Blocks at the wrist provide effective anesthesia for carpal tunnel release

Distal blocks are not recommended even for a short procedure when a tourniquet is used. This study was designed to evaluate the tolerance, effectiveness, patient acceptance and safety of distal blocks at the wrist.

Consecutive patients (n=273, mean age 53 +/-15 yr) undergoing endoscopic carpal tunnel release with a pneumatic tourniquet were included in this study. The median nerve was blocked 6 cm above the wrist crease by injecting 10 mL of 2% lidocaine and 0.5% bupivacaine (v/v). The ulnar nerve was blocked by injecting 8 mL of the same anesthetic mixture below the flexor carpi ulnaris tendon 6 cm above the wrist crease. Finally, 2 mL of local anesthetic were infiltrated sc and laterally below the crease to block the musculocutaneous nerve. The intensity of the block was evaluated after five, ten and 20 min. In addition, pain associated with block performance and tolerance of the tourniquet were evaluated. Finally, neurological complications associated with this technique were investigated. Data are presented as means +/- SD.

At ten minutes after the block was performed, 9% and 32% of patients required an additional injection to complete the block in the median and ulnar territories, respectively. In more than 75% of patients, performance of the block was associated with either no or mild pain. The tourniquet was inflated for 12.6 +/- 5.4 min and was well tolerated in 99% of patients. Finally, neither transient nor permanent neurological deficit were recorded postoperatively.

Blocks at the wrist are effective, well accepted by the patient and safe when a pneumatic tourniquet is used for a short procedure.