The answer is self-deprecating.
One of the definitions of a self-deprecating person is someone who is conscious of his or her weaknesses, difficulties and flaws and is open about it, or at least, isn't afraid to point them out, which they normally do in a humorous way.
In the passage, the speaker recognizes and expresses his shortcomings (to be susceptible to seizure activity, for example) in a humorous tone.