Retropharyngeal Hematoma

Frequency

The frequency of retropharyngeal hematoma is unknown, but it is thought to be rare. In 1991, Thomas et al found only 29 cases in the literature since 1966.[2] In 2001, Munoz et al reviewed another 20 cases.[3] A review in 2006 of retropharyngeal hematomas after stellate ganglion blocks found 27 cases over a 40-year period.[4]

Various precipitating factors have been described. These factors include bouts of coughing, sneezing, straining, vomiting, whiplash injury, blunt head and neck trauma, foreign body ingestion, retropharyngeal infection, carotid artery aneurysm, carotid sinus massage, internal jugular vein cannulation, metastatic disease, and coagulopathic states.

In their review of 29 cases, Thomas et al found that the most common cause was closed cervical trauma, which was responsible for 11 of 29 cases.[2]

Stellate ganglion block is also known to be a cause, with 27 cases reported in the literature up to 2006.[4]

In a study of 68 cases of blunt trauma–induced retropharyngeal hematoma with respiratory symptoms, Tsao et al found that the majority of traumas resulted from falls (54.4%) and traffic accidents (35.3%).[5]

Hyperextension injury due to airbag deployment has been highlighted. Possible iatrogenic causes include instrumentation with laryngoscopy, endotracheal intubation, surgery, endoscopy, feeding tube placement, and dental injections and procedures. Even acupuncture has been implicated.[6]

A study by O’Neill et al identified a series of risk factors for retropharyngeal hematoma following anterior cervical spine surgery. In the study, of 2375 anterior cervical spine procedures (17 occurrences of postoperative hematoma), the investigators reported the following to be risk factors[7] :

• Diffuse idiopathic skeletal hyperostosis (DISH)

• Posterior longitudinal ligament ossification

• Therapeutic heparin use

• Longer surgical time

• Higher number of surgical levels

A retrospective study by Miao et al of patients who developed either retropharyngeal or epidural hematomas following anterior cervical spine surgery also reported posterior longitudinal ligament ossification, longer procedure time, and a greater number of surgical levels to be risk factors for postoperative hematomas, with a higher body mass index identified as another such factor.[8]

However, a study by Song et al of patients who underwent anterior cervical fusion found no specific preoperative risk factors for the development of postoperative retropharyngeal hematomas.[9]

Oral anticoagulant therapy is a rare cause of upper airway hematoma (UAH), with a literature review by Karmacharya et al finding that out of 38 cases of warfarin-related UAH, 66.57% were sublingual and 27.03% were retropharyngeal.[10]

A study by Betten and Jaquint reported on the development of a retropharyngeal hematoma in an elderly woman taking the antiplatelet drugs clopidogrel and aspirin, with symptoms developing about 10 hours subsequent to a fall from a standing position.[11]

Precipitating factors, such as episodes of coughing, sneezing, straining, and vomiting, indirectly contribute to a retropharyngeal hematoma by increasing venous pressure and causing rupture of the venous system.

In traumatic cases, the hematoma is thought to be caused by a tear in the anterior longitudinal ligament, but it can also be due to bleeding from a cervical spinal fracture.

In one case, a spontaneous bleed occurred from a parathyroid in a hemodialysis patient.[12]

The expanding hematoma may affect the airway at different levels as a result of mass effect. Because of the anatomic barriers described above, the bulk of the hematoma could be compressing the nasopharynx, oropharynx, hypopharynx, or esophagus. Thus, the obstruction could be at the level of the upper airway, at the cervical trachea, or at the intrathoracic trachea. This knowledge is significant, as a standard tracheostomy may not resolve the airway obstruction (see Treatment).

Clinical presentation

Because the patient's history can be nonspecific, a high index of suspicion is needed to diagnose a retropharyngeal hematoma. The onset is usually acute but can also be insidious, and patients may present several days after the initial insult.

The airway is the immediate concern, and appropriate management might initially preclude taking a full history and/or the examination. Because of the possibility of associated cervical spinal fracture, appropriate attention should also be given to immobilizing the cervical spine in traumatic cases.

History

Patients with retropharyngeal hematoma may present with a history of trauma to the head and neck area (especially hyperextension of the neck), but the history often includes details that seem trivial, such as episodes of coughing, sneezing, or straining. Patients may experience sore throat, difficulty swallowing (dysphagia), odynophagia, jaw stiffness (trismus), or neck stiffness (torticollis). Patients also may experience having a muffled voice, the sensation of a lump in the throat, and/or pain in the back and shoulders upon swallowing.

