Although carpal tunnel syndrome (a.k.a. median nerve neuritis) is of the main causes of median nerve symptoms, there are a few other cause.
For example, problems with the connection of the median nerve to the brachial plexus can also cause hand pain. (This is where the median nerve meets the muscles, just fyi).
Finally, though most associate the median nerve with hand pain, the median nerve and the thumb are also connected, so people should not ignore symptoms stemming from their thumbs, even if it seems like nothing to worry about. Better to be safe than sorry.