What do I do if the monitoring is less than 24 hours (i.e. 8 hours, 10 hours etc.)?
In the opinion of the American Academy of Neurology and the American Clinical Neurophysiology Society, more than half of the 24 hours of monitoring is adequate to use these codes. If the recording time is less than 12 hours, one should bill the appropriate monitoring code with modifier 52 to indicate the service was reduced in some way (as described in the CPT® book) and to indicate the actual number of hours that the study was performed.
