Perivertebral space

The perivertebral space is one of the seven deep compartments of the head and neck.

Gross anatomy

The perivertebral space is a cylinder of soft tissue lying posterior to the retropharyngeal space and danger space surrounded by the deep cervical fascia and extends from the skull base to the upper mediastinum.

The deep fascia sends a deep slip to the to the transverse process which subdivides the space into:

• prevertebral portion - anteriorly: anteriorly located
• paraspinal portion -: posteriorly located

Contents

• prevertebral portion ¹
  • cervical vertebral body and disc
  • prevertebral muscles
  • scalene msucles
  • vertebral artery and vein
  • phrenic nerve
  • brachial plexus
• paraspinal portion ¹
  • posterior elements of cervical vertebrae
  • paraspinal muscles 

Boundaries

• anterior: danger space and retropharyngeal space
• posterior: fascia attaches to spinous process and ligamentum nuchae
• lateral: surrounded by posterior cervical space
• superior: base of skull
• inferior: the perivertebral space is usually defined from the skull base to superior mediastinum but can be extended to the level of the coccyx

Radiographic features

In general, the prevertebral component is measured on sagittal imaging as the distance between the anterior border of the vertebral body and the posterior border of the trachea ²:

• in adults this should be <7 mm at C2 or <22 mm at C6/7
• in children this is said to be <14 mm at C6

A mass arising from the prevertebral portion is centered on the vertebral body or prevertebral muscles, which causes anterior displacement of the muscles as opposed to a mass arising from the retropharyngeal space which would cause flattening of the prevertebral muscles posteriorly against the vertebral body ¹. 

A mass arising from the paraspinal portion displaces the paraspinal musculature and posterior cervical space fat away from the spine. Extension of malignant and benign lesions into the epidural space from the perivertebral space is common ¹.

CT

• CT is useful to identify details of bone destruction ¹
• post-operative or spontaneous abscess can be differentiated from non-infected fluid by signs of rim enchancement as well as fat stranding, muscle swelling and skin thickening around the lesion ³
• longus colli tendinitis on CT is characterized by soft tissue swelling in the prevertebral portion anterior to the C2-3 vertebral bodies and associated with calcification in the tendon ¹
• chordomas are rare and aggressive tumours arising from notochordal remnants in the axial skeleton; on CT the mass is typically hypodense/isodense and associated with lytic vertebral bone destructionand may extend over a number of levels ⁶

MRI

MRI is the preferred modality for assessing the soft tissue in this space and to detect early infection in the spine ¹:

• Inin the acute phase of vertebral osteomyelitis there is bone marrow oedema and this is detected by signal changes with low signal intensity on T1 weighted images (WI) and high signal intensity on T2-WI, especially fat saturated techniques/spectroscopic inversion recovery (SPIR) or short tau inversion recovery (STIR) sequences⁴
• lymphoma of the vertebra has been described to have a “wrap-around” sign when tumour was present in the bone marrow and paraspinal soft tissue without alteration in the normal shape of the affected vertebra to help differentiate from lesions of bone metastasis and myeloma which tend to show destruction of the bony cortex and bulging contour
  • T1-WI: hypointense with high signal post-contrast 
  • T2-WI: hyperintense with contrast enhancement ⁵
• chordomas appear as homogenous hypointense/isointense lesions on T1-WI, hyperintense on T2-WI and show post-gadolinium high signal; tumour develops within the vertebral bodies and frequently invades perivertebral space/epidural space and can span several vertebral segments ⁶   

Related pathology

• retropharyngeal abscess
• osseous metastases
• chordoma
• osteomyelitis
• schwannoma
• chondromas
• direct invasion squamous cell carcinoma
• pseudotumours
  • anterior herniated disc
  • vertebral osteophytes
  • longus colli tendon calcification
• lymphoma