During the past two decades, improvements in technology and changes in conceptualization have contributed to greater objectivity in the assessment of micturition reflex disturbances.1,2 These changes have been applied principally to analysis of adult dysfunction and have recently been implemented in evaluation of neuromuscular dysfunction of the urinary bladder in infancy and childhood.
These newer methods include gas cystometry,3 integrated sphincter electromyography (EMG),4 measurement of reflex-evoked potentials in micturition reflex pathways,5 and electroencephalography (EEG).6 Complementary urodynamic methods include uroflowmetry,7 measurement of urethral pressure profiles,8,9 and observation of pressure-flow relationships during voiding.10
These studies, when appropriately selected and individualized to the patient as a result of the history and examination, provide valuable information. They delineate the site and nature of the impairment of the nervous mechanisms used in the neural and muscular infrastructure in micturition during infancy and childhood. Finally, they provide a rational basis for selection of pharmacologic agents11 and surgical techniques12 to restore urinary continence.
Gas cystometry technique
Gas cystometry has replaced water cystometry in the evaluation of patients for detrusor reflex instability. The patients are catheterized, and the bladder is inflated with carbon dioxide at room temperature at a constant flow rate of up to a maximum of 200 ml/min. Intravesical pressure is recorded by an isovolumetric strain gauge and transducer amplifier calibrated in centimeters of water.4 Because of the high perfusion rate and brief test interval, additional testing for reflex instability is facilitated. These additional procedures include (1) change in posture from supine to upright, (2) determination of response to subcutaneous injection of bethanechol, and (3) sleep cystometry.
Segmental reflex pathways in spinal shock and spinal spasticity in man
