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British Medical Books Health Issues Computerized Tomography

General

  • three peaks of incidence of spinal injuries
    • C1-C2
    • CC7
    • T12 - L2
  • in children
    • C-spine #-s less frequent
    • higher incidence in midthoracic & upper lumbar spine
    • under 12 years of age - C1-C2 & occipito-atlantal articulation injuries common
    • over the age of 12 - injuries similar to those in adults
  • neurologic damage in 40% of cervical spine injuries
    • in 10% no radiographic evidence of vertebral injury
    • older patients with degenerative arthritic changes & sustained hyperextension injuries
    • on occasion in young individuals

X-ray investigations in C-spine injuries

  • lateral view
  • AP view
  • open mouth view
  • other views
    • swimmer’s
    • flexion-extension
    • oblique

Radiographic Evidence of Injury

Retropharyngeal Soft Tissue Swelling

    • caused by haemorrhage or oedema
    • clue to the presence of underlying fracture or dislocation
    • impossible to establish absolute values
  • upper limits of the normal range in adults
    • 10 mm anterior to the arch of C1
    • 5 mm anterior to the base of C2
    • 7 mm anterior to C3 and the upper margin of C4
    • 20 mm anterior to the C6 and C7

Malalignment

  • anteriorly convex lines on the lateral view
  • on the frontal view (AP)
    • lateral margins of the vertebrae on each side
    • spinous processes in the midline should form a straight line
  • normal lordotic curvature
    • fulcrum of flexion in adults is at C5-C6
    • in children it is at C2-C3 - pseudosubluxation - normal !!!
  • evaluate the width of the intervertebral disc spaces

Craniovertebral junction or upper cevical spine
Dislocations of the atlanto-occipital joint

  • uncommon and usually fatal
    • disruption of the medulla oblongata & complete respiratory arrest
    • alar & apical ligaments, tectorial membrane & posterior atlanto-occipital ligaments disrupted
    • fractures of the atlanto-occipital joint may accompany the dislocation
    • subluxation may occur in Down’s syndrome (ligamentous laxity)

X-ray

  • lateral view
    • marked soft tissue swelling
    • marked widening of space between base of skull and atlas
  • flexion-extension views
    • instability in extension

Rx

    • requires reduction of the dislocation and stabilisation of the atlanto-occipital joint
    • cervical traction is contraindicated because of severe instability
    • immediate application of a halo vest to stabilise the joint
    • respiratory and neurologic status must be carefully monitored
    • recommend early surgical stabilisation of the atlanto-occipital joint

Fractures of the occipital condyle

  • rare and are frequently missed on initial evaluation
  • from axial loading and lateral bending
  • Anderson and Montesano - three types
    • type 1 - impaction
    • type 2 - associated with basilar skull fractures
    • type 3 - avulsion fracture by alar ligaments

X-Ray

  • CT and AP & lateral tomography of the base of the skull

Rx

  • type 1 & 2 stable - rigid cervical orthosis or halo vest
  • type 3 fractures unstable
    • avulsion of the alar ligaments - immobilisation for 12 weeks in a halo vest
    • if instability on flexion & extension films -> occipital to C2 fusion

Fractures of the atlas

  • axial force on the head - occipital condyles driven downwards - lateral masses of C1 displaced
  • 50% have other cervical spinal fractures
    • most commonly type I traumatic spondylolisthesis of the axis
    • posteriorly displaced dens fractures

Dg

  • difficult accurate roentgenographic diagnosis
  • lateral C-spine view
    • shows fractures of the posterior arch
    • anterior arch # may not be visible
    • soft tissue swelling -> # of anterior arch
  • AP & lateral tomography
    • detects fractures in both the anterior and posterior portions of the ring of C1
  • CT scans often fails to show #
  • open mouth view
    • displacement of the lateral masses of C1 laterally
    • if > 7 mm -> transverse ligament ruptured -> atlanto-axial instability

Three primary types

Anterior or posterior arch fracture

  • at the junction of the arch and the lateral mass
  • transverse ligament and lateral masses of C1 are undisturbed -> stability not disturbed
  • must be distinguished from developmental defects

Rx

  • halter traction until painfree and free of muscle spasm
  • followed by flexion & extension views to confirm stability -> thereafter a soft collar 8-12/52

Lateral mass fracture

  • usually on one side only
  • fracture through the posterior arch on the opposite side sometimes occurs

Burst fracture (Jefferson #)

  • characterised by four fractures -> two in the posterior arch & two in the anterior arch

