Neuroradiology (1995) 37:388-394 9 Springer-Verlag 1995

W. L. Davis H.R. Harnsberger

Received: 25 September 1993 Accepted: 29 January 1994

W.L. Davis ( ~ ) 9H.R. Harnsberger Department of Radiology, University of Utah Medical Center, 50 North Medical Drive, Salt Lake City, UT 84132, USA

HEAD

AND NECK RADIOLOGY

CT and MRI of the normal and diseased perivertebral space

Abstract The perivertebral space is in the midline, in the deep tissues of the neck, and can be identified from the skull base above to the mediastinum below. It is a discrete space completely enclosed by the deep layer of deep cervical fascia. The fascial attachments of the perivertebral space divide it into two areas, the anterior prevertebral and posterior paraspinal portions. We made a retrospective analysis of the radiologic and clinical records of 52 patients with lesions in the perivertebral space, to identify the imaging features that mark a lesion as originating in the perivertebral space and define the spectrum of

Introduction The perivertebral space is a distinct, fascially - defined space which extends through the neck from the skull base to the upper mediastinum. The deep layer of the deep cervical fascial cleaves the perivertebral space into anterior prevertebral and posterior paraspinal portions by sending a deep slip to attach to the spinal transverse process [1-3] (Fig. 1). In the past this area has been referred to as the prevertebral space anteriorly and the paraspinal space posteriorly [4-6]. Since the entire deep cylinder of tissues around the vertebral column is circled by the deep layer of deep cervical fascia we suggest that perivertebral space effectively describes this area. Disease within the perivertebral space is relatively uncommon. However, it assumes greater significance because of its proximity to the structures within the spinal canal and the inability of the clinician to palpate this deep tissue adequately [7-9]. CT and M R I are the pri-

pathology which occurs in the space. Mass lesions present in the prevertebral or paraspinal portions. In the former they usually involve the vertebral body, displacing the prevertebral muscles anteriorly. Epidural extension from lesions in the perivertebral space proper is common. Masses in the paraspinal perivertebral space usually displace the paraspinal muscles away from the spine. We found 9 inflammatory lesions, 29 malignant and 6 benign tumors, and 8 miscellaneous lesions. Key words Perivertebral space 9 Neck. Vertebral body malignancy Vertebral body infection

mary modalities used in imaging the deep tissues of the head and neck; both are able to show in detail the normal anatomy and pathology of the perivertebral space [4-7]. Our purpose in this retrospective review of patients with lesions in the perivertebral space was to refine the understanding of the normal imaging anatomy of the perivertebral space, to define specific imaging features on CT and M R I that indicate that a mass is within the space and to describe the spectrum of lesions found in it.

Materials and methods Clinical and radiologic records of 52 patients with perivertebral space pathology who underwent imaging were reviewed. The records were analyzed for patient age, sex, clinical presentation, and outcome. Diagnoses were confirmed by pathology, clinical followup, or characteristic imaging features (e. g. osteophytes, degenerative facet disease or cervical rib) in all cases.

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Fig.la The normal infrahyoid perivertebral space; axial crosssection. The deep layer of deep cervical fascia (dashed lines) circumscribes the central core tissues. It arches anteriorly from transverse process to transverse process to define the prevertebral portion of the perivertebral space. The fascial slip that arches posteriorly to the ligamentum nuchae defines the paraspinal portion. The prevertebral portion contains the vertebral body, vertebral artery and vein, the phrenic nerve and roots of the brachial plexus, which course between the anterior and middle scalene muscles. The longus colli muscles are prominent anterior structures in the prevertebral portion. The paraspinal portion has only the posterior arch of the vertebral body and the paraspinal muscles within it. Note relationship of the retropharyngeal and danger spaces to the prevertebral portion. The deep layer of deep cervical fascia sends a slip anteriorly which becomes the lateral wall of the retropharyngeal and danger spaces. A second horizontal slip of deep cervical fascia divides the anterior retropharyngeal space from the more posterior danger space. The anterior wall of the retropharyngeal space is made up of a part of the middle layer of deep cervical fascia (dotted line). As it is not possible to differentiate retropharyngeal space lesions from danger space lesions on CT or MRI, most authors refer only to the retropharyngeal space, b Sagittal section showing craniocaudad extend of the perivertebral space (Crosshatched). The cephalad attachment of the deep layer of deep cervical fascia is to the skull base. This cylinder of perivertebral tissue can be defined from the skull base to the coccyx

