Pectoral Nerve Block Versus Paravertebral Block In The Incidence of Chronic Pain After Breast Cancer Surgery: A Randomized Clinical Trial

General anesthesia with postoperative NSAI D and opioids is a commonly used technique for postoperative analgesia after breast surgeries. Patients with mastectomy under general anesthesia commonly have pain in the axilla and upper limb that increases hospital stay, costs, and postoperative complications .Thoracic paravertebral block can be performed for analgesia after breast surgery. Ultrasound usage gave an accurate reading of the depth to the paravertebral space and can be used during the whole technique. Breast surgery is usually done with axillary dissection and can be done at single or multiple levels of thoracic paravertebral blocks .Thoracic paravertebral block is associated with multiple complications such as hypotension, pneumothorax, sympathetic block, central spread of local anesthesia or failed block which may cause limitations in the technique. The use of ultrasound in anesthesia increases the success rate of the block and decreases the incidence of variable complications .On the other hand, many interfascial plane blocks have been described. Pectoral nerve block (PECS) has been described as interfascial plane blocks and provide analgesic adjuvants for breast surgery with or without axillary dissection. The block was described as an injection of local anesthetic between the pectoralis major and minor muscles (PEC I) and between pectoralis minor and serratus anterior muscle (PEC 2) .