Video-assisted thoracoscopic lung resection (VATS) is a minimally invasive surgical approach frequently used in the treatment of lung cancers. The most commonly used analgesic technique for this surgery is the paravertebral block with a single peroperative injection of local anesthetic. However, a recent study conducted at our institution revealed that this approach provided less relief than expected in some patients. In light of these results, it becomes crucial to distinguish between technical failures (absence of sensitive anesthesia) and the intrinsic limits of the chosen regional analgesia technique (pain originating from an unanesthetized area or pain despite the presence of sensitive anesthesia) in order to better relieve patients. This study aims to objectively assess the areas of anesthesia obtained through two methods of paravertebral block to evaluate their respective performance and optimize post-VATS analgesic management.