Comparative Effectiveness of Two Different Approaches to Radiofrequency Ablation of Lumbar Medial Branch Nerves

To determine whether the parasagittal approach to lumbar medial branch (LMB) nerve radiofrequency ablation (RFA) will have greater efficacy than the traditional approach to lumbar medial branch nerve radiofrequency ablation.

This will be accomplished by comparing the results between the newly proposed parasagittal approach and the traditional approach of medial branch RFA done on the same patient (different sites) with bilateral low back pain (LBP).

Traditional approach:

The electrode is introduced at a 15-20 degrees' ipsilateral oblique angle to the sagittal plane toward the junction of the superior articular process (SAP) and transverse process (TP) of the vertebral body to target the traversing medial branch nerve. The reason for the proposed angle is to avoid the mamillo-accessory ligament (MAL) that may be ossified in up to 10% of the normal spine and, in such cases, potentially prevent proper coagulation of the medial branch nerve during the RFA procedure.

Parasagittal (new) approach:

Recently, Tran et al. showed that MAL is located more dorsally than it was thought earlier and, therefore, can't interfere with nerve coagulation during the RFA. Consequently, they proposed abandoning the 20-degree angle used for the traditional approach and placing the radiofrequency cannula parasagittally and more dorsally. It is proposed that, in order to achieve maximum nerve coagulation, the electrode should be placed as parallel to the nerve as possible, and placing it parasagittally helps achieve this goal. The remainder of the procedure does not differ from the traditional method.

Inclusion criteria

• Bilateral equally intense axial low back pain
• Pain duration of ≥ 6 months
• Three-day average NRS scores of ≥ 3/10
• Age greater than 18 years
• Failure of conservative treatment, including nonsteroidal anti-inflammatory medications and physical therapy
• Positive response to a series of two bilateral diagnostic lumbar medial branch nerve blocks (≥ 80% pain relief). This is the current standard of care.

Exclusion criteria

• Radicular pain below the knee
• Systemic infection or localized infection at the anticipated introducer entry site
• Pregnancy
• Allergy to Lidocaine
• Bleeding dyscrasias
• Patients unable to give informed consent
• History of lumbar spine surgery at the affected levels
• History of previous bilateral lumbar RFA of medial branches within the past six months.
• Significant comorbid somatization or widespread pain with central sensitization
• Secondary gain identified due to ongoing legal proceedings or worker's compensation
• Cognitive impairment
• Any pre-existing condition at the discretion of the provider that may confound interpretation of results -