Causes Of Dysphagia

\section{What can cause dysphagia} There are different causes for dysphagia that can be classified in three categories : neurological, structural and mechanical, and the neck or head condition \cite{clave}, \cite{paper5}, \cite{cook}, \cite{clave2}. \subsection{Patients with neurological diseases:}

Neurological diseases can cause dysphagia because muscles involved in the swallowing process are less controllable by the brain. Moreover, the sensors that should detect the bolus in the pathway, may not detect it at all or may detect it with an important delay and so the epiglotis can not be closed on time, that would provoke the entry of the bolus in the airway. 64-78\% and 40-81\% of people who had stroke suffer from oropharyngeal dysphagia respectively during the acute phase and during the chronic phase \cite{martino}.
People, who had suffer from sever acute traumatic and chronic traumatic brain injuries, are more than, respectively 70\% and 50\%, to have esophageal dysphagia \cite{terre}. Other famous neurological cause is Parkinson. More than 52\% of patients who have Parkinson's undergo dysphagia \cite{clave2}, \cite{terre}. Furthermore, patients who have dementia, sever amyotrophis sclerosis or advance occulopharyngeal muscular dystrophy are 80-100\% to also suffer from dysphagia \cite{clave}, \cite{Engel_Hoek_2012}. It exists, also, some neuromuscular disease as achalia also named cardio spasm or esophageal aperistalsis. This disease is the failure of the lower esophageal sphincter (LES) muscle to relax. The consequences are low intra esophageal pressure, dilatation of the esophagus or its compression that can create functional obstruction.The hypercontractil esophagus is an other neuromuscular condition that can cause dysphagia as achalasia can \cite{clave}. \subsection{Patients with head or neck