Introduction

The word mediastinum is not an everyday term. It is possible to hear 'chest' a hundred more times than mediastinum. While the mediastinum is not the chest, it is an essential component of the chest. Withstanding its importance, like any part of the body, it can be prone to trauma.

Major trauma is prevalent. In England, it is the primary cause of death among those under 40. Unlike its umbrella term, mediastinal trauma is a rare occurrence. It is a high-risk affair that could lead to life-threatening conditions or death. One such condition is acute mediastinitis or trauma-induced mediastinitis.^{1, 2}

In trauma-induced mediastinitis, death often occurs. The reason is that most patients do not make it to the hospital due to misdiagnosis. Despite this, trauma-induced mediastinitis can have a favourable outcome in most cases. It only holds if diagnosis and treatment start early enough.^2,3

Overview of mediastinitis 

What is the mediastinum?

When you look in the mirror, you recognise the part below your neck as your chest. The chest has several structures other than your lungs, bronchi, and windpipe. The mediastinum is like a luxurious mansion. It houses essential organs like the heart, esophagus, thymus, great blood vessels, trachea, lymph nodes, nerves, and thoracic spine. It doesn't just house them it keeps them safe. Despite this, the mediastinum also acts as a divider between the two pleural sacs.⁴ 

What is mediastinitis?

Mediastinitis is the inflammation of the mediastinum. It can affect its associated structures. It can either be acute or chronic. These top three events often cause acute mediastinitis:⁵ 

1. Sternotomy following cardiac revascularisation of both internal arteries: Acute mediastinitis occurs here due to infection with Staphylococcus aureus
2. Esophageal perforation: It occurs as an adverse effect of medical treatments. The oesophageal flora present causes acute mediastinitis
3. Descending necrotising mediastinitis: it occurs when beta haemolytic streptococcus develops. The bacteria account for 71.6% of acute mediastinitis cases

Overview of trauma-related mediastinitis

What is a trauma and a traumatic event? 

Trauma, in this context, refers to a sudden injured tissue. It is present when a traumatic event occurs. Traumatic events are sudden, violent occurrences that can lead to tissue injury. They can be perforating, blunt, or decelerating. Some traumatic events include:

• Surgeries
• Gunshots
• Stab wounds
• Falls
• Road Traffic Accidents (RTA)

What is traumatic mediastinitis?

It is an inflammatory condition that occurs because of the breach of integrity of the mediastinum caused by a traumatic event. For example, it can be a penetrating wound that damages structures like the oesophagus or trachea, causing inflammation and a possible infection in the mediastinum.⁶  

How does mediastinal trauma occur?

Any traumatic event can give rise to mediastinal trauma. Regardless, It is important to note the differences between mediastinal and chest trauma. Chest trauma is a much broader term covering all tissue injury to the chest structures. Mediastinal trauma, in contrast, narrows its focus to structures within its house. Some examples of mediastinal trauma include:⁶

• Blunt aortic injury
• Mediastinal shift
• Parasternal Injury 

What are the causes of traumatic mediastinitis?

Acute mediastinitis can occur after traumatic events from diseases or medical procedures. Such instances are:

• Boerhaave’s Syndrome: it occurs due to overeating or overindulging in drinks. This habit leads to forceful vomiting, putting the oesophagus at risk of rupture. If rupture occurs, a traumatic event has set in. This traumatic event can lead to acute mediastinitis³
• Esophageal Perforation:  occurs due to ingestion of foreign bodies and medical procedures. Examples of medical procedures that cause oesophagal perforation include:³
  • Upper endoscopy
  • Endoscopic mucosal resection 
  • Oesophageal obturator airway

• Cardiothoracic surgery: surgical procedures are traumatic events. Surgeries like the following can cause acute mediastinitis as a post-operative complication. They include:²
  • Heart-lung transplant
  • Heart transplant 
  • Cardiac surgeries
  • Sternotomy 

Despite this, factors like the following play a significant role in making patients vulnerable to acute mediastinitis. 

• Comorbidity
• Age
• Type of graft 
• Surgery duration 
• Perfusion time 
• Gastric rupture from blunt trauma: Although rare, it is possible. The resultant events lead to posterior mediastinitis occurring when infectious agents are present⁷

What are the symptoms of trauma-related mediastinitis?

