Key Points. Eric R. Oliver M. Boyd Gillespie

Transcription

1 Eric R. Oliver M. Boyd Gillespie Key Points Methicillin-resistant Staphylococcus aureus is an increasingly common cause of deep neck space infections. Ultrasound will likely be applied more frequently for the diagnosis and management of deep neck space infections. Evaluation and maintenance of the airway are the first steps in management of deep neck space infections. Conservative management of deep neck space infections can often be used prior to surgical intervention. Infections of the deep spaces of the neck often present a true clinical challenge. Although antibiotics have reduced their incidence, deep neck space infections remain a relevant health problem. The complex anatomic organization of the neck makes diagnosis and precise localization of deep infections difficult. Clinical suspicion remains critical in that many deep neck infections are not evident on palpation or visual inspection. Although improved imaging and medical protocols exist, surgical intervention remains a critical component of successful management. Etiology Infectious and inflammatory conditions of the upper aerodigestive tract are the primary instigators of deep neck infections. Multiple retrospective studies have revealed dental infections as the most common starting point, followed by oropharyngeal infections. 1-7 Acute bacterial tonsillitis and pharyngitis remain as leading causes in children. Suppuration of lymph nodes after an episode of cervical lymphadenitis may progress to a neck abscess. In the pediatric population, acute rhinosinusitis is a common cause of retropharyngeal lymphadenitis. Oral surgical procedures and endoscopic instrumentation may iatrogenically incite an upper airway infection or traumatize the pharyngoesophageal lumen. Sialadenitis, with or without ductal obstruction, can precipitate infectious spread. A foreign body trapped within the upper aerodigestive tract may initiate infection, while penetrating cervicofacial trauma can both introduce pathogens and serve as a conduit between adjacent spaces. Superficial infections, such as skin cellulitis, may spread along fascial planes. Needle injection associated with intravenous drug use introduces pathogens to the neck in a similar fashion as penetrating trauma. Congenital or acquired lesions such as branchial cleft cysts, thyroglossal duct cysts, or laryngoceles may become infected, with resulting spread. Acute mastoiditis may progress to a Bezold abscess with subsequent spread. Necrotic malignant lymph nodes can form an abscess. Immunocompromised patients must raise the index of suspicion for more virulent or atypical pathogens. Although the etiologic factors are many, a thorough search for the cause often reveals no clear source. Wherever the starting point, the infection may spread from its portal of entry to other regions of the neck through the lymphatic system, arterial or venous channels, or direct extension between spaces and along fascial planes. The inflammatory process may plateau as a soft tissue phlegmon upon presentation, or culminate in a deep focal abscess, which usually demands surgical intervention. Microbiology The microbiology of deep neck space infections most often yields a mixture of aerobic and anaerobic organisms, usually representative of the oropharyngeal flora. Retrospective microbiologic analyses consistently demonstrate polymicrobial isolates. 2,7-11 The commonly cultured organisms, which often reflect the microbiology of odontogenic infections, are Streptococcus viridans, Staphylococcus epidermidis, Staphylococcus aureus, group A beta-hemolytic Streptococcus (Streptococcus pyogenes), Bacteroides, Fusobacterium, and Peptostreptococcus species. Cultures occasionally reveal Neisseria, Pseudomonas, Escherichia, and Haemophilus species. The proportion of community-acquired methicillinresistant Staphylococcus aureus (MRSA)-associated neck space infections is significantly increasing in some regions of the United States, especially in pediatric populations. 12,13 One retrospective review concluded that MRSA is more likely to infect younger patients, but that a medial abscess location was less likely for both MRSA and methicillin-sensitive S. aureus infections. 13 Atypical organisms may also initiate a deep neck infection. Actinomyces are endogenous saprophytic organisms of the oral cavity and tonsil. The most common site of cervicofacial actinomycosis is in the vicinity of the angle of the mandible, and this pathogen may cross fascial planes in its route of spread. A granulomatous reaction with central abscess formation and necrosis with sulfur granules is characteristic. Tuberculous and nontuberculous infection of the head and neck most commonly presents with cervical lymphadenopathy. Histopathologically, caseating necrotizing granulomatous inflammation is present. Cat scratch disease, caused by the pleomorphic gram-negative bacillus Bartonella henselae, manifests with large, tender cervical lymph nodes. Late lesions may form an abscess. Management of atypical neck space infections often leans toward nonsurgical management, because incision and drainage procedures may result in a chronic wound or fistulous tract. Anatomy Accurate diagnosis and application of timely treatment requires an understanding of the complex anatomic organization of the neck spaces. Fascial planes divide the neck into true and potential spaces.

