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Background and Aims Lumbar spine surgery causes severe postoperative pain, which typically persists for at least 3 days. Recently, bilateral ultrasound (US)-guided erector spinae plane (ESP) block has been demonstrated to produce superior analgesic effects than conventional postoperative opioid based analgesia, reducing postoperative opioid consumption and pain scores in patients undergoing lumbar surgery, therefore improving patient satisfaction and recovery In this case report, we describe a rare complication, that to date has not been reported in the available literature. Our patient presented a persistent hypotension period that required norepinephrine infusion for almost 12 hours postoperatively. Here we present the details of this case and a description of possible explanations.

Methods Case report of a 47 year old male is scheduled for elective spine surgery Anesthetic plan consisted of combined anesthesia: total intravenous anesthesia (TIVA) with orotracheal intubation + intrathecal morphine 100 mcg + ESP block at T11 level for postoperative pain management.

Results Throughout the transanesthesic period, low MAP values were detected below 60 mmHg. so standard management with crystalloids and norepinephrine infussion was started, evaluating posible etiologies. The procedure ended and the patient was extubated with standard procedures. in PACU the patient persisted with hypotension that required the norepinephrine infusion for at least 12 hours after the surgery,

Conclusions Recent studies in human cadavers cast doubt on the mechanism of action of the ESP block and it has been proposed that there is more than one mechanism of action interacting. To date, no cases of sympatholisis have been described associated with ESPB.