Symptoms of trauma-related mediastinitis depend on the cause. For example, in oesophagal rupture, acute mediastinitis is sudden. It presents with:

• Substernal pain: Radiation of substernal pains indicates the type of acute mediastinitis present. It could be acute superior, posterior, or inferior mediastinitis.  When it radiates to the neck and ear, it is acute superior mediastinitis. If the pain radiates between the chest and scapular, it is either acute inferior or posterior mediastinitis^3,6

In cardiothoracic post-operation complications, acute mediastinitis presents with:^2,6

• Bacteremia
• Signs of wound infection 
• Drainage from sternotomy incision 

Despite this, classic signs of an inflammatory condition are present in all cases. Symptoms like the following are a constant:

• Tachycardia
• Fever 
• Chills
• Other systemic signs of infection

How is trauma-related mediastinitis diagnosed?

Diagnosis of trauma-induced mediastinitis is not a linear affair. It depends on the primary condition it brings about. For example : 

• Cardiothoracic Surgery: Signs of inflammation are often spotted. Computed tomography can detect signs like tissue drainage and swelling.²
• Oesophageal rupture:  A physician carries out a physical examination to check for:^3,6
  • Tenderness in the sternum and clavicular area
  • Crepitus
  • Hamman sign 
  • Tracheal deviation
  • Signs of compression of the mediastinal structure
• Oesophageal perforation:^3,6
  • Chest radiograph: The physician looks for two criteria to make a diagnosis. These criteria are the benchmarks of acute mediastinitis. They are:
    • Diffuse widening of the mediastinum
    • Air in the mediastinum and soft tissues 

How to manage trauma-related mediastinitis?

Like symptoms and diagnosis, management follows the same route.^2,3,6

• Oesophageal rupture: A surgical repair with administration of appropriate antibiotics
• Oesophageal Perforation:
  • Surgical repair of the oesophagus
  • Percutaneous drainage of the mediastinal abscess
  • Administration of appropriate antibiotics
• Cardiothoracic surgery:
  • Administration of systemic antibiotics
  • Early surgical exploration to debride and drain abscesses
• Gastric rupture: The best way to treat it, as seen in the case study, is video-assisted thoracic surgery (VATS)

What are the complications of trauma-related mediastinitis?

Trauma-induced acute mediastinitis can lead to various complications. When undiagnosed or treated early, death becomes a reality. Some complications associated with acute mediastinitis following oesophageal rupture include:^2,3,6

• Abscess formation
• Extensive pleural emphysema
• Persistent esophagocutaneous fistula 

How to reduce the risk of trauma-related mediastinitis?

The best strategy for avoiding trauma-related mediastinitis is to prevent traumatic events. You can do this by: 

• Follow instructions when operating heavy equipment 
• Avoid texting and driving 
• Don't drive drunk 
• Avoid operating heavy machinery when sleepy 
• Avoid over-eating or over-drinking 
• Watch out for road signs while driving 
• Obey traffic rules 

The health team takes adequate preventive steps in traumatic events such as surgery. The reason is that they are trying to prevent nosocomial infections like Staphylococcus aureus. Some surgical preventive measures include:

• Appropriate handwashing techniques
• Aseptic surgical techniques 
• Sterilisation of the room 
• Sterile preparation of equipment 
• Use of personal protective equipment

Summary

Traumatic events are often neither avoidable nor predictable. They can cause devastating to life-threatening complications. Most of the time, this complication results in the victim's death. Despite this, take active preventive steps for a fighting chance. A good mantra to keep is 'safety first.'

Trauma-related mediastinitis presents as acute mediastinitis. It arises from traumatic events that could range from surgery to actual accidents. When you think about diseases, you expect a path to their management and presentation. This reasoning doesn't apply to trauma-induced mediastinitis. Its symptoms, management, and diagnosis don't follow that path. The reason is simple. Acute mediastinitis, in this context, occurs as a secondary condition. Hence, the primary condition determines the management, treatment, diagnosis, and symptoms.

Misdiagnosis is still one of the reasons for delayed treatment and eventual death. It is helpful to know that acute mediastinitis is a medical emergency, and treatment must be immediate once diagnosed.