Electrorectogram study of the neuropathic rectum

The rectal electrical activity was studied by electrorectogram (ERG) in 28 patients with spinal cord injury (SCI) (mean age 46.6 years, 18 men and 10 women) and nine healthy volunteers (controls). Nineteen patients had an upper motor neuron lesion (UMNL) and 9 a lower motor neuron lesion (LMNL). The ERG was recorded by a monopolar silver-silver chloride electrode applied to the rectal mucosa by suction. Simultaneous recording of the rectal and rectal neck pressures was performed. At least four recording sessions of 120 min each were done for every subject. No complications were encountered during the test. The ERG in normal subjects showed pacesetter potentials (PP) with a regular rhythm and constant frequency and were reproducible in the individual subject. PP were followed by action potentials (AP) which had an inconsistent frequency and were associated with increased rectal pressure. The ERG in UMNL patients exhibited 'dysrhythmia' with irregular frequency, amplitude and velocity. The AP did not show in any recording. LMNL patients had a 'silent' ERG. In conclusion, two patterns of ERG could be identified in SCI patients: dysrhythmic and silent. The cause of the disordered ERG could be due to derangement of the intrinsic rectal conducting system.