There were 31 males and 21 females, whose age range was 13 days to 78 years. CTwas performed in 33 patients while 6 patients had only MRI 13 patients had both. Contiguous 4 or 5 mm axial CT images were obtained. Bolusinfusion intravenous contrast medium was used in 40 of the 44 patients who underwent CT. MRI was performed with a 1.5 T superconducting system. Axial and coronal T1- and T2-weighted spinecho images were obtained using a surface coil with 5 mm thick sections and i mm interslice gap. Two patients received 0.2 mM/kg gadopentetate dimeglumine with Tl-weighted imaging.

Results Of the 52 patients (Table 1), 29 had masses in the perivertebral space secondary to malignant tumors. Metastatic disease involving either the vertebral b o d y or proximal brachial plexus, most frequent type of malignant tumor, was seen in 15 of 29 patients (Fig.2); 8 of these had metastatic breast carcinoma. O f the 29 patients 8 had n o n - H o d g k i n ' s l y m p h o m a , and 2 had c h o r d o m a s destroying the clivus, with anterior extension into the perivertebral space of the nasopharynx and posterior epidural extension. There were 2 patients with direct invasion of the perivertebral space by squamous cell carcinoma (Fig. 3), and 2 patients had p r i m a r y malignant tumors of the vertebral b o d y (multiple m y e l o m a and Ewing's sarcoma) with a mass in the perivertebral space. All malignant perivertebral space masses caused bone destruction (Fig. 2, 4). O f the 29 patients malignant t u m o r 21 had masses in the p r e v e r t e b r a l portion of the perivertebral space, 4 involvement of b o t h p r e v e r t e b r a l and paraspinal portions and 2 involvement of the paraspinal perivertebral space only (Fig. 4); 18 had epidural involvement (Table 2). There were 6 patients with benign tumors in the perivertebral space: 5 had benign schwannomas of the proximal brachial plexus roots which presented as masses in the p r e v e r t e b r a l portion, and one patient had an o s t e o c h o n d r o m a of the cervical spine (Fig. 5). All patients with benign tumors had involvement of the p r e v e r t e b r a l portion only, but 3 had epidural extensions. I n f l a m m a t o r y lesions were seen in 9 patients; 5 had infectious spondylitis of the cervical spine with an associated p r e v e r t e b r a l mass related to abscess or cellulitis (Fig. 6); 2 had postoperative infections of the vertebral b o d y and disc following anterior discectomy, and 2 longus colli tendinitis (Fig. 7). These masses lay in the p r e v e r t e b r a l portion only in 8 patients and one had in-

390

Fig.2 Metastasis from colonic carcinoma in the prevertebral portion. Axial contrast enhanced CT (a) and unenhanced T1weighted MRI (b) show a mass centered in the anterior arch of C1 in the prevertebral portion which extends anteriorly (open arrows) to lift the prevertebral muscles (P) and posteriorly (solid arrow) to enter the epidural space, c internal carotid artery, ] internal jugular vein Fig.3 Direct extension into the perivertebral space proper by squamous cell carcinoma of the nasopharynx, a Axial contrastenhanced CT demonstrates a mass (M) in the right nasopharynx with probable extension into the prevertebral portion of the perivertebral space (arrow). The margins of the mass are indistinct, making it difficult to assess its true extent, b Axial Tl-weighted MRI shows direct invasion by the tumor rn into the right longus colli muscle (arrow) to better advantage. Invasion of the right parapharyngeal and carotid spaces is more clearly seen. PPS'cs normal contralateral parapharyngeal and carotid spaces, P prevertebral muscles Fig.4 Axial CT of metastatic salivary gland tumor in vertebral body and posterior elements. The latter portion extends into the paraspinal portion of the perivertebral space arrows. Note outward displacement of the paraspinal musculature Fig.50steochondroma of the spine. Axial CT demonstrates osteochondroma in the prevertebral portion O anteriorly and an epidural component (arrow) posteromedially

