Most internal medicine subspecialties as well as psych, neuro, radiology would be accomodating with respect to dictation.
You may want to shy away from any of the more procedurally based specialties like surgery, critical care, EM, anesthesia, ophtho, derm, pathology. You should speak with your doctor about your disease status and likely progression and speak with mentors in fields you are interested in.
Good luck.