Management of Parapharyngeal Abscess

Block diagram of the deep spaces of the neck - Rosen's Emergency Medicine

Anatomy and Significance

• Anterior PPS (prestyloid): Contains fat - prone to liquefaction and abscess formation; requires aggressive surgical drainage
• Posterior PPS (poststyloid/retrostyloid): Contains the carotid sheath (carotid artery, internal jugular vein, sympathetic chain, CN IX-XII), lymph nodes; more often causes lymphadenitis and may be managed more conservatively

• Scott-Brown's Otorhinolaryngology, p. 671
• Rosen's Emergency Medicine, p. 965

Aetiology and Microbiology

• Peritonsillar or retropharyngeal abscess (direct spread)
• Dental infection / mandibular molar periapical abscess
• Suppurative cervical lymphadenitis
• Parotitis
• Penetrating trauma, nerve blocks, or surgical procedures (iatrogenic)
• IV drug abuse

Clinical Features

Complications (Life-threatening - must anticipate)

1. Airway obstruction - edema, abscess mass effect
2. Descending mediastinitis - via retropharyngeal/danger space communication (crude mortality up to 2%)
3. Lemierre syndrome - septic thrombophlebitis of the internal jugular vein; suspect when sore throat + sepsis + multisystem involvement
4. Carotid artery erosion, aneurysm, or rupture - any signs of bleeding warrant CT/MR angiography urgently
5. Horner syndrome - sympathetic chain involvement (CN IX-XII neuropathies)
6. Cavernous sinus thrombosis - proptosis, impaired EOM, pupillary changes
7. Aspiration pneumonia / lung abscess / empyema - from abscess rupture into airway
8. Retroperitoneal sepsis - rare but described

Investigations

• Contrast-enhanced CT of neck + chest - gold standard; demonstrates rim-enhancing abscess, extent of infection, and any mediastinal involvement. Always include the mediastinum in the scan field. Cellulitis appears as fat stranding along fascial planes; abscesses show characteristic ring enhancement
• MRI - comparable to CT for delineating extent; useful when radiation is to be minimized
• Ultrasound - may assess whether abscess has sufficiently liquefied and can guide needle aspiration, but limited in deep spaces
• CT or MR angiography - when vascular complications suspected
• Orthopantomogram (OPG) - if dental origin suspected
• Fibreoptic nasendoscopy - assess upper aerodigestive tract and airway patency simultaneously (performed cautiously to avoid triggering gag reflex)

Management: Step-by-Step

Step 1 - Airway Assessment and Securing (Priority Zero)

• Assess for: dyspnea, tachypnea, stridor, inability to manage secretions, agitation, drooling
• Conventional laryngoscopy is often impossible due to trismus, reduced neck extension, laryngopharyngeal edema, and friable mucosa
• Do NOT paralyze before securing airway
• Preferred method: awake fibreoptic nasotracheal or orotracheal intubation with adequate topicalization
• Have emergency tracheostomy prepared and set up before commencing anaesthesia; pre-infiltrate with 2% lignocaine + 1:80,000 adrenaline at tracheostomy site
• Transfer to operating theatre with anaesthetic and surgical teams experienced in difficult airway management
• Supine positioning for CT is only safe once airway is deemed stable

Step 2 - Intravenous Antibiotics (Immediate, Do Not Delay for Cultures)

• Alternatively: amoxicillin-clavulanate, or 2nd/3rd generation cephalosporins with metronidazole
• Review all antibiotic choices once culture and sensitivity results are available
• Note rising resistance: clindamycin 11-18%, erythromycin 14%, penicillins 7-8%
• In children under 2: clindamycin preferred as first line due to MRSA rates

Step 3 - Corticosteroids (Adjunctive)

• Dexamethasone 0.6 mg/kg IV/IM (maximum 10 mg) given with antibiotics
• Associated with decreased need for surgical drainage in select cases
• Reduces pharyngeal edema and systemic inflammation

Step 4 - Surgical Drainage (Decision)

• Confirmed abscess on CT with liquefaction
• Failure to respond to conservative treatment after 24-48 hours (persistent pyrexia, worsening pain)
• Airway compromise from the abscess
• Vascular complications

• Intranodal abscess or phlegmon (cellulitis without pus collection)
• Abscess size <2.5 cm contained within a single neck space
• Most pediatric cases (especially posterior PPS / phlegmon)
• Patient is responding clinically to antibiotics within 24-48 hours

Step 5 - Surgical Approach Options

• Incision anterior to SCM, dissecting along the great vessels
• Approach anterior and medial to the carotid sheath
• Curette abscess wall; break down loculations
• Insert drain (usually corrugated or suction drain)

• Blunt instrument drainage through the oropharynx (medial to the pterygomandibular raphe)
• Risk of inadequate drainage; limited visualization

• Shown in a prospective RCT to reduce hospital stay from 5.2 to 3.1 days and reduce cost by 41%, with no difference in efficacy or complications
• Better for microbiological sampling (increases anaerobe isolation)
• Useful when abscess is superficially accessible
• Scott-Brown's ORL, p. 672; Bailey & Love's Surgery, p. 480

Step 6 - ICU Admission and Monitoring

• Admit to ICU if airway or vascular compromise is present
• Monitor for septic complications, mediastinal spread, vascular involvement
• Patients with stable airways may be admitted to a high-dependency floor bed
• IV fluid resuscitation; nutritional support (NG or parenteral if swallowing compromised)
• Serial clinical and radiological reassessment

Special Considerations

Recent Evidence

Summary Algorithm

Parapharyngeal Abscess
        |
        v
Airway Compromise? ──YES──> Awake fiberoptic intubation
        |                   (+ prepare emergency tracheostomy)
        NO
        |
        v
Contrast-enhanced CT Neck + Chest
        |
   _____|_____
  |           |
Cellulitis/  Abscess
Phlegmon     confirmed
  |           |
IV Abx       IV Abx + Dexamethasone
+ Dex        + Otolaryngology consult
  |           |
Reassess     Failure to respond  ──> Surgical drainage
at 24-48h    at 24-48 hours         (transcervical / US-guided)

• Rosen's Emergency Medicine - Concepts and Clinical Practice, pp. 964-966
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery (Vol 2), pp. 671-674
• Bailey & Love's Short Practice of Surgery (28th ed.), p. 480
• KJ Lee's Essential Otolaryngology, pp. 709-711
• Sheikh Z et al. (2023). Systematic review of deep neck space infections. Clin Otolaryngol. PMID 37147934