Aim: compare effectiveness (satisfaction) and duration of pain relief between patients who perform the conventional thermal radiofrequency on the ganglion impar vs patients who perform the chemical neurolysis with alcohol in patients with non cancer coccydynia patients with non cancer coccydynia not responding to medical treatment will be divided into 2 groups before intervention , control group will receive conventional radiofrequency ablation of ganglion impar , while the study group will receive alcohol neurolysis