Posterior Compartment: Prevertebral and Paravertebral Space Inflammatory Conditions
- Magnetic resonance imaging and computed tomography provide the critical and usually definitive data needed in the diagnosis and management of posterior compartment prevertebral and paravertebral space inflammatory and infectious diseases.
- Prompt and accurate imaging can help to avoid potentially severe neurologic compromise in prevertebral space infections.
- Myelography should be done reluctantly and with the greatest care if found to be necessary.
- Imaging-guided aspiration and/or tissue sampling may be used to assist in the management of these infections.
Infections of the prevertebral space discussed in this chapter and those of the retropharyngeal space (RS) discussed in Chapter 151 can result in significant morbidity and mortality. To some extent, they should be considered together since their imaging picture may overlap; however, the conditions tend to diverge in some instances based on their clinical presentation. Timely diagnosis and proper treatment are critical in preventing sequelae such as airway obstruction, epidural abscess and cervical cord injury, mediastinitis, carotid artery aneurysm, and cavernous sinus thrombosis.
The prevertebral space is discussed in this chapter as the site of origin of infections and other inflammatory diseases of the head and neck. The prevertebral space is mainly involved by inflammatory pathology of the spine, usually discitis and/or vertebral osteomyelitis, or facet infection (Fig. 160.1). Other posterior compartment inflammatory diseases are rare in the absence of penetrating trauma or an open surgical procedure. Differentiating prevertebral space infections from musculoskeletal chronic inflammatory conditions is an important part of this process (Fig. 160.2). Infectious disease originating from the cervical spine must be differentiated early in the diagnostic process from that originating due to pharyngeal disease to avoid a potentially catastrophic neurologic event involving the cervical spinal cord.
A prevertebral space–origin infection will present with neck pain that might be mechanical and perhaps an occipital headache. The combination of fever, neck pain, and limitation of cervical spine range of motion frequently raises the clinical suspicion of meningitis. Such a presentation and/or any neurologic deficit that might be due to cervical cord involvement should elevate the imaging evaluation to a very urgent or emergent status.
Infections of the prevertebral space may mimic those of the RS, causing dysphagia or odynophagia as a presenting complaint in adults; in infants, such swallowing problems may manifest simply as “feeding difficulties.” Airway compromise is possible. Otalgia is possible.
Fever is very common in infection, and the white count should be elevated. Lack of these circumstances suggests, but does not indicate for certain, a noninfectious inflammatory etiology. This is especially true in the immune-compromised population.
The anatomy of the posterior compartment that directs the spread of inflammatory disease in the prevertebral and paravertebral spaces is simple. The prevertebral fascia is thick and relatively resistant to the spread of pathologic processes compared to the fascia of the visceral compartment. This provides a relatively resistant barrier to spread of pus between the prevertebral space and RS, although reactive edema spreads readily from one space to another (Fig. 160.1). A musculofascial sheath associated with the prevertebral longus colli muscles lies posterior to the prevertebral fascia. This deep layer of fascia then reflects laterally over the vertebral transverse processes and the attachments of the scalene muscles to cover the paravertebral portion of the posterior compartment of the neck, as discussed in Chapters 142 and 149 (Figs. 142.3A, 149.1, and 149.2). It is penetrated laterally by small vessels and the cervical nerve rootlets, with the most prominent of the latter being those of the brachial plexus.
The RS lies between the visceral compartment and the prevertebral fascia in free communication with the lateral compartment of the neck and the carotid sheath.
Structures of Interest
The analysis of an inflammatory process or mass of the posterior compartment (prevertebral and paravertebral spaces) depends on a thorough understanding of its relationship to the following structures:
- Superiorly: Hyoid bone as the arbitrary boundary
- Inferiorly: Thoracic inlet, supraclavicular fossa, and posterior chest wall
- Anteriorly: RS and lateral compartments
- Posteriorly: Cervical spine and pre- and paravertebral muscles and fascia and more superiorly the lower clivus if in the prevertebral space; if in the paravertebral space, the posterior boundary is the containing fascia and subcutaneous soft tissues
- Medially: Not applicable in prevertebral space; spinal and neurologic elements if in the paravertebral space
- Laterally: Lateral compartment (mainly the posterior triangle) of the neck/carotid sheath/brachial plexus from the trunks distally