Conference Coverage

Ganglion stimulation boosts cerebral blood flow, improves stroke outcomes



– Stimulation of the sphenopalatine ganglion (SPG) using a small, implanted electrode for 5 days in patients who had just had an acute ischemic stroke led to statistically significant and clinically meaningful improvements in the subset of patients with confirmed cortical involvement in a pivotal, sham-controlled trial.

Dr. Jeffrey L. Saver, professor of neurology, University of California, Los Angeles Mitchel L. Zoler/MDedge News

Dr. Jeffrey L. Saver

SPG stimulation started within 24 hours of an acute ischemic stroke “reduced poststroke disability over the entire outcome range and increased the proportion of patients who were alive and independent 3 months after their stroke” in the subgroup with a confirmed cortical infarction (CCI), Jeffrey L. Saver, MD, said at the World Stroke Congress. Five days of SPG stimulation, done once daily starting within 24 hours of stroke onset, “enhances ipsilateral collateral blood flow” and may also stabilize the blood brain barrier, explained Dr. Saver, professor of neurology and director of the stroke center at the University of California, Los Angeles. The study included a prespecified primary endpoint analysis that focused exclusively on the CCI subgroup, 52% of the total enrolled population.

If the reported data result in Food and Drug Administration marketing approval for the system, Dr. Saver said that he anticipated “substantial uptake” of the strategy, which he tested in patients who had not undergone thrombectomy or thrombolysis treatment. In current U.S. practice, there is “a large group of patients with a missed opportunity for recanalization” who would be candidates for treatment with SPG stimulation, a treatment that appeared to provide benefits beyond current standard care, he said in an interview.

Ongoing studies are also testing whether SPG stimulation can benefit acute ischemic stroke patients who have already undergone treatment with thrombectomy or thrombolysis, he added. The same SPG stimulation device is additionally undergoing U.S. testing as a treatment for headache and has regulatory approval in the European Union for treating headache and migraine.

The ImpACT-24B (Implant for Augmentation of Cerebral Blood Flow Trial, Effectiveness and Safety in a 24-Hour Window) trial involved 1,000 patients at 73 centers in 18 countries, including the United States. The investigators enrolled acute ischemic stroke patients 8-24 hours after stroke onset who had a National Institutes of Health Stroke Scale (NIHSS) score of 7-18.

Each patient received an implant of a short, thin metal electrode placed through the soft palate at the rear roof of the mouth, near the SPG. Neurologists primarily performed the implants in a procedure that had a “skin to skin” time of less than 5 minutes. Patients received either electrical stimulation or a sham stimulation through the electrode immediately after placement and then daily for the next 4 days. The investigators titrated the strength of the treatment stimulation in each patient to maximize its strength while maintaining patient comfort. Subsequent analysis of the results showed that the stronger the tolerated stimulation, the bigger the treatment effect in a clear dose-response pattern, Dr. Saver reported.

The study’s primary endpoint was improvement in the modified Rankin scale (mRS) score at 90 days after the index stroke when measured against historical expectations. By this measure, the overall study cohort showed a small, statistically insignificant improvement in actively treated patients, compared with sham-treated patients. However, in the prespecified, coprimary endpoint cohort of patients with a CCI, active treatment resulted in 50% of patients having a better-than-expected 90-day outcome, compared with 40% of controls, a 48% relative improvement in this measure that met the prespecified definition of statistical significance. The results also showed about a 50% relative improvement in each of three secondary outcomes in the CCI cohort: the percentage of patients with a mRS score of 0-2 after 90 days, the percentage with a mRS score of 0-3 after 90 days, and average stroke-related quality of life at 90 days.

Dr. Saver also reported results of a meta-analysis that combined the results he reported from 520 patients with CCI with results from 87 CCI patients enrolled in the preceding pilot study of this treatment strategy, ImpACT-1. The pilot findings were completely consistent and when combined with the current results strengthened the statistical significance of the primary and secondary endpoints.

“There is a compelling story” of efficacy based on the study results, the dose-response relationship, and the meta-analysis results, Dr. Saver said. “I think it’s a very strong case.”

He also reported “no safety concerns” raised in the new study, with no serious adverse effects seen in or experienced by the patients on active treatment.

“The data are compelling” for safety and efficacy, for this novel approach for treating acute ischemic stroke, commented Pooja Khatri, MD, professor of neurology and director of the acute stroke program at the University of Cincinnati.

The study was sponsored by BrainsGate, the company developing the tested device. Dr. Saver has been a consultant to BrainsGate. Dr. Khatri has been a consultant to Biogen, Greenwich, Lumosa, and PTC Therapeutics.

SOURCE: Saver J et al. Int J. Stroke. 2018 Oct;13(2S):28, Abstract 104.

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