Background: Paravertebral cluneal nerves are constrained within a tunnel consisting of the thoracolumbar fascia and the iliac crest's superior rim as they pass over the iliac crest. Their involvement in low back pain has not been presented previously.
Objective: To develop a diagnostic and therapeutic protocol for radiofrequency ablation of paravertebral and iliac cluneal trigger points.
Study design: In a prospective observational cohort study, clinically painful trigger points were anatomically defined with diagnostic local anesthetic injections containing a steroid. Validated trigger points were ablated and the resolution of low back pain was monitored and analyzed.
Setting: The Spinal Foundation, The Weymouth Hospital, London, United Kingdom.
Methods: Injections at painful trigger points were considered diagnostic if patients reported 50% or more low back pain relief sustained for 10 days or more. These patients were treated with aware state radiofrequency ablation of the trigger points if the back or referred pain remained refractory despite 3 months of core correction physiotherapy. Clinical outcomes were assessed with the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores for low back pain at a minimum follow-up of 2 years.
Results: This prospective feasibility study included 52 patients with an average age of 56.9 ± 14.9 years ranging from 29 to 83. The mean follow-up was 38.33 months ranging from 25 to 66 months. The average symptom duration before the first consultation was 54.8 months. Many patients had multiple failed chronic pain management interventions, including failed epidural steroid injections (28/52, 53.8%); failed facet injections (45/52, 86.5%); failed facet rhizotomies (20/52, 38.5%); and failed sacroiliac joint ablations (34/52, 65/4%). The majority had had spine surgery before presenting with persistent low back or radiating pain. The surgeries were microdiscectomy (38.5%), laminectomy (11.5%), laminotomy (3.8%), endoscopic transforaminal decompression (9.6%), foraminoplasty (1.9%), sacroiliac joint fusion (11.5%), total disc replacement (13.5%), and lumbar fusion (34.6%). Chief concerns were low back (69.2%), buttock pain (71.2%), groin pain (40.4%), trochanteric pain (28.8%), abdominal or flank pain (5.8%), anterior thigh pain (32.7%), and symptoms mimicking sciatica (19.2%). Validated painful trigger points were the lateral (5.7%), superior (48.1%), medial (23.1%), or a combination of 2 (23.1%). The VAS reduction was from 7.25 ± 1.79 to 1.11 ± 0.98 (P < 0.0001). The ODI reduction was from 51.23 ± 9.58 to 7.11 ± 6.69 (P < 0.001). The Prolo score was reduced from 3.59 ± 0.72 to 1.35 ± 0.59. Symptoms resolved completely in 34 (65.4%) patients but persisted slightly in 9 (17.3%) and mildly in another 8 (15.4%). There were no cases of infection, dysesthesia, numbness, or paralysis.
Limitations: Our study suffers from low patient numbers and the absence of another diagnostic test definitively confirming the presence of painful cluneal nerve involvement.
Conclusion: Cluneal trigger points should be considered in the differential diagnosis of pain in the lower back, flank, lower abdominal, buttock, trochanteric, groin, and thigh area. It is one form of so-called "pseudo-sciatica." The authors' diagnostic injection protocol suggests that most patients with cluneal trigger points may successfully be treated with percutaneous radiofrequency ablation.
Keywords: low back pain; radiofrequency ablation; Cluneal nerve trigger points.