2 202 Part 2 The two main fascial divisions of the neck are the superficial cervical fascia and the deep cervical fascia, which further divides into three layers. The superficial cervical fascia, deep to the dermis, envelops the platysma and muscles of facial expression. It incorporates the superficial musculoaponeurotic system and extends from the zygoma to the axillae, clavicles, and deltopectoral region. Deep to the platysma, a potential space separates the superficial and deep cervical fasciae. This space houses adipose tissue, sensory nerves, and blood vessels, such as the anterior and external jugular veins, and facilitates free movement of the skin. The deep cervical fascia is divided into three layers: the superficial, middle, and deep. The superficial layer of deep cervical fascia, or investing fascia, surrounds the neck. Posteriorly it attaches to the superior nuchal line, the ligamentum nuchae of the cervical vertebrae, and the mastoid process. As it transmits anteriorly, it splits and re-fuses to surround the trapezius and sternocleidomastoid muscles. Anterosuperiorly, this layer attaches to the inferior zygomatic arch. As it proceeds inferiorly, it splits to enclose the parotid gland, forming the parotid fascia superficially, and extends along the temporal bone to the carotid canal deeply. It envelops the muscles of mastication and covers the submandibular gland. This layer also forms the stylomandibular ligament, which separates the parotid from the submandibular gland. Inferiorly the investing fascia attaches to the hyoid, clavicle, acromion, and spine of the scapula, but first splits to encompass the intermediate tendon of the omohyoid and form the suprasternal space. The superficial layer of deep cervical fascia contributes to the lateral aspect of the carotid sheath. The middle layer of deep cervical fascia, or visceral fascia, is composed of a muscular and visceral division. The muscular division surrounds the strap muscles (sternohyoid, sternothyroid, thyrohyoid, omohyoid). The visceral division surrounds the buccinator, pharyngeal constrictor muscles, larynx, trachea, esophagus, thyroid, and parathyroid glands. The visceral division forms a pretracheal fascia that overlies the trachea. The visceral division also contributes the buccopharyngeal fascia posterior to the esophagus, which separates the esophagus from the deep layer of deep cervical fascia and forms the anterior border of the retropharyngeal space. The buccopharyngeal fascia forms two raphae: (1) one in the posterior midline that adheres to the alar layer of the deep layer, and (2) the pterygomandibular raphe of the lateral pharynx. The middle layer also contributes to the medial aspect of the carotid sheath. The deep layer of deep cervical fascia, or prevertebral fascia, divides into two layers: the prevertebral and alar layers. The prevertebral layer envelops the paraspinous muscles and cervical vertebrae, lying anterior to the vertebral bodies from the skull base to the coccyx, and attaching laterally to the transverse processes. It covers the scalene muscles and forms the floor of the posterior triangle. As it courses anteromedially, it contributes to the posterior carotid sheath and splits to form the alar layer. The alar layer lies between the prevertebral layer and the buccopharyngeal fascia of the visceral middle layer. The alar fascia separates the retropharyngeal and danger spaces and covers the cervical sympathetic trunk. The carotid sheath extends from the skull base to the thorax, and is a confluence of each layer of deep fascia. The sheath contains the common carotid artery, internal jugular vein, vagus nerve, and ansa cervicalis. Neck Spaces The above fasciae and the structures within the neck form real and potential spaces. Many of these compartments openly communicate with each other, and some spaces are contiguous with distant regions of the body, offering a route of rapid transit for infections. The neck spaces can be organized by their location: the face (buccal, canine, masticator, parotid), suprahyoid neck (peritonsillar, submandibular, sublingual, parapharyngeal), infrahyoid neck (anterior visceral), and along the length of the neck (retropharyngeal, danger, prevertebral, carotid). Also called the lateral pharyngeal or pharyngomaxillary space, the parapharyngeal space is an inverted pyramid with its superior base at the skull base and its inferior apex at the junction of the posterior belly of the digastric muscle and greater cornu of the hyoid bone. The pterygomandibular raphe and medial pterygoid muscle bound the space anteriorly, while the prevertebral fascia bounds it posteriorly. The superior constrictor, tensor, and levator veli palatini muscles form the medial boundary, and the parotid gland, mandible, and lateral pterygoid muscle bound it laterally. The styloid process divides the space into two compartments: the prestyloid compartment, which is anterior to the styloid process, and the post-styloid compartment, which is posterior to the process. The presty loid compartment contains fat, muscle (styloglossus and stylopharyngeus), lymph nodes, deep lobe of the parotid, internal maxillary artery, inferior alveolar, lingual, and auriculotemporal nerves. The poststyloid compartment contains neurovascular structures: carotid artery, internal jugular vein, sympathetic chain, and cranial nerves IX, X, XI, and XII. The parapharyngeal space provides a central connection for the major deep neck spaces. It connects posteromedially with the retropharyngeal space, inferiorly with the submandibular space, and laterally with the masticator space. The carotid sheath courses through the space into the mediastinum. Lateral extension from the peritonsillar space directly invades the parapharyngeal space. These two spaces are best discussed together, because they functionally comprise a single space. The mucosa of the floor of the mouth forms the superior border of the submandibular space, and the digastric muscle and hyoid bone form the inferior. Anteriorly, the mylohyoid muscle and anterior belly of digastric bound the submandibular space, with the posterior belly of the digastric and stylomandibular ligament serving as its posterior borders. The hyoglossus, mylohyoid, styloglossus, genioglossus, and geniohyoid muscles are medial, with the platysma and mandible being lateral. The mylohyoid muscle divides the submandibular space into a superior sublingual compartment and an inferior submaxillary compartment. This sublingual compartment is also called the sublingual space, and contains the sublingual gland and Wharton s duct. The supramylohyoid sublingual space is lateral to the geniohyoid and genioglossus muscles. The sublingual space openly connects to the submaxillary compartment around the free posterior edge of the mylohyoid. The inframylohyoid submaxillary compartment, sometimes itself called the submandibular space, connects to its corresponding space contralaterally and contains the submandibular gland and lymph nodes. The relationship of the mylohyoid to the tooth apices, the mylohyoid line, determines the most likely route of odontogenic infectious spread. The teeth apices anterior to the second molar lie superior to the mylohyoid line and thus involve the sublingual space. Infections of the second and third molars initially involve the submandibular or parapharyngeal space, because their roots extend below the mylohyoid line. The retropharyngeal space, extending from the skull base to the mediastinum at the tracheal bifurcation, refers to the lymph node and connective tissue containing potential space between the middle and deep layers of deep cervical fasciae. The space lies anterior to the alar fascia of the deep layer and posterior to the buccopharyngeal fascia of the middle layer that lines the posterior pharynx and esophagus. The carotid sheath is lateral to the space. It typically becomes involved by direct spread from the parapharyngeal space, or lymphatic spread from the paranasal sinuses or nasopharyngeal region, primarily in children. The danger space, so named because of the potential for rapid inferior spread of infection to the posterior mediastinum through its loose

