In my twenty six months in residency I’ve been called perhaps a couple dozen times by staff in the emergency room for suspected cauda equina. The usual cabal of symptoms are:
- Back pain
- Possible bilateral lower extremity radiating pain
- Possible subjective weakness
- Bowel and/or bladder incontinence
It is the last one that usually gets those physicians and physician extenders who are triaging the patients in the emergency astiring.
The cauda equina are the nerves that continue, after the end of the spinal cord, down to the legs and the sacrum. They provide for movement of the legs, urination, defecation, feeling to the legs and the perineal and “saddle” regions. Compression of these nerves, the majority of the time by a centrally herniated disc, is a neurosurgical emergency and known as cauda equina syndrome. Symptoms of cauda equina syndrome include: numbness or tingling to the inner thighs and perineum thought of as the “saddle” region, weakness especially a foot drop, inability to urinate or deficate, the opposite to include bowel or bladder incontinence, back pain.
Now, I’m sure I don’t get consulted with the vast majority of individuals who come into the emergency room with back pain. Even those individuals who have pain radiating from their back into their legs. But as soon as someone complains that they’re involuntarily urinating that seems to almost guarantee me a call.
Often times it seems that those triaging these patients seem to believe that involuntary urination or defecation has some high sensitivity for identifying patients suffering from cauda equina syndrome when combined with other symptoms as described above.
It turns out however that very few of these individuals have true neurogenic bowel or bladders.
In the perhaps two dozen of these patients I’ve seen I think two or three of them have had true cuada equina.
The question is then, if there is not something organic making these individuals urinate or defecate involuntarily then what is going on with the majority of patients I see who complain of such?
As one paper describes it, I truly believe there is an association between low back pain and urinary incontinence,
A rare association between severe low back pain and urgency incontinence of urine, not explained on the basis of any conventional neurologic or genito-urinary pathology, should be recognized.
For an unexplained reason there is a described association between pain and involuntary urination and defecation. And indeed, in my limited experience the vast majority of patients with both back pain and either bowel or bladder incontinence do not have neurogenic bowels or bladders or cauda equina syndrome.
Indeed, amongst these cabal of symptoms, urinary retention is likely much more sensitive a symptom for cauda equina pathology. With all the back pain that must be seen i the emergency room it’s probably an important point for staff to realize.