What would make the tongue swell and paralyze the vocal cords?

The condition is caused by damage to nerves going to the vocal cord - the nerve impulses in the larynx (voice box) are interrupted, resulting in paralysis of the vocal cord muscles. It can also be caused by brain damage.

Patients with vocal paralysis typically experience hoarseness, vocal fatigue, mild to severe reduction in speech volume, a pain in the throat when speaking, and swallowing things down the wrong way and choking.

The vocal cords, as well as allowing us to produce utterances (speak, etc.) also protect the airway, preventing food, drink and saliva from entering the trachea (windpipe). In extreme cases the resultant choking can lead to death.

Individuals with vocal cord paralysis may find the effectiveness of coughing, swallowing or sneezing in removing laryngeal area waste is undermined reduced vocal cord mobility. This may result in accumulations in the area, allowing for bacterial and viral colonization, and subsequent infections and throat discomfort.