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Received Oct 30, 2017; Revised Mar 7, 2018; Accepted Mar 27, 2018
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1. Introduction
Initial reports on the effectiveness of morphine locally administered to sympathetic ganglia were published thirty years ago [1]. The term ganglionic local opioid application (GLOA) for this procedure was coined in 1986 by Sprotte [2], and to date, GLOA is an accepted technique, especially in Europe.
For GLOA, opioid sometimes combined with a local anesthetic agent is dissolved in physiologic saline solution (e.g., 0.03 mg buprenorphin in 3 ml saline solution). Afterwards and under direct visual control, the sitting patient gets transorally an injection with an atraumatic spinal needle retrotonsillary into the lateral pharyngeal wall at the height of the 2nd cervical vertebra. Preinterventional oropharyngeal disinfection complies with those for oral surgical interventions (chlorhexidine, octenidine oder phenole). By using a spacer, one can assure an infiltration of the needle at a maximum of 10 mm. Special attention should be put on the anatomical proximity to nervus vagus, nervus glossopharyngeus, nervus hypoglossus, and nervus laryngeus superior as well as to arteria carotis interna [3–5].
Since its introduction for pain treatment many years ago, predominantly only several small cohort studies/case series were conducted to analyze the benefits of this method as compared to local anesthetic sympathetic chain blockade and/or intravenous regional sympathectomy (IVRS) in sympathetically maintained pain (SMP) [1], trigeminal neuralgia [2, 4], postherpetic neuralgia, chronic facial pain, complex regional pain syndrome (CRPS) [6, 7], postoperative glossopharyngeal neuralgia [8], and phantom pain [9]. The clinical effects of GLOA can be divided into immediate, intermediate and long-term effects. The short-term analgetic effects occur no later than 20 minutes upon injection and are more distinct in patients with zoster or trigeminal neuralgia. After one month of repetitive GLOA treatment, the level of continuous pain is reported to decline significantly in responders [4]. The long-term effects of GLOA are only documented by few studies but relate distinctively with the immediate effects. In the analysis of Elsner and colleagues, 21% of the patients remained free of pain after three years and the majority of the remaining patients reported significant decrease...