Differential Diagnosis

The patient's presentation of back pain, hyporeflexia in the lower extremities, negative Babinski sign, decreased rectal tone, and postvoid residual bladder volume of 150 mL after a fall suggests a spinal injury. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Cauda equina syndrome: This condition is characterized by low back pain, sciatica, sensory disturbances, and bowel/bladder dysfunction, which aligns with the patient's symptoms, including decreased rectal tone and significant postvoid residual bladder volume. The absence of upper motor neuron signs (negative Babinski sign) also supports this diagnosis, as cauda equina syndrome typically involves lower motor neurons.

• Other Likely diagnoses

  • Conus medullaris syndrome: This is a possibility due to the patient's symptoms of decreased rectal tone and bladder dysfunction, which can occur in conus medullaris syndrome. However, this condition typically presents with a distinct sensory level and more pronounced motor deficits, which are not clearly described in the scenario.
  • Anterior cord syndrome: While this condition could explain some of the patient's motor and sensory findings, it typically results from a direct injury to the anterior spinal cord, leading to loss of motor function below the level of injury and loss of pain and temperature sensation, with preservation of posterior column functions (vibration, position sense). The patient's presentation does not perfectly align with these characteristics.

• Do Not Miss diagnoses

  • Spinal epidural hematoma or abscess: Although not directly suggested by the patient's symptoms, these conditions can present with back pain and neurological deficits. They are medical emergencies requiring prompt diagnosis and treatment to prevent permanent neurological damage.
  • Annulus fibrosus rupture with spinal cord compression: While less likely given the patient's specific neurological findings, any condition causing spinal cord compression can lead to serious neurological deficits and requires urgent evaluation.

• Rare diagnoses

  • Spinal cord infarction: This is a rare condition that could present with acute onset of neurological deficits but is less likely in the context of a recent trauma.
  • Infectious or inflammatory myelopathies: Conditions such as transverse myelitis could present with similar neurological deficits but are less likely given the history of trauma and the specific pattern of deficits described.