Retropharyngeal and Parapharyngeal Abscess – 14 Previous Year DNB Question for Practice

ANATOMY OF RETROPHARYNGEAL SPACE

  • Lies behind the pharynx, between the bucco-pharyngeal fascia covering the pharyngeal constrictor muscles and the pre-vertebral fascia
  • Extends from the base of skull to the bifurcation of trachea.
  • The space is divided into two lateral compartments (spaces of Gillette) by a fibrous raphe.
  • Each lateral space contains retropharyngeal nodes .
  • Node of Rouviere is the most superior of the lateral group of the retropharyngeal lymph nodes.

RETROPHARYNGEAL ABSCESS

  • It is a collection of pus between the posterior pharyngeal wall and the fascia and muscles covering the cervical vertebrae.
  • It occurs in two forms –
  1. The acute primary retropharyngeal abscess which is common in infants, and
  2. Chronic retropharyngeal abscess which is common in adults. 

ACUTE RETROPHARYNGEAL ABSCESS

  • Is the more dangerous type occurring in infants. It is common between the age group of 3 months to 3 years.

Etiology:

  • Infections from tonsils, adenoid and naso pharynx .
  • Rarely foreign bodies like bone pieces and pins .
  • Extension of infection from parapharyngeal space, masticator or parotid space
  • Esophageal perforation

Pathology:

  • The disease consists of suppurative lymphadenitis of the retropharyngeal nodes, situated on either side of midline between the psoterior pharyngeal wall and the aponeurosis over the bodies of the second and third cervical vertebrae.
  • These nodes atrophy between the 3rd and 5th year of life hence acute retropharyngeal abscess is uncommon in children above the age of 4.
  • The suppuration is usually one sided, and most prominent in the oro pharynx.
  • Presents with swelling on posterolateral wall of the pharynx.
  • If not evacuated in time or when it does not rupture, pus may spread along the esophagus or burst in different directions – towards the larynx, the angle to the jaw or even in to the external auditory canal. 

Clinical features:

  • Abscess lies anterior to the prevertebral fascia.
  • It is confined to one side of the midline and presents with dysphagia & difficulty in breathing.
  • It can be palpable per orally by pressing the finger on posterior pharyngeal wall.
  • It may present with High fever and hoarseness of voice.
  • Young infants with retrophryngeal abscess will refuse feed, may have extensive drooling.
  • Constitutional symptoms like fever / toxicity is very common in acute retropharyngeal abscess.

CHRONIC RETROPHARYNGEAL ABSCESS

  • Is commonly known to occur in adults.
  •  Most common cause of chronic retropharyngeal abscess is caries of cervical spine.
  • This is usually caused by tuberculosis.
  • The tuberculous foci occur in the bodies of the cervical vertebrae( Pott’s disease) which later spread into the retropharyngeal space.
  • May be associated with Suppuration of node of Rouviere.
  • This abscess usually is present in midline and is free to spread to either side also.

Symptoms:

  • Pain while swallowing (odynophagia).
  • Torticollis is also common in these patients.
  • These patients may have difficulty in breathing (stridor).

Investigations:

  • Complete blood count show leucocytosis. Blood cultures can also be performed to ascertain the appropriate antibiotics to be used.
  • Xray soft tissue neck – A.P. and lateral views.
  • These pictures show prevertebral soft tissue widening.
  • This can be ascertained by estimating the size of the prevertebral soft tissue which is normally half the size of the body of the corresponding vertebra. If the widening is more than half the body size of the corresponding vertebra then retropharyngeal abscess must be considered. The cervical spine are straightend with loss of the normal lordosis (Ram Rod spine).
  • Above the prevertebral shadow air shadow is seen in almost all cases of retropharyngeal abscesses. This gas shadow is caused by entrapped air which occur during breathing.
  • C.T. scan neck or MRI study of neck will also help in clinching the diagnosis.