v o l v e m e n t of b o t h the p r e v e r t e b r a l and paraspinal portions. A n epidural extension was p r e s e n t in 3 (Fig. 6). We identified miscellaneous lesions of the perivertebral space in 8 patients. 4 s e c o n d a r y to e x u b e r a n t d e g e n e r a t i v e change, 2 with large anterior vertebral b o d y o s t e o p h y t e s and 2 with h y p e r t r o p h i c d e g e n e r a t i v e facet disease (Fig.8); 3 h a d abnormalities related to t r a u m a or surgery. O f these, one h a d p o s t t r a u m a t i c anterior disc herniation, the s e c o n d a h e m a t o m a of the perivertebral space, and the third a c o m p l e x fluid collection resulting f r o m a dural tear during a n t e r i o r cervical d i s c e c t o m y and c o r p o r e c t o m y .

Discussion T h e perivertebral space is a cylinder of soft tissues lying b e h i n d the r e t r o p h a r y n g e a l space in the d e e p m e d i a n soft tissues of the h e a d and neck, the central b o n y strut of which is the cervical spinal column. This space is enclosed within the d e e p layer of d e e p cervical fascia [16], which c o m p l e t e l y encircles the neck, arching f r o m transverse process to transverse process anteriorly and projecting posteriorly to the spinous processes and liga-

391

Table 1 Perivertebral space lesions in 52 patients

Category

Disease process

Patients

Metastases (vertebrae and brachial plexus) Non-Hodgkin's lymphoma Direct invasion by squamous cell carcinoma Primary malignanttumor of the vertebrae Chordoma

15 8 2 2 2

Malignant tumor

Benign tumor Schwanomma(brachial plexus) Osteochondroma Inflammatory Vertebral body osteomyelitis/abscess Postoperative cellulitis/abscess Longus colli tendinitis Miscellaneous Anterior vertebral body osteophyte Hypertrophic degenerative facet disease Anterior disc herniation Hematoma Cervical rib Post-operative CSF collection Table 2 Patients with epidural involvement Lesion Patients/number in group Malignant tumor Benign tumor Inflammatory Miscellaneous Total

18/29 3/6 3/9 0/8 24/52

mentum nuchae (Fig. l). It therefore completely encloses the vertebral bodies and the prevertebral and paraspinal musculature. The fascial attachment to the transverse processes subdivide the perivertebral space into the, the prevertebral and paraspinal portions (Fig. 1) [4-6, 10, 11]. In the past this area has been subdivided into prevertebral and paraspinal spaces when in fact both areas are encircled by the same fascia. We have suggest a unifying term, "perivertebral space" to describe all the core deep tissues underneath the deep layer of deep cervical fascia, incorporating the more traditional terminology by describing prevertebral and paraspinal portions. In this way we have escaped much potentially confusing terminology. The contents of the prevertebral portion include the vertebral body and discs, prevertebral and scalene muscles, vertebral artery, and the roots of the brachial plexus roots (Fig. 1) [12]. In contrast, the paraspinal portion contains only the paraspinal musculature and the posterior elements of the vertebrae. The perivertebral space is usually defined from the skull base to the superior mediastinum (Fig. l) but can be extended to the level of the coccyx. The limited contents of the perivertebral space yield a limited differential diagnosis of lesions found within it