3 Chapter areolar tissue, extends from the skull base to the diaphragm. This potential space lies between the retropharyngeal and prevertebral spaces. The deep layer of deep cervical fascia subdivisions bound this space. The alar layer forms its anterior border, and the prevertebral layer forms its posterior border. Laterally, the transverse processes of the vertebrae enclose the danger space. The sympathetic trunk courses through this space. Infectious infiltration from the retropharyngeal, parapharyngeal, or prevertebral spaces are the primary routes to the danger space. The prevertebral space is enclosed by the prevertebral fascia, vertebral bodies and transverse processes, and extends from the clivus of the skull base to the coccyx. It is a compact potential space that contains dense areolar tissue and lies posterior to the danger space. In addition to the paraspinous, prevertebral, and scalene muscles, it contains the vertebral artery and vein, brachial plexus, and phrenic nerve. The main pathways of spread to the prevertebral space are from infection of the vertebral bodies and penetrating injuries. Tuberculosis of the spine may breach the space and form a Pott s abscess. The superficial layer of deep cervical fascia defines the masticator space upon splitting at the inferior border of the mandible to cover the medial pterygoid and masseter muscles. Next, the fascia continues superiorly to cover the inferior tendon of the temporalis muscle and incorporate with the superficial temporalis fascia. It contains the mandible and muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid). The masticator space also contains the third portion of the trigeminal nerve, which enters through the foramen ovale, the internal maxillary artery, and much of the buccal fat pad. This space occupies a position anterolateral to the parapharyngeal space. The masticator space is also further divided into subspaces: the masseteric space between the masseter muscle and ramus of mandible, the pterygoid space between the pterygoid muscles and ramus, the superficial temporal space between the superficial temporal fascia and temporalis muscle, and the deep temporal space between the deep temporal fascia and temporal bone. Transmission of infection into the masticator space is most commonly from the third mandibular molars. The peritonsillar space consists of loose connective tissue between the capsule of the palatine tonsil and the superior constrictor muscle. The anterior and posterior tonsillar pillars contribute to its anterior and posterior borders, respectively. The posterior tongue forms the inferior boundary. Peritonsillar infections may readily spread to the parapharyngeal space. The superficial layer of deep cervical fascia forms the parotid space as it splits to surround the parotid gland. However, the fascia, which does not enclose the superomedial aspect of the gland, permits communication with the prestyloid compartment of the parapharyngeal space. The space also contains the facial nerve, external carotid artery, and posterior facial vein. It occupies a position lateral to the parapharyngeal space. The carotid, or visceral vascular, space is the potential space within the carotid sheath containing the carotid artery, internal jugular vein, vagus nerve, and sympathetic plexus. Infection from the surrounding parapharyngeal space, penetrating trauma, or intravenous drug use may potentiate spread into this space. The visceral division of the middle layer of deep cervical fascia encloses the anterior visceral space, or pretracheal space, which lies immediately anterior to the trachea. It extends from the thyroid cartilage to the superior mediastinum. It contains the pharynx, esophagus, larynx, trachea, and thyroid gland. Perforation of the anterior esophageal wall by endoscopic instrumentation, foreign bodies, or trauma may introduce infection to this space. Clinical Evaluation The symptoms of deep neck space infection are determined by both the generalized inflammatory process as well as localizing symptoms at the site of infection. Inflammatory symptoms such as pain, fever, swelling, and redness are common. Symptoms such as dysphagia, odynophagia, drooling, hot potato voice, hoarseness, dyspnea, trismus, and ear pain offer further clues about the location of the inflammatory process as well as its potential severity. The onset and duration of symptoms should be elicited. Recent events such as dental work, upper airway surgery or intubation, intravenous drug use, sinusitis, pharyngitis, otitis, or blunt or penetrating soft tissue trauma that preceded worsening symptoms should be identified in order to formulate a differential of likely microorganisms and common pathways of spread. The past medical history should be reviewed to account for antibiotic allergies and immunodeficiency status. Patients with a history of human immunodeficiency virus, hepatitis, diabetes, collagen vascular diseases, hematologic malignancy, and recent chemotherapy or steroid use are at increased risk of atypical pathogens and rapidly progressive disease. A complete head and neck physical examination is required in all patients with a potential deep neck space infection. Palpation of the neck and face may identify localizing tenderness or fluctuance as well as crepitus caused by airway trauma or gas-producing organisms. Otoscopic examination of the ear and nasal passages can rapidly reveal edema, purulence, drainage, and tenderness, as well as ruling out obstructing foreign bodies. Examination of the oral cavity and oropharynx is facilitated by the use of a headlight, which frees up the hands for bimanual examination. Difficulty with mouth opening indicates that inflammation has already spread into the parapharyngeal, pterygoid, or masseteric spaces. An odontogenic source of infection should be considered in the presence of alveolar swelling and decayed, loose, tender, or broken teeth. The floor of the mouth should be assessed for visible edema, which may cause posterior deflection of the oral tongue. Stensen s and Wharton s ducts should be assessed for purulent discharge and palpated for obstructing stones. Visualization of the oropharynx is necessary to assess for asymmetric lateral or posterior wall swelling, and/or deviation of the uvula. Unilateral pharyngeal wall swelling in the absence of associated inflammatory symptoms such as fever and mucosal erythema should raise the possibility of parapharyngeal tumors, which should not be biopsied or incised without further evaluation. A unilaterally enlarged, irregular, or ulcerated tonsil, especially in the setting of prolonged exposure to tobacco and alcohol, may indicate the presence of tonsillar malignancy. A complete cranial nerve examination is recommended. Infections of the upper dentition, paranasal sinuses, facial soft tissues, and parotid place the orbits at increased risk due to retrograde flow through the facial and ophthalmic veins. Edematous eyelids must be manually separated in order to assess the underlying globe. Reduced mobility of the globe and/or an absent papillary light reflex indicates orbital inflammation or abscess that requires urgent attention to save the eye. Awake flexible fiberoptic evaluation of the upper airway is indicated in most cases of suspected deep neck space infections and is mandatory if the patient has hoarseness, dyspnea, stridor, or dysphagia or odynophagia without obvious cause on oropharyngeal examination. Normal pulse oximetry results do not eliminate the need for direct airway evaluation because the oxygen saturation is a poor proxy for airway status and typically does not fall until the airway is completely occluded. The presence of a patent, midline, noninflamed airway should be documented before the patient is transported for radiographic evaluation to prevent an airway emergency while the patient is supine in the radiology suite. Direct evaluation of the airway identifies patients who may be difficult to intubate by standard technique if surgery is required.

