ObjectiveTo investigate the effects of paravertebral injection of doxorubicin on pain behavior and ultrastructure of dorsal root ganglion ( DRG ) neurons in rats with neuropathic pain.MethodsOne hundred male SD rats,aged 3 months,weighing 200-250 g,were studied.The spared nerve injury (SNI) model was established by ligation and separation of tibial and common fibular nerves.The rats were randomly divided into 5 groups ( n =20 each):SNI group and different concentrations of doxorubicin groups (groups A1,A2,A3,A4 ).The animals were anesthetized with intrapetitaneal 10％ chioral hydrate 0.3 ml/100 g.The L4,6 intervertebral foramina was exposed.Normal saline and 0.25％,0.50％,0.75％ and 1.00％ doxorubicin 5 μl were injected into the intervertebral foramina in groups SNI,A1,A2,A3,and A4 respectively.The paw withdrawal latency to the radiant heat stimulation (PWL) and paw withdrawal duration to acetone (PWD) were measured before administration and on day 1-28 after administration.Three rats were chosen in each group on day 28 after administration and DRG were removed to observe the ultrastructure of large and small neurons with electron microscope.ResultsCompared with group SNI,PWL was significantly prolonged and PWD was significantly shortened in groups A1,A2,A3,A4 in a concentration manner ( P ＜ 0.05).Nucleus condensation,mitochondrial swelling,increased lysosomes,chromatin condensation,fibrosis of intercellular substances,and cell necrosis were observed in small neurons.Mitochondrial swelling and increased fibers wcre observed in large neurons and most of large neurons survived.ConclusionParavertebral injection of doxorubicin can reduce neuropathic pain and result in damage to large and small DRG neurons,and small neurons in the DRG are more susceptible and vulnerable to doxorubicin than large neurons in rats.

Objective To observe the clinic effects and safety of thoracic dorsal root ganglion(DRG) pulsed radiofrequency in treating post-thoracotomy pain syndrome(PTPS). Methods 47 PTPS patients were treated with thoracic DRG pulsed radiofrequency. VAS, Oxycodone dosage, medicine side effects before and after operation were recorded. Results The VAS before operation and 1 d, 15 d, 1 m, 3 m, 6 m, 12 m after operation were 6. 3 ±2. 4, 4. 1 ±1. 8, 3. 2 ±1. 3, 2. 5 ±1. 5, 2. 1 ±0. 9, 2. 0 ±0. 8 and 2. 2 ±1. 1 respectively. The oxycodone dosage were (28. 5 ±10. 2)mg, (12. 3 ±5. 7)mg, (8. 3 ±3. 8)mg, (7. 6 ± 3. 1) mg, (7. 0 ± 3. 4) mg, (6. 6 ± 2. 7) mg and (7. 2 ± 3. 2) mg respectively. The difference was significant compared with the preoperative (P＜0. 05). No serious complications occurred. Conclusion Thoracic DRG pulsed radiofrequency was a safe and effective method in treating PTPS.