Dg

  • lateral view
    • soft tissue swelling
  • open mouth view
    • bilateral offset or spreading of the lateral articular masses of C1 in relation to C2
    • if lateral displacement -> than 7 mm -> transverse ligament ruptures with atlanto-axial instability
  • CT - distinction in questionable cases & shows comminuted #
  • AP tomogram very useful

Rx

  • most #-s treated with immobilisation in a rigid cervical orthosis or a halo vest
    • nondisplaced or minimally displaced fractures of the lateral mass and Jefferson fractures
    • prevent displacement and allow fracture healing
  • if the lateral mass of C1 displaced laterally > 7 mm (clinical C1-2 instability)
    • # should be reduced with halo traction
    • halo traction for 3-6 weeks before application of a halo vest to prevent displacement
    • flexion and extension views - no significant C1-2 instability after # healing

Rupture of the transverse ligament (atlanto-axial dislocation)

  • extends between the lateral masses of C1
  • primary stabiliser of the atlanto-axial complex
  • usually associated with rheumatoid arthritis or its variants
  • also with Down’s syndrome (20%)
  • ligamentous laxity in association with severe infections of the head and neck
  • rarely caused by trauma - postero-anterior sheering force
    • from a fall with a blow to the back of the head
    • purely ligamentous injury
    • may be avulsed with a bony fragment from the lateral mass on either side
    • may rupture in its mid substance
  • component of a Jefferson # of C1

Dg

  • lateral radiograph
    • retro-pharyngeal hematoma
    • small flecks of bone avulsed off the lateral masses of C1 - avulsion of the ligament
  • flexion & extension views
    • under the supervision of the physician
    • anterior subluxation of the ring of C1 can be detected on flexion films
    • atlanto-dens interval (ADI) > 5 mm - transverse ligament incompetent (instability)
    • instability can be reduced in extension

Rx

  • primarily a ligamentous injury -> non operative treatment is ineffective
  • surgical stabilisation of the C1-2 complex is the treatment of choice
    • initial treatment -> immobilisation through skull traction
    • posterior stabilisation with a Gallie type of fusion
    • if the posterior arch of C1 is fractured - halo vest for 8-12 weeks to allow healing of the posterior arch before proceeding with a standard C1-2 posterior arthrodesis

Rotary subluxation of C1 on C2

  • uncommon in adults - different entity from rotatory subluxation in children - Traumatic
    • usually caused by MVA
    • often missed initially
    • restricted neck motion
    • Torticollis or wryneck
    • rotary displacement frequently in childhood & early adolescence
    • may occur spontaneously or in association with acute infections of URT
  • both characterized by a tilting of the head in one direction and simultaneous rotation of the head in the opposite direction
  • lesser degrees are due to laxity of the supporting atlantoaxial ligaments
    • transverse & the paired alar ligaments
    • alar ligaments prevent excessive rotation
    • with severe displacement it is likely that one or more of the ligaments are disrupted

Dg

  • open-mouth odontoid roentgenogram
    • “wink sign” - asymmetry of the space between the dens and the articular masses of the axis
  • Lateral X-ray
    • rotation and lateral tilt of the atlas and axis
  • CT and routine AP tomography helpful
    • rotation of C1 in relation to the dens and the fascial skeleton
    • disruption of one facet joint and pivoting about the opposite intact facet joint

Fielding & Hawkins classification

Rx

  • can be reduced by closed means once the direction of the dislocation is determined
  • if reduction stable and alignment satisfactory - immobilised in halo vest
  • if closed reduction is unsuccessful - open reduction & stabilisation
    • posterior cervical arthrodesis

Fracture of the dens

  • often difficult to visualize because of minimal displacement
  • rare in children
  • relatively common in the aged
  • dens may be displaced anteriorly or posteriorly
    • anteriorly with flexion & posteriorly with extension

Dg

  • lateral X-ray
    • soft tissue swelling
    • anterior and posterior cortical margins - ? cortical disruption
    • type III # better visualized on lateral X-ray
  • AP open-mouth projection
    • type I & II fractures better seen
  • CT - not useful
  • tomography
    • performed in both the AP & lateral projections

Diff. dg

  • must be differentiated from a developmental abnormality - os odontoideum
    • which is rounded
    • has a cortical margin around its entire surface
    • usually more widely separated from the base of the odontoid than a fracture
  • in children the synchondrosis between the ossifiation center of the body & dens may be confused with #
  • the os terminale is a small accessory ossification center found at the tip ofthe dens
  • the upper central incisors frequently overlap the dens, and a lucency seen between them - mistaken for a vertical #