4 204 Part 2 Laboratory Evaluation An initial complete blood count typically demonstrates leukocytosis in cases of deep neck infection. A lack of a leukocytic response may indicate viral illness, immunodeficiency, or a condition such as a tumor, which can be confused with deep neck infection. Daily measures of the white blood cell count may be helpful in monitoring a patient s response to treatment such as intravenous antibiotics or surgical drainage. Intravenous steroids are often necessary to reduce upper airway inflammation in deep neck infection and should not be withheld out of concern that steroid-related leukocytosis will make it difficult to monitor treatment response. A basic electrolyte panel should also be obtained to assess glucose level, bodily hydration, and renal function in case general anesthesia becomes necessary during treatment. Imaging Studies Radiographic imaging plays a critical role in evaluation of suspected deep neck infections. Plain film technology is inexpensive, rapid, and widely available, and it provides excellent information in select circumstances. In cases of suspected dental origin, plain film radiography or a Panorex of the jaw can help identify dental sources of infection if not already obvious on physical examination. Translucencies at the apex of the dental root are a common finding with dental-related abscess. Lateral neck films are useful for quickly evaluating the upper aerodigestive tract in cases of suspected retropharyngeal abscess or supraglottitis. Presence of an air-fluid level or greater than 5 mm of thickening in a child or greater than 7 mm of thickening in an adult of the prevertebral tissue at C2 indicate retropharyngeal infection until proven otherwise. Thickening of the epiglottis, commonly known as thumbprint sign, and arytenoids indicate likely supraglottitis with urgent need for direct airway evaluation in a controlled setting with tracheotomy capabilities. Chest radiography is indicated in cases of dyspnea, tachycardia, or cough to rule out aspiration or mediastinitis. Computed tomography (CT) scans of the head and neck are a critical component in the evaluation of deep neck infection because physical examination alone can misidentify the involved space and the number of involved spaces in 70% of cases. 14 CT scans with intravenous contrast provide excellent visualization of most bony and soft tissue structures of the head and neck. The intravenous contrast allows visualization of the great neck vessels and enhancement of areas of inflammation. CT scans are valuable in determining whether the infection is contained within the lymph nodes or has spread beyond into the fascial planes of the head and neck. Although CT is excellent for identifying the presence of deep neck infection, it cannot reliably differentiate between the generalized edema of phlegmon versus purulent abscess because both commonly appear as hypodense collections with peripheral enhancement (Fig. 14-1). The decision to explore the neck therefore should be made on clinical grounds with the expectation that pus will not be found in up to 25% of explorations. 15 Metastatic adenopathy most commonly from a tonsillar primary should be ruled out clinically because this may mimic neck abscess on CT scan, or may contain abscess if secondarily infected (Fig. 14-2). 16,17 The CT scan provides valuable information about which neck spaces require exploration and drainage at the time of surgery. The use of intravenous contrast is contraindicated in most patients with iodine or contrast dye allergy and in patients with compromised renal function. Therefore other imaging modalities are indicated when intravenous contrast cannot be used. Magnetic resonance imaging (MRI) is not routinely used for suspected deep neck infections, but it should be considered in select circumstances when it is superior to CT. In addition, MRI scanning is time consuming and less likely to be tolerated by a patient who is in pain or is having trouble swallowing or maintaining an airway while supine. MRI scans may provide additional detail to CT in infections involving the intracranial cavity, parotid, and prevertebral space. Evaluation of the major vessels of the head and neck is occasionally indicated if there is suspicion of suppurative thrombi of major head and neck vessels such as the sigmoid sinus, internal jugular vein, or cavernous sinus, or if infection followed trauma to the neck such as an intravenous needle stick. MR angiography with venous flow-through provides excellent evaluation of thrombi and pseudoaneurysm, but invasive angiographic techniques may be needed for stenting or balloon occlusion in rare cases of infected pseudoaneurysms. Ultrasonography is used extensively in the evaluation of both benign and malignant lesions of the head and neck in Europe, but has been largely limited to the evaluation of thyroid lesions in the United States. It is likely this modality will be used more in the future to evaluate neck infections because portable ultrasounds are becoming more readily A B Figure Computed tomography scans of deep neck infections may indicate inflammatory phlegmon (arrow) without obvious abscess early in the course of deep neck infection (A) or a mature infection with abscess formation (B).

