Comparison of Volumes of Local Anesthetics on the Efficiency and Safety of Stellate Ganglion Block for CRPS of the Arm

Comparison of Two Volumes of Local Anesthetics on the Efficiency and Safety of Stellate Ganglion Block for the Treatment of Complex Regional Pain Syndrome of the Arm

The purpose of this study is to compare the efficiency and safety of 2ml versus 5ml of local anesthetics used in stellate ganglion blocks for the treatment of complex regional pain syndrome of the arm.

To evaluate if 2ml of 0.2% ropivacaine is less effective in decreasing pain scores by more than 50% when compared to 5ml of 0.2% ropivacaine. To evaluate if 2ml of 0.2% ropivacaine is causes less side effects when compared to 5ml after a stellate ganglion block.

Inclusion Criteria:

• Patients with a diagnosis of complex regional pain syndrome of the arm according to the Budapest criteria and having already received a minimum of 3 stellate ganglion blocks. Only patients having received a minimum of 3 stellate ganglion blocks will be included since it is expected to have a progressive and sustained decrease in pain scores during the first 3 blocks.
• ASA 1 to 3 included

Exclusion Criteria:

• Patient refusal
• Contra-indications to the stellate ganglion block procedure such as coagulopathy, anticoagulants or anti platelet therapy other than aspirin, systemic or injection site infection, important neck deformity (post-radiotherapy or surgery, etc.), severe chronic obstructive pulmonary disease, contralateral diaphragm paralysis or contralateral pneumonectomy
• Allergy to local anesthetics
• Concomitant pain syndrome other than complex regional pain syndrome of the arm
• Liver or kidney failure (CrCl < 30 ml/min)
• Inability to understand à verbal numeric pain score scale after careful explanations
• Inability to consent