Case report

A 51-year-old man presented to the emergency department because of increasing mandibular swelling and fever of 8 days duration related to a painful tooth in his left mandible. He denied any medical condition. He smoked 30 cigarettes a day. The physical examination revealed a poor general status with submandibular swelling and erythema, which extended to the clavicles. Subcutaneous crepitus was palpable in the anterior aspect of the neck and supraclavicular region ( Fig. 1 a ). The remainder of the physical examination was unremarkable.

(a) Patient’s clinical aspect on arrival. (b) Preoperative CT scan showing gas extension.

The patient’s vital signs were as follows: blood pressure 86/59 mm Hg, heart rate 122 beats/min, and temperature 37 °C. The white blood cell count was 14.8 × 10 ⁹ /L, the creatinine 2.29 mg/dL, urea 170 mg/dL, and sodium 121 mM/L. The blood glucose level was higher than 800 mg/dL. Amoxicillin–clavulanic acid and clindamycin were initially prescribed. Blood pressure did not improve after infusion of crystalloids, so a perfusion of norepinephrine was started.

A preoperative computed tomography (CT) scan showed a large amount of gas extending subcutaneously from the upper anterior chest wall and the anterolateral neck bilaterally up to the paramandibular region ( Fig. 1 b).

The patient was taken to theatre within 5 h from admission for drainage of the abscess and gas. Several incisions in the skin and platysma muscle and blunt dissection through all cavities were made. Immediately, a foul odour was noticed. The dissected planes were copiously irrigated with povidone–iodine and saline solution. Drains were inserted and secured. There were no signs of necrosis on the skin at that time, so radical debridement or excisions were not performed. The mandibular left second molar was extracted as the origin of the process. The maxillary right and left second molars were carious and extracted as well. Specimens were sent for culture and antibiotic sensitivity testing. Streptococcus sp. and Candida albicans were isolated. Piperacillin–tazobactam and antifungals were prescribed.

The patient remained intubated because of a concern for his airway. He was transferred to the intensive care unit (ICU) with a diagnosis of CNF of odontogenic origin, septic shock with acute renal failure, and diabetic ketoacidosis, being the first appearance of a previously unknown diabetes mellitus.

On day 2 a large area of the skin on the neck appeared necrotic, therefore the patient was taken back to theatre and all non-viable tissue including skin, fascia, and muscle was excised until vital vascularized tissue was reached. He underwent three further extensive debridements of the infected tissue of the neck and chest under general anaesthesia on days 4, 5, and 8, eventually losing 12% of his total body surface area ( Fig. 2 a ). An elective tracheostomy was performed on day 4. Wound care and dressing was continued every 2 days. He required haemodynamic support with vasoactive drugs until day 11, and insulin therapy throughout all of his stay in the ICU, with poor control of the blood glucose levels. He developed a polyneuropathy of the critically ill patient and the rehabilitation team was consulted.

(a) Surgical wound after complete debridement. (b) Final outcome at 6 months after reconstruction.

The reconstructive operation was scheduled on day 39, once the patient was stable and strong enough for it. As of the large surface to cover and the poor systemic condition of the patient, myocutaneous flaps were deemed inadequate. A new debridement of the wound was performed and a split-thickness skin graft was harvested with a dermatome from his bilateral anterior and lateral thighs, meshed at 1:3. A total coverage of the skin defect was achieved. No complications at either the donor or grafted sites were observed. The patient was decannulated on day 51 without incidence, and was transferred from the ICU to the maxillofacial ward. He was discharged on day 75. Both the grafts and the bilateral thigh donor sites healed very well and did not require any further surgery or procedure ( Fig. 2 b).

Discussion

CNF is uncommon. Tsai et al. reported 54 cases of NF and noted that only two cases involved the head and neck region. Most cases of CNF are odontogenic in origin. All infections in the series studied by Wong et al. were odontogenic in origin, and lower molars were the most common teeth of origin, as in our patient. Other reported causes include tonsillar or pharyngeal trauma infections, postoperative wound infections, pre-existing ulcers, and insect bites.

Any deep space neck infection can potentially lead to NF. It is most often a mixed bacterial synergistic infection involving both aerobes and obligate anaerobes. The virulence of the oral aerobes and anaerobes is responsible for the fulminant course of the infections. Antimicrobial therapy must cover Gram-positive, Gram-negative, and anaerobic bacteria. Once bacterial cultures and sensitivities are established, antibiotic therapy should be sensitivity-directed. Consultation with a microbiologist is recommended.

