What Is Retropharyngeal Abscess

Introduction

A retropharyngeal abscess is a collection of pus that forms in the neck space located behind the pharynx (throat) and in front of the spine. This space is known as the retropharyngeal space. The abscess typically develops as a result of a bacterial infection, often starting in the lymph nodes or tissues in the throat. It is more common in children under the age of five and occurs usually in the period between winter and spring.¹  

Location in the Neck

The retropharyngeal space lies along the length of the neck, its boundaries include:

• Superiorly: the base of the skull
• Anteriorly: buccopharyngeal fascia. This is a layer of tissue located in the neck and throat region. It provides structural support and helps separate the various tissues and structures in the neck and throat region.
• Posteriorly: Alar fascia. This wing-like structure separates the retropharyngeal space into anterior (true retropharyngeal space) and posterior (danger zone). The danger zone serves as a potential pathway for retropharyngeal infections to reach the chest.
• Inferiorly: Continuous with the chest (posterior mediastinum)

Causes

Younger children under 5 years old

The retropharyngeal space has a chain of lymph nodes that drain the nasopharynx, tonsils and middle ear, making upper respiratory tract infections the leading cause of the retropharyngeal abscess.² 

As children grow, these retropharyngeal lymph nodes become smaller and erased, reducing the risk.² 

In older children and adults

Trauma to the throat becomes a more likely cause of abscess formation.²

Tonsil and dental infections may also cause a retropharyngeal abscess.

Bacterial infections

Retropharyngeal abscess is usually caused by various combinations of bacteria (polymicrobial infection) e.g. streptococcus pyogenes and staphylococcus aureus .²    

Other causes include H.influenzae and M. tuberculosis and anaerobic organisms.

Spread from adjacent structures

Infections in the upper respiratory tract, especially in children, can lead to the development of a retropharyngeal abscess.

Infections originating from nearby areas like the throat, adenoids, or middle ear can spread to the retropharyngeal space.

One study also reported a case of retropharyngeal abscess post COVID-19.³

• Trauma or injury to the throat or neck area can create conditions favourable for the development of an abscess. This is the most common cause in adolescents and adults.
• Swallowing a foreign object that causes injury or infection in the throat may contribute to abscess formation.

Symptoms

In the beginning, a retropharyngeal abscess may seem like a regular sore throat, and as the infection progresses, signs of retropharyngeal abscess become more prominent. A recent upper respiratory infection or throat trauma in the person's history should be considered as potential indicators of retropharyngeal abscess.²

General symptoms 

• Fever, unwillingness to eat, ill appearance
• Sore throat
• Difficulty swallowing
• Difficulty breathing
• Drooling
• Hot potato voice-muffled voice or voice change
• Trismus — difficulty in opening the mouth
• Stridor – noisy breathing, especially during inhalation
• Torticollis – the twisted or tilted appearance of the neck
• A stiff neck it may also be red or asymmetrical due to swelling

Diagnosis

Clinical assessment and physical examination

A healthcare provider will begin by taking a detailed medical history, including any recent upper respiratory infections, dental issues, or other potential sources of infection.

Predisposing factors such as diseases, weak immunity, recent dental procedure, recent neck surgery, radiation and IV drug use should be considered.⁴

Imaging studies 

CT Scan

The gold standard to diagnose retropharyngeal abscess is a contrasted CT scan as it can show the source and extent of the infection.⁴ 

X-rays

It may be used to detect airway narrowing or soft tissue swelling in the neck. While CT scans are more detailed, X-rays may still provide valuable information. In children, neck X-rays may suggest a retropharyngeal abscess if soft tissue measurements fall outside the norm.  

Ultrasound 

For children, ultrasound is favoured due to its radiation-free, non-invasive and portable nature. Skilled professionals can use ultrasound to assess the abscess's size and location effectively.² 

Lateral neck x-ray (x-ray taken from the side)

Usually, it is the first choice for the initial assessment of suspected retropharyngeal abscesses, especially in young kids. They offer lower radiation and are more comfortable for patients with a compromised airway.³

Blood tests

Complete blood count

A complete blood count (CBC) can show a high white blood cell count (leukocytosis) and signs of dehydration if fluid intake is poor.

Blood culture

A blood culture is done to identify the bacteria causing the infection and to help select the appropriate antibiotic therapy. 

Treatment

Hospital admission and otolaryngology consultation

All confirmed cases require hospital admission and consultation with an Ear, Nose, and Throat Surgeon (ENT). 

Antibiotics

The correct choice of antibiotics will depend on a sensitivity test that shows what antibiotic the microorganism is sensitive to. Antibiotic treatment is usually given intravenously (in a vein) due to difficulty in swallowing.

For infections caused by an organism that does not respond to conventional antibiotics, MRSA (Methicillin-resistant Staph. aureus) a drug known as vancomycin or linezolid plus cefepime are used.⁵

Drainage

Individuals who are having trouble breathing should have immediate surgical incision and drainage to relieve obstruction.²

Surgical drainage is recommended if there's no improvement after 48 hours of antibiotic therapy,

Almost all deep neck abscesses typically require surgical drainage.⁴ 

Complications

Retropharyngeal abscess is a serious condition with life-threatening complications that include:

Airway obstruction

The infection can lead to the airway becoming so swollen that the patient is unable to breathe. This situation requires urgent medical attention.

