A patient with a sacral-level SCI (S2-S4 complete lesion) has an external anal sphincter that is flaccid with continuous, uncontrolled stool leakage. Which type of neurogenic bowel does this patient have?

A patient with a sacral-level SCI (S2-S4 complete lesion) has an external anal sphincter that is flaccid with continuous, uncontrolled stool leakage. Which type of neurogenic bowel does this patient have?

• A. Reflexive (upper motor neuron) bowel
• B. Areflexive (lower motor neuron) bowel
• C. Normal bowel function
• D. Spastic bowel with hyperreflexia

Answer: (B)

When the injury is at the sacral level and complete, the sacral reflexes that control evacuation and the external anal sphincter are lost. This leads to an areflexive (lower motor neuron) bowel, where the anal sphincter is flaccid and there is continuous stool leakage because the reflexive defecation process and sphincter tone are absent. In contrast, a reflexive (upper motor neuron) bowel comes from injuries above the sacral segments and preserves the sacral reflexes, resulting in a spastic/hypertone anal sphincter and typically different defecation patterns like constipation with possible intermittent leakage. A normal bowel function scenario wouldn’t occur with a complete sacral injury.

When the injury is at the sacral level and complete, the sacral reflexes that control evacuation and the external anal sphincter are lost. This leads to an areflexive (lower motor neuron) bowel, where the anal sphincter is flaccid and there is continuous stool leakage because the reflexive defecation process and sphincter tone are absent. In contrast, a reflexive (upper motor neuron) bowel comes from injuries above the sacral segments and preserves the sacral reflexes, resulting in a spastic/hypertone anal sphincter and typically different defecation patterns like constipation with possible intermittent leakage. A normal bowel function scenario wouldn’t occur with a complete sacral injury.