By Nancy Shaw
Treatment of chronic pain with spinal cord stimulation (SCS) therapy is linked to significant improvements in sleep quality, according to a study presented here at the 2020 Annual Meeting of the American Academy of Pain Medicine (AAPM).
“Marked improvements in sleep quality were observed in the EVOKE study, with greater improvement trending in the closed-loop group,” reported Shrif Costandi, MD, Cleveland Clinic, Cleveland, Ohio.
Sleep disturbances are highly common in people with chronic pain and are part of a cycle of pain exacerbation, with chronic sleep deprivation further causing increases in pain sensitisation. While SCS has demonstrated important benefits in the treatment of chronic pain, the effects of the therapy on sleep are not well-documented and conflicting.
To investigate the effects, Dr. Costandi and colleagues evaluated data on 134 patients with chronic pain who were enrolled in EVOKE, a multicentre, double-blind randomised study comparing closed-loop SCS or conventional open-loop SCS.
At baseline, most patients had compromised sleep, with only 1.6% in the closed-loop group and 3.2% in the open-loop group reporting that their sleep quality was good, as assessed with the Pittsburgh Sleep Quality Index (PSQI).
At the 3-month follow-up, good sleep quality increased to 32.8% in the closed-loop group compared with 28.3% in the open-loop group. The improvements were maintained at 12 months in both groups (30.9% and 27.1%, respectively).
In addition, at 3 months, 75.9% of patients in the closed-loop reported a reduction in PSQI total score from baseline ≥ 3, as did 66.0% of patients in the open-loop group (P = .297). Though the difference was not statistically significant, the trend was maintained at 12 months (76.4% and 62.5%, respectively; P = .138).
“Approximately 30% or more patients in both groups improved to normative levels, with a PSQI score of 6.3 or lower at both time-points,” said Dr. Costandi.
In terms of duration of sleep, mean scores increased from approximately 2 at baseline to 1 at 12-months follow-up, which translates to as much as 2 additional hours of sleep per night.
“We speculate that ECAP measurement may contribute to improved outcomes by confirming the activation of the dorsal column and thus pain inhibition,” said Dr. Costandi. “The addition of closed-loop to maintain activation levels at the target, may increase analgesia even more, and lead to improved sleep outcomes.”