Rectal wall properties in patients with acute and chronic spinal cord lesions

Most patients with spinal cord injuries suffer from constipation or fecal incontinence. This study was designed to observe rectal wall properties and the rectoanal inhibitory reflex in patients with acute and chronic spinal cord injury.

Rectal wall properties were studied by rectal impedance planimetry, a method for simultaneous registration of pressure and rectal cross-sectional area during distention. Twenty-five patients with spinal cord injury (14 with supraconal lesions and 11 with conal/cauda equina lesions) were studied one to four weeks after injury, and 17 were available for follow-up after 6 to 14 months. Results were compared with 15 healthy volunteers.

Rectal tone was significantly higher (P < 0.05) than normal in patients with acute and chronic supraconal lesions but significantly lower (P < 0.05) in patients with acute and chronic conal/cauda equina lesions. The proportion of subjects with single giant rectal contractions was significantly higher than normal (33 percent) after acute supraconal spinal cord injury (77 percent; P = 0.02) but not after acute conal/cauda equina lesions (45 percent; P = 0.69). Phasic giant contractions only occurred in patients with spinal cord injury (once or more in 8 of 25 patients), but they were not correlated with the level of the lesion. Rectal tone and the number of giant rectal contractions did not change significantly from the acute to the chronic phase of spinal cord injury. The amplitude of the rectoanal inhibitory reflex at distention pressures of 5 and 10 cm H2O was significantly lower than normal in patients with acute and chronic conal/cauda equina lesions (acute, -5 and 44 percent vs. 37 and 82 percent (P < 0.05); chronic, 6 percent (P < 0.05) and 66 percent (P = NS)) but not in patients with supraconal spinal cord injury (acute, 32 and 83 percent; chronic, 61 and 85 percent (all P = NS)).

Rectal tone is stimulated by the sacral spinal cord but inhibited by supraspinal centers within the central nervous system. Likewise, rectal contractility is inhibited by supraspinal centers, and the rectoanal inhibitory reflex is stimulated by the sacral spinal cord. Alterations caused by either type of spinal cord lesion are present after one to four weeks and do not change significantly within the first year.