Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature. Deep Neck Space Infections: Changing Trends Deep neck space infections (DNSI) have been recognized since the time of Galen in the 2nd century A.D. Prior to the introduction of antibiotic therapy the only treatment was surgical excision. In 1919 Dean described the anterior approach to the retropharyngeal space that is still used today. Mosher, in 1929, described a submandibular fossa approach to the parapharyngeal space. The pathophysiology as well as management of DNSI is based upon the fascial layers and resulting deep spaces of the neck. The cervical fascia is divided into the superficial and deep layers. The deep cervical fascia is further divided into the superficial or investing layer, the middle or visceral layer and the deep or prevertebral layer. The superficial cervical fascia is a sheet of fibrous connective tissue that encircles the head and neck and is attached to the fascia of the thorax, shoulders and axilla. It contains the platysma muscle. The superficial layer of the deep cervical fascia completely encircles the neck with its attachments being superiorly: the external occipital protuberance, the mastoid process and the zygoma, and anteriorly the mandible and the hyoid bone and inferiorly the scapula, the clavicle and the manubrium of the sternum. It envelops the trapezius and sternocleido mastoid muscles. The middle layer encircles the viscera of the neck including the pharynx, esophagus, larynx, trachea and thyroid gland. It also encloses the strap muscles anteriorly. The deep layer envelops the paraspinous muscles and vertebral bodies. More importantly, anterior to the vertebral bodies it divides into a prevertebral layer and a more anterior alar layer. This creates three potential spaces, namely the prevertebral space, the danger space and the retropharyngeal space. The carotid sheath is formed from contributions of all three layers of the deep cervical fascia and runs from the base of the skull to the level of the clavicle. The deep spaces of the neck can be divided into those which involve the entire length of the neck (including the retropharyngeal space, the danger space and the prevertebral space), those that are limited to above the hyoid bone (the submaxillary, the sublingual and the parapharyngeal spaces) and those limited to below the hyoid bone. This last space is limited to the anterior visceral space. The retropharyngeal space is the potential space that exists between the posterior aspect of the visceral layer and the alar division of the deep layer. It extends from the base of the skull to the level of the 1st or 2nd thoracic vertebrae. It contains two lateral chains of lymph nodes separated by a midline raphe. The danger space lies between the alar and prevertebral layers of the deep cervical fascia. It extends from the base of the skull to the posterior mediastinum at the level of the diaphragm and is limited laterally by its fusion with the prevertebral layer and the vertebral transverse process. The prevertebral space lies between the vertebral bodies and the prevertebral layer of the deep cervical fascia. It extends from the base of the skull to the level of the coccyx. The parapharyngeal space can be compared to an inverted cone with its base lying superiorly at the base of the skull and its apex inferiorly at the hyoid bone. It is divided into a prestyloid and poststyloid component. Its medial and lateral borders are, respectively, the lateral pharyngeal wall and the superficial layer of the deep cervical fascia as it overlies the mandible, the parotid gland and the internal pterygoid. The submandibular space is divided by the mylohyoid muscle into the sublingual space above and the submaxillary space below. These two spaces communicate freely around the posterior edge of the mylohyoid muscle. The entire space is bounded by the mandible anteriorly and laterally. The hyoid bone limits its inferior aspect and the intrinsic muscles of the base of tongue from its posterior border. The sublingual space contains the sublingual gland, the hypoglossal nerve and Wharton's duct. The submandibular space contains the submandibular gland. The anterior visceral space lies in the anterior aspect of the neck, is enclosed by the visceral layer and completely surrounds the trachea, esophagus and thyroid gland. It extends from the thyroid cartilage to the level of the 4th thoracic vertebrae in the superior mediastinum. Prior to the introduction of antibiotics, upper airway infections including tonsillitis, sinusitis and otitis media were the principal causes of DNSI. While these are still common sources in the pediatric population, after antibiotics were introduced, the principal source of infection became odontogenic infections. This is still one of the most common sources of infection today, affecting primarily the submaxillary space Upper aerodigestive tract trauma, both penetrating and iatrogenic including intubation and instrumentation, was, and still is a fairly common source of infections involving primarily