Descending necrotizing mediastinitis

A diagnostic

approach to the mediastinal masses. Oblique-coronal multiplanar reconstruction of contrast-enhanced CT scan of a 33-year-old woman with a descending necrotising mediastinitis. Hypodense para-aortic areas correspond with fluid-collections (arrows) that extend to the retroperitoneum. Pleural effusion in the fissure is also be seen (open arrow). Note the visceral space involvement (arrowhead)

insightsimaging.springeropen.com • CC-by-2.0

Radiopaedia • CC-by-nc-sa 3.0 • de

Descending necrotizing mediastinitis is a severe form of mediastinitis and refers to an acute, polymicrobial infection of the mediastinum that usually spreads downwards from oropharyngeal, cervical, and odontogenic infection.

Epidemiology

Associations

diabetes: more than one-third of patients were noted as having diabetes in one study

Pathology

Continuity of the fascial planes between the neck and mediastinum may allow infection to spread from the oral cavity and neck into the mediastinum. Three potential pathways for the spread of infection may exist from the neck to the mediastinum

retropharyngeal-retrovisceral route to the posterior mediastinum (considered most common)
pretracheal route to the anterior mediastinum
lateral pharyngeal route to the middle mediastinum

Microbiology

Commonly reported aerobic bacteria include

Streptococcus spp. (S. constellatus, S. intermedius, S. agalactiae, S. mitis).

Commonly reported anaerobic bacteria include

peptostreptococcus, Bacteroides fragilis, Prevotella, and fusobacterium

Radiographic features

Plain radiograph

Neck radiography may show subcutaneous emphysema, prevertebral soft-tissue swelling, mediastinal gas, and/or superior mediastinal widening.

CT

CT chest may show mediastinal gas +/- fluid collections. Accompanying CT neck findings include thickening of the subcutaneous tissues in the neck, thickening or enhancement of cervical fascia and muscles, fluid collections, and enlarged lymph nodes.

CT classification

A CT classification system has been proposed by Endo et al. to define the extent of disease and aid patient management.

type 1: localized above the carina
type 2: below carina
- type 2a: extends to the lower anterior mediastinum
- type 2b: extends to the anterior and posterior mediastinum

Treatment and prognosis

It can carry high morbidity and mortality with reported mortality rates ranging from 30-50%.

Patients with type 1 disease may not always require aggressive mediastinal drainage. Those with type 2b disease are advised to undergo complete mediastinal drainage and débridement via thoracotomy, while those with type 2a disease may benefit from subxiphoid mediastinal drainage without sternotomy .

History and etymology

It was first reported by Pearse in 1938.