Question: An EEG was performed on a patient under general anesthesia due to behavioral issues and autism. The EEG was ordered to evaluate her for seizures. What is the best anesthesia code to report? Maine Subscriber Answer: The current CPT® code book does not include a code specific to anesthesia in this situation. Your best option is to report 01999 (Unlisted anesthesia procedure(s)) and append modifier 23 (Unusual anesthesia). Most patients do not require anesthesia during an EEG, so also include a primary diagnosis of the behavioral or autistic disorder (such as F84.0, add descriptor) and, if requested, provide the documentation supporting the reason for anesthesia during the test.