Descending necrotizing mediastinitis: trends in a developing country.

Abstract

Descending necrotizing mediastinitis is believed to be a rare and serious complication of odontogenic and oropharyngeal infections. It is associated with a high (up to 40%) mortality rate, which can be attributed to delays in diagnosis and inadequate surgical drainage. Between May 1999 and September 2002, we treated 7 cases at our institution in New Delhi, indicating that such fulminating infections are not so rare in developing countries. In our 7 cases, a high index of suspicion and early computed tomography helped us make a rapid diagnosis and initiate prompt treatment, which resulted in a favorable outcome in 6 cases (mortality rate: 14.3%).

Introduction

Descending necrotizing mediastinitis is believed to be a rare disease that occurs secondary to the spread of odontogenic and oropharyngeal infections through the fascial planes and into the mediastinum. (1) This rapidly spreading infection is associated with a high mortality rate (up to 40%), primarily because of delays in diagnosis and treatment. (2-4)

In this article, we describe our management of 7 cases of descending necrotizing mediastinitis within a 4-year period.

Presentation, diagnosis, and treatment

Between May 1999 and September 2002, we diagnosed and treated 7 cases of descending necrotizing mediastinitis at our institution in New Delhi. The 7 patients included 5 men and 2 women aged 25 to 54 years (mean: 38.7).

All patients were acutely ill when they were brought to the hospital, and all exhibited neck swelling (table 1). Among the 7 patients, 4 had an underlying odontogenic abscess, 2 had a peritonsillar abscess, and 1 had a retropharyngeal abscess (table 1). The duration between the onset of the primary infection and hospitalization ranged from 3 to 10 days (mean: 6.5). All patients had undergone antibiotic treatment prior to hospitalization.

Diffuse edema and erythema of the neck and chest wall were seen in 3 patients, and crepitus was present in 2. Other symptoms included fever, tachycardia, and different degrees of respiratory insufficiency (which warranted tracheotomy in 4 patients). One patient exhibited frank necrosis of the skin and neck fascia and a copious, foul-smelling discharge. Two patients had uncontrolled diabetes. No patient had a history of any immunocompromising condition.

X-rays of the cervicothoracic region revealed a widening of the mediastinum (figure 1) and gas shadows in 3 patients and pleural effusion in 2. Computed tomography (CT) of the cervicothoracic region was performed on all patients, and it heightened our suspicions of descending necrotizing mediastinitis (figure 2). CT identified either neck abscesses extending into the mediastinum or mediastinal emphysema (table 1). Gas shadows were seen in 4 patients. One patient had a retropharyngeal abscess that extended into the mediastinum, and 2 had pleural effusion.

[FIGURE 1-2 OMITTED]

The clinical picture and radiologic findings in each of these 7 cases led us to suspect descending necrotizing mediastinitis. CT helped determine the level of mediastinal involvement so that we could select the optimal surgical procedure for drainage of the abscesses. The interval between hospitalization and diagnosis ranged from 1 to 3 days (table 1).

All patients were started on a combination of broadspectrum antibiotics with adequate coverage of anaerobes until a culture and sensitivity report was obtained.

Surgical treatment involved cervical drainage via single or multiple incisions for all patients, mediastinal drainage through a thoracotomy for 2 patients, and drainage of the retropharyngeal abscess in 1 patient (table 2). The 2 patients who had pleural effusion had them drained through a chest tube.

The drained pus was sent for culture and sensitivity analysis. Bacteriology revealed that all 7 patients had a polymicrobial infection; 5 exhibited mixed aerobes and anaerobes, and 2 had aerobes only (table 2). The most commonly isolated organisms were Staphylococcus aureus, anaerobic streptococci, Bacteroides spp, and Pseudomonas aeruginosa.

Six of the 7 patients recovered completely and were discharged. The patient who died, a 40-year-old woman, presented late to the hospital with toxemia and did not respond to antibiotics. She had uncontrolled diabetes, necrotizing fasciitis, and myositis of the neck with the loss of a large amount of skin. She also had right-sided pleural effusion. She did not respond to the drainage of the mediastinitis and pleural effusion, and she died 5 days following surgery. The mortality rate in our series was 14.3%.

Ultimately, all 7 patients fulfilled the criteria described by Estrera et al for the diagnosis of descending necrotizing mediastinitis: (1) clinical manifestation of severe infection, (2) demonstration of the characteristic imaging features of mediastinitis, (3) features of necrotizing mediastinal infection at surgery, and (4) establishment of a relationship between the disease and an oropharyngeal infection. (3)

Discussion

Descending necrotizing mediastinitis is a less common but more virulent form of mediastinal infection in which the pathology originates in the fascial spaces of the head and neck and extends down into the mediastinum. Infection spreads along three primary routes: via the retrovisceral space (71% of all cases), the perivascular space (20%), and the pretracheal space (7%). (5) Extension via the pretracheal space leads to anterior mediastinal abscess.

