Despite adequate control of disease activity with standard medical therapies, there remains an ongoing need for complementary and interventional approaches for the management of persistent back pain in patients with ankylosing spondylitis. Although the erector spinae plane block has been described in the literature as a safe and effective analgesic intervention for chronic back pain in various patient populations, to the best of our knowledge, no clinical study has specifically evaluated its use for persistent back pain in patients with ankylosing spondylitis receiving medical treatment. Therefore, the present study aims to evaluate the effects of erector spinae plane block on pain severity and clinical outcomes in patients with ankylosing spondylitis whose disease activity is controlled under treatment but who continue to experience persistent back pain.
Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease primarily affecting the axial skeleton, including the spine and sacroiliac joints. The most prominent clinical manifestations of AS are chronic back pain and progressive spinal stiffness; however, the disease may also involve peripheral joints and entheses. The primary goals in the management of AS are to reduce pain and stiffness, preserve functional capacity, and decrease overall disease burden. Nonsteroidal anti-inflammatory drugs (NSAIDs) constitute the first-line treatment, while biologic agents and disease-modifying antirheumatic drugs (DMARDs) are used in appropriate patients. Back pain in AS represents one of the hallmark symptoms of the disease and mainly arises from inflammation involving the spine and sacroiliac joints. This symptom is frequently associated with functional impairment and reduced quality of life. Although contemporary treatment strategies can effectively suppress disease activity in many patients, a subset of individuals continue to experience persistent symptoms and disease burden despite treatment, a condition commonly referred to as "residual disease." Residual symptoms are frequently reported even in patients achieving clinical remission or low disease activity, and a considerable proportion of these patients continue to suffer from ongoing pain. Therefore, persistent back pain despite controlled disease activity has emerged as an important unmet clinical need, potentially associated not only with inflammatory mechanisms but also with accompanying mechanical factors and comorbid conditions. The erector spinae plane (ESP) block is a regional analgesic technique performed under ultrasound guidance by advancing the needle tip into the fascial plane deep to the erector spinae muscle at the level of the transverse process, followed by injection of local anesthetic and steroid agents. Owing to the cranio-caudal spread of the injectate, the ESP block can provide analgesia across multiple dermatomes. In patients with persistent back pain, ESP block has been described as a complementary interventional option administered at thoracic or lumbar levels, either as a single or repeated procedure depending on the clinical scenario, with the aims of reducing pain severity, improving functional status, and decreasing analgesic requirements. However, the current evidence remains limited for many chronic pain indications, consisting predominantly of case reports, case series, and a limited number of clinical studies. The present study aims to evaluate the effects of erector spinae plane block on pain severity and clinical outcomes in patients with ankylosing spondylitis whose disease activity is adequately controlled under medical treatment but who continue to experience persistent back pain.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
15
The procedure will be performed in the prone position under sterile conditions and ultrasound guidance. Using a 22-gauge needle at the T5-T7 vertebral levels, the fascial plane between the deep fascia of the erector spinae muscle group and the transverse process of the vertebra will be accessed. A combination consisting of 5 cc of 0.5% bupivacaine, 4 cc of 0.9% normal saline, and 1 cc dexamethasone (8 mg/2 mL) will then be injected into the targeted plane. The procedure will be performed by experienced algology specialists with more than 15 years of experience in ultrasound-guided interventional procedures and will be administered in two sessions within one week.
Marmara University Faculty of Medicine Pendik Training and Research Hospital
Istanbul, Pendik, Turkey (Türkiye)
RECRUITINGNumeric Rating Scale (NRS)
The Numeric Rating Scale is used to assess and monitor pain severity. On the scale, "0" indicates no pain, whereas "10" represents the worst pain imaginable. Patients are asked to rate their pain intensity on a scale ranging from 0 to 10. Due to its simplicity and ease of understanding, the NRS is widely used in clinical practice and research.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
Bath Ankylosing Spondylitis Metrology Index (BASMI)
BASMI is an index used to objectively assess spinal mobility in ankylosing spondylitis through physical examination measurements, including cervical rotation, tragus-to-wall distance, lateral spinal flexion, modified Schober test, and intermalleolar distance. BASMI scores range from 0 to 10, with higher scores indicating clinically significant restriction of spinal mobility and greater structural involvement.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
Ankylosing Spondylitis Disease Activity Score-C-Reactive Protein (ASDAS-CRP)
ASDAS-CRP is a composite index used to assess disease activity in ankylosing spondylitis (AS) and axial spondyloarthritis by combining patient-reported outcomes with the objective inflammatory marker C-reactive protein (CRP). An ASDAS-CRP score ≥2.1 is considered indicative of active disease.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)
BASDAI is a patient-reported outcome measure used to assess disease activity in ankylosing spondylitis and axial spondyloarthritis. It consists of six questions evaluating fatigue, spinal pain, peripheral joint pain, enthesitis, and morning stiffness experienced during the previous week. BASDAI scores range from 0 to 10, with scores \<4 indicating low disease activity and scores ≥4 indicating clinically significant active disease. A BASDAI score of ≥4 is widely accepted as an important threshold for treatment decision-making and therapeutic escalation.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
Bath Ankylosing Spondylitis Functional Index (BASFI)
BASFI is a patient-reported outcome measure consisting of 10 questions designed to evaluate functional capacity and activities of daily living in patients with ankylosing spondylitis. BASFI scores range from 0 to 10, with higher scores indicating clinically significant functional limitation and a greater impact of the disease on daily life.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
Istanbul Low Back Pain Functional Scale (ILBPFS)
The Istanbul Low Back Pain Functional Scale was developed to evaluate the functional impact of low back pain on activities of daily living in patients with low back pain. The scale consists of 18 items, with total scores ranging from 0 to 18. Higher scores indicate clinically significant increases in functional limitation. In general, scores of 0-6 indicate mild, 7-12 moderate, and 13-18 severe functional impairment.
Time frame: Assessments will be performed at baseline (T0), 2 weeks after the erector spinae plane block procedure (T1), and 2 months after the procedure (T2).
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