5 Chapter Figure A hypopharynx carcinoma initially diagnosed as a retropharyngeal abscess. available in emergency departments and outpatient clinics. The noninvasive nature of ultrasound makes it an attractive imaging modality for pediatric patients, and the lack of radiation reduces concerns about potential long-term harm. Most ultrasonography practitioners are adept at using the ultrasound to perform fine-needle aspiration, which may be helpful to obtain culture or provide therapeutic drainage. 18 Ultrasound may be limited in cases of significant neck edema or phlegmon, or when the infection involves spaces beyond the focal range of the technology. Even though the fluid levels of abscesses can be seen by ultrasound if they are large and superficial enough, lack of visualization does not rule out the possibility of abscess due to its limitations on serial evaluation of multiple cross-sectional spaces that are better seen on CT. Treatment Airway Management The initial management of any patient with a known or suspected deep neck infection is securing a safe airway. Loss of airway has traditionally been the major source of mortality from deep neck infection. 19 Airway complications should be anticipated in all cases of deep neck infection and especially infections involving the floor of the mouth, the parapharyngeal space, and the retropharyngeal space. Fiberoptic evaluation of the upper airway at the time of initial evaluation often identifies an evolving airway complication before it occurs. Pulse oximetry monitoring is helpful if interpreted in the proper context, but a normal oximetry should not provide false security in a patient who appears to be in airway distress. Patients with airway compromise should not be transported out of an intensive care suite for prolonged radiographic testing until the airway is secure. Intravenous access should be obtained to allow rapid administration of medications and anesthetic agents when needed. First-line airway therapy includes use of an oxygenated face tent with cool mist humidity, intravenous steroids, and epinephrine nebulizers. If the patient has mild airway symptoms and the examination reveals mild edema with less than 50% obstruction at the glottic or supraglottic level, the patient often responds to medical therapy alone while under direct observation in the emergency suite or intensive care unit. Urgent airway intervention is necessary if there are greater levels of stridor and dyspnea, usually accompanied by airway obstruction of more than 50%. Effective communication between the consulting otolaryngologist and critical care/anesthesiology personnel is critical. The otolaryngologist needs to convey the results of the initial airway evaluation with the anesthesiologist and be actively involved in intubation planning. In general, an awake fiberoptic intubation can be successfully performed if the airway is visualized to be large enough to allow the passage of the average flexible bronchoscope (5 to 6 mm). Airway preparation with lidocaine nebulizers and lidocaine jelly lubricated nasal trumpets with or without light sedation allows most adult patients to be intubated comfortably while awake. The patient should be sitting upright, and strong suction should be available to clear airway secretions to improve visualization. A tracheotomy set should be available in the room in case a surgical airway is required. An elective tracheotomy may be considered if extubation is not anticipated within 24 to 48 hours, or if surgical drainage procedures are likely to result in significant or prolonged airway edema. In such situations, elective tracheotomy has been associated with reduced hospital days and reduced costs compared to prolonged intubation. 20 An awake tracheotomy should be planned in cases where minimal or no airway lumen is visualized. Increasing peak airway pressures and frothy airway secretions following successful intubation may indicate the onset of postobstructive pulmonary edema, which typically resolves with positive pressure mechanical ventilation and judicious use of intravenous diuretics. Fluid Resuscitation Poor fluid intake is common when neck infection causes significant dysphagia, odynophagia, or trismus. Dehydration is especially common in infections of the peritonsillar and retropharyngeal spaces, and may be the main etiology of sialadenitis-related infections of the parotid space. Signs of fluid deficit include tachycardia, dry and pasty mucous membranes, and decreased skin turgor. Even so, most patients benefit from timely infusion of 1 to 2 L of isotonic intravenous fluids. Providing adequate fluid resuscitation before surgical intervention reduces the severity of anesthesia-related hypotension. Antibiotic Therapy Prophylactic antibiotics given before dental, oral, and head and neck procedures may reduce the risk of deep neck infection. Prophylaxis should consist of an oral or intravenous dose of a beta-lactamase resistant penicillin or clindamycin given within 30 minutes of procedures on nonsterile body cavities, or a first-generation cephalosporin (e.g., cephalexin) or clindamycin for neck incisions in a sterile field. Prophylaxis is mandatory for any patient with a history of heart murmur, rheumatic valve disease, or vascular or joint prosthetic devices. Deep neck infections require timely treatment with intravenous antibiotics at the time of diagnosis due to the rapidly progressive nature of these infections. Culture is not required before empiric antibiotic therapy because broad-spectrum coverage is usually necessary; most cases involve mixed flora of gram-positive cocci and gram-negative rods with or without anaerobes. 21 Antibiotic coverage may need to be expanded in cases of otologic or sinus infection or nosocomial infections in which Pseudomonas is more common, whereas expanded anaerobic coverage is often necessary for fulminate odontogenic infections. Fluids obtained from aspiration or incision and drainage should be sent for culture due to the increasing rate of resistant organisms in the at-large community. Culture and sensitivity information is especially valuable in the setting of hospital-acquired infections or an immunocompromised host. Due to increasing rates of MRSA in the community, it is likely that more deep neck infection will be caused by this organism in the future. A detailed history and physical examination often identifies patients at risk for atypical infections, which should be confirmed by staining and culturing aspirated fluids or tissue biopsy samples. The choice of antibiotic therapy is typically dictated by the clinical scenario and by culture and sensitivity findings (Table 14-1). Intravenous antibiotic therapy without surgical intervention may be sufficient therapy in certain circumstances. 22 If a patient is clinically stable and if imaging studies demonstrate inflammation without likely

