Lidocaine injection into the rat dorsal root ganglion causes neuroinflammation. Anesth Analg 2009 Mar;108(3):1021-6
Date
02/20/2009Pubmed ID
19224819Pubmed Central ID
PMC2869284DOI
10.1213/ane.0b013e318193873eScopus ID
2-s2.0-61949163669 (requires institutional sign-in at Scopus site) 27 CitationsAbstract
BACKGROUND: Injury of a spinal nerve or dorsal root ganglion (DRG) during selective spinal nerve blocks is a potentially serious complication that has not been adequately investigated. Our hypothesis was that local anesthetic injection into these structures may result in an inflammatory response and hyperalgesia.
METHODS: We evaluated inflammatory and behavioral responses after injection of 4 microL lidocaine or saline into the L5 spinal nerve or DRG of rats after partial laminectomy. Behavioral testing was performed before and after surgery to examine hyperalgesia in response to nociceptive mechanical stimulation of the foot. DRGs were harvested and stained, and rings of immunoreactive glial cells around neurons were counted.
RESULTS: Animals demonstrated hyperalgesia on the ipsilateral paw up to 4 days after lidocaine injection into the DRG but not after injection into the spinal nerve. The number of glial fibrillary acid protein immunopositive glial cell rings, which represent activation of satellite cells, significantly increased in DRGs after injection of lidocaine into either the DRG or the spinal nerve. The number of glial fibrillary acid protein-positive cells in the lidocaine-injected group was significantly larger than in the saline-injected group. Sporadic OX-42 immunopositive cells, which represent activated microglia, were also seen in lidocaine-injected DRGs. Testing for Pan-T expression, which labels activated T lymphocytes, showed no positive cells.
CONCLUSIONS: Lidocaine injection into the DRG may produce hyperalgesia, possibly due to activation of resident satellite glial cells. In a clinical setting, local anesthetic injection into the DRG should be avoided during selective spinal nerve blocks.
Author List
Puljak L, Kojundzic SL, Hogan QH, Sapunar DAuthor
Quinn H. Hogan MD Professor in the Anesthesiology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Anesthetics, LocalAnimals
CD11b Antigen
Ganglia, Spinal
Glial Fibrillary Acidic Protein
Hyperalgesia
Immunohistochemistry
Injections
Lidocaine
Neuritis
Neuroglia
Pain
Rats
Rats, Sprague-Dawley
Spinal Nerves
