A parapharyngeal abscess refers to a purulent inflammation in the parapharyngeal space. It initially manifests as cellulitis and subsequently develops into an abscess.
Etiology
The most common causative agent is hemolytic streptococcus, followed by Staphylococcus aureus and Streptococcus pneumoniae. The main causes of infection in the parapharyngeal space include the following:
Purulent Inflammation of Adjacent Tissues or Organs
Examples include acute tonsillitis, acute pharyngitis, acute infections in areas such as the cervical spine and mastoid, as well as conditions like peritonsillar abscesses or retropharyngeal abscesses that directly rupture or spread into the parapharyngeal space.
Trauma and Foreign Bodies in the Pharynx
Iatrogenic injuries, such as those caused by tonsillectomy, tooth extraction, local injections, or endoscopic procedures damaging the pharyngeal wall, can result in parapharyngeal infection. Injuries to the pharyngeal wall from foreign body punctures or external trauma may also contribute to this condition.
Hematogenous and Lymphatic Spread
Infections in neighboring organs or tissues can extend to the parapharyngeal space through hematogenous or lymphatic dissemination, leading to the development of parapharyngeal abscesses.
Clinical Manifestations
Local Symptoms
The clinical presentation includes severe pharyngeal pain, significant pain on the side of the neck, dysphagia, and unclear speech. When an infection in the prestyloid space involves the medial pterygoid muscle, trismus may occur.
Systemic Symptoms
General symptoms include chills, high fever, headache, fatigue, and loss of appetite. In severe cases, patients may exhibit signs of exhaustion.
Examinations
Patients typically present with an acute and critically ill appearance, along with neck stiffness. Swelling may be observed in the submandibular area and posterior to the mandibular angle on the affected side, with palpation revealing firm, tender areas. In severe cases, the swelling can extend to the parotid region superiorly, along the sternocleidomastoid muscle inferiorly, to the midline of the anterior neck anteriorly, and to the occiput posteriorly. Once an abscess has formed, the swelling may soften and exhibit fluctuance.
The ipsilateral tonsil and lateral pharyngeal wall may bulge toward the midline of the pharynx, but the tonsil itself typically shows no significant pathological changes.
Diagnosis
The diagnosis is generally straightforward based on the patient's symptoms and clinical findings. However, as the abscess is located deep in the tissue, fluctuation may not be palpable externally through the neck. This should not be used as a definitive criterion for excluding parapharyngeal abscess. Imaging techniques such as neck ultrasound or CT scans can demonstrate abscess formation. In necessary cases, fine-needle aspiration of the swollen area on the affected side can confirm the diagnosis. Differential diagnosis may involve distinguishing this condition from peritonsillar abscess, retropharyngeal abscess, or parapharyngeal tumors.
Complications
Spread to Surrounding Areas
Complications may include retropharyngeal abscess, laryngeal edema, mediastinitis, or mediastinal abscesses.
Infection of the Carotid Sheath
This can lead to erosion of the internal carotid artery wall, resulting in life-threatening hemorrhage. If the internal jugular vein is involved, thrombophlebitis or septicemia may occur.
Treatment
Before Abscess Formation
Management involves adequate administration of sensitive antibiotics, along with appropriate use of corticosteroids and other medicinal therapies.
After Abscess Formation
Treatment requires incision and drainage.
External Cervical Approach
For deeper abscesses or significant neck swelling, surgery is performed under local anesthesia. A longitudinal incision is made along the anterior edge of the sternocleidomastoid muscle, with the angle of the mandible as the midpoint. Blunt dissection of soft tissues with hemostatic forceps is performed to access the abscess cavity. After drainage, a drainage strip is placed, and part of the incision may be sutured.
Transoral Approach
For abscesses prominently bulging toward the pharyngeal lateral wall without vascular pulsations, a 2 cm vertical incision is made at the most protrusive point of the lateral pharyngeal wall. Blunt dissection with hemostatic forceps is then used to access the abscess cavity, and the collected pus is drained.