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SPG Stimulation ‘Likely’ of Benefit for Some Acute Strokes

Acute ischaemic stroke patients ineligible for thrombolytic therapy and with confirmed cortical involvement (CCI) may derive benefit from an injectable neurostimulator implant that works on the sphenopalatine ganglion (SPG), a sham-controlled randomized trial found.

In the modified intent-to-treat population, the proportion of patients whose disability level was better than anticipated at 90 days was 49% in the SPG stimulation group versus 45% in the sham group (OR 1.14, P=0.31), reported Jeffrey Saver, MD, of the University of California Comprehensive Stroke Center in Los Angeles, and colleagues.

In the CCI population, 50% of the intervention group had better than expected outcomes compared with 40% of the control group (OR 1.48, P=0.0258), which narrowly missed statistical significance (P<0.025 required), as described in The Lancet.

The research was also presented at the European Stroke Organisation Conference in Milan.

“Although the improvement in 90-day functional outcome among patients with imaging evidence of cortical involvement at presentation was not significant in this trial alone, study findings indicate the use of sphenopalatine ganglion stimulation is likely to be beneficial, on the basis of consistent effects across the primary and all secondary endpoints, and of the presence of an inverted U-shaped dose-response curve,” Saver’s group wrote.

When assessing the U-shaped dose-response relationship between the primary outcome and SPG stimulation intensity in the CCI group, the proportion with favorable outcomes went up from 40% to 70% at low-midrange intensity and declined back to 40% during high-intensity stimulation (P=0.0034).

“Pooled analysis of all completed trials indicated that, among patients with imaging evidence of cortical involvement at presentation, sphenopalatine ganglion stimulation improves functional outcome,” the researchers concluded.

IMPACT-24B (Implant Augmenting Cerebral Blood Flow Trial-24B) was a pivotal, international, double-blind study that randomized 1,078 patients with anterior-circulation acute ischaemic stroke, who were not receiving reperfusion treatment, to SPG stimulation (n=481) or sham treatment (n=519). Median patient age was about 70 years and 51% were women. Among these, 52% of patients had CCI — 244 in the intervention group and 276 in the sham group. No differences in serious adverse events or mortality were seen between the two groups.

Patients were eligible if they had radiological and clinical evidence of acute ischemic stroke in the anterior cerebral circulation, had National Institutes of Health Stroke Scale scores between 7 and 18, and were able to start treatment 8 to 24 hours from stroke onset. Age requirements were 40-85 for women and 40-80 years for men.

Exclusion criteria included pregnancy, oral cavity conditions that might hinder device implantation, uncontrolled high blood pressure, bilateral stroke, bleeding propensity, radiological evidence of intracranial haemorrhage, and others.

Results of the present investigation fall into line with previous pilot trial (IMPACT-24A), which also looked at SPG stimulation within 1 day of stroke onset.

“Additional studies are planned or underway in patients receiving intravenous thrombolytic therapy and endovascular mechanical thrombectomy, to assess whether adding sphenopalatine ganglion stimulation improves outcomes in these patients as well,” the authors wrote.

The study was funded by BrainsGate.

Saver disclosed relationships with BrainsGate.