Backward spread 

It may lead to inflammation in the area close to the spine, discitis osteomyelitis (infection of intervertebral discs and adjacent bones), and the formation of an epidural (spinal) abscess.

Lateral spread (to the sides)

It may affect the carotid (neck) artery, leading to complications such as excessive bleeding, pseudoaneurysm, thrombosis (blood clots), or stenosis (narrowing of a vessel). The jugular vein may also be involved, potentially causing thrombosis.

Backward extension 

It may lead to inflammation in the prevertebral space, discitis osteomyelitis (infection of intervertebral discs and adjacent bones), and the formation of an epidural abscess.

Downward (inferior) extension

Infection involving the danger space, carotid sheath, or visceral space may lead to mediastinitis, a serious and life-threatening infection of the area surrounding the heart.

Acute respiratory distress syndrome

This is a potentially life-threatening condition where the lungs cannot provide enough oxygen to the body, leading to respiratory failure and, ultimately, death. 

Bronchial erosion

Wearing away or damage to the lining of the bronchial tubes, the air passages leading to the lungs. This can result from infections or irritations. 

Sepsis (infection)

When your body has a serious reaction towards the infection, causing damage to your own tissues and or organs. 

Cranial nerve palsies

Dysfunction or weakness of one or more of the cranial nerves, which control various functions in the head and neck. This can affect vision, facial movements, and other sensory or motor functions.

Esophageal perforation

A condition where there is a hole or tear in the oesophagus, the tube that carries food from the mouth to the stomach. It can lead to serious complications such as infection and difficulty swallowing.

Erosion into carotid artery or jugular vein 

Gradual wearing away or damage to these blood vessels, which are located in the neck. This erosion can have severe consequences, including haemorrhage (bleeding)or thrombosis (clotting).

Meningoencephalitis 

Inflammation and infection of both the brain and the surrounding protective membranes (meninges).

Grisel syndrome

It is characterised by non-traumatic atlantoaxial subluxation (misalignment of the 1st and 2nd neck vertebrae), often occurring after infection, particularly in the upper neck area.

Lemierre syndrome

When a blood clot forms in the internal jugular vein, following a throat infection. Smaller blood clots can then travel to other areas of the body causing further infection and various other complications.

Prevention

Prompt treatment of infections

Infections, especially upper respiratory tract infections and throat, must be diagnosed and treated immediately. This is particularly crucial for children younger than 5 and persons with a weak immune system. 

Good oral hygiene

Maintenance of good oral hygiene and regular checkups is important as teeth can be a source of infection that can spread to the retropharyngeal space.

Differential diagnosis

These include abscesses or a mass in adjacent neck spaces (e.g. parapharyngeal and prevertebral abscess) and masses in the retropharyngeal space (e.g. tumour), but also the following:^5,6

Foreign bodies in the airways

Injuries or the presence of a foreign body in the throat can lead to inflammation and symptoms resembling a retropharyngeal abscess.

Pneumonia

Lung infection with symptoms like cough, chest pain, difficulty breathing, and fever but sometimes can cause neck or throat pain, similar to a retropharyngeal abscess.

Mediastinitis

Inflammation or infection of the area surrounding the heart can cause pain, difficulty swallowing, and fever. In severe cases, it may extend to the neck, leading to symptoms resembling a retropharyngeal abscess.

Peritonsillar abscess

Infection and abscess formation near the tonsils. This can cause symptoms similar to those of a retropharyngeal abscess. It often presents with severe sore throat pain, difficulty swallowing, and fever.

Epiglottitis

This is an inflammation of the epiglottis, the flap-like structure at the entrance of the windpipe. It can cause difficulty breathing, a high fever, and severe throat pain.

Pharyngitis (strep throat)

This bacterial infection of the throat can cause severe sore throat, fever, and difficulty swallowing, similar to a retropharyngeal abscess. It is important to diagnose and treat strep throat promptly to prevent complications.

Gastroesophageal reflux disease (GERD)

 A condition where stomach acid pushes up into the food pipe and causes discomfort and irritation. In some cases, GERD can irritate the throat, leading to symptoms that may be confused with a retropharyngeal abscess.

Deep neck space infections

Infections in other deep neck spaces, such as the area surrounding the tonsils (parapharyngeal space) or the area under the lower jaw (submandibular space), can cause similar symptoms to a retropharyngeal abscess.

Summary

A retropharyngeal abscess is a pus collection behind the throat often caused by bacterial infections, more prevalent in children under five. Causes differ by age, with upper respiratory infections predominating in young children and trauma or tonsil/dental infections in older children and adults commonly caused by Group A streptococcus or Staphylococcus aureus. Symptoms initially resemble a sore throat but worsen with fever, difficulty swallowing, and a stiff neck. Diagnosis involves clinical assessment, imaging (CT scan preferred), and blood tests. Treatment entails hospital admission, antibiotics, and incision/drainage if necessary. Complications like airway obstruction and sepsis are life-threatening. Timely diagnosis and treatment are crucial to prevent complications, ensure targeted antibiotic therapy, and improve patient outcomes. Emphasising prompt infection treatment and good oral hygiene can aid prevention, while differential diagnosis includes pneumonia and peritonsillar abscess. Early intervention can minimise the need for surgery and long-term complications, enhancing overall patient care.