Scalp Infiltration With Dexamethasone Plus Ropivacaine for Post-craniotomy Pain

Pre-emptive Scalp Infiltration With Dexamethasone Lipid Microsphere Plus Ropivacaine for Postoperative Pain After Craniotomy

According to recent studies, patients following craniotomy suffer more than minimal pain; two-thirds of patients experienced moderate to severe pain. Postoperative pain most often occurs within 48 hours after surgery. Local infiltration of anesthesia is the most simple and effective analgesia. However, the analgesic effect only lasts for a short-time after surgery, and it cannot adequately meet the needs of postoperative analgesia after craniotomy. Several studies have shown that the mixture of dexamethasone with local anesthetics could reduce the postoperative pain scores better than local anesthetics alone. Lipid microsphere is a relatively new drug delivery system. It is an artificial lipid emulsion. Studies have shown that dexamethasone lipid microsphere, the dexamethasone palmitate emulsion (D-PAL emulsion), has stronger anti-inflammatory effect than dexamethasone. Therefore, the investigators hypothesize that the pre-emptive scalp infiltration with dexamethasone lipid microsphere plus ropivacaine could achieve superior postoperative pain-relief compared to ropivacaine alone for patients undergoing craniotomy.

Inclusion Criteria:

• Patients scheduled for elective craniotomy under general anesthesia;
• Age 18-64 years;
• American Society of Anesthesiologists (ASA) physical status of I or II;
• Anticipated tracheal extubation, full recovery and cooperation within 2 hours postoperatively
• Patients required to fix their head in a head clamp during the operation.

Exclusion Criteria:

• Previous history of craniotomy;
• Plan to delay extubation or no plan to extubate;
• Patients who cannot use the patient-controlled analgesia (PCA) device;
• Patients who cannot comprehend the instructions of a numeric rating scale (NRS) before craniotomy;
• Body mass index (BMI) <15 or >35;
• Allergy to dexamethasone, lipid microsphere, opioids or ropivacaine;
• History of drug abuse or excessive alcohol, chronic opioids use (more than 2 weeks), or use of any sedative or analgesic before surgery;
• History of uncontrolled epilepsy, psychiatric disorders or chronic headache;
• Pregnant or at breastfeeding;
• Symptomatic cardiopulmonary, liver or renal dysfunction or combined with diabetes or other systemic dysfunction;
• Glasgow Coma Scale <15 before the surgery;
• Intracranial hypertension;
• Peri-incisional infection;
• Patients who have received chemoradiotherapy before the surgery or expected to receive postoperative chemoradiotherapy according to the preoperative imaging.