As a noninvasive therapy for the extreme back pain of facet joint osteoarthritis, MR-guided focused ultrasound shows considerable promise, reports Even Weeks, M.D., a FUS Foundation funded fellow at St. Mary’s Hospital in London.
Weeks and his colleagues are conducting a prospective, non-randomized clinical trial to evaluate the safety and efficacy of Insightec’s ExAblate system as a therapeutic technique for facet joint pain. Their goal is to enroll 20 to 25 patients and to follow them for a year to assess adverse effects, pain levels and functional outcome measures.
A week after treatment, the first five patients experienced a 20 to 40 percent decrease in their average Numerical Rating Scores (NRS), which measures pain. At the same time, the patients’ Oswestry Low Back Pain Disability Scores improved by 11 to 34 percent. Owestry scores represent the percentage of disability in activities of daily living. (Shifts of 10 percent or more indicate a significant change in a patient’s condition.)
As Weeks notes, “For each of the five patients, there was a significant, positive change in both the NRS and Oswestry Disability scores. These changes were evident at one week and at one month follow up.” Results were equivalent to those achieved by radio frequency facet rhizotomy.
According to Weeks, St. Mary’s performs 5 to 10 facet joint injections and facet joint radio frequency ablations each week. Because these treatments are limited in providing long-term pain relief, his hope is that MR-guided FUS will prove to be an effective, noninvasive method to achieve complete and long-lasting relief.
To be eligible for study participation, patients must have had a previous positive diagnostic (local anaesthetic and steroid) block or denervation treatment of their facet joints. Following completion of the Phase 1 study, Weeks and his St. Mary’s colleagues will launch a randomized clinical trial comparing MR-guided FUS to interventional radio frequency ablation.
Written by Ellen C., McKenna