(Table 1). Although these processes are relatively uncommon, they are and radiologically clinically important because of their proximity to the airway and epidural-spinal cord area. As the prevertebral portion contains the majority of the normal structures of the perivertebral space, most diseases are found here. Infection and tumor arising in the vertebral body immediately spread into the prevertebral area, and nerve sheath tumors of the brachial plexus also arise primarily within it. The paraspinal component has limited contents and therefore limited differential considerations. The posterior bony elements of the spine may rarely be involved by primary or metastatic tumor. Hypertrophic disease of the facets may, when severe, be palpable. Soft tissue masses are extremely rare. Mass lesions in the two portions have different appearances on cross-sectional imaging. A mass in the prevertebral portion has its center in the vertebral body or prevertebral muscles. Anterior displacement of the latter is helpful in distinguishing prevertebral from retropharyngeal masses, with which the prevertebral muscles are flattened posteriorly against the vertebral body (Fig. 9a) [1, 3, 8, 11, 13]. The center of a mass in the paraspinal portion is within the paraspinal musculature or posterior vertebral body elements and the mass displaces the paraspinal musculature and posterior cervical space fat away from the spine (Fig. 9 b) [6, 10]. The most common abnormality we found was malignant tumor. All malignant lesions arose from and partially destroyed the vertebral body and secondarily extended into the adjacent soft tissues. Vertebral body destruction was more extensive than the prevertebral mass, a feature described in previous reports as helpful in distinguishing tumor from infection [14]. Metastatic malignancy of the vertebral body was the most common

392

Fig.6 Abscess secondary to osteomyelitis in the prevertebral portion, a Axial contrastenhanced CT through C] demonstrates a perivertebral space abscess (open white arrow). There is erosion of the odontoid (black arrow) and enlargement of the predental space (open black arrows), b Sagittal contrast-enhanced Tl-weighted MRI shows anterior location of the abscess (black arrow). Note marked enhancement of the tissue surrounding the odontoid (long white arrow) and effacement of the subarachnoid space anterior to the cervicomedullary junction (short white

arrow). Fig.7 Longus colli tendinitis in the prevertebral portion. Axial contrast-enhanced CT through C2 demonstrates calcification in the longus colli tendon (T) in a patient with acute neck pain Fig.8 Hypertrophic degenerative facet perceived by the clinician as a "mass" on physical examination. Axial contrastenhanced CT (bone window shows a hypertrophic degenerative facet (arrow) protruding into the paraspinal portion Fig. 9 a Axial drawing at the infrahyoid level of a mass in the prevertebral portion (shaded black). The mass has its center within the vertebral body. Note anterior displacement of the prevertebral muscles (arrows) distinguishing this mass from a mass in the retropharyngeal space (RPS), the other important midline space of the neck. The lesion has an epidural component (curved arrow). b Axial drawing of a mass in the paraspinal portion (shaded black). The mass has its center in the posterior elements of the spine and displaces the paraspinal muscles and deep layer of deep cervical fascia (dashed line) away from the spine

9a

9b

L PORTION OF THE PERIVERTEBRAL SPACE

393

f o r m [14, 15] and metastatic involvement of the proximal roots of the brachial plexus was the second most c o m m o n cause of neoplastic involvement [12]. W h e n the t u m o r b r o k e out of the vertebral body in an anterior direction the p r e v e r t e b r a l portion of the perivertebral space was involved early with epidural extension occurring late. Early epidural involvement with minimal perivertebral space t u m o r was seen when the metastatic disease b r o k e out of the vertebral b o d y in a posterior, epidural direction. S c h w a n n o m a of the brachial plexus roots was the most c o m m o n benign tumor. All schwannomas were seen within the p r e v e r t e b r a l portion, along the course of the roots of the brachial plexus [12, 16, 17]. Although these roots p e r f o r a t e the deep layer of deep cervical fascia on their way to the axilla, none of the schwannomas extended through the fascia. The only other benign t u m o r in the perivertebral space was an o s t e o c h o n d r o m a of the vertebral body. T h e r e are several case reports of benign b o n y tumors in the perivertebral space [18]. I n f l a m m a t o r y disease was less frequent. Cervical pyogenic spondylitis would be expected to be m o r e prevalent in an urban center it there were a higher proportion of intravenous drug abusers [14, 19, 20]. H e m a togenous seeding resulting in vertebral b o d y o s t e o m y e litis, secondary perivertebral space abscess, and postop-