Anderson and DeAlonzo

Classified into three types

Type I fractures

  • uncommon
  • oblique # limited to the dens
  • even if non-union occurs after inadequate immobilisation, no instability results

Type II fractures

  • most common (66%)
  • transverse # at the base of the dens
  • 36% non-union rate for both displaced and non displaced fractures
  • several factors important in union
    • displacement > 5 mm have more nonunions
    • other factors include the regional anatomy, the adequacy of reduction, the age of the patient, and type of immobilisation

Rx

  • more unstable when treated with a Gallie type of wiring
  • bone block technique (Brooks-Jenkins procedure)

Type III fractures

  • large cancellous base extending into the body
  • heal without surgery in 90%

Rx

non displaced fractures

  • stable injuries
  • heal with 8-12/52 of immobilisation in either a halo vest or cervical collar

displaced type III #

  • most could be reduced with halo traction
  • continuous traction with extension required to maintain reduction
  • frequent loss of reduction when halo vest applied early

Traumatic spondylolisthesis of the axis (hangman's fractures)

  • incurred during hanging of criminals
  • most common cause MVA with hyperextension of the head
  • weakest point of the pedicle is the interarticular segments
    • arch of C2 fractured anterior to the inferior facet
  • the anterior longitudinal ligament placed under tension & disrupted

Dg

  • lateral view
    • atlantoaxial joint and dens intact
    • fractures of the neural arch of the axis often anterior to the inferior facets
    • avulsion fracture of the anterior inferior margin of the axis or anterior superior margin at C3
    • called hyperextension teardrop
  • oblique views
  • CT definite value in questionable cases

Effendi, Levine & Edwards

  • classified these #s into four types

Type I fractures

  • minimally displaced
  • failure of the neural arch in tension

Rx

  • ligamentous injury minimal
  • stable & heal with 12 weeks of immobilization in a rigid cervical orthosis

Type II fractures

  • > 3 mm of anterior translation and significant angulation
  • result from hyperextension & axial loading - neural arch fracture
  • followed by flexion - stretching of the posterior anulus of the disc and significant anterior translation and angulation
  • C2-3 disc may be disrupted

Rx

  • skull traction with slight extension over a rolled up towel for 3-6 weeks
  • after mobilized in a halo vest for the rest of the 3 month period

Type IIA fractures

  • variant of type II fractures
  • demonstrate severe angulation between C2 & C3 with minimal translation
  • mechanism of injury is predominantly flexion and distraction
  • important to identify this fracture pattern - no traction !!!

Rx

  • halo vest with slight compression
  • applied under image intensification to achieve and maintain anatomic reduction
  • for 12 weeks until union occurs

Type III injuries

  • combine a bipedicular # with posterior facet injuries
  • severe angulation and translation of the neural arch fracture + associated unilateral or bilateral facet dislocation at C2-3
  • frequently neurologic deficits

Rx

  • often require surgical stabilization
  • ORIF to obtain or maintain reduction of the C2-3 facet dislocation
  • bilateral oblique wiring of C2-3 (posterior cervical fusion) + halo vest immobilization for 3 months

Traumatic spondylolisthesis of the axis: treatment rationale based on the stability of the different fracture types.

Muller EJ, Wick M, Muhr G.

Thirty-nine consecutive patients, 22 male and 17 female with an average age of 37.6 years, with traumatic spondylolisthesis of the axis were reviewed. The cause of injury in 75% of the patients was a road traffic accident. The fractures were classified according to Effendi et al., the type II fractures were further divided into three subgroups: flexion, extension and listhesis injuries. There were 10 type I (25.7%) and 29 type II fractures (74.4%); of these, 12 (30.8%) were classified as flexion-type, 2 (5.1%) as extension-type and 15 (38.5%) as listhesis-type. We did not identify any case of type III injury. Overall, 43.5% of the patients had sustained a significant head or chest trauma, with the highest incidence for type II listhesis injuries. Significant neurological deficits occurred in four patients (10.3%); in all four,the fracture was classified as a type II listhesis. All ten type I injuries were successfully treated with a cervical orthosis. Ten of the 12 type II flexion injuries demonstrated significant angulation. Two were treated with internal stabilisation, in seven with a halo device and one with a minerva plaster of Paris (PoP). Healing was uneventful in all ten patients. For the remaining two stable type II flexion injuries, application of a hard collar was adequate, as was the case for the two stable type II extension injuries. Six of the 15 type II spondylolisthesis injuries underwent primary internal stabilisation, and healing was uneventful in all cases. In four (44.4%) of the nine injuries that were primarily treated with a halo device/minerva PoP, secondary operative stabilisation had to be performed. The classification of Effendi et al. provides a complete description of the different fractures. However, further distinction of the type II injuries regarding their stability is mandatory. Type II spondylolisthesis injuries are unstable, with a high number of associated injuries, a great potential for neurological compromise and significant complications associated with non-operative treatment. The majority of type II extension and type II flexion injuries can be successfully treated with nonrigid external immobilisation.

