Medtronic and Boston Scientific announced study results Friday that they said reflected positively on devices they are selling in the fast-growing field of neuromodulation.

Boston Scientific Corp. presented new clinical trial findings Friday for patients using two different modes in a spinal cord stimulation system, while Medtronic announced the results of a long-running trial of its implantable drug pump for patients with muscle spasticity following a stroke. The companies announced the data as an industry conference gathered this week in Las Vegas.

Unlike therapies that cure disease, neuromodulation devices usually seek to alter a patient's nerve activity in the hopes of relieving symptoms like chronic pain or muscle rigidity, often by applying electricity or chemicals near the spine, brain or major nerves.

Analysts say the multibillion-dollar device market is growing at more than 10 percent a year, driven partly by the awareness that such devices could play a role in curbing an epidemic of opioid overuse and misuse. Most neuromodulation devices require surgery and carry different risks than the drugs they are seeking to replace, and typically they are only available after more conservative therapies haven't gotten the desired results.

Boston Scientific on Friday published data from a randomized controlled trial called "Whisper" that found that patients who could use two different stimulation modes with its Precision spinal cord stimulation device achieved better pain control than using one mode alone.

The spinal cord stimulator delivers electric pulses from an implanted generator, similar to a pacemaker. The pulses vary in frequency, pulse width and amplitude in order to disrupt signals in the spinal cord and provide pain relief. The device can provide one therapy mode that causes a mild tingling sensation referred to as paresthesia, and another mode called subperception therapy that doesn't create the tingling.

The study of two groups of patients, one with 70 and one with 55 research subjects, found that people who used paresthesia therapy reported average reductions in baseline pain scores from 7.2 to 2.5, while patients who preferred subperception therapy reported average baseline pain score reductions from 7.1 to 3.8.

But when patients were able to choose which therapy they used, the number of people whose pain was considered "effectively controlled" increased by 62 percent, Boston Scientific reported in a news release. (The full study results weren't posted to as of Friday.)

The study "underscores the importance of providing patients with multiple therapeutic options for the relief of chronic pain in one SCS [spinal cord stimulation] system that can help address their complex needs," said Maulik Nanavaty, president of neuromodulation at Boston Scientific, in a news release.

Meanwhile, Medtronic presented data from its clinical trial called "Sisters," which compared patients' symptom improvements when taking drugs orally for muscle spasticity vs. continuous infusion of lower doses of the same drug with its SynchroMed II implantable drug pump.

Spasticity is excess muscle tone, which causes limbs to become stiff and difficult to move. It happens in as many as 43 percent of stroke survivors within the first year, according to Medtronic's paper on the Sisters trial in the Journal of Neurology, Neurosurgery, and Psychiatry.

The trial enrolled 60 post-stroke patients between 2009 and 2015 and randomized them to use the SynchroMed II to administer the drug baclofen or take the drug orally. It concluded that patients using the implantable drug pump had greater improvement in passive-movement resistance tests than with the oral drug. The study also found pump users showed gains in functional independence scores, compared to a worsening seen in the oral drug population.

The pump group also experienced more adverse events: 48 percent of pump patients had a "treatment-emergent" serious adverse event vs. 29 percent in the control arm. Among the pump patients, the most common problems included urinary tract infection and surgical site infection.

The study report noted that the difference in adverse events was not unexpected, since the pump patients had to undergo surgery and also go through a multiweek process of adjusting their doses and weaning from oral drugs. The report said the adverse events were in line with the known safety profile of the therapy.

"The study results demonstrate that ITB [intrathecal baclofen therapy with a SynchroMed II pump] is superior to oral medications in decreasing muscle tone," Dr. Michael Creamer, the Florida-based lead author and study investigator, said in a release about the report.

Joe Carlson • 612-673-4779