Bilateral Superficial Trigeminal Nerve Blocks are not More Effective than a Placebo in Abolishing Post-operative Headache Pain in Pituitary Transsphenoidal Neurosurgery: A Prospective, Randomized, Doubleblinded Clinical Trial.

Background: Pituitary neurosurgery executed via the transsphenoidal endonasal approach is commonly performed for pituitary adenomas. Reasons for prolonged hospital stay include postoperative headache and protracted nausea with or without vomiting. Bilateral superficial trigeminal nerve blocks of the supra-orbital V1 and infra-orbital V2 (SION) nerves performed intra-operatively as a regional anesthetic adjunct to general anesthesia were hypothesized to decrease 6 hours postoperative morphine PCA (patient-controlled analgesia) use by patients.

Methods: Forty-nine patients, following induction of general anesthesia for their transsphenoidal surgery, were prospectively randomized in a double-blinded fashion to receive additional regional anesthesia as either a block (0.5% ropivacaine with epi 1:200,000) or placebo/sham (0.9% normal saline). The primary endpoint of the study was systemic morphine PCA opioid consumption by the two groups in the first 6-hours postoperatively. The secondary endpoints included (1) pain exposure experienced postoperatively, (2) incidence of postoperative nausea and vomiting, and (3) time to eligibility for PACU discharge.

Results: Of the 49 patients that were enrolled, 3 patients were excluded due to protocol violations. Ultimately, there was no statistically significant difference between morphine PCA use in the 6 hours postoperatively between the block and placebo/sham groups. There was, however, a slight visual tendency in the block group for higher pain scores, morphine use p=0.046, and delayed PACU discharge. False discovery rate corrected comparisons at each time point and then revealed no statistically significant difference between the two groups. There were no differences between the two groups for secondary endpoints.

Conclusion: It was found that a 6-hour postoperative headache after endoscopic trans-sphenoidal pituitary surgery likely has a more complicated mechanism involving more than the superficial trigeminovascular system and perhaps is neuro-modulated by other brain nuclei.