In a patient with acute cervical spinal cord injury being assessed for severity, the return of which reflex signals the end of spinal shock and permits accurate classification using the ASIA Impairment Scale?

• A Biceps jerk
• B Bulbocavernosus reflex ✓
• C Plantar response
• D Cremasteric reflex

Explanation

Spinal shock denotes temporary suppression of all cord function below the injury, including reflexes. It terminates with the return of the bulbocavernosus reflex, an S2 to S4 polysynaptic reflex elicited by squeezing the glans or clitoris, or by traction on a Foley catheter, causing anal sphincter contraction. Deep tendon reflexes such as the biceps jerk reappear much later and do not mark the end of spinal shock, so AIS grading performed earlier may falsely overstate completeness.

Reference: Campbell's Operative Orthopaedics, 14th ed.

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