Difficulty in swallowing (dysphagia) can be caused by neurological impairment affecting the muscles of the oropharynx. It can happen because of a stroke, traumatic brain injury, disorders of cerebral development, neurodegenerative conditions and major head and neck surgery (for example, to remove cancer). Dysphagia may lead to malnutrition, dehydration and aspiration pneumonia.
Treatment options depend on the cause and severity of the dysphagia. Conservative treatments involve swallowing therapy to help the patient relearn swallowing techniques and strengthen oropharyngeal muscles. In severe cases, nasogastric tubes or percutaneous endoscopic gastrostomy tubes may be used to provide nutritional support.
Transcutaneous neuromuscular electrical stimulation (NMES) is usually used as well as traditional swallowing therapy for treating oropharyngeal dysphagia. Swallowing therapy uses exercises to improve muscle function. The aim of NMES is to increase the effectiveness of swallowing therapy by strengthening the muscles involved in swallowing. It also promotes recovery of cortical control of swallowing.
NMES is usually done by a speech and language therapist after appropriate diagnosis and patient selection. Therapists need appropriate training to use the procedure. The speech and language therapist places electrodes in selected positions on the patient's neck. Small electrical currents are then passed through the electrodes to stimulate the peripheral nerve supply of the pharyngeal or laryngeal muscles. Stimulus intensity may be at a low sensory level, or at a higher motor level to trigger muscle contractions. Under the supervision of the therapist, the patient exercises their swallowing muscles while having concurrent electrical stimulation. Treatment duration recommendations vary by device, but can be up to 1 hour. The mild electrical stimulation can produce feelings ranging from tingling and warmth, to a 'grabbing' sensation.
The position of the electrodes and levels of current used vary from patient to patient. There is a range of NMES devices that use different electrode designs, positions and stimulus intensities. At an initial assessment, videofluoroscopy or clinical observation may be used to optimise the placement of treatment electrodes and to determine an appropriate stimulus intensity.