With posterior compartment infection, swelling of the posterior pharyngeal wall and parotid space develops. Trismus is minimal or absent. Involvement of the internal jugular vein within the carotid sheath causes shaking chills, high fever, and bacteremia. Erosion of the internal, external, or common carotid arteries causes profuse hemorrhage. Inferior spread of infection results in neck swelling that obliterates the space beneath the angle of the mandible.
Treatment is surgical drainage plus antimicrobials.
Antimicrobials suggested for submandibular space infections are appropriate since the microbial flora causing these infections tend to be similar. An infection ascending from the mouth, usually due to Staphylococcus aureus, which can involve the opening to Stensen's duct. The infection typically occurs in elderly or chronically ill patients with a dry mouth from decreased oral intake, from drugs with anticholinergic effects, or after general anesthesia. Fever, chills, and unilateral pain and swelling develop. The gland is firm and tender, with erythema and edema of the overlying skin.