Colonic myoelectric activity in persons with spinal cord injury

Colonic myoelectric activity was recorded from six para- or quadriplegic subjects with spinal cord injury and seven normal controls via bipolar electrodes in contact with the rectal mucosa. Recordings were carried out in the fasting (basal) state and after stimulation by a standard meal and by 1.0 mg neostigmine intramuscularly. The recordings were visually analyzed for spike activity, average slow wave frequency, and percentage occurrence of subsets of slow wave frequency (2-4 and 5-12 cycles/min). The spinal-cord-injured subjects had significantly more spike wave activity in the basal state than did the controls (12.6 spikes per 10 min vs 3.3). However, meal stimulation did not lead to an increase in spike activity in the spinal-cord-injured subjects (13.7 spikes per 10 min vs 12.6) while it did in the controls (6.4 vs 3.3 spikes per 10 min). Neostigmine significantly increased spike activity in both groups. There was no difference in average slow wave frequency nor any slow wave subsets between the two groups studied. Thus persons with spinal cord injuries have higher basal colonic myoelectric activity than normals but lack a demonstrable gastrocolic reflex. We conclude that the central nervous system exerts a tonic inhibitory influence on basal colonic motility and appears to participate in the gastrocolic reflex.