Effects of lidocaine on blood flow and endoneurial fluid pressure in a ratmodel of herniated nucleus pulposus

Citation
A. Onda et al., Effects of lidocaine on blood flow and endoneurial fluid pressure in a ratmodel of herniated nucleus pulposus, SPINE, 26(20), 2001, pp. 2186-2191
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurology
Journal title
SPINE
ISSN journal
0362-2436 → ACNP
Volume
26
Issue
20
Year of publication
2001
Pages
2186 - 2191
Database
ISI
SICI code
0362-2436(20011015)26:20<2186:EOLOBF>2.0.ZU;2-5
Abstract
Study Design. An experimental study was conducted to evaluate the effects o f lidocaine on nucleus pulposus-induced pathophysiologic changes. Objectives. To investigate the effects of lidocaine on blood flow in the hi nd paws and endoneurial fluid pressure in the dorsal root ganglia in a rat model of herniated nucleus pulposus, and to clarify the therapeutic mechani sms of nerve root infiltration. Summary of Background Data. It has been shown experimentally that applicati on of nucleus pulposus to the nerve roots increases endoneurial fluid press ure and decreases blood flow in the dorsal root ganglia and the correspondi ng hind paw. These changes are thought to be an important pathogenic mechan ism associated with sciatica caused by disc herniation. Nerve root infiltra tion is one of the nonoperative effective therapies for radiculopathy. caus ed by disc herniation. However, the therapeutic mechanisms still are unknow n. Methods. For this study, 21 Sprague-Dawley rats were used. Autologous nucle us pulposus was applied to the nerve root with a piece of Spongel containin g lidocaine (lido group) or physiologic saline solution (control group). In Series 1 of this study (Blood Flow in the Hind Paw), blood flow in the cor responding hind paws was monitored continuously using a laser Doppler flowm eter before application of the test solutions, and every 5 minutes thereaft er for an additional 3 hours in both the control (n = 5) and lido (n = 5) g roups. In Series 2 of this study (Endoneurial Fluid Pressure in the Dorsal Root Ganglion), endoneurial fluid pressure was recorded with a servo-null m icropipette system using glass micropipettes before and 3 hours after appli cation of the test solutions in both the control (n = 6) and lido (n = 5) g roups. After measurements, dorsal root ganglia were assessed for histology. Results. In Series 1, blood flow in the corresponding hind paw in the contr ol group showed significant reduction as compared with that of the Lido gro up, starting about 90 minutes after application (P < 0.01-0.05). Hind paw b lood flow in the lido group did not show any reduction during measurements. In Series 2, the value of andoneurial fluid pressure in the lido group 3 h ours after application was significantly lower than in the control group (P < 0.01). Interstitial (endoneurial) edema in the dorsal root ganglion in t he lido group appeared to be qualitatively less than in the control group. Conclusions. The data indicate that lidocaine reduces the pathophysiologic changes in the dorsal root ganglion and hind paws induced by nucleus pulpos us. These effects of lidocaine may relate to the mechanisms underlying the therapeutic effects of nerve root infiltration.