Caudal Equine Syndrome (CES) in low back pain patients

by / Thursday, 12 November 2015 /

Caudal Equine Syndrome (CES) in low back pain patients is a rare diagnosis that represents a true neurosurgical emergency. A regrettable failure to diagnose and surgically treat CES leads to permanent bowel and bladder dysfunction, sexual impairment, weakness in the bilateral lower extremities, and permanent disability.  In countries with government-managed health care it is not uncommon that CES represents the only diagnosis that warrants an urgent MRI of the Lumbar Spine to rule out a massive lumbar disc herniation or other potential cause.

Despite the classic constellation of CES symptoms of lower back pain, bilateral leg symptoms, and bowel and bladder dysfunction that is taught to every emergency room physician, neurosurgeon, and orthopedic spinal surgeon in this country this diagnosis is too often missed initially at a time when neurological deficits can be prevented or reversed by emergent surgery.  Because CES is rare, physicians often miss the diagnosis because of misconceptions related to its symptoms and signs and will explain away the red flag warning symptoms and signs of CES to a less serious plausible diagnosis.

The most common misconception in the medical community is that ‘bowel and bladder dysfunction’ in CES represents incontinence where the patient is having ‘accidents’ of either stool or urine.  This is not the case in acute CES since it actually leads to acute urinary retention.  Symptoms of urinary retention are red flag warnings present in over 85% of patients with CES.  Patients with acute CES can actually push out a small portion of their retained urine in a full bladder by bearing down, appearing to be continent to an unknowing physician.  The initial complaints in these patients are consistent with difficulty starting a urinary stream or emptying completely.  Objective evidence of urinary retention is obtained by testing for it by either placing a catheter or using a bladder scanner in a patient after an attempted void. Finding over 500 milliliters of retained urine in the bladder is a red flag sign of CES.

The next most common misconception regarding the diagnosis of CES is that there must be certain findings on physical exam that would raise the clinical concern to a level that would require a mandatory emergent MRI.  Studies indicate that there is nothing on physical exam that will rule in or rule out the diagnosis of CES caused by a massive lumbar herniated disc or another cause that requires emergency surgery. None of the following physical exam findings predict more than 50% of those with CES: loss of motor strength at the ankles, decrease reflexes, loss of sensation around the anus, and a positive straight leg raise.  Bilateral leg symptoms occurring with low back pain is a red flag for CES when combined with bladder dysfunction that suggest retention.
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