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Duke Orthopaedics
presents
Wheeless' Textbook of Orthopaedics

Bulbocavernosus Reflex



- Discussion:
    - bulbocaverosus reflex refers to anal sphincter contraction in response to squeezing the glans penis or tugging on the Foley;
         - reflex involves S-1, S-2, and S-3 nerve roots and is spinal cord- mediated reflex arc;
    - following spinal cord trauma, presence or absence of this reflex carries prognostic significance;
         - in cases of cervical or thoracic cord injury, absence of this reflex documents continuation of spinal shock or spinal injury at the level of 
               the reflex arc itself;
               - period of spinal shock usually resolves w/ in 48 hours and return of bulbocavernosus reflex signals termination of spinal shock;
         - note that spinal shock does not apply to lesions that occur below the cord, and therefore, low lumbar burst frx should not cause spinal 
               shock (and in this situation, the absence of the bulbocaveronsus reflex indicates that there is a cauda equina injury);
                - persistent loss of the bulbocavernosus reflex may be a result of a conus medullaris injury (eg from an L1 burst frx);

- Prognositic Significance:
    - complete absence of distal motor or sensory function or perirectal sensation, together with recovery of the bulbocavernosus reflex,
           indicates a complete cord injury, and in such cases it is highly unlikely that significant neurologic function will ever return;
          - therefore, if no motor or sensory recovery below the level of frx is present, pt has a complete spinal cord injury and no further distal 
                recovery of motor function can be expected;
         - on other hand, any spared motor or sensory function below level of injury is considered incomplete spinal cord injury;
         - potential for recovery of incomplete lesion is determined by part of the cord most severely injured



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, April 25, 2012 2:16 pm