The rectal electrical activity was studied by electrorectogram (ERG) i
n 28 patients with spinal cord injury (SCI) (mean age 46.6 years, 18 m
en and 10 women) and nine healthy volunteers (controls). Nineteen pati
ents had an upper motor neuron lesion (UMNL) and 9 a lower motor neuro
n lesion (LMNL). The ERG was recorded by a monopolar silver-silver chl
oride electrode applied to the rectal mucosa by suction. Simultaneous
recording of the rectal and rectal neck pressures was performed. At le
ast four recording sessions of 120 min each were done for every subjec
t. No complications were encountered during the test. The ERG in norma
l subjects showed pacesetter potentials (PP) with a regular rhythm and
constant frequency and were reproducible in the individual subject. P
P were followed by action potentials (AP) which had an inconsistent fr
equency and were associated with increased rectal pressure. The ERG in
UMNL patients exhibited 'dysrhythmia' with irregular frequency, ampli
tude and velocity. The AP did not show in any recording. LMNL patients
had a 'silent' ERG. In conclusion, two patterns of ERG could be ident
ified in SCI patients: dysrhythmic and silent. The cause of the disord
ered ERG could be due to derangement of the intrinsic rectal conductin
g system.