Clinical Research Directory

Sphenopalatine Ganglion Nerve Block for Postdural Puncture Headache in Obstetrics

The SNOB study is a prospective, randomized, double-blind, placebo-controlled, cross-over pragmatic trial that has been designed in accordance with the CONSORT guidelines. Patient recruitment will occur in the postnatal unit or emergency room, where the patient first presents with PDPH following epidural or CSE for labor or cesarean delivery. We will endeavor to perform anesthesia ward rounds daily in postnatal wards to assess for possible PDPH. Patients will also be identified who return to labor and delivery or the emergency room with complaints of headache following hospitalization that included epidural or CSE during delivery. The RCT intervention is sphenopalatine ganglion nerve block (SPGNB). The active drug is 4% lidocaine (LIDO group); placebo control is saline (SALINE group). The sphenopalatine ganglion is shown in Figure 1. Owing to its location at the posterior wall of the nasopharynx, the SPGNB is readily performed by non-invasive application of topical local anesthetic. Patients are positioned supine with a pillow under their shoulders with their chin raised, so that their neck is extended. Next, 1.5 mL of study drug (4% lidocaine solution or saline) is dripped slowly (over 15 seconds) into each nostril (total 3mL) via a plastic venflon i.v. cannula. The supine, extended-neck position is then maintained for 15 minutes. After that time, the patient is then asked to sit upright to assess the postural headache. If the postural headache is not sufficiently relieved, the procedure is immediately repeated, and may be repeated a third time if needed. Cross-over: After SPGNB, any patient with inadequate therapy (primary outcome; see below) may request to end the study and have an epidural blood patch. On initial enrollment they are advised that all patients requesting an epidural blood patch will be asked to receive an additional cross-over rescue dose of SPGNB which is the opposite of the drug (lidocaine or saline) allocated in their study group. Treatment for up to three 15 min intervals and subsequent assessment is exactly as for the study intervention (see above). If the PDPH is completely relieved by this cross-over medication, the patient will be advised to defer the EBP. If patients refuse the cross-over, this refusal is recorded but their initial request for EBP after the first series of randomized medications is analyzed as our primary endpoint. Outcomes: The primary outcome is initial success assessed after completion of the first series of SPGNB treatment with the study medication (LIDO vs SALINE) - irrespective of the number of treatments required (1, 2 or 3 applications, ie after 15, 30 or 45 min). There are two possible options at this stage: Adequate analgesia; patient does not wish to proceed to EBP; or Inadequate analgesia; patient wishes to proceed to EBP. Secondary outcomes: 1) Success or failure of the cross-over dose to treat PDPH and prevent EBP - irrespective of the number of treatments required (1, 2 or 3 applications, ie after 15, 30 or 45 min); 2) Number of repeat SPGNB treatments required for success in either the initial treatment series or the rescue cross-over series; 3) Time to headache on assuming upright posture; 4) Return to function using the Brief Pain Inventory http://www.npcrc.org/files/news/briefpain\_short.pdf - using the pain interference section (questions 9 A-G). 5) Standardized questionnaire (after each intervention): following questions - each with a binary answer Yes or No: Head/neck pain, Nausea, Photophobia, Tinnitus, Ear stuffiness, Diplopia. If the answer to head/neck pain is "yes", then there are supplementary questions: a) location, b) postural element to pain, c) time pain appears after upright posture, d) severity assessed by VAS 0-10 (11-point verbal scale), where 0=none and 10=worst imaginable.