Hyperbaric oxygen therapy in a case of cervical abscess extending to anterior mediastinum, with isolation of Prevotella corporis

Abstract

We present a case of an odontogenic abscess, first spreading at the lateral cervical level and then in mediastinum. We isolated an anaerobic bacterium, Prevotella corporis, rarely documented in literature. The mortality rates of cervical abscesses secondary to odontogenic infections and complicated by mediastinitis vary from 10% to 40%. Treatment of descending mediastinitis involves multidisciplinary teams such as otorhinolaryngology, thoracic surgeons, infectious disease physicians, anesthetists and intensivists. Due to the combined treatment with surgical drainage within 48 hours of hospitalisation, antibiotics and subsequent hyperbaric oxygen therapy, we have achieved complete recovery of the patient.

Background

Infections of the deep spaces of the neck that can be complicated as mediastinitis are potential complications of odontogenic abscesses.

The prevalence of this pathology is high in young or middle-aged men with a peak between 25 and 33 years.¹ These infections generally originate from the lower molars and spread by gravity to the cervical spaces; therefore, the submandibular space is the most frequently involved space and is followed by the oral and parapharyngeal spaces. These spaces provide a pathway to spread the infection towards the mediastinum. From the aetiopathogenetic point of view, the most involved pathogens are the Streptococci and the Staphylococci as well as most of the anaerobic bacteria.² The antibiotic therapy is the first treatment of choice. Surgery is selected with the aim of ensuring an effective abscess drainage to prevent systemic toxicity and multi-organ failure. Some authors share the choice of early surgical drainage in most cases and especially for cases not responding to antibiotic therapy within 48 hours or if there is evidence of mediastinal involvement.³ The mortality rates of cervical abscesses secondary to odontogenic infections and complicated by mediastinitis vary from 9% to 50%.⁴

Hyperbaric oxygen (HBO) therapy is useful in the treatment of gas gangrene, as it reduces the volumes of gas-harvested collections with subsequent improvement of tissue ischaemia. HBO has a bactericidal action against anaerobic germs that can survive in hypoxic environments where there is a depression of phagocytic functions.^{5 6}

We present a case of an odontogenic abscess, first spreading at the lateral cervical level and then in to mediastinum. We isolated an anaerobic bacterium, P. corporis, rarely documented in literature. Due to the combined treatment with cervicotomy and subsequent HBO, we have achieved complete recovery of the patient.

Case presentation

We present the case of a man of 55 years with a family history of diabetes, hypertension and hypothyroidism.^{7 8} The patient suffered from chronic cholesteatoma otitis and chronic sinusitis. The patient underwent adeno-tonsillar surgery, open tympanoplasty, sinus endoscopy surgery 15, 10 and 5 years ago.^9–12 The patient suffers from a slight mental retardation that makes the description of subjective symptoms more difficult.^13–18 The ear, nose and throat (ENT) objective examination showed the submandibular and left laterocervical region, presence of hard consistency swelling, tender to palpation, fixed on the underlying planes, covered with intact skin and normal appearance. At oropharyngoscopy, trismus was observed with modest mucosal hyperaemia. A laryngeal vestibule asymmetry for partial medialisation of the left ventricular band was present at the rhinopharyngaryngoscopic examination with flexible optic fibres. Vocal cords are normal in appearance and mobility. Laboratory results at the time of admission showed white blood cells (WBC) of 20.4×10⁹/L with 82% neutrophils, 11% lymphocytes and with a erythrocyte sedimentation ratio (ESR) of 50.

The CT scan performed in urgency revealed a hypodense collection, with indistinct margins, which developed in part cranially to the submaxillar left gland, surrounding the mandibular angle and extending mainly downwards, in the paralaringeal seat (figure 1A) and in the space between the left pre-thyroid muscles, up to the plane passing through the lower portion of the thyroid. Multiple gaseous bubbles were identifiable between the laterocervical fascial planes and the adipose tissue of the masticatory space appeared diffusely thickened (figure 1B).

Figure 1.

CT scan of neck showing hypodense fluid collection, extending down from left submaxillary gland in the paralaryngeal space and the space between left pre-thyroid muscles. Also, multiple gas bubbles were noted in the coronal plane.

The dental examination confirmed the odontogenic origin of the abscess collection, finding a widespread periodontosis with mobility of 3.8 that was extracted.

The day after admission, the patient underwent left cervicotomy and drainage of the abscess; part of the drained liquid was sent for gram stain, cultures and antibiogram.

Given the clinical situation, the patient was kept in narcosis for 48 hours and antibiotic therapy was modified, while awaiting the bacteriological examination: meropenem 1000 mg 1 vial for slow venous infusion every 8 hours; teicoplanin 400 mg 1 vial for venous infusion every 24 hours.

On the fifth day, CT neck and thorax with contrast showed that the fluid collection as heterogeneous density in the left lateral region of the neck had extended downwards until reaching the posterior surface of the sternal manubrium (figure 2A). At this level, the lesion appeared in direct continuity with the left brachiocephalic trunk (figure 2B). Taking into account the initial mediastinal involvement, the thoracic surgeons recommended us to continue broad-spectrum antibiotic therapy, under close clinical–radiological surveillance (CT neck and mediastinum every 24 hours), and to initiate the HBO cycle.

Figure 2.

CT neck and thorax with contrast, showing the fluid collection as heterogeneous density in the left lateral region of the neck extending downwards reaching the posterior surface of the sternal manubrium. At this level, the lesion appeared in direct continuity with the left brachiocephalic trunk.