Other precipitating factors include foreign body ingestion, retropharyngeal infection, carotid artery aneurysm, carotid sinus massage, recent internal jugular vein cannulation, metastatic disease, and coagulopathic states. These factors should be excluded in the history, but the onset may be spontaneous.

Difficulty breathing is an ominous symptom that signifies impending airway obstruction.

Physical examination

The initial assessment should include an evaluation of the patient's pulse rate, respiratory rate, temperature, blood pressure, and pulse oximetry reading.

The patient's voice might resemble a hot-potato voice (dysphonia). Patients in respiratory distress, those who present with stridor (noisy inspiration with or without noisy expiration), or those with drooling should be considered to have airway compromise until proven otherwise. Patients assume the position that provides maximum airway patency; this may be supine with their head extended or sitting up and holding onto railings to aid the accessory breathing muscles. Do not force patients to alter their position, as this may worsen their respiratory distress.

On examination, the neck's range of movement may be limited. Ecchymosis may be detected on the lateral aspect of the neck. Palpation may reveal a mass, which is usually unilateral.

Examination of the oral cavity and pharynx may be precluded by trismus. This is due to blood collecting next to the pterygoid muscles.

On inspection of the oral cavity, a mass may be visualized in the posterior pharyngeal wall of the oropharynx. This protuberance tends to be off the midline because of the presence of a midline raphe caused by the superior constrictor muscle. A midline swelling suggests a hematoma in the prevertebral space, behind the dividing raphe. Movement of the laryngeal cartilages may induce or worsen the patient's pain. It should be noted that the retropharyngeal hematoma may extend into the thorax.  

Flexible nasolaryngoscopy is especially helpful in assessment of the airway and in informing the anesthetist of what to expect during intubation. Moreover, an endoscopic exam may be useful in excluding other conditions, such as malignancy, injury, and vocal fold paralysis. Serial examination of the upper airway with a nasolaryngoscope may be helpful in patients who do not need to go directly to the operating room.  

Physical assessment should be ongoing, as the patient's condition may deteriorate hours or days after initial presentation.

The aforementioned study by Tsao et al, which included a literature review, determined that in 95.2% of the report’s patients, each of whom had blunt trauma–induced retropharyngeal hematoma with respiratory symptoms, signs and symptoms developed within 24 hours of trauma, with these commonly including dyspnea (77.9% of patients), dysphagia (36.8%), neck pain (32.4%), stridor (27.9%), hoarseness (26.5%), altered mental state (19.1%), neck swelling (17.6%), and cyanosis (16.2%).[5]

Not all retropharyngeal hematomas warrant surgical intervention. A patient with a small nonexpanding hematoma should be observed in the hospital, and the hematoma should be regularly assessed via clinical examination, flexible nasolaryngoscopy, or radiologic study.

Actual or impending airway obstruction is best treated with tracheotomy, as intubation with a small-lumen tube may not pass the inferior limit of the hematoma. High-pressure ventilation may be needed and may result in poor gaseous exchange. A longer-than-usual tracheotomy tube might be needed.

Surgical evacuation of the hematoma is necessary when the patient has a life-threatening airway obstruction, a rapidly expanding hematoma, or an inability to achieve ventilation after tracheostomy. The advised approach is a lateral approach for pharyngotomy in which the anterior aspect of the carotid sheath is passed.

The deep neck spaces are formed by fascial planes, which divide the neck into real and potential spaces.

Fascial planes

The fascial planes are divided into superficial and deep divisions.

Superficial cervical fascia

The superficial cervical fascia surrounds the muscles of facial expression. The superficial musculoaponeurotic system (SMAS) is included in this layer and extends from the skull to the axillae and chest. It lies below the dermis. Deep to this fascia is a layer that contains fat, lymphatics, and neurovascular bundles. This area is distinct from the deep neck spaces.

Deep cervical fascia

The deep cervical fascia envelops the deep neck spaces and is further divided into 3 layers: the superficial, the middle, and the deep layers of the deep cervical fascia. The carotid sheath is formed by contributions from all 3.

