Dysphagia May Be Sign of Brain Damage in NMOSD and MOGAD Patients

People with neuromyelitis optica spectrum disorder (NMOSD) with difficulty swallowing are more likely to have clinical signs of brain involvement and more extensive disability, a small study suggests.

Measures of a patient’s difficulty with swallowing could be used to indirectly assess brain involvement in NMOSD and the related disorder myelin oligodendrocyte glycoprotein antibody disease (MOGAD), its researchers said their findings indicate.

The study, “Dysphagia in NMOSD and MOGAD as a surrogate of brain involvement?,” was published in the European Journal of Neurology.

Both NMOSD and MOGAD are characterized by the immune system attacking the nervous system. In both conditions, the optic nerve, which connects the eyes to the brain, is primarily affected. However, emerging evidence suggests that more extensive damage to other regions of the brain can occur.

The physical process of swallowing is governed by several interconnected parts of the nervous system. As such, difficulty swallowing — termed dysphagia — is common in people with NMOSD, MOGAD, and other nervous system disorders.

Researchers at the University of Muenster, in Germany, examined the connection between dysphagia and brain involvement in 13 people: eight with NMOSD and five with MOGAD.

In order to measure dysphagia, they used a procedure called flexible endoscopic evaluation of swallowing (FEES). In FEES, a small tube is used to allow clinicians to view the physical process of swallowing as it occurs in the throat, so that any abnormalities — including those that might not be perceptible to the patient — can be identified. Dysphagia was scored on a scale from 0 (no dysphagia) to 3 (severe dysphagia).

Overall, eight of the 13 patients had some amount of detectable dysphagia. Two had moderate dysphagia, and one had severe dysphagia that was symptomatic (that is, noticeable for the patient); the other five patients were asymptomatic.

“The main finding of this study is that dysphagia may occur in both NMOSD and MOGAD patients, even if the patients do not perceive swallowing impairment,” the researchers wrote.

Researchers also compared the data from these patients to data from healthy individuals who had undergone FEES at their clinic in previous studies. For each NMOSD or MOGAD patient, data on two healthy individuals of similar age were used.

Of the 26 healthy individuals, six had mild dysphagia; the rest had no dysphagia. Difficulty swallowing was significantly more common in people with NMOSD or MOGAD.

Among the NMOSD/MOGAD patients, dysphagia was significantly correlated with clinical signs of brain involvement — that is, people with dysphagia were statistically more likely to have clinical data indicative of damage in the brain. However, dysphagia was not significantly associated with brain involvement as assessed by an MRI.

Dysphagia was also significantly correlated with disability — as assessed with the Expanded Disability Status Scale — and with pneumonia (when fluid builds in the lungs). The association between dysphagia and pneumonia indicates that, in people with NMOSD and MOGAD, dysphagia may contribute to other clinical morbidities. The association between dysphagia and disability mirrors similar results found in people with multiple sclerosis.

Collectively, the findings indicate that, “swallowing impairment assessed with FEES could possibly be used as a surrogate parameter of brain involvement in patients with NMOSD and MOGAD,” the researchers wrote.

They added that, since dysphagia can occur in people without these conditions — particularly in older adults — it would be necessary to have well-validated and age-adjusted diagnostic criteria for the use of FEES as a way to indirectly measure brain involvement.

The researchers also noted that this study is limited by its small sample size, and by the inclusion of both NMOSD and MOGAD patients.

“All results of this pilot study should be considered explorative. Future prospective studies are necessary to confirm the results,” the researchers wrote.