Do the case studies of these low brain volume patients have criticism regarding the technology and interpretation of the scans? Also have there been studies where such patients have been studied post mortem to confirm the earlier findings?
That would indeed be useful. I haven't been able to find any such criticism or post-mortem studies.
Lorber's own theory was that brains have spare capacity and primitive brain structures that are more intact are more responsible for the brain functioning than previously thought.
That's true. However, it seems contrary to current neuroscientific theories.