A Definition of New Patient for Selection of E/M Visit Code
Interpret the phrase “new patient” to mean a patient who has not received any professional services, i.e., E/M service or other face-to-face service (e.g., surgical procedure) from the physician or physician group practice (same physician specialty) within the previous 3 years. For example, if a professional component of a previous procedure is billed in a 3 year time period, e.g., a lab interpretation is billed and no E/M service or other face-to-face service with the patient is performed, then this patient remains a new patient for the initial visit. An interpretation of a diagnostic test, reading an x-ray or EKG etc., in the absence of an E/M service or other face-to-face service with the patient does not affect the designation of a new patient.
B Office/Outpatient E/M Visits Provided on Same Day for Unrelated Problems
As for all other E/M services except where specifically noted, carriers may not pay two E/M office visits billed by a physician (or physician of the same specialty from the same group practice) for the same beneficiary on the same day unless the physician documents that the visits were for unrelated problems in the office or outpatient setting which could not be provided during the same encounter (e.g., office visit for blood pressure medication evaluation, followed five hours later by a visit for evaluation of leg pain following an accident).
http://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/Downloads/clm104c12.pdf
Page 51 from the Medicare Internet Only Manual
As seen above they describe physicians of the same speciality same group can not see a patient twice on the same day for the same problem. But what you are describing a spine surgeon and anesthesiologist specialzing in pain management would be two separate specialties. Each physician would be able to bill for the services they provied. It is my understanding is that Medicare does not recognize subspecialities of the same speciality regarding new versus established patients as described in the AMA CPT manual.