Detection of the effects of collagenase on spinal nerve conduction velocity of rats by using evoked potential

Heping LI; Wenquan ZHUANG; Jianyong YANG; Wei CHEN

ABSTRACT

BACKGROUND:

By now, safety of collagenase application is still controvertible and some scholars believed that collagenase might induce the peripheral tissue injury. It attracts much attention in clinic that whether there is nerve injury induced by collagenase chemonucleolysis (CCN) around the injection sites.

OBJECTIVE:

To observe the effects of collagenase on spinal nerve conduction velocity (NCV) of rats detected with evoked potential method so as to probe into the safetyof collagenase application and further demonstrate the safety of percutaneous intervertebral disc CCN.

DESIGN:

Randomly grouping design, animal experiment.

SETTING:

Department of Interventional Radiology, Affiliated First Hospital of Sun Yat-sen University. MATERIALS The experiment was conducted in the Basic Medical College of Sun Yat-son University from July to September 2002. A total of 57 male SD rats were randomly divided into normal group (n=9), acute sham-operation group (n=10), subacute sham-operation group (n=8), chronic sham-operation group (n=7), acute experimental model group (n=9), subacute experimental model group (n=7) and chronic experimental model group (n=7).

METHODS:

After being anaesthetized by intraperitoneal injection of continal (45 mg/kg) to separate and identify dorsal root ganglion (DRG),rats in the experimental group were locally dripped with 1 mL of collagenase (300 U/ML) and those in the sham operation group locally dripped with 1 mL of normal saline. Stimulating electrode was placed in the A point of sciatic nerve and recording electrode in the B point of ganglionic central process segment of DRG in L5 nerve root. Evoked potentials A and B were simulated to continuously record latency twice, and the average value was calculated; Distance between A and B were measured and recorded. NCV = distance between A and B / latency. Evoked potential of a segment ofnerve including DRG was measured in the acute group at one hour after administration, in the sub acute group at one week after administration and in the chronic group at one month after administration. MAIN OUTCOME

MEASURES:

NCV of each group.

RESULTS:

A total of 57 enrolled animals were involved in the analysis. NCV in normal group, acute experimental group, acute sham-operation group, subacute experimental group, subacute sham-operation group, chronic experimental group, chronic sham-operation group were (45.4±10.7), (43.4±5.9), (46.3±6.5), (52.4±10.4), (49.7±8.1), (46.7±11.0) and (44.6±6.5) m/s respectively. There were no remarkable differences in NCV among all the groups by using one-way analysis of variance (F=1.010,P=0.430); It was showed that there were no marked differences in NCV between each two groups by using multiple comparisons (P=0.336).

CONCLUSION:

Collagenase at the therapeutic concentration applied in clinical CCN has no remarkable effects on NCV of rat spinal nerve, and to a certain extent, percutaneous intervertebral disc CCN is relatively reliable.