[Establishment of a new model of neurogenic bladder dysfunction caused by lumbar intervertebral diskhernia and its urodynamic evaluation].

OBJECTIVE

To establish a new rat model of neurogenic bladder dysfunction caused by lumbar intervertebral disk hernia, and to confirm the model by urodynamic examination.

METHODS

Twenty male Wistar rats were divided into two groups at random:experimental group (n = 15) and pseudo-operation group (n = 5). The rats underwent laparotomy to disclose the intervertebral disk of L(6)-S(1), and a 1.50 mm x 4.50 mm blunt screw with flat end was inserted into the intervertebral disk of L(6)-S(1) of the rats in the experimental group so as to establish the model of lumbar intervertebral disk hernia. Computed radiography (CR) was performed 3 days after the operation to conform the successful insertion of the screw. Combined behavioral score (CBS) was used 1 d, 3 d, 1 week, 2 weeks, and 4 weeks after the operation. Four weeks after the laparotomy a vesical fistula above the pubis was made in all of the rats, and then urodynamic examination was performed three days after this operation.

RESULTS

CR after operation confirmed that the blunt screw had been inserted into the lumbar disk of L(6). The CBS scores of the 2 groups at different time points all decreased along with time, and basically remained unchanged 1 week after. The CBS scores of the experiment group were significantly higher than those of the pseudo-operation group (all P < 0.05). The spontaneous vesical contraction rate in the filling period of the experimental group was (4.37 +/- 2.13) times/min, significantly higher than that of the pseudo-operation group [(0.06 +/- 0.13) times/min, t = 4.425, P = 0.000], the maximum bladder capacity of the experimental group was (1.20 +/- 0.34) ml, significantly greater than that of the pseudo-operation group [(0.60 +/- 0.14) ml, t = 5.141, P = 0.002], and bladder compliance of the experimental group was (0.024 +/- 0.012) ml/cm H(2)O, significantly lower than that of the pseudo-operation group [(0.096 +/- 0.088) ml/cm H(2)O, t = 2.891, P = 0.011], and the leak point pressure of the experimental group was (75 +/- 27) cm H(2)O, not significantly different from that of the pseudo-operation group [(62 +/- 23) cm H(2)O]. The urodynamic examination on the conscious rats confirmed the successful establishment of the neurogenic bladder dysfunction caused by lumbar intervertebral disk hernia.

CONCLUSION

A new model of neurogenic bladder dysfunction caused by lumbar intervertebral disk hernia has been established by insertion of a blunt screw into the lumbar intervertebral disk of L(6). The model is confirmed by urodynamic examination.