Required, as in you won't be allowed to sign up for it? No.
Is it advisable to know some neurology? Yes. Then again, from my own neurology rotation, it seemed to be 90%+ strokes. Strokes seem to have very little importance on Step 2. My guess is that over 50% of all the neuro Qs on Step 2 are about conditions I won't ever see in real life.
I hadn't taken a formal neuro rotation, so I just used my neuroanatomy knowledge, plus whatever else I picked up in Internal Medicine. I did have 3-4 questions on tPA, though. 🙂
For CS, you just need to pretend to do a semi-full neurological exam. I didn't have anything that came close to a neurological zebra. Not counting the Friedrich's ataxia patient that wanted a 15-minute discussion on treatment options (sloooooow draping and hand washing to pass time was the key with him j/k)
Seriously, your bedside manner is what counts in the CS exam.
There was a pt with Friedrich's ataxia? Sadly, I have to look that up since I have no idea what it is and HAVE had my neurology rotation. Hmm, not a good sign for my future CS experience.