[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.