Friday, December 11, 2020

Conus medullaris syndrome vs. Cauda equina syndrome

Both of these are orthopedic/neurosurgical emergencies! But in general, CM syndrome is more severe than CE syndrome.

Here's a comparison between the two...

Pro tip: Think of CM syndrome as a clean cut through the conus medullaris (although it's not).


Conus medullaris syndrome

Cauda equina syndrome



    unilateral or bilateral


    symmetrical UMN weakness

    asymmetrical LMN most often


    symmetrical numbness

        'perianal anesthesia' common

    asymmetrical most often (patchy sensory loss)

    ‘saddle anesthesia’ common


    at the level:          HYPOreflexia

    below the level:   HYPERreflexia





Sphincter dysfunction


    Both, urinary and fecal incontinence


    urinary retention only

Radicular pain



Back pain

    more severe


*Cauda equina includes L2 to Coccygeal-1 pair of spinal nerves.

*The nucleus of Onuf (or Onufrowicz) is a small group of neurons in the ventral horn of the S2 (and S3 too according to some authors) segment of the spinal cord. These are motor neurons that supply the external urethral & anal sphincters; also the levator ani and perineal (bulbospongiosus & ischiocavernosus [erector clitoridis in females]) muscles.

PS: I have skipped the anatomical details from the diagram like the dorsal & ventral roots of the spinal nerves, etc. for the purpose of simplicity :)

[- Dr. Suneet Patel

Happy studying, peeps! :)]


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