RCT of SPG Blocks for Post-dural Headache

The postdural puncture headache (PDPH) is a well-documented complication of dural puncture. Depending on a number of factors, the overall incidence of PDPH following unintended dural puncture with an epidural placement needle is typically around 50%, but can be as high as 70% for certain populations.(1, 2, 3)

The headache is characterized by being frontal or occipital in nature, with a typical onset of 6-72 hours after dural puncture. It is normally exacerbated by the upright position and improved by the supine position. Associated symptoms may include photophobia, nausea, vomiting, dizziness, tinnitus, neck stiffness, decreased hearing and visual changes. (2) These symptoms tend to be extremely debilitating in affected patients, severely limiting their functional capacity until the resolution of the headache.(2) The compromise is even greater when considering these women also need to care for a newborn, as the time after birth is important for forming attachment and encompasses many new obligations for the new mother.

The treatment of the PDPH often begins with conservative treatment including supportive therapies such as hydration, bed rest, acetaminophen, NSAIDs, and oral opioids. In addition, some evidence exists for the use of caffeine (1,2). While these do not hasten recovery, they may improve symptoms. For PDPH of all etiologies, 72% will resolve spontaneously in 7 days and 89% by 14 days. (1)

For patients with moderate to severe symptoms or long lasting headaches, the gold standard for treatment of headaches that do not resolve is the epidural blood patch (EBP) (1,2,4). This treatment has been shown to be effective in 70-98% of patients (1,2,4). However, it has numerous contraindications including: fever, infection, coagulopathy, active neurological disease, patient refusal. In addition, a potential complication is yet another dural puncture. Also, while the EBP is generally very safe, it is an invasive procedure with its own complications; it has been associated with very rare but serious complications including: moderate long-lasting backache, meningitis, epidural abscess formation, epidural hematoma formation, and neurologic deficit development. (5-8)

The sphenopalatine ganglion (SPG) is a parasympathetic ganglion with fibers that innervate the cerebral and meningeal blood vessels cause vasodilation and activation of nociceptive fibers in the meninges, which is perceived as referred pain from the head by the sensory cortex. (9) So blockade of these fibers can theoretically relieve headache symptoms from other causes. The SPG block has been safely used for many years to treat chronic facial or head pain from cluster headaches, trigeminal neuralgia, postherpetic neuralgia, atypical facial pain from cancer, and CRPS I and II. (9)

The SPG block is safe and easy to perform. The only contraindications include patient refusal, a true allergy to local anesthetic, and Hereditary Hemorrhagic Telangiectasia (HHT). (9,10) Documented potential complications include transient nausea and epistasis. (9,10) The SPG is located in the pterygopalatine fossa, which is just posterior to the middle turbinate, and anterior to the pterygoid canal. It is about 5 mm in size and there is a 1 to 1.5 mm-thick layer of connective tissue and mucous membrane surrounding the ganglion, so drug enters easily by a topical application. (9-11) There are multiple approaches to the blockade of this ganglion, but the easiest and least invasive is the transnasal approach involving entering the nare with the application of lidocaine jelly on a cotton swab directed posteriorly in the nasal passage to the SPG. (9) The cotton swab should remain in place for 10 minutes. (9,10)

Recently, the SPG block has also been shown to be effective in relieving the symptoms of the PDPH in case series and case reports. One case series performed SPG blocks in 3 parturients with confirmed PDPH in the emergency room using 2% viscous lidocaine. All 3 patients had good relief after the intervention and did not require EPB. The authors suggested that the procedure can be safely and accurately performed in the emergency room, which will reduce visit time, provide good pain relief, and the EBP can be deferred. (10) Another case series of 32 patients with confirmed PDPH of multiple etiologies showed that the SPG block prevented the need for EBP in 69% of the cases. (12)

In addition, a recent randomized placebo controlled trial of SPG block vs. saline for acute headache in the ER showed that for patients with acute anterior headache, SPG block with bupivacaine resulted in a reduction of HA symptoms. However, reduction of headache symptoms was also seen in the SPG block with saline group, indicating a possible placebo effect of the performance of the block. (13)

The purpose of the study is to assess the effectiveness of the SPG block with lidocaine vs. SPG block with placebo on preventing the need for EBP in women who develop PDPH after accidental dural puncture during placement of LEA for labor.