Our study was approved by the ethical and scientific review board of Zhejiang Provincial People’s Hospital. Written informed consent was obtained from every patient. Between January 2020 and December 2020, we included 40 patients (5 men, 35 women) who were diagnosed as CTS in this retrospective study. CTS diagnosis standard was made by clinical history, physical examination, ultrasound and electrophysiological evaluation. Clinical history included tests of sensibility and muscle strength, questioning symptoms of sensory and thenar atrophy examinations. We checked Phalen’s test and Tinel’s sign on percussion of the wrist. The criteria of CTS in electrophysiological were median distal motor nerve latency＞4.2ms (stimulation, 2cm proximal to the wrist crease) or median sensory nerve conduction velocity＜45m/s (between the 2cm proximal to the wrist crease and middle crease of the long finger).
Exclusion criteria were poor general physical condition, pregnancy, carpal fractures, contraindicate for corticosteroid drugs, previous wrist surgery and previous treatment of CTS. 20 patients (Group A) underwent ultrasound-guided corticosteroid injection combined with needle release and other 20 patients (Group B) had mini-open surgery. Follow-up time was 3 months. All patients finished Boston Carpal Tunnel Questionnaire, ultrasound and electrophysiological examination before and 3 months after treatment.
Ultrasound-guided treatment procedures
Ultrasound-guided treatment as an outpatient procedure was routinely performed in the ultrasound interventional room. Ultrasound examinations were performed by a senior ultrasound doctor using the Mindray Resona7 with a 5–12MHz transducer (Mindray, Shenzhen, China). 5mL disposable sterile syringe (with needle) was used for administration of local anesthesia and release TCL.
The patient sit in a chair and affected hand was positioned to the side with the palm up in extended position. All treatment procedures were performed by C.C.X with the probe covered with surgical gloves. Acoustic coupling agent was used on the probe inside of the surgical gloves. Patient’s skin was disinfected with complex iodine for 3 times, ranging from metacarpophalangeal joint to 5cm above the carpal canal. Place the probe on the wrist with longitudinal section then long axis of median nerve will be clearly shown. The insertion point is 0.5cm proximal to the compression point of the median nerve. The direction of the needle entry is from the proximal to distal end of the median nerve. Try to avoid stabbing the median nerve, radial artery and ulnar neurovascular bundle when inserting the needle. Wipe the needle entry point with complex iodine cotton balls, under ultrasound guidance, 4mL mixture solution which contains 2mL 2% lidocaine and 2mL 0.9% sodium chloride (in a ratio of 1:1) was injected. Then local anaesthesia layer by layer was performed to the median nerve surface. Under the continuous guidance of ultrasound, acupuncture compression of the TCL at the median nerve continuously, from proximal to distal and from shallow to deep. The operation was completed until there was no resistance to the acupuncture of TCL. Under real-time ultrasound guidance, 2mL mixture solution which contained 1mL 2% lidocaine and 1mL betamethasone (Schering Pharmaceutical Co., Ltd. in Shanghai, China) (in a ratio of 1:1) was injected, mixture solution could be seen diffusing in the carpal tunnel (Figure 1). After the needle was pulled out, pressed the needle path by hand for 5 minutes, and then pasted a adhesive bandage at the insertion point. To prevent infection, the wound must keep dry for 48 hours. The whole process lasts about 5-10 minutes. During the operation, all patients had no pain or discomfort. There were no postoperative complications, and the patient was reexamined 3 months after the operation.
Mini-Open surgery procedures
The patient was placed in supine position under general anesthesia. A pneumatic tourniquet was set at 40kpa pressure, total time of 1 hour and interval 15 minutes. The size of the incision was about 2cm and the shape of it was longitudinal. The skin and subcutaneous tissues were cut open in turn to expose the carpal canal, the thickened and adherent transverse carpal ligament was cut open, the epineurium and bundle membrane of the nerve were loosened, the nerve bundle decompression was performed, and the wound was rinsed after complete hemostasis (Figure 2). After checking nerve release, reclosed layer by layer until to the skin.
Boston carpal tunnel questionnaire, ultrasonic and electrophysiological evaluations before and after treatment
Boston Carpal Tunnel Questionnaire is the most used to assess symptom severity and functional status. It includes two parts: Symptom Severity Scale (SSS) and Functional Status Scale (FSS) . SSS has 11 questions and FSS contains 8 items. According to mean score, patients are divided into five grades: minimal (0.1–1 point), mild (1.1–2 points), moderate (2.1–3 points), severe (3.1–4 points) and extreme (4.1–5 points).
In ultrasound examinations, median nerve’s flattening ratio (FR) and cross-sectional area (CSA) were measured according to El Miedany and colleagues’ grading system . Depending on CSA of median nerve at inlet, severity is divided into follows: mild: 10-13mm2, moderate: >13-15mm2, Severe: >15mm2 . FR was the ratio of the nerve’s transverse axis to the anteroposterior axis. It was assessed at the level of the pisiform bone. Transverse carpal ligament (TCL) was measured on the cross-section at the level of hamate bone.
In electrophysiologic examinations, we recorded the median nerve’s distal motor latency (DML), sensory conduction velocity (SCV) and sensory nerve action potential (SNAP). According to recommendations of the American Association of Neuromuscular and Electrodiagnostic Medicine  and American Academy of Orthopedic Surgeon work group (AAOS) , CTS severity was classified as follows: negative: normal findings of all tests (both comparative and segmental studies), minimal: abnormal on comparative or segmental tests, mild: normal DML with finger-wrist tract SNCV slowed, moderate: increased DML with finger-wrist tract SNCV slowed, severe: increased DML with finger-wrist tract absence of sensory response, extreme: thenar motor absence of response.
Statistical analyses were performed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). All quantitative data were expressed as mean±standard deviations (SD). All qualitative data were expressed as number and percentage. We used student t test to compare quantitative data between groups and Mann-Whitney U test to compare qualitative data. P values＜0.05 were considered statistically significant.