What are the motor and sensory findings characteristic of cauda equina syndrome?

Updated: Jun 14, 2018
  • Author: Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

In cauda equina syndrome, muscle strength in the lower extremities is diminished. This may be specific to the involved nerve roots as listed below, with the lower lumbar and sacral roots more affected, leading to diminished strength in the glutei muscles, hamstring muscles (ie, semimembranosus, semitendinosus, biceps femoris), and the gastrocnemius and soleus muscles.

Sensation is decreased to pinprick and light touch in a dermatomal pattern corresponding to the affected nerve roots. This includes saddle anesthesia (sometimes including the glans penis or clitoris) and decreased sensation in the lower extremities in the distribution of lumbar and sacral nerves. Vibration sense may also be affected. Sensation of the glans penis or clitoris should be examined.

Muscle stretch reflexes may be absent or diminished in the corresponding nerve roots. Babinski reflex is diminished or absent.

Bulbocavernosus reflexes may be absent or diminished. This should always be tested.

Anal sphincter tone is patulous and should always be tested since it can define the completeness of the injury (with bulbocavernosus reflex); it is also useful in monitoring recovery from the injury.

Urinary incontinence could also occur secondary to loss of urinary sphincter tone; this may also present initially as urinary retention secondary to a flaccid bladder.

Muscle tone in the lower extremities is decreased, which is consistent with an LMN lesion.


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