You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Dysphagia and explain in detail?
Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right.It may be a sensation that suggests difficulty in the passage of solids or liquids from the mouth to the stomach, a lack of pharyngeal sensation or various other inadequacies of the swallowing mechanism. Dysphagia is distinguished from other symptoms including odynophagia, which is defined as painful swallowing, and globus, which is the sensation of a lump in the throat. A person can have dysphagia without odynophagia (dysfunction without pain), odynophagia without dysphagia (pain without dysfunction) or both together. A psychogenic dysphagia is known as phagophobia.

Classification
Dysphagia is classified into the following major types:
Oropharyngeal dysphagia
Esophageal and obstructive dysphagia
Neuromuscular symptom complexes
Functional dysphagia is defined in some patients as having no organic cause for dysphagia that can be found.

Signs and symptoms
Some patients have limited awareness of their dysphagia, so lack of the symptom does not exclude an underlying disease. When dysphagia goes undiagnosed or untreated, patients are at a high risk of pulmonary aspiration and subsequent aspiration pneumonia secondary to food or liquids going the wrong way into the lungs. Some people present with "silent aspiration" and do not cough or show outward signs of aspiration. Undiagnosed dysphagia can also result in dehydration, malnutrition, and kidney failure.Some signs and symptoms of oropharyngeal dysphagia include difficulty controlling food in the mouth, inability to control food or saliva in the mouth, difficulty initiating a swallow, coughing, choking, frequent pneumonia, unexplained weight loss, gurgly or wet voice after swallowing, nasal regurgitation, and patient complaint of swallowing difficulty. When asked where the food is getting stuck, patients will often point to the cervical (neck) region as the site of the obstruction. The actual site of obstruction is always at or below the level at which the level of obstruction is perceived.The most common symptom of esophageal dysphagia is the inability to swallow solid food, which the patient will describe as becoming stuck or held up before it either passes into the stomach or is regurgitated. Pain on swallowing or odynophagia is a distinctive symptom that can be highly indicative of carcinoma, although it also has numerous other causes that are not related to cancer. Achalasia is a major exception to usual pattern of dysphagia in that swallowing of fluid tends to cause more difficulty than swallowing solids. In achalasia, there is idiopathic destruction of parasympathetic ganglia of the Auerbachs (Myenteric) plexus of the entire esophagus, which results in functional narrowing of the lower esophagus, and peristaltic failure throughout its length.

Complications
Complications of dysphagia may include aspiration, pneumonia, dehydration, and weight loss.

Cause
Following table enumerates possible causes of dysphagia:

Difficulty with or inability to swallow may be caused or exacerbated by usage of opiate and/or opioid drugs.

Diagnosis
Esophagoscopy and laryngoscopy can give direct view of lumens.
Esophageal motility study is useful in cases of esophageal achalasia and diffuse esophageal spasms.
Exfoliative cytology can be performed on esophageal lavage obtained by esophagoscopy. It can detect malignant cells in early stage.
Ultrasonography and CT scan are not very useful in finding causes of dysphagia, but can detect masses in mediastinum and aortic aneurysms.
FEES (Fibreoptic endoscopic evaluation of swallowing), sometimes with sensory evaluation, is done usually by a Medical Speech Pathologist or Deglutologist. This procedure involves the patient eating different consistencies as above.
Swallowing sounds and vibrations could be potentially used for dysphagia screening, but these approaches are in the early research stages.

Differential diagnosis
All causes of dysphagia are considered as differential diagnoses. Some common ones are:
Esophageal atresia
Paterson-Kelly syndrome
Zenkers diverticulum
Esophageal varices
Benign strictures
Achalasia
Esophageal diverticula
Scleroderma
Diffuse esophageal spasm
Polymyositis
Webs and rings
Esophageal cancer
Eosinophilic esophagitis
Hiatus hernia, especially paraesophageal type
Dysphagia lusoria
Stroke
Fahrs disease
Wernicke encephalopathy
Charcot–Marie–Tooth disease
Parkinsons disease
Multiple sclerosis
Amyotrophic lateral sclerosis
Rabies
Cervical SpondylosisEsophageal dysphagia is almost always caused by disease in or adjacent to the esophagus but occasionally the lesion is in the pharynx or stomach. In many of the pathological conditions causing dysphagia, the lumen becomes progressively narrowed and indistensible. Initially, only fibrous solids cause difficulty but later the problem can extend to all solids and later even to liquids. Patients with difficulty swallowing may benefit from thickened fluids if the person is more comfortable with those liquids, although, so far, there is no scientific study that proves that those thickened liquids are beneficial.
Dysphagia may manifest as the result of autonomic nervous system pathologies including stroke and ALS, or due to rapid iatrogenic correction of an electrolyte imbalance.In older adults, presbyphagia - the normal healthy changes in swallowing associated with age - should be considered as an alternative explanation for symptoms.

Treatments
There are many ways to treat dysphagia, such as swallowing therapy, dietary changes, feeding tubes, certain medications, and surgery. Treatment for dysphagia is managed by a group of specialists known as a multidisciplinary team. Members of the multidisciplinary team include: a speech language pathologist specializing in swallowing disorders (swallowing therapist), primary physician, gastroenterologist, nursing staff, respiratory therapist, dietitian, occupational therapist, physical therapist, pharmacist, and radiologist. The role of the members of the multidisciplinary team will differ depending on the type of swallowing disorder present. For example, the swallowing therapist will be directly involved in the treatment of a patient with oropharyngeal dysphagia, while a gastroenterologist will be directly involved in the treatment of an esophageal disorder.

Treatment strategies
The implementation of a treatment strategy should be based on a thorough evaluation by the multidisciplinary team. Treatment strategies will differ on a patient to patient basis and should be structured to meet the specific needs of each individual patient. Treatment strategies are chosen based on a number of different factors including diagnosis, prognosis, reaction to compensatory strategies, severity of dysphagia, cognitive status, respiratory function, caregiver support, and patient motivation and interest.

Oral vs. nonoral feeding
Adequate nutrition and hydration must be preserved at all times during dysphagia treatment. The overall goal of dysphagia therapy is to maintain or return the patient to, oral feeding. However, this must be done while ensuring adequate nutrition and hydration and a safe swallow (no aspiration of food into the lungs)