Meningomyelocele: a clinical, urodynamic and neurophysiological evaluation.

A total of 11 children with chronic meningomyeloceles underwent a clinical neurological, urodynamic and neurophysiological evaluation to define further the level and type of lesion present in the lumbosacral spinal area. The neurophysiological evaluation was correlated with detrusor activity. Detrusor hyperreflexia was present in 45 per cent of the patients and functional activity of the somatic sacral reflex arc was demonstrated in 4. Absolute interruption of the somatic sacral reflex arc was found in the remaining patients with detrusor areflexia. All patients had evidence of a lower motor neuron lesion on clinical neurological evaluation, with weak or absent myotatic and musculocutaneous reflexes. Electromyographic evaluation revealed signs of severe partial to complete denervation of the affected muscle groups. However, increased motor unit potentials were observed in 5 patients after coughing and stimulation of the perianal skin. The bulbocavernosus reflex was absent clinically and electrophysiologically in all 6 patients tested. However, this finding did not indicate absolute interruption of the reflex arc, since further temporal and spatial stimuli resulted in an increase in motor unit potentials. Somatosensory cortical evoked potentials were useful in demonstrating an intact afferent input system to the spinal cord and brain area. However, lumbosacral evoked potentials appeared to be the least useful neurophysiological method to demonstrate partial preservation of the input to the spinal cord level. Therefore, detrusor and external urethral sphincter function may be documented on urodynamic and neurophysiological evaluation when the clinical examination has revealed a complete lower motor neuron lesion. The complexity of the lesion caused by the malformation in patients with meningomyelocele is shown.