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.

The primary objective of this study is to compare the effects of two different ultrasound-guided injection techniques on pain intensity, functional status, neuropathic pain components, and quality of life in patients with suspected superior cluneal nerve (SCN) entrapment. Pain severity will be assessed using the Visual Analog Scale (VAS), functional status using the Oswestry Disability Index (ODI), neuropathic pain components using the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), and quality of life using the Short Form-12 (SF-12). The study aims to determine which injection technique provides superior clinical outcomes.

The secondary objective is to evaluate lumbosacral angle, lumbar lordosis angle, pelvic tilt, sacral tilt, and the presence of scoliosis, and to investigate the relationship between these postural and radiological parameters, SCN entrapment, and treatment response.

Through this study, ultrasound-guided injection techniques used in the diagnosis and treatment of SCN entrapment will be comparatively evaluated, addressing an important gap in the current literature and providing high-level scientific evidence to guide clinicians in the management of chronic low back and gluteal pain.

This study is designed as a prospective, randomized, single-blind clinical study comparing two different ultrasound-guided injection techniques in patients with suspected superior cluneal nerve entrapment. The study population will consist of patients presenting to the Algology Outpatient Clinic of Health Sciences University Gaziosmanpaşa Physical Medicine and Rehabilitation Training and Research Hospital during the study period, who meet the inclusion and exclusion criteria, have chronic low back and/or gluteal pain, are suspected of having SCN entrapment based on clinical examination, have not benefited from conservative treatment, and voluntarily agree to participate in the study.

Based on a power analysis with 95% power, a total of 54 patients are planned to be included in the study, with 27 patients allocated to each group.

Inclusion Criteria:

• 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
• Failure to respond to conservative treatment
• Ability and willingness to provide written informed consent

Exclusion Criteria:

• 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
• Pregnancy
• Known allergy to the medications used in the injection
• Prominent radicular pain associated with neurological deficit
• History of interventional procedures applied to the lumbar region within the last 6 months
• Initiation of another lumbar interventional or medical treatment during the follow-up period
• Suspected bilateral superior cluneal nerve entrapment
• Sphincter dysfunction related to neurological disease
• Bleeding diathesis or coagulation disorders

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.

Individual participant data will not be shared due to institutional data protection policies and the absence of participant consent for data sharing beyond the scope of the current study.