Ganglion Impar Phenol Injection in a Pediatric Patient with Refractory Cancer Pain

Dear Editor, Cancer pain is still a major issue despite the World Health Organization ladder. Up to 30% of the patients experience poor pain control, especially at late stages and during the last year of life [1]. While opioids are the gold standard for treatment of moderate to severe cancer pain, at least 10–15% may benefit from interventional procedures [2,3]. The main reason to advocate interventional pain management (IPM) is either a lack of efficacy of the opioids and the co-adjuvant therapy or intolerable side effects of such therapy. IPM includes neurolytic procedures (celiac plexus neurolysis, superior hypogastric neurolysis, and impar ganglion neurolysis), continuous epidural and intrathecal analgesia radiofrequency, and vertebral or bone cement augmentation [4]. Most of the IPM experience has been done on adult population, and the information in pediatric population is limited. Neurolytic injection on the impar ganglion is reported since 1990. This ganglion is a single retroperitoneal structure, marking the end of the paired paravertebral sympathetic chains. It is responsible for visceral-perineal pain that is sympathetically maintained [5]. There are no reports of neurolytic impar ganglion injection in pediatrics. There is only one case report to our knowledge of impar ganglion injection but only with local anesthetics in a teenager with persistent coccygodynia [6]. We would like to report our experience in a toddler with refractory perineal-cancer-related pain in whom we performed an impar ganglion neurolysis as a part of his pain management. A 3-year-old patient was referred to our Pain Clinic due to severe pain related to an embryonal bladder/prostate rhabdomyosarcoma. The main complaint was a painful tenesmus secondary to the pelvic floor invasion of the mass, leading to a severe discomfort. There was no surgical or radiotherapy treatment offered at that time. Pain management was based on a morphine continuous infusion plus patient-controlled-analgesia controlled by the parents (0.14 mg/kg/h). Acetaminophen and ketorolac were also provided around the clock. Ondansetron was given for nausea and midazolam for sedation. Several options were discussed with the parents, including a continuous epidural analgesia, a lower end block (intrathecal neurolysis of the lower sacral rootlets), and an impar ganglion neurolysis [7]. The impar approach was elected, and the patient was scheduled for the procedure under general anesthesia. After a thorough informed consent, the patient was induced using a conventional intravenous medication with propofol 1 mg/kg, rocuronium (0.5 mg/kg), and fentanyl (2 mcg/kg). Anesthesia was maintained using sevoflurane in a oxygen/air mixture. The airway was secured with an orotracheal tube, and the patient was placed on a prone position. Under aseptic conditions a 22-gauge needle was used to mark the sacrococcygeal union in AP and in the lateral position. After that, the needle was introduced via the sacrococcygeal ligament to be positioned just anterior to the union, but posterior to the colon. A positive image was obtained using real-time fluoroscopy to avoid any intravascular, epidural, or nerve spread and also to avoid visceral puncture (Figure 0001a). The view was confirmed in AP position. A total of 0.5 mL of contrast was needed to obtain the characterized picture (half-moon on the lateral, and in AP view, a circular image at the level of the impar ganglion) (Figure 0001b). A local anesthetic test dose was not offered because of the bias of the general anesthesia administered. The same volume of contrast was then injected in the form of phenol 10%. There were no adverse events recorded during the procedure, and the patient was awakened and transferred later to the post anesthetic care unit. Impar-ganglion block. The patient experienced a severe decrease his visual analog scale (VAS) scores, about 70%, using the face, legs, activity, cry, consolability scale, and in the frequency of the breakthrough pain episodes. Also, he had an improvement in his quality of life, specifically in the sleep pattern. Unfortunately, the patient developed a malignant intestinal obstruction due to his tumor with subsequent progressive respiratory distress and died 5 days later. Despite the improvement in the VAS, the patient did not decreased the amount of opioid or co-adjuvants. One major drawback for lower end blocks is the ideal need for a prognosis block, not only for the pain decrease but also for side effects. Therefore, a very important issue during the planning of an intrathecal neurolysis is the possible complications related to bladder and rectal incontinence. There are no reports to our knowledge addressing this subject in pediatric population. Pain relief using continuous epidural analgesia is also suitable for children, but it is not widely used as in adults [8]. Continuous intrathecal analgesia could be used as a replacement for continuous epidural analgesia, especially if the expectancy of life is greater than 3 months [9]. The target of epidural analgesia for pain relief in pelvic procedures is the sacral rootlets. For the previous reason, motor block should be taken into account [10]. One advantage of impar ganglion procedures is the simplicity of the procedure itself and the possibilities of integrate it to an IPM algorithm (Figure 0002). In adults, lower end blocks are well established in adult population [7]. Proposed interventional algorithm for perineal cancer-related pain. Impar ganglion neurolysis. If negative, lower end block (LEB, intrathecal neuroloysis). Consider always a test dose. *Only if the expectancy of life is less than 1 year. ¥ If it is not suitable to perform or negative an impar ganglion neurolysis or an LEB, a continuous epidural or continuous intrathecal should be offered. This case highlights the role of impar ganglion neurolysis as a therapeutic strategy in pediatric patients with reluctant perineal pain.