RETRO-PHARYNGEAL SPACE INFECTION
Introduction
This is a true ENT emergency and will result in high mortality / morbidity if unrecognized.
Note that in most textbooks the situation of retropharyngeal air and/or frank abscess is described for this infection.These signs however are very late signs.
More commonly it will be the early signs that are seen. This will take the form of increased soft tissue retropharyngeal space, representing a retropharyngeal cellulitis (occurring before abscess or gas formation)
Pathophysiology
Diagram representing the late complication of a retropharyngeal space infection- a retropharyngeal space abscess.
Causes
More commonly seen in infants / young children, but the condition may also occur in adults.
Causes include:
●Direct extension from an URTI.
●Predisposing trauma:
●Penetrating foreign body lodgment, (bones or button batteries in children)
●Direct penetrating trauma to the pharynx.
Beware especially of young children with a history of penetrating injury to the back of the throat, (sticks, pencils).
If a child has such a history X-rays should be done (looking for gas as evidence of penetration) on presentation and antibiotics should be given. Close follow up will be essential.
Complications
1.Airway obstruction especially with abscess formation, however severe cellulitis may also cause this.
2.Adjacent spread
●Inferior extension, leading to mediastinitis.
Or more uncommonly:
●Posterior extension leading to osteomyelitis or meningitis.
●Lateral extension, leading to invasion of the carotid sheath.
3.Generalized septicemia.
4.Abscess rupture with asphyxia and bronchopneumonia, (high mortality).
5.Dehydration due to fever and reduced oral intake.
Clinical Features
Important points of history
1.URTI symptoms, in particular that appears out of proportion to the clinical examination findings.
2.Check for any history of recent penetrating injury to the back of throat, (in particular children falling while having sharp objects in their mouths is common in this regard)
3.A history of foreign body ingestion followed by the development of persistent and increasingly severe symptoms.
Important points of examination
1.Fever.
2.Drooling
3.Unable to take food or liquids
4.Jaw trismus.
5.Throat examination:
●An important clinical clue is the throat that may look relatively normal on examination, yet the patient complains of severe symptoms and appears unwell.
This may indicate retropharyngeal space infection or even epiglottitis.
6.Stridor:
●May occur especially in young children, and is a late sign of abscess formation or severe swelling due to cellulitis.
●Stridor here is generally of slower onset than is seen in croup or epiglottitis.
7.Neck stiffness may occur.
Note the differential diagnosis of neck stiffness in children includes:
●Meningitis
●SAH
●Retropharyngeal infection
●Trauma
Other less common causes include:
●Large cervical lymph nodes
●Osteomyelitis
●Tetanus
●Upper lobe pneumonias
●Dystonic reactions
8.There may be some generalized neck swelling.
Investigations
Blood tests:
●FBE
●CRP
●U&Es / glucose
●Blood cultures.
Plain radiography of the neck
Lateral neck radiograph of a five year old girl, who presented with a fever, a WCC of 58,000, and some neck pain and stiffness. There is severe soft tissue retropharyngeal edema, (even accounting for the slightly flexed position of the neck) indicating a retropharyngeal cellulitis. (Radiograph, courtesy Dr Mike Taylor)
A lateral soft tissue x-ray of neck, done in full inspiration and with neck extended, (to avoid factitious increase in retropharyngeal space especially in children), is a very useful investigation.
Look for:
●Increase in retropharyngeal soft tissue (or pre-vertebral spaces), aretropharyngeal cellulitis.
●Streaks of air, traumatically introduced, or as a result of gas forming organisms.
●Occasionally an air/fluid level seen within an abscess.
●Foreign body.
●There will often be associated laryngeal involvement, look for swollen or “thumb printed” epiglottis, (which is situated anteriorly) and narrowing of the airway.
Large amount of retropharyngeal air seen in a 77 year old female, who complained of persistent pain after swallowing a chicken bone. She had a perforation of the esophagus.
The air is quite obvious in this radiograph, however signs may be far more subtle, being represented by just a few faint steaks of air behind the esophagus.
CT scan:
This may be problematic in an uncooperative patient or one with a compromised airway.
However it is the best imaging investigation for this condition
●It will confirm the diagnosis in cases where the plain lateral neck x-ray is not diagnostic.
●It will more readily distinguish complications from a pure cellulitis. Some smaller abscesses and retropharyngeal air may only bee seen on CT
●It will define far more accurately the extent of disease.
CXR
●If mediastinal extension is suspected.
Management
1.Immediate attention to the airway. If there is significant obstruction urgently notify
●Anesthetics/ICU
●ENT surgeon.
Tracheotomy may be required.
Equipment for an emergency surgical airway should be kept at close hand.
2.IV access for fluids and blood samples.
3.Urgent antibiotics:
●Cefotaxime
●Flucloxacillin
●Metronidazole
See latest edition of Antibiotic Guidelines for exact dosing regimes.
4.Surgery:
●Abscesses may require surgical drainage.
Disposition
All patients will require hospital admission, usually to a HDU/ ICU
Urgent referral to Anesthetics and ENT, for airway problems.
References:
1.Otolaryngologic Emergencies in Emergency Medicine 4th ed Tintinalli p.1068.
Dr J. Hayes
Reviewed February 2012.