CPT 64633-64636 are not coded by level but by facet joint so if the physician states he did L4-S1, there are only 2 joints included if unilateral and 4 if bilateral. It is assumed the top of L4 is not included because the physician would have to state L3 as well.
Ideally, L4, L5, S1 should be documented as L4/L5, L5/S1 with the side or sides ablated.
More on documentation:
Codes 64633-64636 were introduced in 2012 and are based on the number of facet joints that are treated. One or two facet joints at the same level can be treated, depending on whether the procedure is performed unilaterally or bilaterally. When both facet joints at the same level are treated, the parent code (64633 or 64635) should be appended with modifier 50 (bilateral procedure). Since the bilateral modifier accurately describes the work, it would not be appropriate to report two units of service in this circumstance.
Note that the number of nerves injected does not affect code selection. This is reflected in the term "nerve(s)" which is included in the code descriptors. Therefore, only one unit of service should be reported for each joint regardless of the number of nerves injected.
In keeping with other procedures involving the vertebra, the code structure is based on spinal region. Codes 64633 and 64634 specify the cervical or thoracic region while codes 64635 and 64636 specify the lumbar or sacral region. Codes 64634 and 64636 are add-on codes. These codes are reported for each additional facet joint at a different vertebral level in the same spinal region. Since these codes are reported for each additional level, modifier 51 is not appended to these codes. If the additional level(s) are treated bilaterally, modifier 50 is reported.
In order to report these procedures appropriately, physicians must clearly document the vertebral region level (s) (Cervical, Thoracic, Lumbar) , the facet joints (eg L3/4, L4/5) involved and if unilateral or bilateral. Although the number of nerves and/or lesions might be noted in the clinical note, these factors do not influence the code selection nor the number of units reported. Note that per CPT instructions code 64633 is reported for denervation of T12-L1.
Please remember these codes are INCLUSIVE of:
Fluoroscopy or CT Guidance
Injection of any contrast, steroid or local anesthetic agent
Practitioners are reminded that correct coding of diagnoses or procedure codes does not insure appropriateness of a procedure. Clinically appropriate use of procedures should be documented in the applicable E&M encounter or procedure note.
DO NOT report these codes for non-destructive therapies such as "Pulsed radiofrequency" or if done with ultrasound guidance. These services are reported using the unlisted code 64999.
64633 Destruction by neurolytic agent, paravertebral facet joint nerve(s) with imaging guidance (fluoroscopy or CT); cervical or thoracic, single facet joint
64634 Destruction by neurolytic agent, paravertebral facet joint nerve(s) with imaging guidance (fluoroscopy or CT); cervical or thoracic, each additional facet joint (List separately in addition to code for primary procedure)
64635 Destruction by neurolytic agent, paravertebral facet joint nerve(s) with imaging guidance (fluoroscopy or CT); lumbar or sacral, single facet joint
64636 Destruction by neurolytic agent, paravertebral facet joint nerve(s) with imaging guidance (fluoroscopy or CT); lumbar or sacral, each additional facet joint (List separately in addition to code for primary procedure)
I hope this helps.