Intravenous acetaminophen for postoperative supratentorial craniotomy pain: a prospective, randomized, double-blinded, placebo-controlled trial

OBJECTIVE Acute pain control after cranial surgery is challenging. Prior research has shown that patients experience inadequate pain control post-craniotomy. The use of oral medications is sometimes delayed because of postoperative nausea, and the use of narcotics can impair the evaluation of brain function and thus are used judiciously. Few nonnarcotic intravenous (IV) analgesics exist. The authors present the results of the first prospective study evaluating the use of IV acetaminophen in patients after elective craniotomy. METHODS The authors conducted a randomized, double-blinded, placebo-controlled investigation. Adults undergoing elective, supratentorial craniotomies between September 2013 and June 2015 were randomized into two groups. The experimental group received 1000 mg/100 ml IV acetaminophen every 8 hours for 48 hours. The placebo group received 100 ml of 0.9% normal saline on the same schedule. Both groups were also treated with a standardized pain control algorithm. The study was powered to detect a 30% difference in the primary outcome measures: narcotic consumption (morphine equivalents, ME) at 24 and 48 hours after surgery. Patient-reported pain scores immediately postoperatively and 48 hours after surgery were also recorded. RESULTS A total of 204 patients completed the trial. No significant differences were found in narcotic consumption between groups at either time point (in the treatment and placebo groups, respectively, at 24 hours: 84.3 ME [95% CI 70.2-98.4] and 85.5 ME [95% CI 73-97.9]; and at 48 hours: 123.5 ME [95% CI 102.9-144.2] and 134.2 ME [95% CI 112.1-156.3]). The difference in improvement in patient-reported pain scores between the treatment and placebo groups was significant (p < 0.001). CONCLUSIONS Patients who received postoperative IV acetaminophen after craniotomy did not have significantly decreased narcotic consumption but did experience significantly lower pain scores after surgery. The drug was well tolerated and safe in this patient population.