1	Imaging of the Retropharyngeal and Prevertebral Space Zahir Javeri, MD Rajan Jain, MD John J. Corrigan, MD Suresh C. Patel, MD Division of Neuroradiology, Department of Radiology Henry Ford Hospital, Detroit, MI
2	Material & Methods Thin section CT with multi-planar reformats and high-resolution MRI studies allow visualization of the retropharyngeal and prevertebral anatomy. CT, MRI, plain X-Rays, and sketch diagrams from our teaching files will be used to demonstrate the normal anatomy and various pathological processes in the retropharyngeal and prevertebral spaces.
3	Fascia of the Neck The cervical fascia provides the structural support of the soft tissues of the neck The different layers of the cervical fascia cleaves the soft tissues of the neck into different compartments which are divided into the suprahyoid and infrahyoid neck spaces by the hyoid bone Loose fatty tissue is present around the different layers of cervical fascia. The fat provides natural contrast and appears hypoattenuating on CECT and hyperintense on MR TIWI which are the modalities of choice. Pathology is detected by effacement/displacement of the fat along the fascia. Soft tissue air directly identifies the fascia
4	Fascia of the Neck (cont.) Superficial Cervical Fascia Deep Cervical Fascia Superficial Layer of the Deep Cervical Fascia Middle Layer of the Deep Cervical Fascia in the Suprahyoid Neck Middle Layer of the Deep Cervical Fascia in the Infrahyoid Neck Deep Layer of the Deep Cervical Fascia There are multiple layers of the deep cervical fascia Specifically, the buccopharyngeal fascia, alar fascia, cloison sagittale and prevertebral fascia form the boundaries of the retropharyngeal and prevertebral spaces Sibson’s Fascia
5	Fascia forming boundaries of the Retropharyngeal and Prevertebral space Buccopharyngeal fascia- Loose connective tissue layer that extends from the skull base inferiorly and forms the external covering of the pharyngeal constrictor muscles. Alar fascia- Extends from skull base to C6-T4. Separated from the prevertebral fascia by loose connective tissue and forms the posterior wall of the carotid sheath
6	Fascia forming boundaries of the Retropharyngeal and Prevertebral space Cloison sagittale (sagittal partition)- Sagitally oriented fascial slips on either side of the neck which extends from the anterior tubercles of cervical vertebrae to the buccopharyngeal fascia anteriorly. Separates retropharyngeal and danger spaces from parapharyngeal space and forms the medial wall of the carotid sheath. Prevertebral fascia- Arches anteriorly from the cervical transverse process to the opposite transverse process and covers the longus colli and longus capitis muscles. Extends from the skull base to the coccyx and fuses with the anterior longitudinal ligament at T3.
7	Retropharyngeal Space Borders Anteriorly: Buccopharyngeal space separating it from the parapharyngeal mucosal space. Posteriorly: Alar fascia which separates it from the prevertebral space. Laterally: Cloison sagittale which separates it from the parapharygeal space. Superiorly: Skull base Inferiorly: Extends to T2-T6 at which level the alar fascia fuses with the prevertebral fascia.
8	Retropharyngeal Space (cont.) Contents Fat Lymph nodes are only present in the suprahyoid portion (Medial and lateral retropharyngeal nodes of Rouviere) Common Pathologies- Reactive adenopathy, abscess, cellulitis, tonsillitis Other Pathologies- Retropharyngeal effusion Congenital- Hemangioma, lymphangioma Inflammatory- Traumatic penetration (foreign body), trauma, scrofula Neoplastic- Nodal metastases, Lymphoma, Squamous Cell Carcinoma, Melanoma, Thyroid carcinoma, Direct invasion from meningioma or chordoma
9	Distinguishing Imaging Features of the Retropharyngeal Space The epicenter of a retropharyngeal mass is located posteromedial to the parapharyngeal space, medial to the carotid space and anterior to the prevertebral space. Retropharyngeal masses displace the prevertebral muscles posteriorly and efface the retropharyngeal fat. Retropharyngeal masses are anterior to the prevertebral muscles or invade them from anterior to posterior.
10	Danger Space Indistinguishable from the retropharyngeal space on CT or MRI. Potential pathway for the spread of cranial and cervical infections into the middle and lower mediastinum. Potential space that lies between the alar fascia and true prevertebral fascia which extends from the skull base to the posterior diaphragm at which level the alar fascia fuses with the prevertebral fascia.
11	Danger Space (cont.) Borders- Parapharyngeal space laterally, retropharyngeal space anteriorly and prevertebral space posteriorly. Contents- Fatty areolar tissue Common Pathologies- Channel for infection and tumor into the mediastinum Inflammatory: Cellulitis, abscess, necrotizing fasciitis Neoplastic: Invasion from squamous cell carcinoma, lipoma, liposarcomas
12	Prevertebral Space Definition- Potential space enclosed by the prevertebral fascia that extends from the skull base to the coccyx. The transverse process of the vertebral bodies separates the anterior compartment (prevertebral space) from the posterior compartment (paraspinal space) Borders- Space between the prevertebral fascia and cervical vertebrae from the skull base to the coccyx Contents- Prevertebral muscles, Anterior longitudinal ligament, cervical vertebrae and discs, longus colli and longus capitis muscles, fat, vertebral artery and vein, phrenic nerve.
