Necrotising fasciitis is a serious, destructive and progressive soft tissue infection that can quickly become life-threatening. The disease is divided into two subtypes based on the causative bacteria. Type 1 is caused by streptococci (not group A), enterobacteria or obligate anaerobes, and type 2 is caused by group A streptococci (12).
The condition begins with thrombosis in small blood vessels in the periphery of the focus of infection, leading to acute inflammation and to oedema in subcutaneous tissues and possibly the skin (Figure 3). Necrosis then occurs in the infected tissue. This spreads rapidly along the superficial fascia, nerves, arteries and veins (12). Left untreated, the majority of patients will develop sepsis within 48 hours (12). Owing to its rich vascular supply, necrotising fasciitis rarely occurs in the head and neck area, with a reported annual incidence of only 2 cases per 1 000 000 population (12). The most common cause of necrotising fasciitis in the head and neck area is odontogenic infection, but the condition can also occur secondary to pharyngitis, tonsillitis, acute otitis media and dermatological infections (12). If an odontogenic origin of necrotising fasciitis is suspected, the patient should be referred immediately to a maxillofacial surgery department or alternatively to the nearest department of otorhinolaryngology or plastic surgery.
Contrast CT is necessary to determine the location and extent of the infection, as well as to reveal any primary focus, for example periapical lucencies on tooth roots. Contrast CT can furthermore show asymmetric fascial thickening, gas bubbles along the fascial planes, oedema of muscle and soft tissues, and possibly fluid accumulation in fascial spaces indicating an abscess (13). Prompt treatment with radical surgical debridement of necrotic tissue and antibiotics is important. Norwegian national guidelines recommend combination therapy with cefotaxime and metronidazole with the addition of clindamycin if indicated (14).