Lumbar facet injection for the treatment of chronic piriformis myofascial pain syndrome: 52 case studies

Abstract

Jen-Ting Huang,1 Han-Yu Chen,2 Chang-Zern Hong,2 Ming-Ta Lin,3 Li-Wei Chou,4,5 Hsin-Shui Chen,6,7 Chien-Tsung Tsai,8 Wen-Dien Chang9  1Department of Orthopedic Surgery, Taichung Veterans General Hospital, 2Department of Physical Therapy, Hung-Kuang University, Sha Lu, 3Kuan-Ta Rehabilitation and Pain Clinic, Taichung, Taiwan; 4Department of Physical Medicine and Rehabilitation, China Medical University Hospital, 5School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; 6Department of Rehabilitation Medicine, Bei-Gang Hospital, School of Medicine, China Medical University, Yun-Lin, Taiwan; 7School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan; 8Department of Rehabilitation Medicine, Da-Chien Hospital, Miao-Li City, Taiwan; 9Department of Sports Medicine, China Medical University, Taichung, Taiwan Background and aims: The aim of this study was to demonstrate the effectiveness of lumbar facet joint injection for piriformis myofascial pain syndrome. Methods: Fifty-two patients with chronic myofascial pain in the piriformis muscle each received a lumbar facet injection into the ipsilateral L5–S1 facet joint region, using the multiple insertion technique. Subjective pain intensity, trunk extension range, and lumbar facet signs were measured before, immediately after, and 2 weeks after injection. Thirty-six patients received follow-up for 6 months. Results: Immediately after the injection, 27 patients (51.9%) had complete pain subsidence, 19 patients (36.5%) had pain reduction to a tolerable level, and only 6 patients (11.5%) had no pain relief to a tolerable level. Mean pain intensity was reduced from 7.4±0.9 to 1.6±2.1 after injection (P<0.01). This effectiveness lasted for 2 weeks in 49 patients (94.2%), and lasted for approximately 6 months in 35 (97.2%) of 36 patients. The mean range of motion increased from 13.4±6.8 degrees to 22.1±6.0 degrees immediately after injection, and further increased 2 weeks and 6 months later. Immediately after injection, 45 patients (86.5%) had no facet sign. In addition, 90.4% and 94.4% of patients had no facet sign after 2 weeks and after 6 months, respectively. Conclusions: It is important to identify the possible cause of piriformis myofascial pain syndrome. If this pain is related to lumbar facet lesions, lumbar facet joint injection can immediately suppress piriformis myofascial pain symptoms. This effectiveness may last for at least 6 months in most patients. This study further supports the importance of eliminating the underlying etiological lesion for complete and effective relief of myofascial pain syndrome. Keywords: facet joints, injection, piriformis, chronic myofascial pain, pain intensity, range of motion, lumbar facet sign