Megaesophagus, also known as esophageal dilatation, is a disorder of the esophagus in humans and other mammals, whereby the esophagus becomes abnormally enlarged. Megaesophagus may be caused by any disease which causes the muscles of the esophagus to fail to properly propel food and liquid from the mouth into the stomach (that is, a failure of peristalsis). Food can become lodged in the flaccid esophagus, where it may decay, be regurgitated, or maybe inhaled into the lungs (leading to aspiration pneumonia). Humans
Megaesophagus may occur secondary to diseases such as achalasia or Chagas disease. Achalasia is caused by a loss of ganglion cells in the myenteric plexus. There is a marked lack of contraction within the muscles involved in peristalsis with a constant contraction of the lower esophageal sphincter. Dilation of the esophagus results in difficulty swallowing. Retention of food bolus is also noted. Other animals
Dogs
Megaesophagus can also be a symptom of the disease myasthenia gravis. Myasthenia gravis is a neuromuscular disease where the primary symptom is weakness in various body parts of the dog. However, when myasthenia gravis occurs in older dogs it is thought of as an immune-mediated disease. Often when myasthenia gravis is diagnosed in older dogs the first symptom the dog may manifest is megaesophagus. Myasthenia gravis occurs when acetylcholine receptors (nicotinic acetylcholine receptors) fail to function properly, so that the muscle is not stimulated to contract. There is an invention known as the "bailey chair" that uses the force of gravity to push down liquids and food into the dogs stomach.
These 3 patients were diagnosed with MCS and had suffered from traumatic brain injuries.In summary, those with minimally conscious state and non-traumatic brain injuries will not progress as well as those with traumatic brain injuries while those in vegetative states have an all around lower to minimal chance of recovery. Because of the major differences in prognosis described in this study, this makes it crucial that MCS be diagnosed correctly. Incorrectly diagnosing MCS as vegetative state may lead to serious repercussions related to clinical management. History
Prior to the mid-1990s, there was a lack of operational definitions available to clinicians and researchers to guide the differential diagnosis among disorders of consciousness. As a result, patients were lumped together into broad categories often based on the severity of the disability (e.g. moderate, severe, extremely severe). These diagnoses were performed without regard to salient differences in behavioral and pathological characteristics. In a three-year period spanning from 1994 to 1996, three position statements regarding the diagnostic criteria of disorder of consciousness were published. The "Medical Aspects of the Persistent Vegetative State" was published by
the American Academy of Neurology (AAN) in 1994. In 1995, "Recommendations for Use of Uniform Nomenclature Pertinent to Patients With Severe Alterations in Consciousness" was published by the American Congress of Rehabilitation Medicine (ACRM). In 1996 the "International Working Party on the Management of the Vegetative State: Summary Report" was published by a group of international delegates from neurology, rehabilitation, neurosurgery, and neuropsychology.