Wheatley et al reviewed the English-language literature on descending necrotizing mediastinitis published from 1960 through 1989 and found 43 cases. (4) In 1999, Iyoda et al wrote that 84 cases had been reported in Japan. (6) Although this disease is said to be rare, we encountered 7 cases within a 4-year period.

Most of these infections are polymicrobial and include mixed aerobic and anaerobic organisms. Chow et al reported that anaerobes had been recovered from 94% of patients; 52% had mixed infection and 88% had polymicrobial infections. (7) Alsoub and Chacko found that the most frequently isolated aerobic organisms were Bacteroides spp, streptococci, and staphylococci. (8) Estrera et al emphasized that the symbiosis between anaerobic and aerobic organisms results in increased virulence and spread, which becomes a fulminant necrotizing process. (3) The most common organisms in our series were S aureus, anaerobic streptococci, Bacteroides spp, and P aerztginosa.

Patients with descending necrotizing mediastinitis usually present with toxic shock and respiratory difficulty. Other presenting signs may include erythema and edema of the neck and upper chest and, in severe fulminant infections, frank necrosis of the skin, fascia, and muscles. Crepitus is present in some cases.

X-ray examination of the neck and chest may demonstrate mediastinal widening and gas bubbles, which become evident late in the course of the disease. (9) CT has proved to be useful in helping clinicians establish an early diagnosis with great confidence. CT findings can also help guide the choice of surgical approach for draining the mediastinum and for conducting postoperative follow-up. If only the superior mediastinum is involved and the infection is contained above the level of T4 posteriorly and the tracheal bifurcation anteriorly, the mediastinum can be drained transcervically. If infection has spread below this level, mediastinal drainage is best accomplished via a subxiphoid or transthoracic approach in addition to the transcervical route. (3,4) Although some authors recommend transthoracic mediastinal drainage routinely for all these patients, we have found that transcervical drainage is sufficient if the diagnosis is made early and the disease is limited to the superior mediastinum.

Good management also entails the prompt use of broad-spectrum antibiotics. The choice of antibiotic can be changed once the culture and sensitivity report has been obtained. (10)

Another important factor in the management of these patients is the use of tracheotomy; in fact, tracheotomy might be the integral part of a patient's treatment. (11) Wheatley et al proposed performing a tracheotomy in all patients. (4) Tracheotomy is preferred over endotracheal intubation because esophageal and cervical edema may make it difficult to regain control in case the endotracheal tube becomes accidentally dislodged after cervical drainage. We recommend tracheotomy only for patients who are in severe respiratory distress.

Aggressive surgical debridement is required for patients with frank necrosis of the tissues. (10,12)

Complications of descending necrotizing mediastinitis include compromise of pulmonary function by pleural and extrapleural effusion, exsanguination from vessel erosion, cranial nerve palsies (in nerves IX, X, and XII), epidermal abscess, disseminated intravascular coagulation, and multiorgan failure. (7,13) Two of our patients presented with pleural effusion.

The high mortality rate is a matter of concern. The two primary reasons for the high number of fatalities are (1) the fulminant and rapidly spreading nature of the infections and (2) the delay in diagnosis and, hence, treatment. The reported mortality rates associated with this disease in Europe and the United States range from 17 to 40%. (2-4) The low mortality rate in our series (14.3%) may be attributable to the high index of suspicion we maintain in cases of odontogenic and peritonsillar abscess and to obtaining CT to identify the disease at an early stage when it can still be controlled.

We emphasize that if this disease is diagnosed at an early stage before the abscess has spread beyond T4 posteriorly and the tracheal bifurcation anteriorly, cervical drainage of the mediastinal infection can be effective. Only 1 of our patients died, and this was because she had a fulminant infection and uncontrolled diabetes. She presented at a late stage with necrosis of the skin, fasciitis, myositis, pleural effusion, and respiratory inefficiency. Although we initiated immediate tracheotomy, surgical debridement, and insertion of a chest tube to drain the pleural effusion, the patient succumbed to multiorgan failure brought on by toxemia.

In an era when antibiotics have lowered the incidence of fulminant infections worldwide, we encountered 7 cases of descending necrotizing mediastinitis in a span of less than 4 years, which indicates that fulminant infections are still not so rare in developing countries such as ours. Still, the survival rate in our series was high because we were able to clinch the diagnosis early so that prompt and appropriate surgical drainage could be performed.

References

(1.) al-Ebrahim KE. Descending necrotising mediastinitis: A case report and review of the literature. Eur J Cardiothorac Surg 1995;9: 161-2.

(2.) Isaacs LM, Kotton B, Peralta MM, Jr., et al. Fatal mediastinal abscess from upper respiratory infection. Ear Nose Throat J 1993; 72: 620-2, 624-6, 631.

(3.) EstreraAS, Landay MJ, Grisham JM, et al. Descending necrotizing mediastinitis. Surg Gynecol Obstet 1983;157:545-52.

(4.) Wheatley MJ, Stirling MC, Kirsh MM, et al. Descending necrotizing mediastinitis: Transcervical drainage is not enough. Ann Thorac Surg 1990;49:780-4.