In the sixth day, the culture exam isolated P. corporis bacteria and, taking into account the antibiogram, the therapy was modified by replacing the teicoplanin with the metronidazole 1000 mg 1 vial every 6 hours. The patient underwent a prolonged cycle of HBO with two daily sessions for the first 8 days followed by one daily session for another 10 days.

The radiological pattern was unchanged until the 16th day when, at the CT study, it was possible to detect a slight reduction in extension, especially in the more cranial portion, of the latero-cervical fluid collection without significant changes in the extent of collection in the mediastinal site.

Given the persistence of the retrosternal collection, it was considered appropriate to perform an ultrasound of the jugular region that documented a corpuscular collection, with finely irregular margins, of about 60 mm in size on the jugular site from which 5 cc of liquid strongly corpusculated were aspirated by transcutaneous way.

Outcome and follow-up

Starting from the 20th day, the radiological pattern was normalising as well as the biomoral exams (WBC 5.3×10⁹/L, neutrophils 54%, lymphocytes 37%, ESR 41) for which antibiotic therapy was reduced: meropenem 500 mg 1 vial every 12 hours and metronidazole 500 mg 1 vial every 12 hours.

At 35 days from the surgery, the patient was discharged with home therapy (metronidazole cpr 250 mg 1 cpr every 12 hours) for another 7 days.mphocytes

After 7 days, the antibiotic therapy was definitively suspended after an ambulatory control with ENT objective examination not altered.

Discussion

In a recent review, dental infections accounted for 70.6% of deep neck infection cases. Odontogenic infections and poor oral health should be taken into consideration because they can lead to rarely but lethal diseases such as descending mediastinitis, which requires aggressive surgical treatment and aggressive antibiotic therapy. Deep neck abscess is associated with a mortality rate of 10%–40% despite treatment. The complication developed in 11.4% of cases.¹⁹ For Cramer et al, in adults, delay in surgical drainage did not increase morbidity and mortality for those who received surgery 1 to 2 days after hospitalisation and significantly increased the rate for those who received surgery 3 to 7 days after recovery. Adult patients in whom operative drainage was delayed were more likely to have diabetes mellitus, meet sepsis criteria, have more advanced American Society of Anesthesiologists (ASA) class and use steroids for a chronic condition. Rate of postoperative septic shock was significantly more likely in those in whom drainage was delayed, as was the rate of unplanned intubation or prolonged ventilation. The association between timing of surgery after admission and postoperative morbility and mortality was not observed in paediatric patients.²⁰ In our case, we have complied with the literature data; in fact, the patient received surgery on the day after the admission.²¹ Descending mediastinitis is a rare but severe form of mediastinitis caused by the spread of infection from the deep space of the neck. The deep spaces of the neck are limited by several layers of deep cervical fascia. Thus, any infection of these spaces could potentially involve the mediastinal space causing fulminant mediastinitis. Moreover, the existing intra-thoracic negative pressure and the gravity facilitate the diffusion. The most common causes of descending mediastinitis are cervico-facial and odontogenic infections. Ingestion of foreign bodies, penetrating neck injuries and immunocompromised status such as those with uncontrolled diabetes, chemotherapy or immunodeficiency are not rare.²² With ultrasound guide, we aspirated 5 cc of fluid accumulated near left jugular site.

Delayed recognition and treatment can lead to severe sepsis or septic shock with multi-organ failure.^23–26

The oro-maxillo-facial infections are usually combined infections, including aerobic and anaerobic microorganisms. Few studies reported Prevotella as an isolated anaerobic bacterium from different oral infections such as periodontal abscess, chronic periodontitis and abscesses in buccal, submandibular, pterygomandibular, sublingual or in other head and neck districts.²⁷

The theoretical mechanisms described for the development of mediastinitis support the suggestion that gaseous gangrene is a feature of the pathogenic process. There is a convincing theoretical basis and experimental and clinical trial evidence to support the use of adjunctive HBO therapy in this kind of deep neck space and mediastinal infections. Adjunctive HBO therapy might decrease the mortality and limit the morbidity and diffusion in patients with mediastinitis. HBO is a useful method against infection by increasing free radicals, which helps neutrophil-mediated killing of some uncommon bacteria. Moreover, HBO therapy has a bactericidal action against certain anaerobes. The most commonly used treatment schedule involves breathing 100% oxygen at 2.5 atmospheres absolute for a total of 90 min.^28–30 We used this protocol in two daily sessions for the first 8 days followed by one daily session for another 10 days.

The descending mediastinitis, originated from an infection of the deep spaces of the neck, must have a multidisciplinary management to obtain the best therapeutic results. Treatment of descending mediastinitis involves multidisciplinary teams such as otorhinolaryngology, thoracic surgeons, infectious disease physicians, anaesthetists and intensivists. In fact, due to a timely surgical drainage, associated with antibiotic therapy and HBO treatment, we saved the patient’s life with excellent clinical outcomes.

Learning points.

• The mortality rates of cervical abscesses secondary to odontogenic infections and complicated by mediastinitis vary from 10% to 40%.

• Surgical drainage within 48 hours of hospitalisation reduces morbidity and mortality.

• Treatment of descending mediastinitis involves multidisciplinary teams such as otorhinolaryngology, thoracic surgeons, infectious disease physicians, anaesthetists and intensivists.

• Surgical drainage, associated with antibiotic and hyperbaric oxygen therapy, gave good clinical outcomes in descending mediastinitis.