What is the clinical meaning of a negative bulbocavernosus reflex in spinal cord injury patients?

Abstract

Study design: This is a retrospective cohort study. Objective: To highlight some issues about the clinical meaning of a negative bulbocavernosus reflex (BCR) in spinal cord injury (SCI) patients. Settings: Research group University Antwerp Belgium. Methods: The study included 170 patients in whom the BCR was examined at a mean of 7 years post SCI. Changes over time were explored in a subset of patients. Results: BCR was negative in 45%. There was no influence of age and gender, nor could a relation be found with the American Spinal Injury Association Impairment Scale score. The anal sphincter reflex (ASR) was positive in 13% of patients with negative BCR. With a mean interval of 45 weeks, BCR changed in 32% of a subset of 44 patients (14 became positive, 3 negative), while the neurological condition did not change and no treatments had been given that could influence the outcome. The data show that a negative BCR may not only be due to a disrupted reflex nervous pathway (which in some patients is different from that of ASR), but may also be caused by a difficulty to provoke the reflex. Conclusion: A negative BCR test indicates interruption of the reflex neurologic pathways, but can also depend on the ease to elicit the reflex. By also doing ASR, this dilemma can be partly solved.