(5.) Moncada R, Warpeha R, Pickleman J, et al. Mediastinitis from odontogenic and deep cervical infection. Anatomic pathways of propagation. Chest 1978;73:497-500.

(6.) Iyoda A, Yusa T, Fujisawa T, et al. Descending necrotizing mediastinitis: Report of a case. Surg Today 1999;29:1209-12.

(7.) Chow AW, Roser SM, Brady FA. Orofacial odontogenic infections. Ann Intern Med 1978;88:392-402.

(8.) Alsoub H, Chacko KC. Descending necrotising mediastinitis. Postgrad Med J 1995;71:98-101.

(9.) Stevens DL. Streptococcal toxic-shock syndrome: Spectrum of disease, pathogenesis, and new concepts in treatment. Emerg Infect Dis 1995;1:69-78.

(10.) Allen D, Loughnan TE, Ord RA. A re-evaluation of the role of tracheostomy in Ludwig's angina. J Oral Maxillofac Surg 1985;43:436-9.

(11.) Adams EM, Gudmundsson S, Yocum DE, et al. Streptococcal myositis. Arch Intern Med 1985;145:1020-3.

(12.) Alexander DW, Leonard JR, Trail ML. Vascular complications of deep neck abscesses. A report of four cases. Laryngoscope 1968;78:361-70.

(13.) Ris HB, Banic A, Furrer M, et al. Descending necrotizing mediastinitis: Surgical treatment via clamshell approach. Ann Thorac Surg 1996;62:1650-4.

From the Department of Otolaryngology, Safdarjung Hospital, New Delhi.

Reprint requests: Neena Chaudhary, MS, K- 19 Hauz Khas Enclave, New Delhi-110016, India. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

Table 1. Preoperative findings

     Age/   Primary           Clinical
Pt   sex    infection         manifestation         CT finding

1    39/M   Dental abscess    Fever, toxic look,    R submandibular and
                              R submandibular and   cervical abscess
                              neck swelling,        with anterior
                              erythema              mediastinitis

2    28/F   Dental abscess    Fever, dyspnea, ill   B cervical abscess
                              look, B neck          with anterior
                              swelling up to the    mediastinitis
                              anterior chest wall

3    37/M   Peritonsillar     Fever, B swelling     B cervical abscess
            abscess           of the entire neck    with anterior
                                                    mediastinitis

4    54/M   Dental abscess    Fever, toxic look,    R submandibular and
                              dyspnea, R            cervical abscess
                              submandibular and     with posterior
                              neck swelling with    mediastinitis and R
                              erythema up to the    pleural effusion
                              upper chest

5    40/F   Retropharyngeal   Very toxic look,      B cervical abscess
            abscess           dyspnea, B neck       with mediastinal
                              swelling with an      emphysema and R
                              8 x 7-cm wound        pleural effusion
                              sloughing over the
                              anterior and the R
                              side of the neck,
                              foul-smelling
                              greenish discharge

6    48/M   Dental abscess    R submandibular and   R cervical abscess
                              neck swelling,        with anterior
                              erythema              mediastinitis on
                                                    the R side

7    25/M   Peritonsillar     L submandibular and   L cervical abscess
            abscess           neck swelling         with posterior
                                                    mediastinitis

     Primary
Pt   infection         Interval *

1    Dental abscess       2

2    Dental abscess       1

3    Peritonsillar        2
     abscess

4    Dental abscess       3

5    Retropharyngeal      1
     abscess

6    Dental abscess       3

7    Peritonsillar        2
     abscess

* Number of days between presentation and diagnosis.

R = right; B = bilateral; L = left.

Table 2. Intra- and postoperative data

Pt   Surgery                      Microbiology                Outcome

1    R cervical drainage of the   Staphylococcus aureus,      Survived
     abscess, anterior cervical   Bacteroides
     drainage of the              melaninogenicus
     mediastinitis

2    B cervical drainage of the   S aureus, Enterobacter      Survived
     abscess, tracheotomy,        spp
     cervical drainage of the
     mediastinitis

3    B cervical drainage of the   Pseudomonas aeruginosa,     Survived
     abscess, cervical drainage   B melaninogenicus,
     of the mediastinitis         anaerobic streptococci

4    R cervical drainage of the   Streptococcus pneumoniae,   Survived
     abscess, R thoracotomy       Enterococcus spp
     and chest tube insertion,
     tracheotomy

5    B cervical drainage of the   Escherichia coli, S         Died
     abscess, debridement of      aureus, Bacteroides
     the wound, R thoracotomy     fragilis, anaerobic
     and chest tube insertion,    streptococci
     tracheotomy

6    R cervical drainage of the   P aeruginosa, S aureus,     Survived
     abscess, cervical drainage   Bacteroides spp
     of the mediastinitis,
     tracheotomy

7    Cervical drainage of the     Streptococcus viridans,     Survived
     abscess and the              Fusobacterium spp,
     mediastinitis                anaerobic streptococci

R = right; B = bilateral.