The patient, who is experiencing chronic pain in the lower extremities persisting for more than three months, is scheduled to undergo lumbar sympathetic ganglion block. To evaluate the technical success of the sympathetic blockade, temperature and perfusion index (PI) will be measured at one-minute intervals over a 20-minute period before and after the procedure on the treated side and the opposite side foot. Additionally, other variables related to the procedure will be assessed before the procedure, after the procedure, before discharge, and during follow-up outpatient visits or phone surveys at 1 week and 1 month after the procedure.

Patients aged 19 to 85 experiencing lower limb pain and scheduled to undergo lumbar sympathetic ganglion block at the Seoul National University Hospital Pain Center will be directly informed about the study, and their participation will be sought and registered. Continuous monitoring of electrocardiography, blood pressure, and pulse oximetry will be conducted before and after the procedure.

Upon admission to the pain center's operating room, the patient will assume a prone position. Thermometers will be attached to the soles of both feet, and perfusion index probes will be attached to the second toe on both sides. Using fluoroscopy guidance, a needle will be inserted at the painful side, either right or left, at the L3. After confirming the needle's position in front of the desired vertebral body using contrast medium in lateral and anteroposterior (AP) views, 7 mL of 0.5% ropivacaine will be injected. Baseline temperature and PI values will be recorded before drug administration, followed by recording every minute for 20 minutes after injection.

Other variables related to the procedure will be assessed before and after the procedure, before discharge, and through outpatient visits or phone surveys at one week after the procedure.

Inclusion Criteria:

• Lower extremity pain
• Pain for more than 3 months
• 19 - 85 years

Exclusion Criteria:

• If the patient refuses to undergo the procedure
• In the presence of vascular disorders in the lower extremities
• If the patient has previously undergone lumbar sympathetic ganglion removal or neurolysis
• When there are abnormalities in blood coagulation tests
• If there is a systemic infection or infection at the injection site
• In the presence of anatomical deformities at the injection site
• If the patient has allergies to the injected medication
• In other cases where the researcher deems the patient unsuitable for participation