Paravertebral Block (PVB) combined with general anesthesia (GA) is a conventional pain treatment for breast surgery but sometimes failures can occurs. The efficacy of this block has to be evaluated. Also, for the intra-operative analgesic evaluation of this block, it is necessary to measure intra-operative analgesia index. A monitor of nociception for patients under GA, the PhysiodolorisTM device, offers an index for measuring nociceptive inputs during surgery in anesthetized patients : the ANI index (based on the single R-R interval analysis). The purpose of this observational and prospective study is to assess the variations of this ANI index during breast surgery with or without axillary node dissection with a PVB. This will allow us to quantify the analgesic effect of a PVB during GA for unilateral radical breast surgery with or without axillary node dissection.

Inclusion Criteria:

• American Society of Anesthesiologists score (ASA) I or II
• Woman
• Patients aged over 18 years
• BMI between 17 and 30 kg/m2
• Radical mastectomy with or without axillary node dissection.

Exclusion Criteria:

• Preoperative consumption of opioid
• Local Anesthesia allergy
• Local skin inflammation at the puncture area
• Inability to respond to pain assessment using a Numerical Rating Score (NRS)
• Any contra-indication or patient's refusal for regional anesthesia B blocker medication
• Pace maker
• Inability to perform the PVB (at the appreciation of the anesthesiologist)
• Change of surgical procedure other modified radical mastectomy with or without axillary node dissection.
• Patient with a severe side effect or who cannot be controlled by additional therapy will be removed from the trial

women undergo for a breast surgery with or without axillary node dissection