Enhancing the Effect of Stellate Ganglion Block in the Treatment of Posttraumatic Stress Disorder: A Double-blind Randomized Controlled Trial of Bupivacaine vs Bupivacaine + Ketamine

The most common treatment for Post-traumatic Stress Disorder (PTSD) is trauma-focused therapy and/or prescription of medication(s). However, these treatments may not directly reduce symptoms associated with PTSD, making it difficult for patients to be treated for this condition and recover. Stellate ganglion block (SGB) is a medical procedure that involves injection of a local anesthetic (a medication that causes reduced sensation/feeling in a given area) around the stellate ganglion, which is a collection of nerves near the base of the neck. This procedure causes a short-lived, temporary shutdown of nerve signals (up to 5-7 hours) and is commonly performed in Canada for certain pain and medical conditions. In the last decade, several studies, including those involving members of military groups, have shown that SGB can result in a rapid and sustained drop in symptoms related to PTSD such as overwhelming anxiety, increased irritability, heightened alertness, and exaggerated startle. Considering these results and the known safety of this procedure (as demonstrated by previous research and use in other illnesses), SGB has been increasingly used to treat PTSD among veterans in the United States but has not yet been thoroughly evaluated in Canada. More research is thereby needed to use SGB as a method of PTSD treatment in Canada, and to better understand how it works to reduce symptoms associated with this condition. The use of the SGB procedure for PTSD has not yet been approved by Health Canada for the general population. WHY IS THIS STUDY BEING DONE? The purpose of this study is to better understand how SGB works in helping reduce symptoms associated with PTSD, and to understand if infusing bupivacaine (the standard local anesthetic used for SGB) with ketamine increases the effectiveness of the procedure. Combining ketamine with local anaesthetics such as lidocaine or bupivacaine is a specialized approach used in interventional pain management. Research has shown that this combination works safely in providing powerful relief for severe treatment resistant chronic conditions. However, combining ketamine in the context of an SGB injection, or as a supporting treatment for PTSD symptoms, has yet to be studied. To do this, the study will have two Parts. The first Part is the Randomized Controlled Trial (RCT), and the second Part is the study extension. In Part I, participants will be randomized into groups where they will either receive one SGB injection of bupivacaine alone, one injection of bupivacaine combined with ketamine, or no injection. We will also be collecting additional information through the use of pupillometry (a non-invasive technique that measures the size and reactivity of your pupil) to monitor the effectiveness of each individual procedure. Additionally, during this project we hope to obtain feedback from both the participant and their family/support network about their experience and satisfaction with the SGB procedure and its effects. This will help us understand for whom SGB works best and will provide us with information and experience for introducing SGB into programs within The Royal. A series of questionnaires will also be asked to understand more about each participant. In Part II, all participants who meet eligibility criteria, including those who received no injection during Part I, will have the option to finish and exit the study, or continue and receive one standard SGB injection (bupivacaine) during the extension. This means those who received an injection during the RCT will have the option for a second injection, and those who were randomized to the Control Group will have the option to receive one injection.