the RPS. Occasionally, infections of the parotid or submandibular gland can be complicated by involvement of the deep spaces. Not only of historical interest, but also with the current resurgence of TB, infections of the prevertebral space as a result of tuberculosis of the cervical spine must be considered. A relatively new etiology is IVDA involving the neck veins as a source of IV access. Finally, in a large percentage of DNSI the initial source is never identified. The signs and symptoms of DNSI depend upon the particular space or spaces involved. Since the introduction of antibiotics, localizing symptoms such as fluctuance and pointing have become less common. Nonetheless nonspecific symptoms such as fever are still very common and can be seen with infections of any space. Pain and swelling are commonly present and may help identify the space involved. Dysphagia is more common when the parapharyngeal and retropharyngeal spaces are involved. Trismus is seen with involvement of the submaxillary space or anterior aspect of the parapharyngeal space. Other symptoms may include respiratory distress if the abscess partially compromises the airway or dental complaints if this is the source of infection. Other findings may include oropharyngeal abnormalities such as swelling of the lateral or posterior pharyngeal walls, in parapharyngeal or retropharyngeal abscess. In terms of the microbiology of deep neck space infections, important changes have occurred. Today nearly 40% of infections are caused by mixed flora. Other changes include the emergence of gram negative organism, primarily Klebsiella pnumoniae, as important pathogens as well as an increase in the prevalence of anaerobic infections. Notwithstanding, streptococcal species, primarily alpha strep and staph aureus, are still the most commonly isolated organisms. Due to the widespread use of antibiotics certain patterns of resistance have emerged. Currently, methicillin resistant staph aureus is responsible for a number of serious infections. Abscess secondary to IVDA is likely to harbor these organisms. The frequency of beta-lactamase production by oral anaerobes has also increased. It is believed that nearly 15% of Bacteriodes species produce beta lactamase and thus are resistant to penicillin. IVDA and the AIDS epidemic have given rise to certain differences between these groups and the general population in terms of presentation and organisms responsible for infection. In a study by Lee in 1990 he looked at patients who presented with DNSI at San Francisco General Hospital. He divided them into a group at high risk for AIDS, based on a history of IVDA, homosexual behavior or symptoms of AIDS-related complex, and a low risk group. The presence of infection with the AIDS virus was not confirmed by serological testing. He found that in the high risk group the infections were more commonly found in the midcervical and supraclavicular regions. In terms of the organisms causing infection, he found a higher percentage of skin flora including MRSA as well as some uncommon pathogens such as Eikonella corodens, a common oral flora anaerobe. No opportunistic or nonpathogenic organisms were isolated. These findings are no doubt related to the fact that IVDA abusers made up a large percentage of the high risk group in this particular study. With a resurgence of tuberculosis among the immunocompromised population as well as the population in general, one has to be aware of Pott's diseases of the cervical spine as a source of prevertebral space infections with the potential for spread to the other deep spaces of the neck. Important differences in presentation that can lead to early diagnosis include initial complaints consisting mainly of neck pain and stiffness as well as neurological findings including paraplegia. Plain films of the neck can be very useful, usually demonstrating widening of the retropharyngeal space as well as anterior osteolytic lesions of the cervical vertebral bodies and disappearance or narrowing of the intervertebral disc. Diagnosis can be difficult in that as many as 14% of patients will have negative tuberculin skin tests and up to 50% of cultures can be negative. The treatment of this abscess also differs in that anterior spinal fusion is often necessary and 18 months of antituberculous therapy is the currently recommended treatment. One's suspicion of a retropharyngeal abscess can be confirmed very nicely with a plain soft tissue lateral x-ray of the neck. The normal dimensions of the retropharyngeal and retrotracheal space were elucidated by Wholley in 1958. The normal dimensions of the RPS in both children and adults is 7mm as measured from the most anterior aspect of C2 to the soft tissues of the posterior pharyngeal wall. The retrotracheal space as measured from the anterior-inferior aspect of C6 to the posterior pharyngeal wall should be no more than 14mm in children and 22mm in adults. Other useful radiologic signs in patients with RPA is loss of the normal cervical lordosis with straightening of the cervical spine