WALANT Technique (Wide Awake Local Anesthesia No Tourniquet) for Carpal Tunnel Release.

This is a multicenter, prospective, randomized, open-label study assessing the interest of the association of the WALANT local infiltration technique with analgesic troncular blocks (TRONC) at the wrist, for the endoscopic CTR.

This study compares two groups:

• CONTROL group (usual technique) : TRONC (using a long-acting LA : Ropivacaine) + Tourniquet
• WALANT group (experimental technique) : TRONC (using a long-acting LA : Ropivacaine) + WALANT ( using a short-term LA : Lidocaine + epinephrine)

RA procedures will be systematically performed under ultrasound guidance, 45 min befor surgery. Before each procedure, a skin disinfection will be carried out using an alcoholic iodine solution. The needle approach will be in-plane (IP) or out-of-plane (OOP). Efficiency will be assessed before transfer to the operating room.

• Troncular blocks (TRONC) Patients will be installed in supine position, the arm at 90° of abduction and in external rotation. The probe will be positioned to have an axial view of the nerves at the wrist. The initial identification of the median (nM) and ulnar (nU) nerves will be systematically done before each TRONC. The nM will be located on the anterior forearm. The nU will be visualized in contact with the ulnar artery in the forearm. The operator will inject 3 to 7 mL of Ropivacaine 3.75 mg/ml per nerve. An infiltration of 2 ml of Ropivacaine 3.75 mg/ml will be performed laterally above the flexion fold of the wrist in order to block the branches of the lateral cutaneous nerve of the forearm, the terminal sensory branch of the musculocutaneous nerve (nMC). A 22 Gauge x 50 mm needle will be used for TRONC.
• WALANT infiltration ("WALANT" group) An infiltration of the subcutaneous area in front of the transverse ligament will be performed between the thenar and hypothenar eminences, from the flexion fold of the wrist over a length of 5 cm. The path of the nM in the palm of the hand will be checked before each procedure. 3 to 7 ml of 1% lidocaine (10 mg/ml) combined with 0.005 mg/ml epinephrine and 8.4% sodium bicarbonate (1 ml per 10 ml of lidocaine) will be injected. The addition of sodium bicarbonate will reduce the pain due to lidocaine injection. A 24 Gauge x 50 mm needle will be used for WALANT.
• Usage of pneumatic Tourniquet A pneumatic tourniquet will be placed at the root of the arm in all patients. A cuff with size and shape adapted to the patient will be used. The tourniquet will be inflated in all patients of "CONTROL" group, and if necessary, corresponding to the failure of the WALANT technique, in patients of "WALANT" group. The inflation pressure will be determined according to the patient's systolic blood pressure (SBP). It will be inflated 75 to 100 mmHg above SBP

Inclusion criteria

• Patients undergoing endoscopic carpal tunnel release
• Consent for participation
• Affiliation to a social security system

Exclusion criteria

• Chronic pain syndrome or fibromyalgia
• Contraindication for locoregional anesthesia
• ASA 4
• Pregnant or breastfeeding women
• Patients under protection of the adults(guardianship, curators or safeguard of justice)
• Communication difficulties or neuropsychiatric disorder