Conus medullaris syndrome

Conus medullaris syndrome is caused by an injury or insult to the conus medullaris and lumbar nerve roots. It is a clinical subset of spinal cord injury syndromes. Injuries at the level of T12 to L2 vertebrae are most likely to result in conus medullaris syndrome.

Patients present with a combination of severe back pain and upper and lower motor neurone deficits, similar to cauda equina syndrome, which include 1-3:

  • saddle anaesthesia
  • loss of bladder reflex: urinary retention
  • loss of bowel reflex: incontinence 
  • lower limb motor weakness, paraesthesia and numbness (mixed upper and lower motor neurone pattern)

Unlike cauda equina syndrome which will only have lower motor neurone deficits, conus medullaris will have a combination of upper and lower motor neurone involvement 3

The conus medullaris lies in close proximity to nerve roots and injury to this region results in combined upper motor neurone and lower motor neurone features

Conus medullaris injury can result most commonly from:

Depending on the suspected aetiology in addition to MRI that is almost invariably indicated,  CT and catheter angiography may also be required. The features will vary according to the causative pathology and are therefore discussed separately. 

The prognosis depends on upon the timing of patient presentation, the severity of deficits and underlying pathology. Early diagnosis and treatment may facilitate improvement in symptoms. Approximately 10% of patients may regain functional recovery.

Share article

Article information

rID: 31247
Section: Syndromes
Tag: pm, spine
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Case 1: spinal cavernoma
    Drag here to reorder.
  • Drag
    Case 2: metastasis
    Drag here to reorder.
  • Drag
    Case 3: myxopapillary ependymoma
    Drag here to reorder.
  • Drag
    Case 4: spondylodiscitis
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.