Researchers looked at how spinal stimulation treatment affects patients with chronic pain and poor sleep.

In collaboration with Albany Medical Center, researchers from Florida Atlantic University’s Schmidt College of Medicine have conducted a study to understand better spinal cord stimulation’s effect on chronic pain and sleep.

About 65 million adults in the United States are affected by chronic pain. Between 67% and 88% also suffer from sleep disturbances, including longer and more frequent nocturnal awakenings and poorer sleep quality. Sleep disorders also may exacerbate pain by contributing to the development of obesity, diabetes mellitus, and depression.

Because chronic pain and sleep are thought to be correlated, researchers wanted to examine if spinal cord stimulation could improve aspects of sleep and treat a multitude of chronic pain conditions.

The treatment involves an implantable spinal cord stimulator that sends low levels of electricity directly into the spinal cord to relieve pain. However, its impact on patient’s lives has yet to be determined.

Study participants were surveyed about their sleep, pain, functional status, and overall quality of life throughout the study period.

The surveys were given before spinal stimulation and either 6 months or a year post-operatively. Participants also were asked about their satisfaction with the spinal cord stimulation procedure and if they would have the surgery again.

Researchers examined the relationship between pain outcome measures using the insomnia severity index, a clinical screening tool that assesses the severity of both nighttime and daytime components of insomnia.

With the tool, they established the minimally clinical important difference – the smallest noticeable change that a patient perceives as clinically significant and could indicate a change in their management.

The study, published in the journal Stereotactic and Functional Neurosurgery, successfully established minimally clinical important difference ranges for the insomnia severity index outcome measure to help gauge improvement in insomnia after spinal cord stimulation.

Results showed an insomnia severity index improvement of 30% or more in 39.1% of the participants and an Epworth sleepiness scale of 30% or more in 28.1%.

Minimally clinical important difference values of 2.4 to 2.6 correlated with improvement in disability and depression in the participants. The study revealed associations between sleep and pain and depression but no correlation between sleep and spinal cord stimulation success.

“The physiologic mechanisms of both pain and sleep are complex, and the relationship between the two is poorly understood,” said Julie Pilitsis, MD, PhD, senior author and dean and vice president for medical affairs, FAU Schmidt College of Medicine. “By recognizing the intersection of sleep disorders and chronic pain, treatment plans can be more focused and can thus lead to drastic improvements in overall health, beyond the improvement in sleep or pain alone.”

Spinal cord stimulation success was measured by the change between the pre-operative scores and the scores between 6 and 12 months post-operatively.

The insomnia severity index asks seven questions to assess an individual’s level of insomnia, with higher scores indicating increased nocturnal sleep disturbance. The Epworth sleepiness scale quantifies daytime sleepiness based on a patient’s likelihood to doze off during eight daily activities, with higher scores indicating increased daytime sleepiness.

To determine which patients had improved sleep, researchers looked at improvement in insomnia severity index or Epworth sleepiness scale of 30 percent or more.

“Our study includes pertinent sleep conditions in our analysis, as the interplay between sleep and chronic pain is important to consider in patients undergoing spinal cord stimulation,” said Pilitsis. “As more studies are conducted on minimally clinical important difference thresholds, assessing the clinical response to spinal cord stimulation will improve.”

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