PARAVERTEBRAL BLOCK (PVB) involves the injection of local anesthetic (LA) into a wedge-shaped space lateral to the spinal nerves as they emerge from the intervertebral foramina, producing ipsilateral somatosensory and sympathetic nerve blockade.Since its initial application in abdominal surgery, the technique has been adapted for rib fracture, flflail chest, open cholecystectomy, hepatic-biliary surgery, outpatient inguinal hernia repair, major breast cancer surgery, and open thoracotomy patient populations.Based on several recent systematic reviews and metaanalyses,TPVB and TEA are equal in analgesic effect after thoracic surgery. Moreover, TPVB is associated with fewer side effects,such as urinary retention,nausea/vomiting,pruritus and hypotension. It can also be used for patients with coagulation disorders. Kang et al. argued that TPVB can significantly improve postoperative rehabilitation in patients undergoing thoracoscopic radical lung cancer surgery .
Chronic post-thoracotomy pain（CPTP）will not only have a negative impact on patients' physiology and psychology, but also affect postoperative recovery.A number of researches have demonstrated that Injury to the intercostal nerve during surgery predominantly accounts for the onset of CPTP.It is closely related to postoperative local acute inflammation and neuroinflammation. Thoracic paravertebral block (TPVB)has become a new trend for post-thoracotomy pain management.Glucocorticoids,as a adjuvant, are reported to prolong the effects of local anesthetic for peripheral nerve blocks.Diprospan is a long-acting glucocorticoid. It has been widely used in clinical treatment of various pain syndromes for powerful analgesic and anti-inflammatory effects. At present, most clinical reports are limited to the acute postoperative period, and there are few studies focusing on the long-term postoperative analgesic effect of diprospan.Therefore, it is reasonable for us to hypothesise diprospan, as a longer-acting glucocorticoid, can provide more lasting analgesic effects,or even reduce the incidence of CPTP