Superior cluneal nerve (SCN) entrapment is an underdiagnosed cause of chronic low back and gluteal pain. Although diagnostic nerve block is considered the gold standard for confirming SCN entrapment, there is no consensus regarding the optimal injection approach. This prospective observational study aims to compare the clinical effectiveness of proximal and distal ultrasound-guided SCN block techniques in patients diagnosed with SCN entrapment. Pain intensity and functional outcomes will be evaluated over the follow-up period to assess differences between the two approaches.
Age between 18 and 75 years
Chronic low back and/or gluteal pain lasting longer than 3 months
Localized point tenderness and/or paresthesia on palpation over the unilateral posterior iliac crest
Clinical suspicion of superior cluneal nerve entrapment based on physical examination
Active local or systemic infection
Cognitive impairment or psychiatric disorders interfering with study participation
History of malignancy or cancer-related pain
Uncontrolled diabetes mellitus or severe comorbid conditions adversely affecting general health
The study population will consist of adult patients aged 18 to 75 years presenting with chronic low back and/or gluteal pain lasting longer than three months, who are clinically suspected of having superior cluneal nerve entrapment based on physical examination findings. Eligible participants will be those who have not responded to conservative treatment and who attend the Algology Outpatient Clinic during the study period. Only patients with unilateral symptoms who meet all inclusion and exclusion criteria and who provide written informed consent will be included in the study.
Cohort
Prospective
Ultrasound-guided distal superior cluneal nerve injection
Procedure/SurgeryThe ultrasound probe will be placed over the posterior superior iliac crest to visualize the fibro-osseous tunnel where the superior cluneal nerve passes. Using an in-plane approach, the needle will be advanced toward the target area, and the injection will be administered at the fascial exit point of the nerve. A total injectate volume of 5 cc (2 cc bupivacaine, 2 cc dexamethasone, and 1 cc normal saline) will be administered. All procedures will be performed in the prone position under standard aseptic conditions.
Ultrasound-guided proximal superior cluneal nerve injection
Procedure/SurgeryPatients randomized to the proximal injection group will undergo ultrasound-guided injection above the iliac crest level. The target will be the plane beneath the posterior layer of the thoracolumbar fascia. Using an in-plane approach, the injectate will be delivered into the interfascial plane. A total injectate volume of 5 cc (2 cc bupivacaine, 2 cc dexamethasone, and 1 cc normal saline) will be administered under ultrasound guidance. Patient positioning and aseptic conditions will be identical to those used in the distal perineural injection group.
Visual Analog Scale (VAS)
Primary Outcome Measure Visual Analog Scale for Pain (VAS): Change in pain intensity assessed using the Visual Analog Scale (VAS).The VAS is a 10-cm horizontal scale ranging from 0 (no pain) to 10 (worst imaginable pain).Higher scores indicate greater pain intensity, and a reduction in VAS score represents clinical improvement.
Oswestry Disability Index (ODI)
Oswestry Disability Index (ODI): Change in disability related to low back pain assessed using the Oswestry Disability Index (ODI).The validated and reliability-tested Turkish version of the ODI will be used in this study.The ODI consists of 10 items, each scored from 0 to 5, yielding a maximum total raw score of 50.The total score is converted to a percentage using the following formula:ODI percentage = (Total score / 50) × 100 Higher percentage scores indicate greater disability. Disability levels are interpreted as follows: * 0-20%: Minimal disability * 21-40%: Moderate disability * 41-60%: Severe disability * 61-80%: Crippling disability * 81-100%: Bed-bound or exaggerated symptoms A decrease in ODI percentage score indicates improvement in functional status.
Leeds Assessment of Neuropathic Symptoms and Signs (LANSS)
Assessment of neuropathic pain features using the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) questionnaire.The LANSS scale consists of 7 items with a total score ranging from 0 to 24.A score of ≥12 indicates the presence of neuropathic pain mechanisms.Higher scores reflect greater neuropathic pain components.
Short Form-12 Health Survey (SF-12)
Health-related quality of life assessed using the Short Form-12 Health Survey (SF-12).The SF-12 generates two composite scores: * Physical Component Summary (PCS) * Mental Component Summary (MCS) Both PCS and MCS scores are calculated according to standard scoring algorithms.Higher scores indicate better physical and mental health-related quality of life, respectively.In this study, PCS and MCS scores will be analyzed separately to evaluate physical and mental aspects of quality of life.
Baseline Postural and Radiological Characteristics in Patients with Superior Cluneal Nerve Entrapment
Baseline postural and radiological characteristics will be assessed prior to intervention in patients with superior cluneal nerve entrapment. Previously obtained standing lateral lumbosacral and pelvic radiographs will be used. Lumbar lordosis, sacral slope, lumbosacral angle, and pelvic tilt will be measured as radiographic angles in degrees on standing lateral images and categorized as decreased/normal/increased (lumbar lordosis, sacral slope, lumbosacral angle) or anterior/normal/posterior (pelvic tilt). Scoliosis will be evaluated based on physical examination and review of existing radiographs and MRI scans; when clinically indicated, standing scoliosis radiographs will be obtained. Scoliosis will be assessed using the Cobb method and recorded as present or absent. These findings will be descriptively reported.
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