6 206 Part 2 Table 14-1 First-Line Antibiotic Alternatives for Deep Neck Infection Community-Acquired Infection (gram-positive cocci; gram-negative rods; anaerobes) Alternatives Ampicillin-sulbactam 1.5 to 3 g. IV every 6 hours Clindamycin (if penicillin allergic) 600 to 900 mg IV every 8 hours Compromised Patients/Nosocomial Infection (Pseudomonas; Methicillin-Resistant Staphylococcus aureus) Pseudomonal and Gram-Negative Alternatives Ticarcillin-clavulanate 3 g IV every 6 hours Piperacillin-tazobactam 3 g IV every 6 hours Imipenem-cilastatin 500 mg IV every 6 hours Ciprofloxacin (if penicillin allergic) 400 mg IV every 12 hours Levofloxacin (if penicillin allergic) 750 mg IV every 24 hours Methicillin-Resistant Staphylococcus aureus Clindamycin 600 to 900 mg IV every 8 hours, plus vancomycin 1 g IV every 12 hours Necrotizing Fasciitis (Mixed Gram-Positive and Expanded Anaerobes) Ceftriaxone 2 g IV every 8 hours, plus clindamycin 600 to 900 mg IV every 8 hours, plus metronidazole 500 mg IV every 6 hours abscess or an abscess contained within a lymph node, then a 48- to 72-hour trial of empiric intravenous antibiotic therapy is appropriate. A trial of empiric antibiotics is recommended in almost all stable pediatric cases because even sizable collections may respond favorably to intravenous antibiotics and steroids alone. 23 In general, the patient should be given nothing by mouth and closely monitored for changes in clinical status and elevation in white blood cell count. Repeat imaging and/or surgical intervention is necessary in cases that fail to improve or worsen during the observation period. If significant clinical improvement is noted with intravenous antibiotics after 48 to 72 hours, therapy is continued for 24 hours beyond normalization of symptoms followed by a 2-week course of an equivalent oral antibiotic. Patients requiring surgery usually need 48 to 72 hours of intravenous antibiotics postoperatively before being discharged home on oral therapy. Surgical drainage is indicated in most cases of deep neck infection. Surgical drainage is necessary under the following circumstances: (1) air-fluid level in the neck or evidence of gas-producing organisms; (2) abscess visualized in the fascial spaces of the head and neck; (3) threatened airway compromise from abscess or phlegmon; (4) failure to respond to 48 to 72 hours of empiric intravenous antibiotic therapy. The main goals of surgical intervention include providing a fluid or tissue sample for tissue staining and culture and sensitivity testing, and providing therapeutic irrigation of the infected body cavity while establishing a stable external drainage pathway to prevent the reaccumulation of abscess. Figure An infected thyroglossal duct cyst that responded to needle aspiration followed by excision several weeks later. Needle Aspiration Needle aspiration without incision often suffices for small abscesses contained within the confines of a lymph node or when an acute infection is caused by suspected congenital cysts or fibrotic pseudocysts (Fig. 14-3). Recurrent infection is common in head and neck cysts; therefore complete surgical excision should be planned after the acute inflammation subsides. For adults, aspiration can be performed at the bedside when the neck mass is palpable and the patient cooperative. Children younger than 12 years of age typically require conscious sedation to prevent errant aspiration. Applying lidocaine ointment to the skin surface for 20 minutes before the aspiration aids in patient comfort. Lidocaine injections often hurt as much as the therapeutic aspiration itself and may obliterate the palpable contours of the mass, making the aspiration more difficult. Slow advancement of a 16- or 18-gauge intravenous catheter on a control syringe while applying negative pressure usually allows localization of the abscess. The needle can be removed from the catheter and the catheter flushed with 1 to 2 ml of sterile saline when the pus is too thick to fully aspirate. Image-guided techniques using ultrasound or CT are being increasingly used when the initial unguided fine-needle aspiration is unsuccessful or the mass is nonpalpable. 24,25 Image guidance also allows placement of small pigtail catheters using Seldinger technique for drainage and flushing. Transoral Incision and Drainage The peritonsillar space can be accessed transorally in a cooperative adult without significant trismus. The procedure is often more likely to succeed and be more comfortable to the patient if intravenous fluid rehydration, pain medication, antibiotics, and steroids are administered at least an hour before the procedure. Following application of topical anesthetic spray, 1 to 2 ml of 1% lidocaine with 1 : 100,000 epinephrine is injected into the mucosa of the lateral soft palate. An initial attempt to drain the space by aspiration is reasonable and helps locate the abscess pocket. If the space cannot be decompressed with aspiration alone, a 1- to 2-cm incision is performed through the mucosa and submucosa along the normal curvature and 1 cm behind the edge of the anterior tonsillar pillar. Gentle vertical spreading of the incision with a hemostat will access the peritonsillar space and allow egress of the abscess. Irrigation with sterile saline using a 20-mL syringe and 18-gauge angiocatheter can easily be performed through the incision. The patient can be discharged home on oral pain medication and antibiotics with outpatient follow-up arranged within 48 to 72 hours. Tonsillectomy at a later date is an option for patients with a history of peritonsillar abscess, recurrent or chronic tonsillitis, or obstructive symptoms from tonsillar hypertrophy. Approximately 16% of adults and 7% of children will experience a recurrent peritonsillar abscess at a later date after an initial episode. 4 Alternatively, acute quinsy tonsillectomy at the time of presentation can be considered in cases of recurrent peritonsillar abscess, recurrent acute tonsillitis, or if a general anesthetic is needed due to patient discomfort or poor exposure. Acute