as well as air in the soft tissues. CT imaging has truly revolutionized the diagnosis and management of DNSI's. The CT scan allows identification of the clinical stage of the infection and thus differentiates cellulitis from abscess. The CT scan characteristics of a deep neck abscess are singular cystic or multiloculated appearance, low density CT number, the presence of air and/or fluid, contrast enhancement of the abscess wall and anatomical boundaries that fit the fascial space. CT imaging is also useful in defining the vascular structures of the neck and their potential involvement, as well as delineating exactly which neck spaces are involved Treatment of deep neck space infections can be divided into nonsurgical, and surgical therapy. Nonsurgical treatment consists of IV antibiotics that are either empirical, covering gram positive and anaerobic organisms, or based on cultures obtained from needle aspiration if the particular abscess is amenable to needle drainage. Surgical drainage can be divided into internal or external drainage based on the principals set forth by Dean and Mosher in the early 20th century. Internal or intraoral drainage is appropriate for isolated, uncomplicated RPA, peritonsillar abscess and sublingual abscess clearly limited to the floor of mouth. When the infection involves the retropharyngeal space and is complicated by airway compromise or extension to other spaces, then external drainage is appropriate. The external approach is also used for drainage of the parapharyngeal, the submaxillary or the anterior visceral space because of the important structures found in these spaces. Several factors determine the course of treatment with which a particular patient is treated. In the past, most patients were treated with surgical drainage at an early stage. In those that were treated conservatively their response to antibiotic therapy and any signs of impending complications were used to gauge which patient required formal surgical drainage. With the introduction of CT technology, the CT scan has become not only a powerful diagnostic tool but also a key factor in the management algorithm of DNSI's. Complications, although rare nowadays, are important to keep in mind because of their potential for severe morbidity and even death, as well as the fact that their early recognition is important in the decision making process regarding management. Aspiration is most commonly seen as a result of spontaneous intraoral drainage of a retropharyngeal or possibly parapharyngeal abscess, with its resultant airway compromise or pneumonia. Airway compromise can also be a result of intraoral swelling. In the past this was most commonly seen with Ludwig's angina. Due to the anatomic relationships of the retropharyngeal and anterior visceral space and their extension into the mediastinum, mediastinitis as well as resulting pericarditis or empyema are fortunately rare but well-recognized potential complications. Due to the close proximity of the parapharyngeal space, through which infections can spread from one space to another, to the vascular structures of the neck, septic thrombophlebitis of the internal jugular vein is a fairly common complication that can lead to septic thromboemboli with proximal extension leading to lateral sinus thrombosis and distal embolization resulting in pneumonia. An extremely rare but catastrophic complication is vascular erosion of the great vessels of the neck. This is usually heralded by sentinel bleeds from the mouth or ear canal. We have seen a dramatic decline in the prevalence of and mortality from deep neck space infections since the introduction and widespread use of antibiotics. However, as we have seen, this has also changed the nature of the disease in important ways. These infections are still fairly common, particularly in the pediatric population. With advances in technology we have become more efficient in the diagnosis and management of these infections. However, the surgical principles with which they are treated are the same today as when they were first described in the early 20th century. Because of their potentially devastating complications as well the new challenges posed by IVDA, the AIDS epidemic and the resurgence of tuberculosis it is important for all otolaryngologists to be familiar with the diagnosis and management of deep neck space infections. Case Presentation A 10-month-old Latin American boy presented with a 10-day history of fever and nasal congestion. Six days prior to admission, he was started on Bactrim for a presumed otitis media. Two days prior to admission he developed difficulty feeding and right-sided neck swelling. On physical exam, he was in no acute distress, was drooling and held his head preferentially to the left side. His temperature was 100.4°F. There was marked right-sided cervical adenopathy without fluctuance, pooling of secretions in the oral cavity and swelling of his posterior oropharyngeal wall. His ear exam was normal. His WBC was 25,000. 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