Middle-aged diabetic women with tooth extraction had ipsilateral swelling over middle one-third of sternocleidomastoid and displacement of tonsils towards contralateral side. Diagnosis is

The most common aetiology of parapharyngeal abscess in an adult is tooth extraction. The infection produces a triad of symptoms such as prolapse of tonsil and tonsillar fossa, trismus, and external swelling behind the angle of the jaw. Retropharyngeal abscess is commonly seen in children below 3 years. In Ludwig's angina, the floor of the mouth is involved. (Ref: Diseases of ENT, PL Dhingra, 7th edition, pg no. 301)