Technical considerations for approaches to the ultrasound-guided maxillary nerve block via the pterygopalatine fossa: A literature review

Background and objectives Blockade of the trigeminal nerve and its branches is an effective diagnostic tool and potential treatment of facial pain. Ultrasound-guided injections in the pterygopalatine fossa (PPF) to block the trigeminal nerve divisions and sphenopalatine ganglion have been described but a consensus has yet to be reached over the ideal approach. We sought to delineate and compare the various approaches to the ultrasound-guided trigeminal divisions blockade via the PPF. Methods The literature search was performed by searching the National Library of Medicine's PubMed database, the Cochrane Database of Systematic Reviews and Google Scholar within the date range of January 2009-March 2019 for keywords targeted toward "trigeminal nerve," "maxillary nerve," or "pterygopalatine fossa," "ultrasound," and "nerve block," using an English language restriction. Six papers were included in the final review: one prospective double-blinded randomized controlled trial, one prospective descriptive study, one case series, two case reports, and one cadaveric study. Results There are three main approaches to the ultrasound-guided trigeminal nerve branches blockade via the PPF: anterior infrazygomatic in-plane, posterior infrazygomatic in-plane, and suprazygomatic out-of-plane approaches. Each showed injectate spread to the PPF in cadaver, adult and pediatric patients, respectively.1-5Injectate used varied from 3 to 5 mL to 0.15 mL/kg. Conclusions These studies demonstrated that the PPF is a readily accessible target for the ultrasound-guided maxillary nerve block via three main approaches.2The ideal approach is yet to be determined and must be further explored.