Describe the deep neck space infections.

Peritonsillar Abscess (quinsy)

• Deep neck space infections are collections of pus within the potential spaces bounded by the layers of deep cervical fascia.
• They matter because these spaces communicate with each other and with the mediastinum, so infection can spread rapidly and threaten the airway and life.
• A peritonsillar abscess (quinsy) is a collection of pus in the peritonsillar space, between the tonsillar capsule and the superior constrictor, at the superior pole
• It is the commonest deep neck infection, in young adults, and follows acute tonsillitis or arises from infection in WEBER’S glands in the supratonsillar region
• Organisms are mixed — group A streptococcus with anaerobes, particularly Fusobacterium
• The classical features, each of which should be named — severe unilateral sore throat and odynophagia; trismus, from irritation of the pterygoid muscles.
• Signs — unilateral bulging of the soft palate and anterior pillar; the tonsil displaced downward and medially; the uvula deviated to the opposite side; and ipsilateral cervical lymphadenopathy
• The differential — severe unilateral tonsillitis without abscess (peritonsillitis); a parapharyngeal abscess; infectious mononucleosis; a tonsillar or supratonsillar malignancy.
• Management — needle aspiration or incision and drainage under local anaesthesia, at the point of maximum bulge, or at the junction of a line from the base of the uvula to the last molar tooth
• Aspirate first with a needle, which confirms pus and excludes a vascular lesion, and guard the needle or blade so that it cannot pass more than 1 cm — because the internal carotid lies 2.5 cm laterally
• Plus — intravenous antibiotics covering streptococci and anaerobes (benzylpenicillin with metronidazole, or co-amoxiclav); analgesia; fluids; and a single dose of corticosteroid, which reduces pain and trismus and speeds recovery
• Interval tonsillectomy at 6 weeks is considered, particularly for a second quinsy, a history of recurrent tonsillitis, or airway compromise; a first quinsy in a patient with no prior history does not automatically require it.
• "hot" (immediate) tonsillectomy is practised in some centres, draining the abscess and removing the tonsil at once

Parapharyngeal, Retropharyngeal and Other Spaces

• The retropharyngeal space lies between the buccopharyngeal fascia and the prevertebral fascia, from the skull base to the mediastinum
• Acute retropharyngeal abscess is a disease of children under 5 years, arising from suppuration of the retropharyngeal lymph nodes (nodes of Rouvière).
• Features — fever and irritability, refusal of feeds, drooling, a muffled cry, neck stiffness and hyperextension of the neck (an important sign), stridor and torticollis
• A soft, unilateral bulge of the posterior pharyngeal wall is seen; a lateral soft-tissue neck radiograph shows widening of the prevertebral soft tissue (taken in inspiration with the neck extended to avoid a false positive), with contrast CT as the definitive investigation
• Chronic retropharyngeal abscess arises from tuberculosis of the cervical spine, is midline, and is drained externally, never through the mouth, with antitubercular treatment
• The parapharyngeal (lateral pharyngeal) space is an inverted cone from the skull base to the hyoid, divided by the styloid process into an anterior (prestyloid, muscular) and a posterior (poststyloid, neurovascular) compartment
• The posterior compartment contains the carotid sheath and cranial nerves IX to XII and the sympathetic chain — so infection there gives HORNER syndrome, cranial nerve palsies, carotid ERosion and internal jugular thrombosis
• Sources — tonsil, pharynx, teeth, parotid, and spread from other spaces
• Features — trismus, a tender swelling below the angle of the mandible, medial displacement of the lateral pharyngeal wall and tonsil, fever and toxicity
• LUDWIG’S angina is considered separately
• The complications that make these infections dangerous — airway obstruction.
• Management principles common to all — secure the airway first.
• The most dangerous error IS attempting intubation OR instrumentation IN A compromised airway without preparation — a partially obstructed airway can be lost completely, and the equipment for a surgical airway must be open and ready before induction
• Trismus separates quinsy from tonsillitis, and is the single most useful sign at the bedside