Inclusion Criteria:  Clinical diagnosis of complex regional pain syndrome Clinical diagnosis of postherpetic neuralgia Clinical diagnosis of phantom limb pain Clinical diagnosis of chronic post-surgical pain Clinical diagnosis of post-traumatic pain syndrome Upper extremity pain lasting more than 3 months  Patients with a new or known diagnosis of chronic neuropathic pain lasting more than 3 months in the upper extremity  Exclusion Criteria:  Refusal of a patient Any vascular disease in the upper extremities Previous history of thoracic sympathetic or stellate ganglion neurolysis (e.g. -thermocoagulation, radiofrequency neuromodulation, and/or chemical neurolysis) Coagulopathy Systemic infection or local infection at the needle injection site Major deformation at the level of the neck (radiotherapy, surgery, etc.) Known allergy to local anesthetics of amide type Inability to understand a numeric rating pain scale (cognitive dysfunction) Patients whose palm temperature on the ipsilateral side is > 35°C in the thermography before the procedure