Investigating Composite Biomarkers for Pain Catastrophizing

The site of injections will be determined by palpation of the contracted First Dorsal Interosseus (FDI) muscle. The skin will be cleaned with alcohol before injection. A bolus injection of hypertonic saline (7% NaCl) will be administered to the FDI muscle using a 1 mL syringe with a disposable needle (27G), and 30 the volume of the bolus will be 0.2 mL .

The site of injections will be determined by palpation of the contracted First Dorsal Interosseus (FDI) muscle. The skin will be cleaned with alcohol before injection. A bolus injection of 0.2 mL isotonic saline (9 mg/mL) will be administered to the FDI muscle as control.