Deep Neck Infections
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Direct answer
Deep neck infections are emergencies of anatomy: pus collects in the potential spaces between the deep cervical fascia — submandibular, parapharyngeal, retropharyngeal, pretracheal and the "danger space" — and spreads along them from the tonsils, teeth or pharynx toward the mediastinum. Ludwig's angina, the bilateral cellulitis of the submandibular space from an infected lower molar, pushes the tongue up and back into the airway and is the classic airway emergency where oral intubation may be impossible and tracheostomy under local anaesthesia saves the life. Retropharyngeal abscess, typically in children under five, threatens descent through the danger space (between the alar and prevertebral fascia, running from the skull base to the diaphragm) into fatal descending necrotising mediastinitis; parapharyngeal infection threatens the carotid sheath, where Lemierre's syndrome — septic thrombophlebitis of the internal jugular vein with Fusobacterium necrophorum — follows tonsillitis. Management is uniform: secure the airway, image with contrast CT, drain the collection, and give intravenous antibiotics.
What you must remember
- Ludwig's angina: rapidly spreading bilateral cellulitis of the submandibular and sublingual spaces, usually from the second and third lower molars; firm floor of mouth, elevated and posteriorly pushed tongue, trismus, drooling, no fluctuance to aspirate — airway compromise is the killer.
- Airway rule in Ludwig's: assess early, intubate awake (fibreoptic) if possible, and be ready for a surgical airway under local anaesthesia; paralytic rapid-sequence intubation can be a last visible airway.
- Retropharyngeal abscess: children under about 5 (suppurative retropharyngeal nodes atrophy later) and adults after trauma or foreign body; stiff neck, torticollis, dysphagia, muffled voice; lateral neck radiograph shows widened prevertebral soft tissue (more than about 7 mm at C2 level in children).
- Danger space (space 4) between the alar and prevertebral fascia extends from the skull base to the diaphragm — the highway for descending necrotising mediastinitis, the complication that kills retropharyngeal and prevertebral infections.
- Parapharyngeal (lateral pharyngeal) space infection: trismus, medial displacement of the lateral pharyngeal wall (beyond the tonsil), and carotid sheath proximity — herald bleeds, Horner syndrome, or IX–XII palsies demand urgent intervention.
- Peritonsillar abscess (quinsy): the commonest deep-space collection in young adults — severe unilateral odynophagia, trismus, muffled "hot potato" voice, uvula pushed to the opposite side; treated by needle aspiration or incision and drainage with antibiotics, with interval tonsillectomy for recurrence.
- Lemierre syndrome: post-anginal sepsis with Fusobacterium necrophorum, internal jugular vein septic thrombophlebitis, septic pulmonary emboli and metastatic abscesses — think of it in a young adult "not recovering" from tonsillitis with rigors and chest signs.
- Principles: contrast-enhanced CT of neck (and chest when mediastinal spread is suspected) defines the collection; management combines airway protection, intravenous antibiotics (amoxicillin–clavulanate or clindamycin with metronidazole cover for anaerobes), and surgical drainage — transoral for retropharyngeal, external for parapharyngeal and Ludwig's collections.
How to work through it
Run three cases in order of airway risk. First, the 45-year-old diabetic with a bad molar, two days of swelling under the jaw, now sitting forward, drooling, unable to swallow his saliva, tongue pushed up, trismus. This is Ludwig's angina. Do not lie him flat and do not sedate him: sit him up, call anaesthesia and ENT senior, attempt awake fibreoptic intubation with a tracheostomy set open in theatre; only after the airway is secured start IV broad-spectrum antibiotics (clindamycin or amoxicillin–clavulanate plus metronidazole, covering anaerobes), a CT to map collections, and external drainage of the submandibular spaces plus dental extraction of the offending tooth. The diabetic setting matters: immunosuppression accelerates necrotising change and mandates early surgical review.
Second, the 3-year-old with fever, stiff neck, refusal to eat and a bulge behind the pharyngeal wall. A lateral neck radiograph shows prevertebral widening; CT confirms a rim-enhancing retropharyngeal collection. Small collections may respond to IV antibiotics alone; significant collections are drained transorally, and the child is watched for the dreaded descent — chest CT at the first sign of mediastinal extension, because danger-space spread to the mediastinum converts an ENT infection into an ICU-thoracic emergency.
Third, the 20-year-old a week after "tonsillitis", now with rigors, unilateral throat pain, trismus and a swelling pushing the tonsil medially and the uvula across — quinsy at minimum, and if he has pleuritic chest pain and hypoxia, contrast CT of neck and chest to catch Lemierre syndrome: jugular vein thrombosis and septic pulmonary emboli. Drain the quinsy (needle aspiration or incision under local), start antibiotics with anaerobic cover (Fusobacterium), and manage the septic thrombophlebitis with prolonged antibiotics — anticoagulation individualised — with interval tonsillectomy once healed.
Where students slip
The recurring marks-loser is calling Ludwig's angina "a dental abscess" and draining the tooth while the airway dies — the exam answer sequence is airway, antibiotics, drainage. The second slip is underestimating the retropharyngeal abscess in adults: it is not only a paediatric disease after foreign-body or instrumentation trauma, and its mediastinal descent through the danger space is the specific complication named in questions. Third, the anatomy muddle between spaces: parapharyngeal collections push the tonsil and lateral pharyngeal wall medially with marked trismus, retropharyngeal collections push the posterior wall forward with stiff neck, and peritonsillar collections push the uvula across — three directions, three diagnoses. Finally, remember the organism expectations: mixed aerobic-anaerobic flora in odontogenic space infections, Fusobacterium necrophorum in Lemierre, and group A streptococcus in quinsy.
Frequently asked questions
What is Ludwig angina and why is the airway the first priority?
A rapidly spreading bilateral cellulitis of the submandibular and sublingual spaces from an infected lower molar, elevating the tongue into the airway; obstruction kills before sepsis does, so awake intubation or tracheostomy precedes drainage.
What is the danger space and its clinical significance?
The potential space between the alar and prevertebral fasciae, extending from the skull base to the diaphragm; infection here descends into the posterior mediastinum, causing descending necrotising mediastinitis.
How does a retropharyngeal abscess present and how is it drained?
In a young child with fever, stiff neck, torticollis and dysphagia; lateral neck radiograph shows widened prevertebral soft tissue and CT defines the collection, drained transorally with antibiotics (external drainage only for complications).
What is Lemierre syndrome?
Septic thrombophlebitis of the internal jugular vein with Fusobacterium necrophorum bacteraemia following tonsillitis or pharyngitis, producing septic pulmonary emboli and metastatic abscesses in a young adult.
How is quinsy managed?
Needle aspiration or incision and drainage under local anaesthesia with antibiotics and analgesia acutely, followed in selected patients by interval tonsillectomy weeks later.