Ligamentum flavum in the cervical region is thin or not fused at the midline. The distinct elastic resistance offered by the ligamentum flavum before entering the epidural space when using the loss of resistance (LOR) technique may be blunted or even absent. The investigators inferred that the size and elasticity of the ligamentum flavum, in combination with mildline appraoch, the gaps could be responsible for a failure to recognize a LOR in some patients. If so, the investigators hypothesized that the paramedian approach would be advantageous for finding cervical epidural space more easily during cervical epidural steroid injections (CESIs). Therefore, the investigators randomly divide our patients into 2 groups; the midline approach group and the paramedian group. Then, the investigators examine the patterns of the pressure changes at the moment of a puncture of the ligamentum flavum during CESIs.