cauda equina vs conus medullaris

1. What is conus medullaris (CM) syndrome?
2. What is cauda equina (CE) syndrome?
3. How do CE and CM differ in the level of vertebral injury?
4. What are common causes of CE vs. CM?
5. What are the effects on the lower extremities of CE vs CM?
6. What are the sensory findings in CE vs. CM?

Answers:
1. Conus medullaris is an injury to the sacral cord and lumbar nerve roots within the spinal canal, usually resulting in an areflexic bowel and bladder and lower limbs.
2. Cauda equina syndrome is injury to the lumbosacral nerve roots within the neural canal, resulting in an areflexic b/b, lower limbs, and absent bulbocavernous reflex.
3. CM occurs with an L1-L2 injury and affects the sacral cord (S1-S5). CE occurs with a L2-sacral injury and affects to the LS nerve roots.
4. Common causes of CM include L1 fracture, tumors, gliomas, vascular injury, and spina bifida with cord tethering. Common causes of CE include L2 or below fx, fractures of pelvic ring, spondylosis.
5. In CM, there is normal motor function of the LEs and they may be areflexic. CE causes flaccid paralysis of the LEs and areflexia. CE is more asymmetric than CM.
6. CM has a saddle distribution sensory loss and no pain. CE has sensory loss in nerve root distribution and pain is present.