Differential Diagnosis for Severe Back Pain with New Onset Urinary Symptoms

The patient presents with severe back pain that has not responded to initial treatment and new onset urinary symptoms. Considering the history of back surgery and the recent exacerbation of symptoms, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Cauda Equina Syndrome: This condition is characterized by compression of the cauda equina, a bundle of spinal nerves and spinal nerve roots, and is a known complication of back surgery or severe disc herniation. The new onset urinary symptoms, such as a weak urinary stream and inability to voluntarily stop urination, are classic signs of cauda equina syndrome, making this the most likely diagnosis given the patient's presentation.

• Other Likely Diagnoses

  • Spinal Stenosis: Given the patient's history of back surgery and current severe back pain, spinal stenosis could be a contributing factor, especially if the stenosis is causing nerve compression that leads to pain and possibly some urinary symptoms.
  • Disc Herniation: A new or worsening disc herniation could explain the severe back pain and, if the herniation is large enough, could also cause compression of nerves leading to urinary symptoms.
  • Urinary Retention due to Medication Side Effects: Although less likely given the combination of symptoms, certain medications (e.g., anticholinergics, opioids) can cause urinary retention. However, the patient's medication list does not clearly indicate recent changes that would suggest this as a primary cause.

• Do Not Miss Diagnoses

  • Spinal Epidural Abscess: This is a serious condition that can cause back pain, neurological deficits, and, in some cases, urinary symptoms due to spinal cord compression. It is less common but can be life-threatening if not promptly diagnosed and treated.
  • Spinal Hematoma: Bleeding into the spinal canal can compress the spinal cord or nerves, leading to severe back pain and neurological symptoms, including urinary dysfunction. This condition requires immediate medical attention.
  • Malignancy: Although less likely, metastatic disease to the spine can cause back pain and neurological symptoms, including urinary retention or incontinence, due to spinal cord compression.

• Rare Diagnoses

  • Arachnoiditis: Inflammation of the arachnoid membrane surrounding the spinal cord can cause severe back and leg pain, and in some cases, urinary symptoms. This condition is relatively rare and often associated with previous spinal surgery, infection, or contrast dye used in myelograms.
  • Tarlov Cysts: These are rare, fluid-filled sacs that can compress nerve roots, leading to a variety of symptoms including back pain and, less commonly, urinary symptoms.

The workup for this patient in the emergency department should include:

• A thorough neurological examination to assess for any deficits.
• Urgent MRI of the spine to evaluate for cauda equina syndrome, spinal stenosis, disc herniation, spinal epidural abscess, spinal hematoma, or malignancy.
• Urinalysis to rule out urinary tract infection.
• Consideration of immediate consultation with a neurosurgeon or spinal surgeon given the suspicion of cauda equina syndrome or other serious conditions requiring prompt intervention.
• Review of current medications to assess for any potential contributors to urinary retention.