But, at the same times, when we understand the reality of our injury and dysfunctions, we can often stop second guessing and doubting ourselves. No more "Am I going nuts ? Is this all just in my head ?"

Not all neuro psychologist are the same. Some have a bias against concussions causing long term symptoms and try to say we are just depressed or malingering (making things up). So, it helps to find a good, objective neuro psychologist. One directly affiliated with a brain injury rehabilitation hospital or clinic would likely be a good start.