Dermatomal Distribution and Radiocontrast Study of Ultrasound Guided Sacral Foramen Injection, a Modification of Sacral Erector Spinae Plane Block

AbstractBackgroundWe evaluated the analgesic efficacy of modified sacral erector spinae plane block (S-ESPB) in patients of carcinoma cervix undergoing intracavitary brachytherapy through a single-arm prospective study.MethodsTen consecutive consenting patients scheduled for intracavitary or interstitial brachytherapy for carcinoma cervix were recruited in the study. The patients received modified S-ESPB for the therapy, supplemented by sedoanalgesia. Dermatomal mapping and monitoring of pain score, vital signs, and additional fentanyl requirements were monitored up to 24 hrs for each patient. Radiocontrast was injected along with the local anesthetic (LA) in each patient, analyzed by CT scan later on. Summary statistics were calculated.ResultsS-ESPB block provided surgical anaesthesia for all patients. Median cumulative fentanyl requirement was122 mcg (interquartile range: 50 to 250 mcg) over 24 hrs. Mapping of dermatomal sensation revealed sensory loss for upto 6 hours in the S2 - S5 dermatomes in all patients. Radiological evaluation of contrast spread demonstrated spread along the presacral area, sciatic and pudendal nerve tracts and broad ligament.ConclusionThe use of modified S-ESPB resulted in clinically useful analgesia in patients undergoing intracavitary brachytherapy. We demonstrated that anesthesia could be obtained in the distribution of sacral, sciatic, and pudendal nerve distributions using this method. <br>