Adding intraoperative IV acetaminophen, in addition to standard analgesics, will decrease opioid requirements over the first 12 hours of postoperative recovery following craniotomy. Opioids exacerbate symptoms of nausea and vomiting. Reducing postoperative opioid use hopefully will reduce incidence of nausea and vomiting in patients after craniotomy.

Inclusion Criteria:

• At least 18 years of age

• Weigh at least 50 kg (110.23 lbs)

• Undergoing open, elective intracranial procedure for

  • tumor resection
  • aneurysm clipping
  • revascularization

• Have an ASA (American Society of Anesthesiologists) physical status of 1, 2, 3, or 4

• Able to provide written informed consent

Exclusion Criteria:

• Significant medical disease, laboratory abnormality, or condition that, in the opinion of the investigator, would compromise patient welfare or would otherwise contraindicate study participation
• Unable to communicate symptoms
• Current daily opioid use (>40 mg morphine equivalent)
• Tramadol use
• Treated with MAO (monoamine oxidase inhibitors) inhibitors within 10 days of surgery
• Treated with any amount of acetaminophen within 8 hours of anesthesia for surgery
• Allergic or hypersensitive to acetaminophen or any contraindications per manufacturer's guidelines
• Pregnancy
• Impaired liver function
• Participation in interventional clinical study within the last 30 days
• Known or suspected history of alcohol or drug abuse
• Surgery for resection of acoustic neuroma
• Transphenoidal tumor resection