The Functional Impact of the Absence of a Bulbocavernosus Reflex in the Postoperative Period After a Motor-Complete Traumatic Spinal Cord Injury

Bulbocavernosus Reflex Has No Prognostic Features During the Acute Evaluation of Spinal Cord Injuries

The bulbocavernosus reflex (BCR) has been used during the initial evaluation of a spinal cord injury patient as a metric to determine prognosis and whether the patient is in "spinal shock." This reflex has been less utilized over the last decade, and therefore a review was performed to assess the value of BCR in patient prognosis. The North American Clinical Trials Network (NACTN) for Spinal Cord Injury (SCI) is a consortium of tertiary medical centers that includes a prospective SCI registry. The NACTN registry data was analyzed to evaluate the prognostic implication of the BCR during the initial evaluation of a spinal cord injury patient. SCI patients were divided into those with an intact or absent BCR during their initial evaluation. Associations of participants' descriptors and neurological status on follow-up were performed, followed by associations with the presence of a BCR. A total of 769 registry patients with recorded BCRs were included in the study. The median age was 49 years (32-61 years), and the majority were male (n = 566, 77%) and white (n = 519, 73%). Among included patients, high blood pressure was the most common comorbidity (n = 230, 31%). Cervical spinal cord injury was the most common (n = 470, 76%) with fall (n = 320, 43%) being the most frequent mechanism of injury. BCR was present in 311 patients (40.4%), while 458 (59.6%) had a negative BCR within 7 days of injury or before surgery. At 6 months post-injury, 230 patients (29.9%) followed up, of which 145 had a positive BCR, while 85 had a negative BCR. The presence/absence of BCR was significantly different in patients with cervical (p = 0.0015) or thoracic SCI (p = 0.0089), or conus medullaris syndrome (p = 0.0035), and in those who were American Spinal Injury Association Impairment Scale grade A (p = 0.0313). No significant relationship was observed between BCR results and demographics, AIS grade conversion, motor score changes (p = 0.1669), and changes in pin prick (p = 0.3795) and light touch scores (p = 0.8178). In addition, cohorts were not different in surgery decision (p = 0.7762) and injury to surgery time (p = 0.0681). In our review of the NACTN spinal cord registry, the BCR did not provide prognostic utility in the acute evaluation of spinal cord injury patients. Therefore, it should not be used as a reliable marker for predicting neurological outcomes post-injury.

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

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.