ENT (Otorhinolaryngology) · MU Sofia

37. Parapharyngeal abscess. Retropharyngeal abscess.

Covers parapharyngeal and retropharyngeal abscesses in turn, starting with the parapharyngeal space's contents and its division by the styloid process into anterior and posterior compartments. It then sets out causes, organisms, clinical signs, imaging such as CT and the lateral neck X-ray with its prevertebral measurement thresholds, treatment, complications and differential diagnosis. A side-by-side table contrasts the two conditions by age, neck swelling, bulge site, cranial nerve palsy and mediastinal spread.

Inside: 2 sections · 2 labelled pictures · 1 table · 15 flashcards · 5 min

Topic 37 of 52 in the MU Sofia syllabus for ENT (Otorhinolaryngology) (Medicine, Year 4). The free AceMed note covers it in 2 sections, about 770 words (5 min of reading), with 15 flashcards.

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  1. Parapharyngeal abscess. Retropharyngeal abscess.
  2. Retropharyngeal Abscess

Parapharyngeal abscess. Retropharyngeal abscess.

1. Parapharyngeal Abscess - Pharyngomaxillary or Lateral Pharyngeal abscess.

1. Definition: A parapharyngeal abscess is a collection of pus within the parapharyngeal space, located lateral to the pharynx, extending from the skull base to the hyoid bone, usually secondary to infections of the tonsils, pharynx, teeth, or salivary glands.

It is a serious and potentially life-threatening condition. Contains:

  • Internal carotid artery
  • Internal jugular vein
  • Cranial nerves IX–XII

Sympathetic chain

⚠ Infection here may spread to major vessels and mediastinum.

2. Etiopathogenesis

  • Odontogenic (Main cause in adults): Infection from the lower 2nd and 3rd molars.
  • Pharyngeal (Main cause in children): acute tonsillitis, peritonsillar abscess (Quinsy), or pharyngitis.
  • Otogenic: Spread from Bezold's abscess (mastoiditis) or petrositis.
  • Traumatic: Penetrating injuries or iatrogenic (local anesthetic injection).
  • Causative organisms: Group A β-hemolytic Streptococcus, Staph aureus, Anaerobes (Bacteroides, Fusobacterium)

Pathogenesis

  1. 1. Infection spreads from adjacent structures
  2. 2. Involvement of parapharyngeal space
  3. 3. Cellulitis → localized pus formation
  4. 4. May extend to carotid sheath or mediastinum

3. Classification - The space is divided by the styloid process and its attached muscles into:

  1. 1. Anterior (Pre-styloid) Compartment: Contains fat and lymph nodes. Infection here usually from tonsils or pharynx causes trismus (due to irritation of the medial pterygoid muscle).
  2. 2. Posterior (Post-styloid/Retrostyloid) Compartment: Contains the Carotid Sheath (carotid artery, internal jugular vein, CN IX, X, XI, XII). More dangerous → neurovascular complications

4. Clinical Picture

  • Trismus: Characteristic of the anterior compartment.
  • Medial Bulging of the Tonsil: The lateral pharyngeal wall is pushed medially, often displacing the tonsil.
  • External Swelling: Induration and swelling at the angle of the mandible.
  • Cranial nerve palsies (IX–XII) in post-styloid abscess
  • Systemic Signs: High fever, odynophagia (painful swallowing), and torticollis (neck tilt).

5. Paraclinical & Radiological Examinations- clinical susp

  • CT Neck with IV Contrast: Gold standard. Shows a low-density fluid collection with rim enhancement.
  • Shows abscess location and extent
  • Differentiates cellulitis vs abscess
  • Blood Tests: Marked leukocytosis and elevated CRP.
  • Needle Aspiration: For culture and sensitivity.

6. Treatment options

  • Airway Management: Priority in all deep neck infections, Tracheostomy if airway compromised
  • Antibiotics: IV broad-spectrum: Ceftriaxone + Metronidazole (to cover anaerobes) or Clindamycin.
  • Surgical Drainage: Mandatory once abscess is confirmed
  • Approaches:
  • External cervical approach (most common)- I and D
  • Intraoral approach (selected pre-styloid abscesses)

7. Complications

  • Airway obstruction
  • Carotid artery erosion or rupture
  • Internal jugular vein thrombosis
  • Cranial nerve palsies
  • Mediastinitis
  • Septicemia
  • Aspiration pneumonia

8. Differential Diagnosis

  • Peritonsillar abscess
  • Retropharyngeal abscess
  • Acute tonsillitis
  • Lymphadenitis

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