Retropharyngeal Space Overview

Summary Thoughts: Retropharyngeal Space

The retropharyngeal space (RPS) spans the length of the neck from the skull base to the mediastinum. As its name indicates, it lies posterior to the pharynx. More inferiorly in the neck it lies posterior to the esophagus. It is located anterior to the cervical and upper thoracic spine and the prevertebral muscles. Anatomically, an additional fascia divides the RPS into 2 components: (1) an anterior true RPS and (2) a posterior danger space (DS). With imaging, it is rare to be able to delineate a lesion as residing in only 1 of these 2 spaces, so for most purposes the 2 are considered as 1 RPS.

The RPS contains only medial and lateral RPS lymph nodes and fat . This results in a very short differential diagnosis for pathology in this space, primarily a tumor or infection affecting the nodes. While this makes diagnosing easier, the RPS is actually an imaging and clinical "blind spot," with RPS nodes being inaccessible to direct observation or physical examination. Additionally, nonnecrotic nodes often appear isodense to prevertebral muscles on CECT and frequently lie far lateral in the RPS and medial to the internal carotid arteries. Therefore, it is critical that the clinician methodically searches the RPS for adenopathy on imaging, particularly in patients with head and neck (H&N) malignancies.

After nodal disease from tumor and infection, the next most common pathology is a frequently seen but poorly understood process known as retropharyngeal edema . While this process does not require treatment, it is a clue to other pathology in the H&N. Most importantly, it may pose a diagnostic challenge, as it mimics the appearance of retropharyngeal abscess, which often requires surgical intervention.