Spinal Trauma Imaging Approach to Diagnosis Part II

Hyperextension Injury

• Hangman’s Fx aka traumatic spondylolisthesis of C2 with a fracture of pars interarticularis or pedicles (unstable)
• MVA is the most common cause
• Mechanism: acute hyperextension of upper C/S similar to judicial hanging (never actually seen and most deaths are due to asphyxiation)
• Secondary flexion may tear PLL and disc
• Associated injuries: 30% have other c-spine fx especially Extension teardrop at C2 or C3 due to avulsion by ALL
• Cord paralysis may only present in 25% due to bony fragments dissociation and canal widening

• Hangman fx and extension teardrop
• Cervical degeneration and previous fusion is a key predisposing factor due to the lack of mobility and suppleness, rendering C/S easy to fracture
• Imaging: initial x-radiography then CT that helps to delineate another injury such as facet/pedicle Fx further. MRI may help if complicated by Vertebral A. damage
• Management: if type 1 injury then closed reduction and rigid collar for 4-6 weeks, halo bracing if type 2 (>3-5mm displacement) Fx/instability, anterior or posterior spinal fusion at C2-3 if type 3 Fx (>5-mm displacement)

• Extension teardrop Fx (stable) potentially unstable if put in extension
• Avulsion of an inferior anterior body by ALL. More seen in elderly with superimposed C/S spondylosis
• Key radiography: a smaller anterior-inferior body corner, no disruption of ligamentous alignment. Typically at C2 or C3 due to sudden hyperextension and ALL avulsion
• Complication: central cord syndrome (m/c incomplete cord injury) esp. in superimposed spondylosis and canal stenosis by the laxity of ligamentum flavum and osteophytes
• Management: hard collar isolation

Vertical (axial) Compression Injury

• Jefferson Fx (named after British neurosurgeon who defined it) (unstable but neurologically intact Fx) 7% of all C/S injuries. Stability is dependent if the transverse ligament is intact or torn, which can be noted by overhanging of C1 lateral masses over C2 >5-mm combined (left image)
• Mechanism: C1 compression (e.g., diving into shallow waters) causing burst Fx-classically 4-parts of the anterior and posterior arch of C1. Variations exist.
• Complications: 50% show other C/S Fx, 40% show Odontoid C2 Fx esp. if extension and axial loading occur

• Imaging: x-radiography followed by CT scanning to evaluate subaxial injury and complexity of C1 injury. Note Jefferson Fx with pillar and transverse foramina fx requiring posterior occipital-cervical fusion (below right image).
• Management: rigid collar immobilization if the transverse ligament is intact. Halo brace or fusion if the transverse ligament is ruptured

Cervical Injuries With Variable Mechanisms of Trauma

• Odontoid process fractures:
• These occur with a variety of mechanisms, flexion, extension, lateral flexion. Elderly with superimposed spondylosis are at higher risk.
• Anderson & D’Alonzo classification (below). Type 2 is the most common and most unstable. Type 3 has the best chance of healing d/t more massive bleed into C2 body and better healing potential.
• Imaging: x-radiography can miss some Fx. CT scanning is essential.
• On x-radiography note tilting of the Dens on lateral and APOM views. CT will reveal the injury and classify it.
• Complications: cord injury, non-union

• CT scanning: type 2 odontoid fracture (unstable)
• Management: type 1 (alar ligament avulsion) most stable observed and treated with rigid collar.
• In young patients, Halo brace is used to treat type 2
• Older patients do not tolerate Halo
• Operative C1-2 fusion if unstable is Dx and cord signs or other complicating factors are present

Normal Radiographic Variants & Anomalies Simulating Pathology

• Pediatric spine appears different especially in children younger than 10-years old.
• Normal variations; ADI 5-mm and may increase or decrease on flexed/extended views by 1-2-mm
• C2-3 may appear as pseudo-subluxation due to normal ligamentous laxity in children (below arrow)
• Pediatric vertebral bodies usually are narrower and anteriorly wedged due to the presence of cartilaginous tissue

• APOM view appears different in children, and some asymmetry of C1 articular masses is normal (below top image) and should not be confused with Jefferson Fx
• In adults, any asymmetry or “overhanging” of C1 articular masses is pathological and may indicate Jefferson fx

• Standard ossification centers of the Atlas synchondrosis in children should not be mistaken for fractures

• Persistent ossiculum terminal of Bergman is a typical variant/anomaly of tenacious un-united ossification center and should not be confused with type odontoid fx

• Os odontoideum
• Un-united growth center that currently considered as an un-noticed injury that disturbed normal growth in a child younger than 5-years-old
• It may be a cause of C1-2 instability and should be evaluated with flexed and extended cervical views
• Should not be confused with type 2 Dens fracture because it typically more demonstrates greater mineralization of bone

• Incomplete bilateral agenesis of the C1 posterior arch
• Anomalous closure of C1 posterior arch
• Should not be confused with a fracture
• However, local or cord symptoms may develop after trauma in some cases
• Relatively rare anomaly developing due to failed chondrogenesis and ossification of posterior ossification centers of the Atlas

• Patients with Down syndrome may suffer from increased ligamentous laxity and other abnormalities
• Increased risk of subluxation at C1-2

• Burst Fx (unstable) 2-columns are damaged
• Mechanism: axial loading with frequent flexion after falls and MVAs
• The thoracolumbar region is the most vulnerable due to the increased fulcrum of motion
• Key radiography: acute compression fracture and collapse of body height, retropulsion of posterior body and acute kyphotic deformity on the lateral view
• On the frontal view: interpedicular widening (below yellow arrow), regional soft tissue swelling (below green arrow)

• Imaging: x-radiography should be followed by CT scanning w/o contrast
• MRI if neurologically unstable due to cord or conus injury
• Complications: cord damage by acutely retropulsed bone fragments
• Management: non-operative if neurologically intact and <50% body retropulsed with minimal kyphosis
• Operative (fusion) if 50% or more body retropulsed, laminar/pedicle Fx, neuro compromised

18-Year Old Female Following Trampoline Accident

• AP & lateral L/S views
• Note acute compression fracture, a vertebral body extending to posterior elements
• Widening of the inter-spinous distance between T11-T12 (below arrow)
• Radiolucent fracture line is seen through the T12 body on the AP projection
• CT scanning was performed

• Sagittal reconstructed Thoracic and Lumbar CT slices in bone window
• Note acute compression fracture, the T12 body extending into pedicle and lamin
• Dx: Chance fracture of T12
• MR imaging was performed

• T2 Wl sagittal MRI
• Findings: acute compression fracture T12 body extending to posterior elements causing rapture of interspinous and flavum ligaments
• Mild compression of the distal cord above the conus is noted with a minimal signal abnormality
• Dx: Chance fracture

• Chance Fx aka (Seatbelt Fx) – is a flexion-distraction injury (unstable)
• M/C in lower thoracic-upper lumbar
• All 3-columns fail: column 3 torn by distraction, columns 1 and 2 fail on compression (Denis classification)
• Causes: MVA, falls
• Imaging: initial x-radiography should be followed by CT scanning w/o contrast to assess bone fragments retropulsion/canal compression. MRI may help to evaluate potential cord damage and ligaments tearing
• Management: non-operative immobilization if neuro intact
• Operative decompression and fusion

Spinal Trauma Imaging Approach

Resources:

• emedicine.medscape.com/article/824380-overview
• emedicine.medscape.com/article/248236-overview#a9
• emedicine.medscape.com/article/397896-overview#a3
• www.aafp.org/afp/1999/p331.html