Which psychometric test ("IQ test") was used - WAIS is standard for adults though there are others?

Has the study that you refer to, published in 1977, been independently replicated since then?

One thing to bear in mind is the results of a psychometric test (an "IQ score") is not one number - it is a composite of different cognitive abilities. Since 1977 we have learned that these are associated with different parts of the brain. What this means is that a brain injury of whatever kind may lead to different effects on the different cognitive abilities.