7 Chapter tonsillectomy may be more difficult and bloody than nonacute tonsillectomy due to the surrounding inflammation; therefore the surgeon should have access to adequate lighting, suction, electrocautery, tonsil packs, and suture. Transoral incision and drainage is also a preferred method of surgery for select deep neck space infections. Odontogenic infections limited to the alveolus may respond to removal of the offending tooth to drain the infected root, although neck incision is necessary when infection has spread beyond the alveolar tissues. A neck incision with dependent drainage of the bilateral floor of the mouth through the mylohyoid muscle is mandatory in cases of Ludwig s angina to reduce the risk of airway obstruction. The buccal space can be accessed via transoral incision of the buccal mucosa with blunt dissection parallel to the facial nerve through the buccinators muscle. The masticator space can be entered by incision of the retromolar trigone with blunt dissection through the masseter. After drainage and irrigation, a 1 2 -inch Penrose drain or gauze wick can be placed through the incision and secured with a silk suture if ongoing drainage is deemed necessary. Otherwise, the wound can be left open to close secondarily or closed loosely with interrupted Vicryl or chromic suture. The retropharyngeal space is often best entered transorally, especially because many infections in this space originate from the adenoids and are located in the high oropharynx or nasopharynx, which is difficult to access through the neck. After securing the airway and inserting a tonsil gag, transmucosal needle aspiration of the likely site of infection is performed. Once the abscess pocket is identified, the overlying mucosa is incised and blunt dissection used to enter the pocket. Caution should be exercised when dissecting beyond the lateral pharyngeal walls to prevent inadvertent injury to the carotid artery. Drains are typically not placed due to the potential for drain aspiration and potential difficulties with drain removal. If a drain or wick is placed, it can be brought out through the mouth and taped securely to the face. Alternatively, a small ellipse of mucosa and submucosa can be excised at the site of incision to slow the healing process and allow several days of drainage before wound contraction. Transcervical Incision and Drainage Transcervical incision and drainage is the traditional surgical approach to deep neck space infection. The location of the incision is dictated by the neck spaces that require exploration. If the skin above a neck abscess has become fluctuant, adequate drainage can often be achieved under local anesthesia with or without sedation via an incision oriented along the relaxed skin tension lines. In general, the deep neck spaces can be accessed by one of three potential incisions that provide both excellent anatomic exposure as well as cosmetic healing. The preauricular parotid incision with neck extension allows access to the parotid and temporal spaces. A horizontal neck incision in a natural skin crease provides access to the masticator, parapharyngeal, pterygoid, submandibular, prevertebral, retropharyngeal, carotid, and lateral neck spaces. The parapharyngeal and pterygoid spaces are entered by retracting the submandibular gland anteriorly while dissecting superior and medial to the posterior belly of the digastric muscle along the medial surface of the mandibular ramus. The prevertebral and retropharyngeal spaces are entered by first identifying the prevertebral fascia by retracting the strap muscles medially and the carotid sheath laterally at a level inferior to the carotid bifurcation. The space can then be bluntly dissected superiorly in the midline to the level of the abscess. The midline horizontal neck incision can be made to access the region of the strap muscles, thyroid, and trachea. A horizontal incision in the lower left neck with dissection to the prevertebral fascia medial to the carotid sheath provides a drainage conduit for the esophagus and upper mediastinum. A horizontal submental incision provides a direct route to the bilateral submandibular spaces and floor of mouth. After securing the airway by an awake fiberoptic intubation or tracheotomy, the proposed incision site is marked on the neck, injected with 1% lidocaine with 1 : 100,000 epinephrine, and sterilely prepped and draped. In most cases, the patient should not be paralyzed during the procedure in order to allow monitoring of adjacent cranial nerves. The guiding principle of surgery for deep neck infection is obtaining adequate access and drainage of the infected space while minimizing risk to normal structures. Following incision through the superficial cervical fascia, blunt dissection with a small curved hemostat and Kitner sponge can help separate normal structures while creating a pathway to the infected compartment. Finger dissection of neck tissues should be avoided in patients with a history of transcervical IV drug abuse because broken needles may be left in the neck soft tissue. Access to the deep neck often requires excision of enlarged lymph nodes that block access to the infected space; however, care should be exercised not to overdissect because this may increase the risk to normal nerves and vessels that may be displaced or obscured by inflammation. Once the deep neck space is entered, any fluid or pus should be cultured, followed by irrigation with copious amounts of isothermic normal saline. External drainage is maintained by placement of a 1 2 to 1-inch Penrose drain, which is brought out through the incision and secured to the neck skin with a suture. The remainder of the incision can be closed loosely with 4.0 nylon sutures. Selected Complications of Deep Neck Infections Lemierre s Syndrome Lemierre s syndrome is a rare thrombophlebitis of the internal jugular vein most often caused by the anaerobic, gram-negative bacillus Fusobacterium necrophorum. 