Bulbocavernosus reflex is one way of knowing whether an individual suffers from spinal shock. It is a polysynaptic reflex which is helpful for spinal shock patients and in knowing the state of the spinal cord injuries. The test procedures include monitoring anus contraction by pressing the glans penis or pulling of an attached Foley catheter. Reflex is actually spinal mediated and usually involves the S1 to S4. If there is no sacral spinal cord trauma and absence of reflex is observed then this usually indicates spinal shock. Generally this is one of the reflexes that come back after a spinal shock.
If reflex has returned but still there is lack of sensory and motor function then this only shows complete Spinal Cord Injury. In this instance it is unlikely that the vital neurologic function will ever return (Wheeless’ Textbook of Orthopaedics). If spinal shock is not involved yet there is absence of this reflex then it could indicate an injury of the sacral nerve roots. Other name for Bulbocavernosus reflex is Bulbospongiosus reflex. This can also be tested electrophysiologically through rousing the vulva or penis and recording from anal contraction. This test is usually performed to confirm if there is motor or sensory function of the sacral roots and in the conus medullaris.
Spinal shock generally last forty-eight hours and the termination of spinal shock signals the come back of bulbocavernosus reflex. But it should be remembered that spinal shock is not observed in injuries that happens below the cord. Since this does not cause a spinal shock thus the absence of bulbocavernosus reflex indicates the presence of cauda equina injury or Conus medullaris injury. Several studies have been conducted in this area and you can check one in specific study entitled “Neurourologic findings in Conus Medullaris and Cauda Equina Injury” (Arch Neurol 1983).