erative infection were identified [21]. All resulted from vertebral body infection and presented within the prevertebral portion. There are r e p o r t e d cases of osteomyelitis involving the posterior elements of the spine with an i n f l a m m a t o r y mass in the paraspinal portion [22]. Longus colli tendinitis is the least well described i n f l a m m a t o r y lesion of the p r e v e r t e b r a l portion [23--25]. This clinical entity, which usually presents with acute neck pain, is a benign, self-limiting disease similar to calcific tendinitis. On CT it is seen as soft tissue swelling in the p r e v e r t e b r a l portion, anterior to C2-C3 vertebral bodies, associated with calcification in the longus colli tendon. Awareness of this lesion prevents it f r o m being mistaken for an infectious disease requiring surgical intervention. Malignant and benign lesions of the perivertebral space can both extend into the epidural space (Table 2). The tough surrounding deep layer of deep cervical fascia, and the close proximity of the spinal canal m a k e s early extension into the epidural region c o m m o n . Although contrast-enhanced CT shows the extent of disease in the perivertebral space, the high incidence of epidural involvement suggests that M R I m a y be the modality of choice in investigating disease in this region

[15].

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8. Levitt GW (1970) Cervical fascia and deep neck infections. Laryngoscope 80: 409-435 9. Everts EC, Echevarria J (1973) The pharynx and deep neck infection. In: Paparella MM, Shumrick DA, eds. Otolaryngology: head and neck, vol 3. Saunders, Philadelphia pp 318-340 10. Silver AJ, Mawad ME, Hital SK, Sane R Ganti SR (1984) Computed tomography of the carotid space and related cervical spaces. AJR 150:723-728 11. Davis WL, Harnsberger HR, Smoker WRK, Watanabe AS (1990) Retropharyngeal space: evaluation of normal anatomy and diseases with CT and MR imaging. Radiology 174:59-64 12. Armington WG, Harnsberger HR, Osborn AG, Seay AR (1987) Radiographic evaluation of brachial plexopathy. AJNR 8:361-367 13. Carrau RL, Cintron FR, Astor F (1990) Transcervical approaches to the prevertebral space. Arch Otolaryngol Head Neck Surg 116:1070-1073 14. Van Lom KJ, Kellerhouse LE, Pathria MN (1988) Infection versus tumor in the spine: criteria for distinction with CT. Radiology 166:851-855

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21. Wright RL (1982) Infections of the spine and spinal cord. In: Youmans JR (ed) Neurological surgery, vol 4. A comprehensive reference guide to the diagnosis and management of neurosurgical problems, 2nd edn. Saunders, Philadelphia, pp 3441-3458

ANNOUNCEMENTS

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22. Ehara S, Khurana JS, Kattapuram SV (1989) Pyogenic vertebral osteomyelitis of the posterior elements. Skeletal Radiol 18:175-178 23. Artenian D J, Lipman JK, Scidmore GK (1989) Acute neck pain due to tendinitis of the longus colli: CT and MRI findings. Neuroradiology 31:166-169 24. Hayes CW, Conway WF (1990) Calcium hydroxyapatite deposition disease. RadioGraphics 10:1031-1048

25. Hall FM, Dockem WE Hayes CW (1986) Calcific tendinitis of the longus colli: diagnosis by CT. AJR 147: 742743 26. Harnsberger HR (1990) Handbooks in radiology. Head and neck imaging. Mosby-Year Book Medical, St. Louis

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