My Wife just has a typical $5 pen with a light on it and that's sufficient for her doctoring duties, actually come to think of it, I think we found it laying around lol. For a neurosurgeon any application requiring light will be of a higher quality than any pen you can likely get. If they were a GP or even, *gulp*, a proctologist; then I could possibly see the point.
Was there any indication they required such a present? It might be sort of useless to them. No offence.
(Edit: Actually going back to my Wives studies there was quite a few differentials for neural complications from a persons retinal responses. Perhaps a Penlight would be of use. Although having said that it's likely mandatory and they probably already have 20 of them)
Perhaps a carton of Beer?