In clinical practice, carpal tunnel syndrome (CTS) is the common disease of peripheral neuropathy and usually happened to female, mid-age population, overweight persons, and those who overused their hands for work or production. Some research claimed this might be correlated to anatomical characteristics such as the longer anteroposterior diameter or smaller cross section area of the wrist. Preliminary symptoms often start with sensory domain (pain, tingling, paresthesia and especially night awakening due to symptoms mentioned above) and then progress to motor domain (thenar muscle atrophy and clumsiness) if left untreated.

Depending on the severity, patient's willingness and convenience, there are many options for CTS. For those whose symptoms are mild to moderate, conservative therapies are usually the first choice, including physiotherapies, local injection and night splints. Local steroid is proven to be effective to relieve the symptoms of CTS shortly up to 3 months. However, the effects will decline gradually and repetitive injections is suggestive. The patients with severe symptoms which comprise thenar muscle atrophy will be advised to receive decompression surgery.the surgery can alleviate the illness with high success rate up to 70%. Unfortunately, there are still patients who will relapse or undergo side effects, for example, finger weakness.

In recent years, acupuncture researches focused on CTS intervention have been outgrowing and promising. Whereas, there are still lack of evidence which stands for the therapeutic effects comparing with local steroid injection. This limits the built-up of suspect mechanism of acupuncture intervention for CTS.

This is a preliminary, randomized and single-blinded study which started since 2016 and last for a year. The investigators utilize ultrasound to guide the depth of needle penetration which prevents unnecessarily tissues injury such as artery or dry needle injury. This procedure also guarantees the needles lie directly on the upper surface of the median nerve. One group will receive electrical stimulation and another won't. The investigators use electromyography, cross-section area of median nerve, visual analog scale, Boston Carpal Tunnel Syndrome Questionnaire, six-item scale, The disabilities of the arm, shoulder and hand score and Jamar grip dynamometer as outcome measurements. The results gathered from two experimental groups will be compared with the data from the control group whose participants only receiving local steroid injection once in the first week. The participants are all above 18 years old and complain of illness for a least 3 months without any surgery or local injection for a least 1 year. The investigators set up strict exclusive criteria and sample size estimation is 70.

Inclusion Criteria:

1. All participants are must above 20 years old,
2. All participants are willing to join and can be cooperated with all the interviews and examinations.
3. The symptoms are compatible with carpal tunnel syndrome, including numbness, pain, paresthesia, tingling, burning sensation over a least 2 fingers and hand motor limitation which are dominated by median nerve.These symptoms have to sustain for more than 3 months and be diagnosed by electromyography, physical examination and physicians.
4. Those who underwent local injection including glucose, steroid or anaphylaxis will be recruited if the treatments finished more than a year.

Exclusion Criteria:

1. symptoms due to radiculopathy (When the patient also complains of symptoms radiating to the elbow or neck movement pain, the orthopedic doctor will make the definite diagnosis. )
2. Those who underwent decompression surgery.
3. CTS due to traumatic injury (confirmed by image)
4. Those who underwent local injection within a year.
5. CTS due to rheumatoid arthritis
6. CTS due to cancer
7. CTS due to peripheral artery occlusive disease
8. Those who have past history of psychosis.
9. Pregnancy(every woman will be confirmed by urine pregnancy test)