Spontaneous descending retropharyngeal abscess
- M Rahman,
- Published 28 April 2009
Retropharyngeal abscesses are rare but can occur spontaneously in adults and are potentially life threatening. Such a diagnosis should be considered so that aggressive treatment can be initiated as soon as possible to avoid life threatening mediastinal complications.
Retropharyngeal abscess is an infection within the tissues of the retropharyngeal space, one of the deep fascial spaces of the neck. This space is located immediately behind the nasopharynx, oropharynx, hypopharynx, larynx and trachea. Due to its anatomic relationships, a retropharyngeal abscess should be regarded as potentially life threatening.
Retropharyngeal abscesses occur commonly in children and are usually due to complication of lymphatic infection.1 This is rare in adults as the lymph nodes in the retropharyngeal space, apart from the solitary node of Rouviere, disappear after the age of 5 years. In adults, the most common cause of retropharyngeal abscess is a penetrating injury or oesophageal foreign body.2,3 Other causes include chronic infective conditions such as tuberculosis, particularly tubercular involvement of the cervical spine.4
We describe a case of a spontaneous retropharyngeal abscess in an adult with no precipitating or risk factors present.
A normally very healthy 69-year-old man was referred as an emergency to the ENT department at Gloucestershire Royal Hospital with a 5-day history of worsening dysphagia and odynophagia. This was associated with a voice change and minimal breathing difficulty. Over the previous 2 days, he had also developed some swelling, predominantly over the front of his neck above the sternal notch with tenderness and redness overlying it. This was associated with intermittent fevers. He was otherwise systemically well, and gave no history to suggest any preceding illness prior to this acute episode.
On examination, he was febrile with a diffuse anterior neck swelling in the midline, just above the sternal notch, with inflammatory skin changes. The swelling was firm and there was some movement on swallowing. There was no evidence of dental disease. Flexible nasoendoscopy revealed oedematous lateral pharyngeal walls and symmetrical narrowing of the airway at the level of the epiglottis. The vocal cords were normal.
In view of the anterior neck swelling, with its minimal movement on swallowing, the symmetrical lateral pharyngeal wall swelling and the associated inflammatory changes, a provisional clinical diagnosis of thyroiditis was made.
A lateral soft tissue x ray of the neck showed increased thickening of the retropharyngeal tissues at the level of larynx as well as tissue thickening anterior to the larynx. Other investigations on admission included a raised C-reactive protein (485) and white cell count (14.2) as well as a normal PA chest x ray. Despite its rarity in the adult population, especially in the absence of any trigger, a retropharyngeal collection had to be considered given the lateral soft tissue neck x ray findings. An urgent CT scan was therefore requested.
The patient was commenced on intravenous cefuroxime and metronidazole prior to a CT scan being performed due to the raised inflammatory markers.
Given the CT findings, the decision was made to take the patient to the operating theatre that night. The anaesthetists were able to intubate the patient with little difficulty and the neck abscess was drained via an external approach. A corrugated drain was left in situ and the patient spent the first night of his admission on the intensive care unit. The patient returned to the ward the following morning and over the next 2 days improved rapidly. However, he developed absolute dysphagia after 3 days. Given the concern of a re-accumulation of pus, a repeat CT scan was requested. This revealed an extensive re-accumulation of pus in the neck, which extended posterior to the trachea and oesophagus and into the upper mediastinum (fig 3). The most inferior extent of the collection was at the level of the tracheal carina. The patient was therefore referred and transferred to the cardiothoracics team in Bristol, where he underwent a right thoracotomy and drainage of the mediastinal abscess. The cultures of pus grew group A Streptococcus species and no anaerobic organisms. On advice from the microbiologists, he was continued on the same intravenous antibiotics (cefuroxime and metronidazole) for a further 2 weeks.
OUTCOME AND FOLLOW-UP
The patient returned to Gloucester after 12 days and, as he was getting better clinically with improvement biochemically in his inflammatory markers and radiologically on a repeat CT scan, he was discharged on oral antibiotics. He was seen in the outpatient department 4 weeks later and a further CT scan showed a significant improvement with a minimal residual fluid collection (figs 4 and 5). No precipitating cause of his spontaneous retropharyngeal abscess was ever found. To ensure no intra-luminal pathology had been missed, flexible gastroscopy was performed which was, not surprisingly, normal. The patient has now been discharged from ENT entirely well.
The retropharyngeal space extends from the skull base superiorly down into the mediastinum to the level of T6. Posteriorly, it is limited by the prevertebral fascia, and anteriorly by the buccopharyngeal fascia, pharyngobasilar fascia over the three pharyngeal constrictor muscles and the oesophagus. Laterally it is limited by the carotid sheath. There is direct communication from this space to the parapharyngeal space. Within the retropharyngeal space are two vertical paramedian chains of lymph nodes which drain potential infections in the nasopharynx, oropharynx, paranasal sinuses and possibly the middle ear.
Given the frequency of infection in these areas in childhood, it is not surprising that the retropharyngeal nodes can suppurate and cause abscess formation. However, these nodes atrophy in late childhood and hence retropharyngeal abscess formation in adults is rare.5 There are causative factors that may precipitate the development of a neck abscess, though, and these are more usual in adults. These include penetrating injuries of the neck, oesophageal foreign bodies2,3 or chronic infective conditions such as the tuberculous involvement of the cervical spine.4 There is little, to our knowledge, in the literature reporting spontaneous abscess formation in the retropharyngeal space in adults.
Delay in diagnosis and treatment of a retropharyngeal abscess can lead to complications such as spontaneous rupture of the abscess leading to tracheobronchial aspiration or airway compromise due to laryngeal oedema. Given the inferior extent of the retropharyngeal space, it is not surprising that mediastinitis and abscess formation can also occur. Therefore, early recognition and aggressive management of a retropharyngeal abscess are essential due to the significant morbidity and associated mortality.6 Mortality rates as high as 30%, even now, are still reported.7 This case was surgically challenging as the retropharyngeal abscess extended into the mediastinum which is potentially a fatal scenario.8
Our management of draining the abscess via the neck such that the superior mediastinum can also be accessed is a recognised initial surgical option.7 However, there is a recognised recurrence rate with this approach and other centres advocate a more aggressive initial management9 due to unacceptable recurrence rates which can be as high as 70% with cervical drainage alone.9
In conjunction with aggressive surgical therapy, broad spectrum antibiotics should always be administered pending more directed antimicrobial therapy from culture of pus obtained at surgery.7 The bacterial content of these abscesses tends to be a mixed flora representing the common upper respiratory tract commensals. In our case, the cultures grew group A streptococcus, which is a common pathogen involved10 and was sensitive to ceftriaxone. Anaerobic bacteria play a major aetiological role in the development of these abscesses,11 however, no anaerobes were present in this case.
Retropharyngeal abscesses are rare.
Retropharyngeal abscesses predominantly occur in childhood.
In adults, if they occur, there is usually an obvious precipitating cause.
The retropharyngeal space extends into the mediastinum where abscesses can spread.
Retropharyngeal abscesses can occur spontaneously in adults.
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication.