Ultrasound imaging of sacral reflexes

To investigate the reliability of examination of the guarding reflex of the pelvic floor by dynamic perineal ultrasonography in children with bladder dysfunction and in controls.

A total of 40 patients with nonneurogenic bladder/sphincter dyssynergia, 40 with spina bifida, and 40 controls underwent a dynamic ultrasound examination of the pelvic floor while coughing and while being tapped on the abdominal wall. The reflex action of the puborectal muscle in females, and the combined action of the puborectal muscle and external sphincter muscle in males, were recorded.

Of the 40 patients with nonneurogenic bladder/sphincter dyssynergia, 38 had a normal reflex action of the puborectal muscle during the abdominal tap and 36 had a normal reflex action when coughing. Two of these patients had unexplained underactive bladder syndrome and were using clean intermittent catheterization, and two could not be assessed because of hypermobility of the bladder neck when coughing but had a normal reaction during abdominal tapping. Of the 40 patients with spina bifida, none had puborectal activity during coughing and 5 had some puborectal activity during tapping. Of the 40 controls, 39 had normal reflex activity during both coughing and tapping.

The question of whether a child has nonneurogenic or neuropathic bladder/sphincter dysfunction is often difficult to answer on the basis of urodynamic studies alone. Dynamic perineal ultrasound recording of the S2-S4 reflex arches provides reliable additional information and is noninvasive to the patient.