Long-term analgesic effects of peripheral nerve block in patients with central post-stroke pain: A retrospective series

Background Central post-stroke pain (CPSP) has a detrimental effect on the quality of life of post-stroke patients. However, no definitive and effective method has been established yet for the treatment of CPSP. Objective We aimed to examine the applicability of single-injection peripheral nerve blocks (PNBs) for the treatment of CPSP. Subjects In this retrospective study, we included 22 patients (mean age = 56.3 years; 13 men and 9 women) diagnosed with CPSP who visited an outpatient rehabilitation clinic in Seoul National University Bundang Hospital between December 2018 and April 2020. Methods The patients underwent ultrasound-guided single-injection PNB (lidocaine + epinephrine [1: 200,000]) according to the primary site of pain. The level of pain (measured using a numeric rating scale) was recorded before and after the PNB, and the occurrence of adverse events were also measured. The primary outcome of this study was the amount of pain reduction after PNB. Secondary outcome measures obtained 1 month after the PNB included the pain reduction rate 1 month after the PNB, the patient-reported satisfaction and effectiveness regarding the PNB, intention for re-injection, and the patients' willingness to recommend this procedure to others. Results The mean pain reduction after PNB was 3.3 +/- 2.8. PNB was associated with pain reduction that persisted for greater than 1 month in 68% (15/22) of the patients. Thirteen of 22 patients reported a pain reduction of 50% or more. The mean pain reduction rate was 43.6%. Of the 22 patients, 13 were willing to undergo a second round of treatment with PNB. Nine of them underwent the procedure. No adverse events were observed in this study. Conclusions Our study provides preliminary data suggesting that PNB could be an effective and feasible method to treat CPSP.