arm intervention GP1 : after skin disinfection and oral premedication , ultrasound guided cervical bilateral bloc ,with10 ml of bupivacaine 0.25 was realized in each side of deep cervical space; then general anesthesia was performed with local protocol

GP2 control no specific intervention only general anesthesia was performed with local protocol

with a linear probe and after disinfection vascular neck axis are identified at first. At the cricoid cartilage we conducted an apical scan to locate the carotid bifurcation.at this level is carried out a lateral translation to the visibility of the deep cervical space below the sternocleidomastoidien muscle then a needle 50 is introduced in plane. we proceed in inundation of cervical space

In addition to the standard monitoring , we associate that of narcosis (BIS, Covidien LLC.Mansfield, USA) whose level is maintained between 40 and 60, a monitoring of the capnia, maintained between 35 and 40mmHg, we associate an analyzer of gas.The maintenance of the anesthesia is provided by sevoflurane adjusted according to the values of the bi-spectral index. Remifentanil is administered by the electrical pump as a function of the variation in blood pressure and heart rate, which should not exceed 20% of their baseline values during the surgical procedure.All our patients were operated by the same team.

Ten minutes before closure, each patient receives 1 g of paracetamol (Perfalgan®) and 50 to 100 mg of tramadol depending on his weight. The remifentanil syringe pump is stopped when the skin is closed and the total dose is calculated for each patient.

the investigator proceed to evaluate pain at H0, H2, H4, H6, H12 and H24 postoperative hour. Each time the patient had a Visual analogic scale (VAS) greater than or equal to 40mm(from 0 to 100) a titration of 3 mg intravenous morphine every 5 minutes until VAS <40mm . Total dose of morphine required was calculated 24 hours after surgery