Which condition is characterized by a "saddle” anesthetic distribution?

The condition characterized by a "saddle" anesthetic distribution is cauda equina syndrome. In this syndrome, the cauda equina—a bundle of spinal nerve roots located at the lower end of the spinal cord—is compressed, leading to neurological deficits in the lower extremities and the perineal region. This results in a distinctive sensory loss in the "saddle" area, which includes the buttocks, inner thighs, and genital region.

Saddle anesthesia can also involve loss of reflexes and motor function in the pelvic region, contributing to other symptoms such as bowel or bladder dysfunction. The compression causing these symptoms can arise from various causes, such as a herniated disc, tumors, or trauma, but the key feature of saddle anesthesia specifically points to cauda equina syndrome as the condition where this symptom is most classically observed.