Sphenopalatine Ganglion Block to Treat Shoulder Pain After Laparoscopic Surgery: A Prospective, Randomized, Double Blinded Trial

Purpose of the Study The purpose of this pilot study is to evaluate the efficacy of sphenopalatine ganglion block (SPGB) block to manage shoulder tip pain (STP) after laparoscopic surgery.

Background The laparoscopic technique has increasingly become a popular approach for many gynecologic, urologic, thoracic, bariatric and general surgical procedures. While laparoscopic surgery results in less postoperative pain than traditional open surgical techniques, it is associated with three distinct types of postoperative pain: incisional, visceral, and shoulder. The pain experienced in the shoulder is referred from irritation of the diaphragm and is referred to as shoulder tip pain (STP) to differentiate it from pain that originates in the shoulder. STP may persist for longer than incisional and visceral pain and may be the most difficult to treat. Narcotic and non-narcotic analgesics have only limited success in relieving STP, but none of these reliably eliminates STP, and they may be associated with undesirable systemic side effects. Recently the SPGB has been described as a means of managing STP (Grant 2018).

The SPGB was originally described more than 100 years ago as a treatment for headache (Sluder 1908). Since it was first described, the SPGB has been touted to relieve many types of pain, primarily of the head, but also pain extending down to the lower back (Berger 1986).

The SPG is located in pterygopalatine fossa adjacent to the sphenopalatine foramen. It is posterior to the middle nasal turbinate and separated from the nasal cavity by as little as 2 mm of mucosa. The proximity of the SPG to the nasal cavity facilitates renders it accessible to local anesthetic block. When local anesthetic is applied to the posterior nasopharyngeal mucosa, drug diffuses into the SPG and inhibits nerve conduction. The local anesthetic can be administered by injection, via a cotton-tipped applicator, or by simply dripping it into the nose when the patient is positioned with neck extension (Barre 1982).

Study Design This will be a randomized controlled trial to treat STP with local anesthetic or placebo in after laparoscopic surgery. The primary outcome variable will be reduction of STP.