Neurogenic dysphagia: the role of the neurologist
- University of Wales College of Medicine
- Heath Park, Cardiff, CF4 4XN, Wales
- Professor C M Wiles, University of Wales College of Medicine, Heath Park Cardiff, Wales CF4 4XN. Telephone 0044 1222 743798; fax 01222 744166; email wiles{at}cardiff.ac.uk
The dual role of the oropharynx as a conduit for air and nutrition means that neurogenic dysphagia causes morbidity or death from (1) upper airway obstruction; (2) aspiration causing chemical pneumonitis or small airway obstruction with distal collapse and secondary infection; (3) dehydration and malnutrition
A slowed ability to eat a meal, loss of salivary control with drooling, episodic coughing, and choking and nasal regurgitation also cause considerable distress.
As well as their role in the diagnosis of the underlying disease, neurologists are well placed to help elucidate the mechanism of the dysphagia and to give advice in a multidisciplinary context about dysphagia management bearing in mind the patient’s diagnosis, prognosis, and disability. Understanding of normal bulbar function and the methods of assessment and treatment have each improved in recent years.
Normal function1-3
Cranial nerve involvement in bolus preparation (V—motor and sensory— and VII), bolus propulsion (X and XII), and palatal elevation (X) is well appreciated. The airway is protected by apposition of the true and false vocal cords and of the arytenoids against the base of the epiglottis (the sphincteric action of the larynx); the epiglottis inhibits direct contact of the bolus with the laryngeal vestibule (all X). Upward and forward movement of the hyoid and larynx (V, VII, C1–3) enhances airway protection and pulls open the relaxed upper oesophageal sphincter. Breathing is centrally inhibited during the swallow (deglutition apnoea) and, after it, structures return to their original position passively, or aided by the infrahyoid muscles.
Swallowing was originally perceived as a brainstem reflex triggered by more or less “phagetic agents”4: subsequently the sequence of activation of the muscles involved in deglutition was delineated5 and the concept developed of a central pattern generator anatomically related to the nucleus ambiguus and the nucleus of the tractus solitarius and under …
