Ketamine May Reduce Chronic Pain in Adolescents
Subanesthetic ketamine infusions are a safe and effective way to relieve chronic pain in adolescents, a new study suggests.
Ketamine, a Schedule III drug, has been used successfully to treat various chronic pain syndromes in adults, according to researchers from Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, in Washington, D.C., who conducted a longitudinal case series to determine the feasibility of ketamine injections in an outpatient setting.
“Our purpose was to look at the clinical outcomes related to our adolescents who were receiving what we considered subanesthetic dosing of ketamine,” said study author Kathy Ann Sheehy, CNS, a nurse specialist at the hospital.
The study included 63 adolescents with chronic pain conditions such as complex regional pain syndrome (CRPS), fibromyalgia and headache, and were treated in the hospital’s tertiary outpatient interdisciplinary Pain Medicine Care Complex from January 2013 to April 2014. The patients received 111 treatments (277 ketamine infusions; maximum dose of 1 mg/kg per hour) during the study period. They were divided into two groups: CRPS (n=23) and all other chronic pain syndromes (n=40). Main outcome measures were self-reported pain scores using a numeric rating scale and morphine-equivalent intake.
The researchers found that ketamine significantly decreased pain scores in 37% of the injections administered. A reduction of 20% or greater was considered significant. Patients with CRPS experienced the greatest reduction compared with the other chronic pain syndromes (P=0.029). The researchers noted that the ketamine infusions did not change the overall morphine-equivalent intake (P=0.3).
“When we looked at the difference between the types of pain syndromes, CRPS was the one that was the most statistically significant as a pain syndrome for reduction in pain scores and reduction in opioid use,” Ms. Sheehy said. “[With] the other pain scores, although overall there was a reduction, we didn’t see a reduction in headaches or other types of complex pain syndromes.”
An analysis of comorbidities showed that:
- 23% of the patients had psychiatric/psychological disorders (e.g., anxiety, depression, bipolar disorder);
- 10% had a history of trauma;
- 10% had postural orthostatic tachycardia syndrome (POTS);
- 7% had diabetes mellitus;
- 7% had a malignancy; and
- 5% had sickle cell disease.
The researchers found that the patients with POTS and trauma experienced the greatest pain reduction and chronic headache patients had the smallest decrease. “Our assumption for that is that both of those are autonomic sympathetic conditions, and most of our CRPS kids actually had trauma,” Ms. Sheehy said.
No adverse events were reported and the ketamine injections were well tolerated, according to the study authors. They said more research on complex pain syndromes, especially CRPS in adolescents, is needed.