26 Although this syndrome is rare, awareness is important given the characteristic presentation and potentially fatal outcome if not recognized and treated. The syndrome typically follows a period of pharyngitis before progressing to fever, lethargy, lateral neck tenderness and edema, occasional trismus, and septic emboli most commonly seen as bilateral, nodular infiltrates on chest radiograph or septic arthritis. The bacterium is thought to spread via the tonsillar veins to the internal jugular system where the bacterial endotoxin induces platelet aggregation and septic thrombus formation. Diagnosis is confirmed by neck CT with IV contrast demonstrating a filling defect in the internal jugular system. First-line therapy includes intravenous beta-lactamase resistant antibiotics with or without heparin anticoagulation. Surgery to excise the jugular vein may be indicated in patients with a worsening clinical course despite appropriate medical therapy or in the event of neck abscess formation. Cavernous Sinus Thrombosis Cavernous sinus thrombosis is a life-threatening infection with a mortality rate of 30% to 40% caused by retrograde spread of infection from the upper dentition or paranasal sinuses via the valveless ophthalmic venous system to the cavernous sinus. 27 Symptoms include fever, lethargy, orbital pain, proptosis, reduced extraocular mobility, and dilated pupil with sluggish pupillary light reflex. The diagnosis is best confirmed by magnetic resonance study of the brain with contrast to demonstrate dural enhancement in the region of the cavernous sinus. Treatment includes critical care life support, broad-spectrum intravenous antibiotics, and anticoagulation therapy. Carotid Artery Pseudoaneurysm or Rupture Rare cases of carotid artery pseudoaneurysms or rupture have been reported after spread of infection from the retropharyngeal or parapharyngeal spaces to the carotid space. 28 Hallmarks of this complication include a pulsatile neck mass, Horner s syndrome, palsies of cranial nerves IX through XII, expanding hematoma or neck ecchymosis, or bright red blood from the nose or mouth in the setting of a deep neck infection. The complication requires immediate surgical ligation of the carotid artery. Mediastinitis Mediastinitis is a relatively rare complication of deep neck infection with a mortality rate of 30% to 40% caused by spread of infection along the retropharyngeal and prevertebral planes of the neck into the upper mediastinum. 29,30 Presentation includes diffuse neck edema, dyspnea, pleuritic pain with deep breathing, tachycardia, hypoxia, and

8 208 Part 2 pleural effusion or mediastinal widening on chest radiograph. Thoracic CT scan with intravenous contrast often reveals the presence of fluid collection, air-fluid levels, or stranding or infiltration of the mediastinal fat. Broad-spectrum intravenous antibiotics are necessary due to a high frequency of multiple pathogens including gram-positive, gramnegative, aerobic, and anaerobic species. If limited to the anteriorsuperior mediastinum, transcervical drainage via a bilateral cervicotomy with blunt dissection along the prevertebral plane often provides sufficient access for drainage, irrigation, and placement of soft rubber drains. Thoracotomy should be strongly considered in cases that extend beyond the upper mediastinum or that involve more than one mediastinal compartment. In a meta-analysis of 69 patients with mediastinitis from cervical abscess, the mortality rate was 19% among patients who underwent both cervical and thoracic drainage, and 47% among those who underwent cervical drainage alone. 31 Necrotizing Fasciitis Necrotizing fasciitis is a severe form of deep neck infection that occurs more often in older age groups (age older than 60 years) and immunocompromised patients, especially patients with poorly controlled diabetes. 32 The origin of the infection is commonly odontogenic and involves mixed aerobic and anaerobic flora. Clinical presentation may consist of a rapidly progressive cellulitis with pitting neck edema and orange-peel appearance from obstructed dermal lymphatics with or without subcutaneous crepitus. Neck CT with intravenous contrast reveals tissue gas in more than 50% of cases, and widespread, nonloculated hypodense areas without peripheral enhancement consistent with liquefaction necrosis. Treatment requires critical care support, management of immunocompromising conditions, broad-spectrum intravenous antibiotics, and surgical exploration. Findings at surgery consistent with necrotizing fasciitis include foul odor, brown, watery fluid collections, and liquefied and grayish fat and muscle that pull apart with minimal finger pressure. Debridement of dead tissue until a bleeding, viable edge or vital nerves or vessels are reached is recommended. The wound is thoroughly irrigated, packed with moist gauze, and left open for a second-look procedure in 48 to 72 hours. Surviving patients may require skin grafting or flap reconstruction once the infection subsides. Adjuvant hyperbaric oxygen therapy can be considered if available. 33 Mortality may be as high as 20% to 30% in treated patients, and is highest in patients with mediastinal extension. 32 Bottin R, Marioni G, Rinaldi R, et al. Deep neck infection: a present-day complication. A retrospective review of 83 cases ( ). Eur Arch Otorhinolaryngol. 2003;260: Huang TT, Liu TC, Chen PR. Deep neck infection: analysis of 185 cases. Head Neck. 2004;26: Ossowski K, Chun RH, Suskind D, et al. Increased isolation of methicillinresistant Staphylococcus aureus in pediatric head and neck abscesses. Arch Otolaryngol Head Neck Surg. 2006;132: Parhiscar A, Har-El G. Deep neck abscess: a retrospective review of 210 cases. Ann Otol Rhinol Laryngol 2001;110: Thomason TS, Brenski A, McClay J, et al. The rising incidence of methicillinresistant Staphylococcus aureus in pediatric neck abscesses. Otolaryngol Head Neck Surg. 2007;137: Weber AL, Siciliano A. CT and MR imaging evaluation of neck infections with clinical correlations. Radiol Clin North Am. 2000;38: For complete list of references log onto