Gastrointestinal disorders are frequently encountered by neurologists practicing in a hospital setting. Common problems include abdominal pain, upper or lower gastrointestinal bleeding, constipation with or without ileus, and diarrhea. These symptoms could be present in any hospitalized patients regardless of their primary diagnosis. However, some of these conditions may be more common in neurologically ill patients. These include dysphagia in stroke patients, altered bowel habits in patients with degenerative diseases such as Parkinson disease, or fecal incontinence in spinal cord disorders. In this chapter, we will focus on pathologies frequently seen by hospital neurologists. We will start with swallowing disorders including a discussion of their pathophysiology and the management plan. We will then discuss abdominal pain, gastrointestinal bleeding, diarrhea, and ileus, all problems that may need to be initially assessed and treated by practicing neurologists who take primary responsibility of hospitalized patients. We will finally elaborate on hepatic encephalopathy, a major complication of liver failure and a frequent cause of neurological consultation for evaluation and treatment.
A 75-year-old man with history of hypertension, type 2 diabetes, hypercholesterolemia, and prior myocardial infarction (MI) presented with acute onset of left face, arm, and leg weakness. Further diagnostic workup revealed acute ischemia in the right internal capsule. He choked badly when given a sip of water. Fluoroscopic video swallowing study showed prolonged stasis of food in the pharynx with occasional regurgitation to the nasopharynx and frequent passage into the laryngeal inlet.
What is the mechanism of swallowing? What are the cranial nerves (CNs) involved in each phase?
The mechanism of swallowing is best described by breaking it into three important phases: oral preparatory, pharyngeal, and esophageal. The oral preparatory phase consists of chewing and making a bolus of appropriate size and consistency so that it can be propelled down the pharynx and esophagus. This phase involves CN V, VII, and XII. During the pharyngeal phase, food is propelled from the hypopharynx to the esophagus. This requires closure of the nasopharynx by approximation of the soft palate to the posterior pharynx, and closure of the laryngeal inlet by the epiglottis so that food is propelled to the esophagus and not the trachea. These actions involve CN VII, IX, X, and XII. The esophageal phase is mediated by peristalsis of the esophagus to propel food to the stomach. As food arrives to the lower end of the esophagus, the gastro-esophageal sphincter relaxes, letting the food enter the stomach.
What are the common causes of swallowing difficulty?
Swallowing difficulty, or dysphagia, is a symptom of numerous medical conditions. The cause of dysphagia most commonly encountered by a neurologist is primarily neurological, although other causes should not be ignored. Common neurological problems leading to swallowing difficulty are stroke, myasthenia gravis (MG), amyotrophic lateral sclerosis (ALS), Parkinson disease (PD), multiple sclerosis (MS), and muscular disease.