The superficial layer of the deep cervical fascia is an investing fascia that surrounds the neck. It covers the sternocleidomastoid muscle, trapezius, the muscles of mastication, and the submandibular and parotid glands. Its superior aspect is limited by the nuchal ridge, mandible, zygoma, mastoid, and hyoid bones. Inferiorly, it extends to the clavicles, sternum, scapula, hyoid, and acromion. This layer contributes to the fascia that covers the digastric muscle and to the lateral aspect of the carotid sheath. It envelops the anterior belly of the digastric muscle and forms the floor of the submandibular space. Laterally, this fascia helps to define the parotid and masticator spaces.

The middle layer of the deep cervical fascia has 2 divisions: muscular and visceral. The muscular division surrounds the strap muscles (ie, sternohyoid, sternothyroid, thyrohyoid, omohyoid). The visceral division covers the constrictor muscles of the pharynx and esophagus, the larynx, trachea, and thyroid gland. In doing so, it creates the anterior wall of the retropharyngeal space. Both divisions contribute to the formation of the carotid sheath. The middle layer attaches to the base of the skull superiorly and extends inferiorly as low as the pericardium by means of the carotid sheath. Some authors refer to the middle layer as the pretracheal fascia.

The deep layer of the deep cervical fascia is also subdivided in layers: prevertebral and alar. The prevertebral division adheres to the anterior aspect of the vertebral bodies and extends laterally to the transverse processes of the vertebrae. The alar division lies between the prevertebral division and the visceral division of the middle layer and defines the posterior border of the retropharyngeal space. It surrounds the deep neck muscles and contributes to the carotid sheath. The muscular division of the middle layer of the deep cervical fascia fuses with the alar division of the deep layer of the deep cervical fascia at the level of T1-2.

The carotid sheath is a pipelike fibrous sheath that extends from the base of skull to the thorax. It is composed of all 3 of the aforementioned layers. It contains the common carotid artery, the internal jugular vein, and the vagus nerve.

Deep neck spaces

Within the deep regions of the neck are 11 spaces created by planes between the fascial layers. These spaces may be real or potential and may expand when pus separates the layers of fascia. The deep neck spaces communicate with each other, forming avenues by which blood or infections may spread. The relevant spaces are described briefly below.

Parapharyngeal space

The parapharyngeal space (ie, lateral pharyngeal space, pharyngomaxillary space, pterygomaxillary space, pterygopharyngeal space) is in the shape of an inverted pyramid bounded by multiple components of the fascial system. The inferior boundary of this space is the lesser cornua of the hyoid bone. The entire space is situated superior to the hyoid. The superior boundary of the space is the skull base. Its medial boundary is the pharynx and its overlying fascia. Laterally, the space is limited by the superficial layer of the deep cervical fascia that overlies the mandible, medial pterygoids, and parotid.

The posterior border is medially formed by the prevertebral division of the deep layer and by the posterior aspect of the carotid sheath at the posterolateral corner. The anterior boundary is the interpterygoid fascia and the pterygomandibular raphe. The parapharyngeal space can be subdivided into anterior and posterior compartments by a line that extends from the medial aspect of the medial pterygoid plate to the styloid process.

The prestyloid (anterior) part contains the maxillary artery, inferior alveolar nerve, lingual nerve, and auriculotemporal nerve.

The poststyloid (posterior) compartment contains the carotid sheath (ie, carotid artery, internal jugular vein, vagus nerve) and the glossopharyngeal and hypoglossal nerves, sympathetic chain, and lymphatics. It also contains the accessory nerve, which is in a relatively safe position behind the sternocleidomastoid muscle at this level. The parapharyngeal space communicates posteromedially with the retropharyngeal space and inferiorly with the submandibular space. Laterally, it is connected to the masticator space. The carotid sheath travels through this space into the chest. This space provides a central connection for all other deep neck spaces. It is often involved by lateral extension of peritonsillar abscesses and was the most commonly affected space before the advent of modern antibiotics.

Retropharyngeal space

Some consider the retropharyngeal space a third medial compartment in the parapharyngeal space because the 2 communicate laterally. It lies between the visceral division of the middle layer of the deep cervical fascia and the alar division of the deep layer of deep cervical fascia posteriorly. It extends from the skull base to the tracheal bifurcation around T4, where the visceral and alar divisions fuse. It contains mainly lymphatics.

The retropharyngeal space is found immediately posterior to the nasopharynx, oropharynx, hypopharynx, larynx, and trachea.

