There's not enough known about Paul to diagnose any brain abnormalities, nor does his blindness after his vision fall into any of the supposed categories. There are also the other happenstances:
And he was three days without sight, and neither did eat nor drink. And there was a certain disciple at Damascus, named Ananias; and to him said the Lord in a vision, Ananias. And he said, Behold, I am here, Lord. And the Lord said unto him, Arise, and go into the street which is called Straight, and enquire in the house of Judas for one called Saul, of Tarsus: for, behold, he prayeth, and hath seen in a vision a man named Ananias coming in, and putting his hand on him, that he might receive his sight.Then Ananias answered, Lord, I have heard by many of this man, how much evil he hath done to thy saints at Jerusalem: And here he hath authority from the chief priests to bind all that call on thy name. But the Lord said unto him, Go thy way: for he is a chosen vessel unto me, to bear my name before the Gentiles, and kings, and the children of Israel.
In this case you have the initial vision, then the vision he received while still suffering blindness -- the one leading him to Ananias and the vision of Ananias informing him to seek Paul. Had Paul had an illness-inspired dream, it likely would have fueled his hatred of Christians rather than converted him to Christianity.
Based on Paul's writings, he was a visionary man given to revelations. That he was an apostle is clear from his writings and was a witness of the resurrection of Christ. Some assume this vision and his initial vision on the road to Damascus were the same, but if he is the man he spoke of "that was taken to the third heaven where he saw and heard inexpressible words, which a man is not permitted to speak," he may have seen or encountered Jesus there.
I'm not certain what Paul said in this case (2 Corinthians 10:5) that was so objectionable or which contradicts Jesus' words in the Sermon on the Mount. In the context of his times, how can we judge how delusional he is when compared to the other Christian leaders of his time? We're not only crossing a language barrier, but a cultural barrier as well. Based on what we don't know about Paul (which greatly outweighs what we do know), that may be unfair.