 Management:

  • Airway control.
  • In majority of cases incision and drainage is done and the pus is immediatly aspirated out using suction. 
  • When the abscess points towards the neck then it should be opened through an incision over the neck, preferably along the posterior border of sternomastoid muscle. The dissection is carried out behind the great vessels of the neck and in front of the prevertebral muscles.
  • The surgery is followed by a course of antibiotics mostly Cephalosporin group/ Clindamycin/ Penicillin along with metronidazole.

PARAPHARYNGEAL ABSCESS

ANATOMY OF PARAPHARYNGEAL (PHARYNGOMAXILLARY/LATERAL PHARYNGEAL)SPACE

  • Pyramidal in shape, base – base of skull; apex – hyoid bone
  • Medial: buccopharyngeal fascia covering the constrictor muscles
  • Posterior: prevertebral fascia
  • Lateral: medial pterygoid muscle, mandible and deep surface of parotid gland
  • Styloid process and the muscles attached to it divide the space into anterior and posterior compartments.
  • Prestyloid compartment contents: 
    • Retromandibular portion of the deep lobe of the parotid gland 
    • CN V branch to tensor veli palatini muscle 
    • Ascending pharyngeal artery and venous plexus
    • Fat
  • Poststyloid compartment contents:
    • Carotid artery
    • Internal jugular vein 
    • CN IX to XII
    • Cervical sympathetic chain

PARAPHARYNGEAL ABSCESS

Source of infection:

  • Dental infection
  • Peritonsillar abscess
  • Parotid abscess
  • Submandibular gland infection
  • Masticator space infection.
Clinical Features:
  • Fever, sore throat, odynophagia, and swelling in the neck down to the hyoid bone.
  • May present with medial bulging of pharynx
  •  Anterior compartment infections: 
    • triad of prolapse(medial deviation) of tonsil and tonsillar fossa,Trismus (due to spasm of medial pterygoid muscle),External swelling( in upper one-third of sternocleidomastoid muscle) behind the angle of jaw
  • Posterior compartment infections
    • Bulge of pharynx behind the posterior pillar
    • Paralysis of CN IX, X, XI, XII & Sympathetic chain
    • Swelling of parotid region
    • Minimal trismus or tonsillar prolapse.
    • Torticollis (due to spasm of paravertebral muscles) 
    • Posterior space abscess can erode into the carotid artery or cause septic thrombophlebitis of the internal jugular vein (Lemierre syndrome).

Diagnosis:CT scan

Treatment:

  • Airway control.
  • Parenteral broad-spectrum antibiotics (eg, ceftriaxone, clindamycin) and surgical drainage are generally needed.
  • Posterior abscesses are drained externally through the submaxillary fossa. Anterior abscesses can often be drained through an intra-oral incision

Exam Question of

  • The most likely diagnosis in a patient having lower third molar extracted due to dental caries and then developed high fever and pain and on examination, tonsil deviated medially and there was swelling in upper one-third of sternocleidomastoid muscle is Parapharyngeal Abscess.
  • Retropharyngeal abscess is confined to one side of the midline and presents with dysphagia & difficulty in breathing.
  • Retropharyngeal abscess can be palpable per orally by pressing the finger on posterior pharyngeal wall.
  • Retropharyngeal Abscess may present with High fever and hoarseness of voice.
  • Post-styloid space of parapharyngeal space contains cranial nerve IX ,XII  and Lymph nodes.
  • Retropharyngeal abscess lies anterior to the prevertebral fascia.
  • Parapharyngeal space is also known as Lateral pharyngeal space.
  • The medial bulging of pharynx is seen in Pharyngomaxillary abscess.
  • Trismus in parapharyngeal abscess is due to spasm of  Medial Pterygoid muscle.
  • Most common cause of chronic retropharyngeal abscess is caries of cervical spine.
  • Chronic retropharyngeal abscess is associated with tuberculosis of spine and suppuration of Rouviere lymph node.
  • Retropharyngeal abscess may present with swelling on posterolateral wall of the pharynx.

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Question of NBE /NEET / DNB

Retropharyngeal and Parapharyngeal Abscess

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