key: cord-0051701-na4msgg0
authors: Anthony Cometa, M.; Zasimovich, Yury; Smith, Cameon R.
title: Percutaneous sphenopalatine ganglion block: an alternative to the transnasal approach
date: 2020-10-17
journal: Int J Obstet Anesth
DOI: 10.1016/j.ijoa.2020.10.002
sha: e6df22e5055690a8127f99b1c8a944f2fc6bf009
doc_id: 51701
cord_uid: na4msgg0

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In several case series the sphenopalatine ganglion (SPG) block has been reported to effectively treat postdural puncture headache (PDPH). [1] [2] [3] To understand the proposed mechanism behind the SPG block, the cerebrovascular dynamics of PDPH must be understood. Boezaart measured the increase in cerebral blood flow (CBF) due to vasodilation associated with cerebral spinal fluid loss and reported the decrease in CBF due to vasoconstriction that occurred immediately following blood being introduced into the epidural space. 4 The pain associated with PDPH is due to meningeal nociceptive stimulation from cerebral vasodilation, which is carried via the trigeminal nerve. This trigemino-vascular network mediates the parasympathetic autonomic vasomotor system and includes the SPG as an essential component. 5 The SPG has a parasympathetic root, therefore, blocking the SPG decreases vasodilatory parasympathetic autonomic activity and vasoconstriction ensues. This mechanism for PDPH relief is shared by the SPG block and epidural blood patch.

The transnasal SPG block uses a long cotton tip applicator, soaked in local anesthetic advanced into the nasal cavity. 2 The only randomized controlled trial to date demonstrated no difference in efficacy when the transnasal block was performed with local anesthetics versus saline. 6 We believe the efficacy of the transnasal route SPG block is inconsistent due to requiring precise placement of the applicator, as well as absorption of the local anesthetic across multiple barriers, including the nasal mucosa, sphenopalatine foramen, and fat space within the pterygopalatine fossa (PPF). Additionally, in the current COVID-19 pandemic, recommendations from the Society for Obstetric Anesthesia and Perinatology (SOAP) suggest that this technique is inadvisable in known or suspected COVID-19 patients because the transnasal route risks aerosolization. 7 Due to significant discomfort reported by patients, the lack of efficacy of the transnasal approach, and risk of aerosolization, we do not endorse the transnasal route. Rather, we propose a percutaneous approach, which in our experience has a higher success rate and is well tolerated by patients.

A suprazygomatic, percutaneous, needle-based approach to blocking the SPG is an alternative to the transnasal technique. This approach can be performed using real-time ultrasound guidance to place a 25-gauge spinal needle into the PPF, delivering 5 mL of 0.5% ropivacaine bilaterally (Fig. 1) . 8 

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