1. Get a faculty member to be your PI. Even if they don't do anything, some journals require the corresponding author to be a faculty member, and at the very east, they can give you some guidance
2. Make sure you're in good standing with your school's IRB. In general, IRB's do not require approval for case reports, but IRBs at certain institutions have a preferred consent form.
3. Find a journal. Not all journals publish case reports, so find a list of neurology journals, and once you find a journal you're interested in, go to its website, go to author instructions, and see what their scope of publishing is (both in terms of topics and whether they accept case reports). If a journal is open-access only, you should avoid it, unless you can cove the publishing costs. Another way to find a journal is to look at the journals that published the papers you have referenced in your paper. There is also an online BLAST you can do to help you find journals that have published similar material in the past, however, given that not all journals publish case reports, this may not be very fruitful.
4. When you find a journal, figure out if they will require a consent from the patient. If so, get the patient to sign a consent.