A 39-year-old woman presents with increasing numbness down both legs and new onset numbness around her groin and buttocks that began that morning. She also experienced urinary incontinence. She reports a 1-month history of lower back pain with bilateral lower extremity radiculopathy. Last week she had a magnetic resonance imaging (MRI), which showed a large L5-S1 disc herniation that occupies the spinal canal (Figure 1). On physical examination, the patient has 4 out of 5 weakness in all muscle groups of both legs and hyporeflexia of the lower extremities. She has diminished 2-point discrimination in the groin and buttocks and decreased rectal tone.
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The cauda equina consists of peripheral nerve roots (L1-S5) that continue from the spinal cord (picture a horse tail leaving the spinal cord) and is surrounded by a dural sac within the lumbar spinal canal. Lumbar disc herniations that compress peripheral roots can cause a number of symptoms such as lower back pain, leg pain, and numbness and weakness in the lower extremities.1 A large disc herniation that occupies the central canal can compress the cauda equina causing severe motor and sensory impairment, or cauda equina syndrome (CES).
Symptoms of CES may vary and include lower extremity pain and weakness, saddle anesthesia, and loss of bowel or bladder function. Loss of bladder function is a required element of CES and can vary from difficulty initiating a urinary stream to full incontinence. If symptoms of CES exist, an urgent MRI must be performed to confirm the diagnosis and prepare for surgery.1,2
Neurologic deficits can progress rapidly and become permanent with CES unless the disc herniation is removed and pressure is taken off the nerve roots. Emergent surgical decompression should be performed within 24 to 48 hours of symptom onset to improve neurological recovery.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Spector LR, Madigan L, Rhyne A, Darden B 2nd, Kim D. Cauda equina syndrome. J Am Acad Orthop Surg. 2008;16(8):471-479. doi:10.5435/00124635-200808000-00006
2. Gitelman A, Hishmeh S, Morelli BN, et al. Cauda equina syndrome: a comprehensive review. Am J Orthop (Belle Mead NJ). 2008;37(11):556-562.