A hematoma in the space may push forward and occlude the airway at the level of the pharynx, appearing as anterior displacement of one or both sides of the posterior pharyngeal wall due to the midline fascial raphe.

Prevertebral space

The prevertebral space is located anterior to the vertebral bodies and posterior to the prevertebral division of the deep layer of the deep cervical fascia. It lies just posterior to the danger space (see below). Laterally, it is bounded by the fusion of the prevertebral fascia with the transverse processes of the vertebral bodies. It extends from the skull base to the coccyx.

Danger space

The danger space is just posterior to the retropharyngeal space and anterior to the prevertebral space, between the alar and prevertebral divisions of the deep layer of the deep cervical fascia. It extends from the skull base to the posterior mediastinum and diaphragm. Laterally, it is limited by the fusion of the alar and prevertebral division with the transverse processes of the vertebrae. Some authors consider the danger space a component of the prevertebral space.

The term danger space is derived from the fact that infection in this space tends to spread rapidly because of the loose areolar tissue that occupies this region. This spread can lead to mediastinitis, empyema, and sepsis.

For an excellent description of all the fascial planes and deep neck spaces, see the Medscape Reference article Deep Neck Infections.

Surgical drainage of deep neck space hematoma has no absolute contraindications. However, for patients with airway compromise due to the hematoma, the need to establish a safe airway takes priority and should be addressed before any surgical procedure is initiated. Once the airway is secured, surgical drainage can be performed.

Studies include the following:

• CBC (with special attention to the WBC count and differential, as well as the hemoglobin level)
• Hematologic laboratories to evaluate for bleeding diathesis
• Complete metabolic panel
• Type and screen for potential blood product transfusion

See the list below:

• A lateral soft tissue radiograph of the neck shows widening of the retropharyngeal area, the prevertebral area, or both.

  • The radiograph should be obtained during inspiration, and the patient's neck should be in the normal extended position.

  • The area to examine is between the vertebrae and the radiolucent airway at the anterior aspect. At the level of C2, a measurement of up to 7 mm is considered normal for all age groups. At the level of C4-6, the normal measurement is up to 15 mm in patients younger than 16 years or 22 mm in adults.

    Lateral soft tissue radiograph of an elderly patient who presented with a retropharyngeal hematoma after a fall.
    Chest radiograph of the same patient as in the image above. Note the soft tissue shadow in the superior mediastinum.

• Many authors consider contrast-enhanced CT scanning of the neck and chest to be the investigation of choice (see the image below).

  • Enhanced CT scans delineate the hematoma and help to differentiate blood from pus.

  • The level of obstruction and extent of the hematoma are shown.

  • Small vertebral body fractures may be revealed.

  • Data obtained with CT scan can facilitate the planning of anesthesia and surgery.

  Sagittal image from a contrasted computed tomography (CT) scan of the neck in a patient with a retropharyngeal hematoma. Note that the patient is intubated and the posterior pharyngeal wall is displaced anteriorly. Courtesy of Case Reports in Emergency Medicine journal [Betten DP, Jaquint JL. Traumatic Retropharyngeal Hematoma in a Patient Taking Clopidogrel. Case Rep Emerg Med. 2018 Aug 13. Online at: https://www.hindawi.com/journals/criem/2018/6147473/].

• Gadolinium-enhanced magnetic resonance imaging (MRI) of the neck and chest can also accurately delineate the extent of the hematoma and help to differentiate blood from pus. However, this imaging modality is less often used, because patients with retropharyngeal hematoma are not appropriate candidates for long scanning times, especially since respiratory distress can evolve.   

• Imaging is helpful in monitoring the progression of the hematoma, and some authors advise repeat CT scanning if the patient's condition deteriorates.

Most authors advise that patients with small nonexpanding hematomas can be treated conservatively, with repeated assessments of the size of the hematoma made via nasolaryngoscopy, CT scanning, or MRI.

Admission is advised until the hematoma resolves. The prophylactic use of antibiotics is considered controversial.

Bleeding tendencies should be addressed on an urgent basis with input from a hematologist. A particularly difficult case to manage is that of a hemophilic patient with high levels of inhibiting antibodies to factor VIII. A recent case report has highlighted the successful use of recombinant activated factor VII in a life-threatening retropharyngeal hematoma.[13]

Endotracheal intubation with admission to intensive care is an option in more severe cases.

