American Board of Internal Medicine (ABIM) Certification Practice Exam

Cauda equina syndrome is characterized by which of the following features?

1. Severe chronic pain without neurological signs

2. Urinary retention and saddle anesthesia

3. Only lower extremity weakness

4. Gradual onset of symptoms over months

The correct answer is: Urinary retention and saddle anesthesia

Cauda equina syndrome is a serious condition resulting from the compression of the cauda equina, a bundle of spinal nerves located at the lower end of the spinal cord. One of the hallmark features of this syndrome is the presence of urinary retention and saddle anesthesia, which refers to loss of sensation in the inner thigh, buttocks, and perineal area that correlates with the distribution of the nerves affected. In cauda equina syndrome, the nerves that control bladder function can become compromised, leading to urinary retention as the bladder cannot fully empty. Saddle anesthesia occurs when the sensory nerves become damaged, impacting the areas that would come into contact with a saddle, hence the term. These symptoms often suggest that there is a significant neurological compromise that requires immediate medical intervention; thus, the urgency of recognizing urinary retention and saddle anesthesia is critical for effective management and prevention of irreversible deficits. Other options do not properly characterize cauda equina syndrome. Severe chronic pain without neurological signs does not adequately encompass the neurological deficits seen in this condition. Lower extremity weakness can indeed occur, but it is not the only symptom, as it usually accompanies other signs. Gradual onset of symptoms over months is also incorrect since cauda equina syndrome typically presents acutely,