Dramatic Benefit of Stimulation on Dysphagia After Stroke

January 29, 2018

LOS ANGELES — Electrical stimulation of the pharynx appears to be a promising new approach to the treatment of dysphagia, or difficulty swallowing, in patients who have sustained a stroke, a new study suggests.

In the study, three 10-minute sessions of pharyngeal electrical stimulation — one each day for 3 days — dramatically increased the number of patients ready to have their tracheotomy tube removed after having been ventilated in intensive care after a stroke.   

While the current study is relevant to a relatively limited group of patients, the technology has implications for the much wider population of stroke patients who have dysphagia, a common problem in the subacute phase of stroke that can prolong hospital stay in up to a third of patients. 

The PHAST-TRAC study was presented here at the International Stroke Conference (ISC) 2018 by Philip Bath, MD, University of Nottingham, United Kingdom, scientific committee chair of the trial.

"These data are ground-breaking," Dr Bath commented to Medscape Medical News. "There is very little that helps dysphagia at present. Our results showed a very large effect — with almost 60% of patients responding to this electrical stimulation. This looks like a real game changer." 

Many stroke patients are "stuck in hospitals and cannot be discharged to onwards care because they have dysphagia," Dr Bath added. "If this electrical stimulation therapy shows similar benefit in this larger population — which is now being tested — then that would have a major effect on clinical practice. It would open up a whole new rehabilitation environment."

Commenting on the current results for Medscape Medical News, Larry Goldstein, MD, Kentucky Neuroscience Institute, Lexington, agreed. "The utility of this technology may be much wider than the population in this particular study," he said. "The proportion of patients who have difficulty swallowing is very large. It is potentially a major step forward."

Dr Bath explained that swallowing problems are very common after stroke. "More than half of patients experience difficulty swallowing when first admitted. That proportion falls away somewhat, with about a third of patients still having problems swallowing after a few days. It is a very powerful indicator of bad outcome, being associated with feeding difficulties, dehydration, malnutrition, aspiration pneumonia, and prolonged hospital stay."

He noted that the electrical stimulation of the pharynx is thought to stimulate nerves that control swallowing function.  "When the part of the brain that is dominant in controlling swallowing is affected by a stroke, the patient is likely to suffer from dysphagia. The aim of this study is to try and reprogram the nondominant side of the brain to take over the function of swallowing." 

Courtesy of Phagenesis

The device involves a catheter, including a feeding tube that is inserted into the stomach and around that a sheath with incorporated electrodes that stimulate the back of the throat. The current is controlled by a small base station that can be operated by a nurse. The idea is to excite the nerves passing up from the pharynx to the brain to see whether that can stimulate reprograming of the swallowing control mechanism.

The current study involved patients who had been on ventilation for aspiration pneumonia or because of severe dysphagia causing pooling of saliva, which threatens the airway. "Often these patients can be removed from the ventilator but they still need a tracheal tube to help with breathing, sometimes for several weeks," Dr Bath said. "There are often patients who are otherwise ready to leave, but because they can't protect their airway there is the risk of pneumonia."  

For the single-blind study, patients were randomly assigned to active electrical stimulation with the Phagenyx device (Phagenesis Ltd) for 10 minutes each day for 3 days, or sham control. The plan was to enroll 140 patients, but the trial was stopped after 70 patients because of significant benefit in the treatment group.

The primary endpoint was readiness for decannulation — removal of the tracheal tube — after 3 days' treatment. This was achieved in 17 patients (49%) in the active stimulation group vs 3 patients (9%) in the control group, an absolute difference of 40 percentage points. The odds ratio was 7.0 (95% confidence interval, 2.4 - 19.9; P = .0008).

In a second open-label phase of the study, 15 of 18 patients who had been randomly assigned to active treatment and who hadn't responded initially were given a second round of 3 days' treatment, and another 4 patients responded. The sham group was also offered treatment, and 16 of 30 patients treated responded (53%). 

"Overall, when considering all the patients treated, there was a 58% response rate with one or two courses of therapy," Dr Bath reported.  

"I love the hypothesis of this approach — reprogramming the central pathways — but it is possible that it might just be strengthening the pharyngeal muscles," Dr Goldstein commented. "But whatever the mechanism, it does seem to produce a sizable benefit."

He added that he would like to see data on other harder endpoints, such as feeding tube placement or aspiration pneumonia. "If future studies show an effect on important clinical endpoints like this, then that would make a great difference."

Dr Bath responded: "We don't have long-term follow-up for hard outcomes as yet, but we have got time-to-discharge data, and patients who responded to treatment had much shorter length of stay than those who didn't. So this leads us to believe this will be a very economically worthwhile treatment."

He added that a previous pilot study of 30 patients had shown very similar results.

Dr Bath elaborated on the population in the current study. "This trial is addressing stroke patients who go to ICU [intensive care unit] and need ventilation. The numbers of these patients vary enormously in different countries with different systems of care. In some countries, up to 25% of stroke patients will go through ICU and about a quarter of these will need some ventilation. Getting the tracheotomy tube out of these patients can be a major problem and prevents patients from being discharged to regular rehabilitation wards or facilities."

He noted that a subgroup analysis shows that the patients who respond best were those who hadn't been on ventilation or cannulation very long. "When patients are in ICU for a long time, everything starts to atrophy and it is more difficult to get things working again, so this is to be expected."

He reported that the device has been approved in Europe and is being used in countries where more stroke patients tend to be cared for in ICU, such as Germany, Italy, and Austria, where the PHAST-TRAC study was conducted. "It is anticipated that the results of this study will increase such use," he added.

The device has not yet been approved in the United States.

But the more exciting use of this device will be in more general stroke patients who have dysphagia but have not been in the ICU and are being cared for in regular rehabilitation wards. Dr Bath estimated that around 30% of stroke patients fit this description. A larger trial in this population, called PHEED, is getting underway.

The PHAST-TRAC trial was funded by Phagenesis Ltd.  Dr Bath has received honoraria and travel expenses from the company.

International Stroke Conference (ISC) 2018. Abstract LB16. Presented January 26, 2018.

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