Carpal tunnel syndrome (CTS) is a common musculoskeletal disorder, which is caused by compression of the median nerve as it travels through the wrist. There are several treatments for CTS, including conservative and surgical options. Though local corticosteroid injection has been considered more effective than physical therapy for treatment of CTS and has significant short-term benefits, long term benefits are not evidenced. Several studies in recent years reported significantly superior longer-term benefit of D5W and PRP compared with corticosteroid injections and other conservative managements. In addition, percutaneous release of the transverse carpal ligament (TCL) was developed to treat CTS in recent years. Because the effectiveness of the recently developed techniques in treating CTS has not been well established, the investigators aim to investigate whether combining US-guided partial release of the transverse carpal ligament with a needle plus D5W hydrodissection is more beneficial for CTS comparing to either treatment alone.

Carpal tunnel syndrome (CTS) is a common musculoskeletal disorder, which is caused by compression of the median nerve as it travels through the wrist. The prevalence of CTS ranges from 3% to 7.43%, and it carries a significant economic burden, influencing the number of workdays lost. Risk factors for CTS include occupations that need repetitive hand movements, female gender, age, pregnancy, obesity, diabetes, and specific anatomical and physiological traits. The symptoms and signs of CTS include tingling, numbness, nocturnal paresthesia, and pain in the median nerve distribution, whereas thenar atrophy and weakness of grasping manifest in the late stages. The widely-accepted pathophysiology includes increased pressure in the carpal tunnel, median nerve microcirculation injury, synovial tissue hypertrophy, and connective tissue compression of the median nerve. The interactions of mechanisms can lead to venous outflow obstruction, edema, and then ischemia and nerve injury ultimately. The diagnosis of CTS is made via the patient's history and physical examination, and electrodiagnostic tests may be done to differentiate among diagnoses. In recent years ultrasonographic image study of the median nerve can be applied in the evaluation and/or diagnosis of CTS. There are several treatments for CTS, including conservative and surgical options. For mild to moderate CTS, non-surgical treatments such as splinting, physical therapy, ultrasound (US)-guided corticosteroid injection, oral medications, and manual therapies are recommended. Although a systemic review showed that surgical approach yield better midterm and long term outcomes than conservative managements, there are some complications of open carpal tunnel release, including neuroma of the palmar cutaneous branch of the median nerve, infection, hypertrophic scars, postoperative pain, and persistent or recurrent symptoms. Therefore, surgical treatment is recommended only after 7 conservative management failure, or for more severe CTS.

Though local corticosteroid injection has been considered more effective than physical therapy for treatment of CTS and has significant short term benefits, long term benefits are not evidenced. In the recent decade, ultrasound guided regenerative medicine was developed to treat CTS, among which five percent dextrose in water (D5W) and platelet-rich plasma (PRP) are two commonly used injectates. Several studies in recent years reported significantly superior longer-term benefit of D5W and PRP compared with corticosteroid injections and other conservative managements. The mechanism of regenerative medicine for CTS can be divided into pharmacological and mechanical effects. The pharmacological effect includes initiating tissue proliferation in the absence of inflammation, whereas the mechanical effect can be refer to hydrodissection. In addition, percutaneous release of the transverse carpal ligament (TCL) was developed to treat CTS in recent years.

Acupotomy, using a needle-knife derived from traditional Chinese medicine to release TCL and promote local blood circulation, is a safe and effective option when performed via ultrasound guidance. Other than using a needle-knife, partial release of TCL with a needle is another choice. In a prospective study in 2022, ultrasound guided partial release of TCL using an 18-G needle was done in patients with CTS, and the result revealed that 86.2% wrists showed successful treatment outcomes at 6 months after intervention. Another cohort study in 2024 showed that treating severe CTS with ultrasound-guided partial release of TCL using a 21-G curved needle resulted in improved outcomes at the 6-week follow-up. Because the effectiveness of the recently developed techniques in treating CTS has not been well established, the investigators aim to investigate whether combining US-guided partial release of the transverse carpal ligament with a needle plus D5W hydrodissection is more beneficial for CTS comparing to either treatment alone. The investigators hypothesize that adding percutaneous release of the TCL to D5W hydrodissection could bring more therapeutic effects.

Inclusion Criteria:

• age between 20 to 80 years old
• diagnosed with CTS on the basis of clinical condition and an electrophysiological analysis
• the NRS of pain or paresthesia≧3
• with symptoms lasting for a minimum of 3 months.

Exclusion Criteria:

• history of polyneuropathy, thoracic outlet syndrome, brachial plexopathy, or inflammatory arthropathy
• onset of CTS during pregnancy, hypothyroidism, or systemic infection
• previous corticosteroid injection or wrist surgery for CTS
• hypersensitivity to dextrose injection
• the anatomic structure of the wrist is not suitable for needle release of TCL.