Patients may experience impaired swallowing as a result of several specific problems. The first of these—oropharyngeal dysphagia—is impaired swallowing associated with deficits in oral and pharyngeal structure or function. Such patients are at especially high risk for aspiration, and many of them have silent aspiration. Patients at risk for oropharyngeal dysphagia include those with nervous system damage, such as that caused by stroke, head injury, or spinal cord injury; neuromuscular diseases, such as muscular dystrophy or cerebral palsy; progressive neurologic diseases, such as Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, or dementia; and head or neck cancer. Patients who have undergone facial, oral, or neck surgery; experienced neck trauma; or been intubated for longer than 3 days are also at risk.

The second type of impaired swallowing is associated with esophageal dysphagia and aspiration risk from gastroesophageal reflux disease, esophageal dysmotility or structural abnormality, delayed gastric emptying, or nasogastric tubes.

Finally, impaired swallowing can be associated with tracheostomy or ventilation support because of decreased sensation of the oral and pharyngeal cavities; decreased sensation of food or fluids penetrating the laryngeal vestibule and aspirating (dropping below the level of the vocal cords); decreased ability to cough aspirated material off the vocal cords; and decreased laryngeal elevation and airway closure.