13	Prevertebral Space Common Pathologies- Vertebral body osteophyte, Diskitis/Osteomyelitis, Prevertebral abscess, Vertebral Metastases Other Pathologies- Neoplastic: Squamous cell carcinoma, Chordoma, Schwannoma, Neurofibroma, Non-Hodgkins lymphoma Vascular: Vertebral artery aneurysm, pseudoaneurysm, dissection, thrombosis
14	Distinguishing Radiologic Features Prevertebral Space- The prevertebral muscles and fat are displaced anteriorly which is a clear distinguishing characteristic from retropharyngeal lesions Prevertebral masses are centered within the prevertebral muscles or vertebral body Prevertebral lesions can arise from and destroy the vertebral body Infection and tumor can spread into the epidural space Paraspinal Space- Lesions are centered within the paraspinal or scalene muscles Lesions bow the posterior cervical space fat away from the spine
15	Normal Imaging Anatomy (CECT)
16	Normal Imaging Anatomy (T1WI)
17	Retropharyngeal Effusion/Edema Etiology Infectious/Inflammatory: Pharyngitis, cellulitis, tonsillitis, suppurative lymphadenitis, longus colli tendonitis Neoplastic: Neoplastic invasion, lymphatic obstruction Traumatic: Retropharyngeal hematoma, foreign body, emphysema Iatrogenic: IJV thrombosis, post surgical collection, radiation therapy Pathogenesis Probable obstruction/disruption of the retropharyngeal lymphatic drainage
18	Retropharyngeal Effusion
19	Retropharyngeal Effusion (cont.)
20	Post – operative Retropharyngeal effusion/hematoma
21	Lemierre Syndrome with Retropharyngeal Effusion Nonenhancing central filling defect (arrow) within the IJV after infection of the oropharynx. The predominant pathogen is a gram-negative anaerobic bacillus, Fusobacterium necrophorum Enlarged vein diameter with enhancement of the vessel wall and surrounding fat stranding Associated edematous fluid collection in the retropharyngeal space Normal contrast enhancing right internal jugular vein (broken arrow)
22	Progression of Retropharyngeal Infections Reactive Lymphadenopathy Initial response to infection with retropharyngeal lymphadenopathy Suppurative lymphadenitis Lymph node enlargement with surrounding inflammation Retropharyngeal cellulitis/phlegmon Inflammation, diffuse thickening and fat stranding Retropharyngeal Abscess Rim enhancing fluid collection with surrounding inflammation Usually secondary to nodal rupture with resultant fluid collection
23	Retropharyngeal Lymphadenitis and Abscess Ring enhancing left retropharyngeal abscess with a scalloped contour to the abscess wall indicating progression towards rupture of the abscess wall and dissection into the neck. These findings are an indication for early surgical intervention.
24	Retropharyngeal Abscess Etiology Visceral/mucosal space infections (pharyngitis or tonsillitis) Nodal rupture/lymphadenitis Ventral spread from diskitis/osteomyelitis Tuberculosis (scrofula)
25	Retropharyngeal Abscess
26	Retropharyngeal and Prevertebral Infection
27	Retropharyngeal Emphysema Penetrating Trauma Accidental: Foreign bodies, gunshot or stab wounds Iatrogenic: Endoscopy, Intubation trauma, Post-surgical Retropharyngeal Emphysema Surgical: Perforation with air dissecting into and separating the deep fascial planes Infection: Fasciitis with spread of infection into the fascial planes.
28	Hemangioma
29	Vascular Lesions “Kissing Carotids” Axial CT showing the retropharyngeal course of the bilateral internal carotid arteries (arrows). The retropharyngeal fat is medially displaced.
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31	Diskitis/Osteomyelitis
32	Pseudomass/Anterior Osteophyte Large fractured anterior bridging osteophyte at C5-C6 projecting into the prevertebral space in a patient complaining of neck pain and dysphagia. The left longus colli muscle is anteriorly displaced (arrow).
33	Nasopharyngeal Carcinoma Invading the Prevertebral space Enhancing nasopharyngeal carcinoma (arrow) infiltrating the left longus colli muscle suggestive of prevertebral space involvement. The right longus colli muscle appears intact.
34	Chordoma Invading the Prevertebral Space
35	Combined Retropharyngeal/Prevertebral Pathology
36	Neoplasms Involving the Prevertebral and Retropharyngeal Spaces Axial contrast enhanced CT of a patient with B-cell Lymphoma showing large left nasopharyngeal enhancing soft tissue mass (arrow) with an enlarged left lateral retropharyngeal lymph node (broken arrow). The left longus colli muscle is displaced posteriorly.
37	Longus Colli Tendonitis Definition- Inflammation of the longus colli muscle tendon secondary to calcium hydroxyapatite deposition at the insertion of the oblique fibers CT findings Prevertebral calcifications off midline separate from the vertebral body extending from C1-C5. Edema surrounding the longus colli muscle with retropharyngeal edema and effusion MR Findings T2WI show hyperintense swelling of the longus colli with retropharyngeal edema TI with Gadolinium shows prevertebral soft tissue enhancement and retropharyngeal edema without wall enhancement Differential Diagnosis Retropharyngeal edema Retropharyngeal abscess (no calcifications) Diskitis/osteomyelitis Etiology- Patients present with neck pain and odynophagia 2-7 days after a history of minor head and neck trauma. Patients can also present with fever and paraspinal muscle spasm
38	Longus Colli Tendonitis Afebrile young male with dull neck pain. Axial and sagittal CT images show calcifications (arrow) at the insertion of the oblique fibers of the longus colli muscle with bursitis and associated retropharyngeal/prevertebral effusion (broken arrow)
39	Longus Colli Tendonitis
40	Vertebral Artery Aneurysm Dissecting aneurysm of the left vertebral artery with opacification of the true lumen (arrow) and a surrounding area of thrombosis (broken arrow). There is a large prevertebral () and retropharyngeal hematoma (*)
41	Retrovisceral Space Extension of the Thyroid Gland