Systemic naloxone infusion may trigger spasticity in patients with spinal cord injury: case series.
OBJECTIVE
Three patients with spinal cord injury (SCI) and 3 able-bodied (AB) patients were infused with naloxone during a study to examine their neuroendocrine function. An unanticipated side effect occurred during the naloxone infusion. All 3 patients with SCI, but none of the AB patients, experienced profoundly increased spasticity during the naloxone infusion. Our report describes this side effect, which has potential implications for the clinical treatment or scientific evaluation of individuals with SCI.


METHODS
All patients were in good general health and medication free for 11 days or longer before the study. Each patient was placed on a 30-hour protocol to analyze pulsatile release of gonadotropins. Physiologic saline was intravenously infused on day 1 to serve as a control period for naloxone infusion on day 2.


RESULTS
AB patients experienced no muscle spasm activity or any other side effects at any time during the study. In contrast, all 3 patients with SCI experienced a profoundly increased frequency and duration of spasticity in muscles innervated by the nerve roots caudal to their level of injury. In all 3 patients with SCI, spasticity increased only during the period of naloxone infusion. Within 1 hour of stopping naloxone, spasticity returned to baseline levels.


CONCLUSIONS
Naloxone infusion produced a differential effect on the muscle activity of men with SCI compared to AB men with intact spinal circuits. Consistent with previous studies, the results of this study indicate a relationship between opioid neuromodulation and spasticity after SCI.
The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Lois Pope Life Center, Room 1-27, 1095 NW 14th Terrace, Miami, FL 33136, USA. NBrackett@miami.edu
Nancy L
NL
Brackett
Emad
E
Ibrahim
Andrei
A
Krassioukov
Charles M
CM
Lynne
D000328:Adult; D002574:Cervical Vertebrae; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009128:Muscle Spasticity / Q000139:chemically induced*; D009270:Naloxone / Q000008:administration & dosage / Q000009:adverse effects*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000009:adverse effects*; D009489:Neurosecretion / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000150:complications* / Q000503:physiopathology; D013904:Thoracic Vertebrae
D009292:Narcotic Antagonists; D009270:Naloxone