Staggered rhizotomy of anterior and posterior sacral roots for bladder reservoir function in spinal cord injury: a canine experimental study and preliminary clinical report

Abstract

Objective: To report an experimental study and preliminary clinical results of staggered anterior and posterior sacral rhizotomy for restoring function of the bladder and preventing reflex incontinence in supra-conal spinal cord injury (SCI).

Methods: Ten T10 spinal cord transected mongrel dogs were divided into three groups. In group 1 (n= 2), laminectomy only was performed (control). In group 2 (n= 4), all L7-S3 posterior roots were microsurgically cut (complete deafferentation). And in group 3 (n= 4), the L7, S1, S3 posterior roots and S2 anterior root were cut (staggered deafferentation and deefferentation). Intraoperative electrical stimulation and postoperative cystometrography (CMG) were carried out. In the clinic, three patients with spastic bladder caused by a supra conal complete SCI underwent staggered rhizotomy and were followed up for 6 years.

Results: In the canine experimental study, resection of the S2 anterior root combined with L7, S1 and S3 posterior rhizotomy, stimulating the S2 posterior root (four dogs) resulted in a minimal rise in pressure in the bladder and urethra, which was only about 10% of that obtained by stimulating the S2 proximal posterior root while its anterior counterpart was intact (eight dogs, Student's t-test, P < 0.01). The CMG study showed that groups 2 and 3 had similar volume/pressure curves; in both groups the tendency was to develop flaccid bladders. In the clinic, three cases underwent staggered rhizotomy of the anterior and posterior roots in S3 and S4. Good bladder reservoir and compliance was achieved over six years of follow-up.

Conclusion: Staggered rhizotomy of the anterior and posterior sacral roots at different spinal cord levels has the same denervation effect as a complete posterior rhizotomy, and good bladder reservoir function can be achieved by this procedure.

Figure 1

Identification of the anterior and posterior roots of S2.
Ant, anterior; post, posterior.

Figure 2

Site of intraoperative electrical stimulation. (A) at the extradural common nerve; (B) at the intradural posterior root with the anterior root intact; (C) at the posterior root with the anterior root cut.

Figure 3

Bladder and urethral pressure changes with S2 root stimulation at different sites after L7, S1 and S3 posterior roots had been resected (A, B, and C correspond to A, B and C of Fig. 2).

Figure 4

Postoperative CMG tests at the sixth week.