General risk factors for NF include diabetes mellitus, peripheral vascular disease, intravenous drug use, alcoholism, immunosuppression, obesity, and old age. NF frequently occurs in people with some form of immune deficiency or more than one chronic underlying illness, where impaired leucocyte function may be a contributing factor. Diabetes mellitus is the most common. Delamaire et al. found that all steps of polymorphonuclear neutrophil functioning are altered in diabetic patients, which may increase the risk of vascular complications and infectious episodes. On the other hand, Lin et al. reported 47 cases of NF of the head and neck and they noted no statistically significant differences in risk factors, such as age, toxic habits, underlying medical disease or trauma, or surgical history, when comparing survivors and non-survivors. They found that the most common associated systemic disease was diabetes (in 72.3% of the 47 cases) and it was poorly controlled in 24 patients. Nevertheless it was not a significant prognostic factor ( P = 0.29). They also compared the initial blood glucose levels and found no significant difference between survivors and non-survivors ( P = 1.0). Flanagan et al. reported a length of hospitalization twice as long for diabetic patients compared to non-diabetic patients in their study.

Early recognition of this life-threatening disease is critical for a successful outcome. The initial signs are frequently very similar to those of acute cellulitis or an abscess, so a high index of suspicion is needed. Some findings can point to the diagnosis, such as odontogenic infections that spread to the lower neck, abnormal accumulation of gas in the tissues, very rapid progression, and orange-peel appearance of the skin. Cutaneous anaesthesia, well-defined areas of erythema and tenderness, and a dusky or grey skin discoloration should also raise a suspicion of NF. Subcutaneous crepitus may not be present. The infection quickly spreads and the patient suffers from fever and pain of the affected area. Systemic symptoms become more severe, with typical signs of septicaemia. The patient gradually goes into septic shock and multi-organ failure.

Even if NF is not immediately suspected, patients with extensive abscess formation generally undergo prompt surgical drainage. The lack of bleeding and the greyish fascia and muscles seen intraoperatively, and the gradual cyanotic skin discoloration, confirm the diagnosis. The pathogenesis behind this necrotic development is thought to be endarteritis obliterans in the nutrient vessels going through the fascia. Our patient presented with fever, neck swelling and erythema, and subcutaneous emphysema. As of his poor general status, a CT scan was immediately obtained showing the marked subcutaneous emphysema and the mandibular abscess.

A normal CT does not rule out NF. Not every case will present with frank abscess formation or subcutaneous air. In these cases, serial monitoring should be considered if the patient fails to improve clinically. There is emerging evidence supporting a role for magnetic resonance imaging in the early differentiation of non-necrotizing cellulitis from NF.

Wide debridement of the affected tissues including all necrotic skin and muscle must be performed. Apparently normal tissues may become involved soon after surgery, and repeated debridements are often necessary. Aggressive surgery removes the source of infection and toxins, and removal of infarcted tissue improves the penetration of antibiotics. Early thorough debridement is essential. Multiple reviews have demonstrated that debridement within 24 h is important for lowering mortality. Indeed, delayed recognition and insufficient drainage are the primary causes of the high mortality. Interventional radiology might allow additional drainage in critically ill patients who cannot tolerate further surgical insult. Our patient was taken to the operating room within 5 h from admission and a total of six operations were performed under general anaesthesia; multiple bedside minor debridements under sedation were also performed in the ICU.

Immediate reconstruction after treatment of NF is contraindicated. Multiple debridement surgeries should be performed to ensure a stable wound with good vascular granulation.

Once the patient is stable and the skin edges are able to stick to the wound, reconstruction can be considered. The reconstructive options depend on the local, regional, and systemic disease processes. Traditionally, reconstruction has been performed with skin grafts and flaps, as in burn reconstruction. In cases of massive soft tissue defects with autograft reconstruction limited by donor-site availability, artificial alternatives may be useful. Rai et al. described the use of amniotic membrane dressings over the surgical wound to increase the rate of healing and granulation tissue formation, making the defect smaller and more suitable to accept a secondary reconstructive procedure if required. They also reported a lower frequency of dressings, decreased pain and inflammation, and minimal long-term cosmetic and functional deformities without the need for a secondary reconstructive procedure in some cases. Regional or free flaps are the recommended procedure for large defects as they allow good mobility of the skin. Pectoralis major, latissimus dorsi, and trapezius flaps have been used for these means. Free flaps such as the anterolateral thigh flap or the scapular flap can provide a larger surface area of coverage, and several flaps may be harvested if necessary. Taking into consideration all the options, we chose to use split-thickness skin grafts from the thighs because of the large surface to cover and the poor systemic condition of the patient. We did not find any communication between the neck and the oral cavity, and the great vessels in the neck were not exposed. For these reasons a split-thickness skin graft seemed to be the best option for our patient. We did not observe any skin retractions or limitations of the mobility of the neck at the 6-month follow-up.