In the event of real or anticipated airway compromise, preparations for urgent tracheotomy should be made.

A tracheotomy under local anesthesia may be the only safe option. This is especially true if a very difficult intubation is anticipated. A senior anesthetist should be involved in the decision, and the procedure should be performed by an experienced surgeon.

Ventilation and oxygenation are the primary concerns. Achieving these objectives is an anesthetic challenge because of the presence of lower tracheal obstruction, and patient care is best provided by a clinician experienced in difficult airway management. Immobilization of the cervical spine is an important consideration when trauma is involved.

As an interim measure, orotracheal intubation may be a feasible option, but each case should be considered on its own merits. Flexible nasolaryngoscopy should provide enough information for the clinician to decide whether an attempt at orotracheal intubation is worthwhile.

Other measures include use of positive end-expiratory pressure (PEEP) and posture changes, low-frequency jet ventilation, and administration of helium-oxygen mixtures. PEEP should be used with caution, as this may worsen airtrapping. A possible jet ventilation strategy is the use of 40-60 psi (275-413 kPa) at a rate of 12 L/minute with an inspiratory-expiratory ratio of 1:4. This method has been used successfully in ventilating adult patients with severe fixed narrowing of the trachea just above the carina due to retrosternal goiter.

Helium-oxygen mixtures are less dense than oxygen alone and work by reducing turbulence and improving laminar flow. Helium cylinders may contain oxygen, and helium-oxygen mixtures from a cylinder typically contain only 21% oxygen. Administration of supplemental oxygen via a t-piece or nasal prongs is advised.

Femorofemoral cardiopulmonary bypass before the induction of anesthesia has been described for tumors that obstruct the lower trachea.

For further details, please see the Medscape Reference article Tracheostomy. A cricothyroidotomy could be helpful depending on the level of obstruction.[14]

Because of the inferior extent of the hematoma, a longer-than-normal tracheostomy tube should be placed.

When the hematoma continues to expand or when ventilation is difficult despite the aforementioned measures, surgical evacuation of the hematoma is indicated. This may be done via an oral or transcervical approach. The oral approach avoids a scar but risks reaccumulation of the hematoma because no drain can be left. The transcervical approach is therefore favored. For this approach, an incision is made along the anterior border of the sternocleidomastoid muscle. The carotid sheath is located and retracted, and the retropharyngeal space is opened.

After the hematoma is evacuated and hemostasis is achieved, a large, closed-suction drainage system is inserted, and the wound is closed in layers.

In exceptional cases, thoracotomy may be necessary to alleviate airway compromise.

The patient should be observed in a unit in which adequate tracheotomy care is available. The unit should offer immediate access to an on-site anesthetist should the patient's airway deteriorate.

In cases in which a cause is identified, it should be addressed. To the authors' knowledge, recurrence has not been described.

Complications of retropharyngeal hematoma occur as a result of mass effect, rupture, or infection.

The mass of the blood in the retropharyngeal space can compress the airway, which lies immediately anterior to it.

Rupture can lead to asphyxiation or aspiration pneumonia.

The hematoma is an ideal culture medium, and infection may supervene. Infection may spread laterally to the carotid sheath. The infection may spread posteriorly. Osteomyelitis of the vertebrae requires long-term antibiotic therapy. Subluxation at any level may follow. Inferior spread of infection may be life threatening. Mediastinitis, purulent pericarditis, pericardial tamponade, bronchial erosion, and mediastinal abscess may follow. The pus may spread to the pleural cavity, causing pleuritis, pyopneumothorax, or empyema. Necrotizing fasciitis requires extensive debridement. Generalized sepsis may follow.

Jugular vein thrombosis may cause tenderness over the anterior border of the sternocleidomastoid muscle, vocal cord paralysis, or sepsis. Aggressive antimicrobial therapy is indicated.

Once the initial airway insult is managed, an uncomplicated recovery should be the goal. However, among the patients with spontaneous onset reported in the literature, only a few have survived. This suggests an especially poor prognosis for this subgroup of patients.

Several questions must still be addressed, as follows:

• When can a hematoma be considered safe (ie, what size is small enough for observation alone and what other risk factors for surgical intervention can be identified)?

• What is the best way to assess the size of the hematoma: nasoendoscopy, CT, and/or MRI? How often should the study be repeated?