Medical Coding And Billing Modifiers – Everything you need to know about Medical Transcription Training, Medical Transcription Programs, Medical Trans. … diagnosis would be the neuromusculoskeletal condition necessitating the treatment. The corresponding diagnostic codes (ICD-9 codes) must be listed to substantiate medical necessity. … A modifier indicates that a service or visit was altered in some way from the stated CPT descriptor without. Below is a list of approved modifier …