Optimal neurophysiological parameters in neuromuscular electrical stimulation in the treatment of dysphagia in multiple sclerosis - a pilot study

The reported incidence of dysphagia in multiple sclerosis (MS) varies between
33% and 90% and is higher in more disabled patients. Dysphagia is associated
with an increased risk of aspiration pneumonia, increase in health-care cost
and increase in mortality and a decrease of quality of life (QOL). Patients
with oropharyngeal swallowing problems are commonly referred to a
speech-therapist for further assessment and treatment.
Limited evidence is available for treatment of dysphagia in MS. A significant
decrease of dysphagia in MS after treatment with neuromuscular electrical
stimulation (NMES) was found, but in other studies the results of the effect of
NMES on dysphagia were inconsistent. Therefore, the need for research into the
optimal parameters for the application of NMES is clear.

Primary Objective: To develop a protocol for NMES for dysphagia to determine
optimal electrode placement and stimulation parameters in MS patients.
Secondary Objective: To determine variability in location, morphology, and type
of motor dysfunctions of hyoid muscles visualized with ultrasonography in MS
patients.

With this pilot study we will be able to develop a protocol for the application
of NMES for dysphagia in order to find individualized optimal electrode
placement and stimulation characteristics based on location, morphology and
type of motor dysfunctions that are present. In a follow up study the effect of
the NMES in the treatment of dysphagia in MS patients will be tested in a
randomized controlled trial following the developed protocol.

An explorative fundamental study based on a convenience sample. The DYMUS will
be used to screen patients for dysphagia. Fiberoptic endoscopy (FEES) will be
assessed by a speech and language therapist to determine the severity of the
dysphagia. Within two weeks a proficient physiotherapist will use
ultrasonography to determine the location and assess the morphology of the
hyoid muscles. Immediately thereafter an experienced speech therapist will use
electrical stimulation to stimulate the hyoid muscles. Simultaneously,
ultrasonography will be used to guide optimal electrode placement and
stimulation characteristics. Displacement of the hyoid bone will be measured
and abnormalities in muscle contractions will be noted. For every electrode
position, optimal stimulation parameters (amplitude (*A), pulse duration and
frequency (Hz)) will be determined by noting the thresholds for muscle
contraction. The comfort of the patients during stimulation will be taken into
account in finding optimal stimulation parameters.

The patients receive neuromuscular electrical stimulation during a test
setting.

Burden:
All examinations take place within clinical staff rooms and departments of
Nieuw Unicum.

The participants will have 2 or 3 contact moments to complete the entire
examination. The total duration of the study is approximately 4 weeks.
Time investment: 3 sessions of 15 + 60 + 10 = 85 minutes in total.

Risks:
FEES
Despite of the various advantages of FEES, this diagnostic procedure is not
without risks. The most probable consequences are discomfort, gagging and/or
vomiting, vasovagal syncope, epistaxis, mucosal perforation and laryngospasm.
Those consequences do not appear frequently. Langmore, Pelletier & Nelson
(1995) reported 2 incidences of laryngospasmen (0.03%), 4 vasovagal episodes
(0.06%) and 20 incidences of epistaxis (0.3%) in 6000 FEES examinations.

Ultrasonography
An ultrasound is a completely painless and harmless procedure.

NMES
NMES is a specialized non-invasive form of electrical stimulation therapy
designed to treat dysphagia. The electrical current may start off as a slight
tingling sensation and build to a pulling sensation. For NMES no associated
risks are known at this time (NICE, 2014). Side effects include redness and
irritation to the skin, which typically clears with topical moisturizer in 24
to 48 hours. Up to one day after NMES, myalgia of the hyoid muscles can be
experienced.