Intraoperative urodynamics in spinal cord surgery: a study of feasibility

Abstract

Intraoperative monitoring (IOM) of bladder function in spinal cord surgery is a challenging task due to vegetative influences, multilevel innervation and numerous supraspinal modulating factors. Despite routine use of urodynamics in neurosurgery for implantation of bladder stimulators or denervation of nerve fibres in spastic reflex bladders, application of IOM in patients with spinal cord tumours or tethered-cord syndrome is not widespread. Combining urodynamics with sphincter electromyography (EMG) in IOM enables identification of bladder efferents responsible for contraction and continence. We monitored four patients with ependymoma of the Cauda equina, one patient with tethered-cord syndrome and two patients with cervical intramedullary tumours. In all patients undergoing operations of the Cauda equina, identification of bladder efferents responsible for detrusor contraction was possible. There was good correlation between preoperative bladder dysfunction, preoperative urodynamics and intraoperative pressure increase by bladder contraction or latency between stimulation and contraction. This method proved unsuitable for intramedullary tumours where no contraction of the bladder could be observed while stimulating the spinal cord. Intraoperative monitoring of urodynamics is an effective tool for identifying bladder efferents in the Cauda equina. Intraoperative conclusions on bladder dysfunction through registration of pressure increase and latency are possible.

Fig. 1

Patient 4. Ependymoma Cauda equina L5/S1, bladder function impaired, residual urine

Fig. 2

Patient 1. Ependymoma Cauda equina L3, bladder function impaired, residual urine. Stimulation intensity 5 mAmp, pdet 35 cm H₂O, Latency 10 s

Fig. 3

Patient 2. Ependymoma Cauda equina L5, bladder function not impaired. Stimulation intensity 3.1 mAmp, pdet 68 cm H₂O