Corticobulbar involvement

-begins with reduction in tongue mobility
-early in the progression of the disease tongue base posterior movement and pharyngeal contraction are affected – causes residual matter in the pharynx after the swallow
-usually at the same time that as tongue base posterior movement and pharyngeal contraction are affected the pharyngeal swallow becomes delayed
-reduced pressure generated by tongue – causes increasing difficulty as food increases in thickness
-reduced lip closure – drooling and food spillage
-reduced velar function - reduced anterior velar bulging to keep food in the oral cavity while holding a bolus
-later in the disease progression laryngeal elevation is reduced – air way closure is impaired (aspiration)
 

Corticospinal involvement

-do not experience swallowing problems until many years after diagnosis
-the first sign of swallowing problems is slowly progressive weight loss
-characterized by reduced velar movement and reduced pharyngeal wall contraction