Ultrasound-guided superficial cervical plexus block for analgesia in patients undergoing craniotomy via suboccipital retrosigmoid approach: study protocol of a randomised controlled trial.

introductionScalp nerve block has been proven to be an alternative choice to opioids in multimodal analgesia. However, for the infratentorial space-occupying craniotomy, especially the suboccipital retrosigmoid craniotomy, scalp nerve block is insufficient. METHODS AND ANALYSIS: The study is a prospective, single-centre, randomised, paralleled-group controlled trial. Patients scheduled to receive elective suboccipital retrosigmoid craniotomy will be randomly assigned to the superficial cervical plexus block group or the control group. After anaesthesia induction, superficial cervical plexus nerve block will be performed under the guidance of ultrasound. The primary outcome is the cumulative consumption of sufentanil by the patient-controlled intravenous analgesia pump within 24 hours after surgery. Secondary outcomes include the cumulative consumption of sufentanil at other four time points and numerical rating scale pain severity score. ETHICS AND DISSEMINATION: The protocol (version number: 2.0, 10 April 2019) has been approved by the Ethics Review Committee of China Registered Clinical Trials (Ethics Review No. ChiECRCT-20190047). The findings of this study will be disseminated in peer-reviewed journals and at scientific conferences. TRIAL REGISTRATION NUMBER: NCT04036812.