Question: What distinguishes 92585 from 92586? Connecticut Subscriber Answer: Both 92585 (Auditory evoked potentials for evoked response audiometry and/or testing of the central nervous system; comprehensive) and 92586 ( limited) describe auditory EP studies in which electrical recordings are made via electrodes placed on the scalp in response to auditory stimulations. CPT revised 92585 in 2001 to clarify that the procedure describes a comprehensive auditory evoked response (AER) exam. The comprehensive AER exam includes middle latency and late cortical responses, as well as evaluation of brainstem response. By combining these three types of auditory EPs, the physician can evaluate the status of several areas of the central auditory nervous system (for example, auditory periphery and brainstem, pathways between midbrain, etc.). Similarly, CPT added 92586 in 2001 to describe a limited audiometry examination, which describes limited auditory brainstem response (ABR) testing used primarily in infant screening evaluations. The physician obtains and replicates the ABR screening at one or two levels for each ear only (as opposed to three, as necessary to report 92585).