Carpal tunnel syndrome (CTS) is the most common and disability-causing entrapment neuropathy; however, a standardized protocol for first-line management has yet to be established. Different treatment approaches have their own positive and negative aspects.

The aim of this study is to compare the effectiveness of ultrasound-guided local steroid injection and intramuscular steroid injection in mild-to-moderate CTS. Patients will be assessed for pain levels, functional/symptom status, hand-finger strength, side effects, patient satisfaction, median nerve ultrasonographic measurements, and EMG before and after treatment .

Patients evaluated through a detailed clinical examination and medical history review according to inclusion and exclusion criteria will provide written informed consent and will be assigned to one of three treatment groups using block randomization.

The patients' basic sociodemographic information (age, gender, body mass index, employment status, education level, marital status) and clinical data (dominant hand, duration of symptoms, comorbidities, hand to be treated, Tinel's/Phalen's sign, sleep quality, pain intensity, electrophysiological parameters.) will be recorded.

The first group (local steroid) will receive an ultrasound-guided local steroid injection (1 ml of 40 mg triamcinolone + 1 ml lidocaine) along with a nighttime wrist splint. The second group (intramuscular steroid) will receive a gluteal intramuscular injection (1 ml of 40 mg triamcinolone + 1 ml lidocaine) along with a nighttime wrist splint. The third group will receive only a nighttime wrist splint. All patients in the study groups were provided with prefabricated volar wrist splints to be used at night and, whenever possible, during the day for 2-3 hours. No medication or exercise therapy will be given to the patients.

All groups were evaluated based on examination findings (Tinel's/Phalen's test), pain intensity (VAS day and VAS night), hand grip strength (HGS), finger pinch strength (FGS), the Turkish version of the Boston Carpal Tunnel Questionnaire scores, sleep quality, the patient's subjective impression of improvement (satisfaction), electrophysiological parameters (two times), and ultrasound measurements (cross-sectional areas [CSA] and flattening ratio [long diameter/short diameter]) at the proximal inlet of the median nerve (at the level of the scaphoid and pisiform bones, at the level of the distal wrist crease) before treatment (baseline), at the end of treatment (two weeks), and six weeks after treatment. The evaluation parameters/outcomes will be made by the same researcher blind to the groups.

Patients will be questioned about undesirable effects at the end of the 2nd and 6th weeks after the treatment.

Inclusion Criteria:

• Age ≥18 years
• Presence of typical CTS symptoms (numbness, tingling, paresthesias, or pain that may be provoked by nighttime or activity-related posture
• VAS score of ≥ 3/10
• Symptom duration longer than 12 weeks
• Positive Tinel's and/or Phalen's sign
• Electrophysiologically mild or moderate CTS being diagnosed.
• Volunteer to participate in study

Exclusion Criteria:

• Patients with shoulder, elbow, wrist, or finger problems (e.g., impingement syndrome, epicondylitis, history of fractures in the wrist, de Quervain's tenosynovitis, trigger finger, Complex Regional Pain Syndrome (CRPS), Dupuytren's contracture).
• Patients with a history of trauma or surgery in the affected hand, or those with significant anatomical deformities.
• Patients with systemic diseases such as rheumatological disorders, hypothyroidism, amyloidosis, diabetes, gout, or chronic kidney failure.
• Patients with conditions that may mimic CTS, such as polyneuropathy, plexopathy, cervical radiculopathy, or thoracic outlet syndrome.
• Patients with cognitive dysfunction or communication issues.
• Patients with severe CTS, neurological deficits (e.g., thenar atrophy, muscle weakness in thumb abduction/opposition), or those requiring surgical intervention.
• Patients who have received local steroid injections or physical therapy to the hand/wrist within the last 6 months.
• Patients who are receiving or will receive another/additional treatment for CTS.
• Pregnant or lactating women.
• Patients with active malignancies or local/systemic infections.
• Patients who are receiving any active treatment (e.g., NSAIDs, oral/intramuscular steroids, acupuncture, other pain medications).
• Patients with upper extremity involvement due to first motor neuron damage (e.g., stroke-hemiplegia, tetraparesis, multiple sclerosis).
• Patients with a bifid median nerve, persistent median artery, ganglion cyst, tenosynovitis, or tendinitis in the wrist.
• Use of a wrist splint during the last 6 months.
• Allergy to corticosteroids or local anesthetics, and blood diathesis

single blind