Effects of epidural administration of a mixture of betamethasone and lidocaine on nerve root inflammation and epidural space adhesion in rabbits

Objective To investigate the effects of epidural administration of a mixture of betamethasone and lidocaine on nerve root inflammation and epidural space adhesion in rabbits. Methods Twenty-four adult male New Zealand white rabbits weighing 2.0-2.1 kg, were randomly divided into 2 groups ( n = 12 each): control group and treatment group. A catheter was inserted into epidural space at L2,3 interspace. Twenty-four hour after epidural catheter placement, talcum powder 0.5 mg/kg was injected into epidural space to make the model of nerve root inflammation and epidural space adhesion. Three days later a mixture of lidocaine 2.5 mg/kg and betamethasone 0.25 mg/kg was injected via the epidural catheter in treatment group, while the equal volume of normal saline was given in control group. At 21 days after administration of lidocaine and betamethasone, the spinal cord was removed, and dura mater and nerve root were checked with naked eye, light microscope and electron microscope.The neutrophil count in the dura mater was determined. Results There was nerve root inflammation and epidural space adhesion in control group. The nerve root inflammation and epidural space adhesion was not observed in treatment group. The neutrophil count was reduced in treatment group (21 ± 12) compared with control group (250 ±43) ( P < 0.01) . Conclusion Epidural administration of a mixture of betamethasone and lidocaine can alleviate nerve root inflammation and epidural space adhesion. Key words: Betamethasone;  Lidocaine;  Injections, epidural;  Radiculopathy;  Epidural space; Adhesions