Injuries to the lower cervical spine (C3-C7)

  • different from those involving the upper cervical region
  • from minor compression & avulsion # to severe fractures and fracture-dislocations

Goals of treatment

    • realign the spine
    • prevent loss of function of uninjured neurologic tissue
    • improve neurologic recovery
    • obtain and maintain spinal stability
    • obtain early functional recovery

Whiplash injury

  • flexion & extension movements of the cervical spine caused by sudden deceleration of the trunk and continued oscillatory movements of the unrestrained head
  • usually with automobile accidents
  • results in sprain or intervertebral disc injury without associated # or dislocation
  • spine is usually straightened because of associated muscle spasm (loss of lordosis)
  • at times there are fractures
    • commonly involve the posterior elements, particularly the articular pillars and laminae

Hyperextension Injuries

  • C-spine hyperextended by blows to the head
  • three principle forms
  • distinguishing features
    • age of the patient
    • presence or absence of spondylosis or degenerative arthritis
    • degree of force

Hyperextension strain

  • generally in younger individuals from high-impact trauma
  • most show evidence of facial injury and have signs and symptoms of acute central spinal cord syndrome

Hyperextension injuries with spondylosis

  • more common in older individuals with spondylosis or degenerative arthritis of the C-spine
  • low-impact trauma
  • often just a simple fall from a standing height
  • incomplete cervical cord lesion in 75% (often central cord syndrome) and complete lesions in 25%

Hyperextension Fracture Dislocation

  • rare injury

Unilateral facet dislocation

  • usually from flexion and rotation of the cervical spine
  • most common site at C5-6 or C6-7, less common C3-4,C4-5 & C7-T1
  • may present with an isolated nerve root injury or an incomplete neurologic deficit
  • purely ligamentous or with facet fracture

Dg

  • lateral view
    • about 25% displacement of one vertebra upon the other, measuring about 4–5 mm
    • articular pillars visualised - in the true lateral profile above the injury
      • in the oblique profile below the injury or vice versa
    • “bow tie” or “butterfly” appearance
      • the rotated articular pillar is projected at the anterior margin of the unrotated pillar
    • reduction in the distance between the spino-laminar line and the posterior cortex of the articular pillars at the level of a unilateral locked facet
  • AP view
    • spinous processes displaced toward the affected side at the level of injury
  • oblique views
    • demonstrate the facet locking
  • CT
    • demonstrate both facet locking and facet fractures
    • back-to-back half-moons

Rx

  • closed reduction
    • successful in less than 50% of patients
    • if can be reduced in skull traction –> halo vest immobilisation for 3 months
  • open reduction & posterior cervical fusion - if skull traction does not reduce the dislocation
    • better results than those whose fractures were left unreduced
    • triple wiring or oblique facet wiring for additional rotational control
    • postoperative immobilisation in a rigid cervical orthosis for 6 to 8 weeks
  • old unreduced dislocation
    • chronic pain, limitation of rotation, and radiculopathy
    • foraminotomy with decompression of the involved nerve root & posterior cervical fusion

Bilateral facet dislocations

  • flexion-rotation injuries, combined with distraction forces

Dg

  • approximately 50% anterior subluxation of one vertebral body on the vertebra below
  • usually both facet capsules, posterior longitudinal ligament, posterior anulus fibrosus & disc disrupted
  • superiorly located vertebra displace anteriorly to such a degree that the facets become locked in a position anterior to the facets of the vertebral body below
  • more frequently neurologic deficits

Rx

  • closed reduction
    • more easily reduced with closed traction methods than unilateral dislocations
    • unstable - redislocation frequent when treated with prolonged skeletal traction or even in a halo vest
    • some heal with spontaneous anterior interbody fusions, but this unpredictable
  • open reduction and internal fixation
    • interspinous process wiring technique (Bohlman triple-wire technique)
    • association of disc herniation with unilateral and bilateral facet dislocations 10%
    • identified by myelography, postmyelography CT scanning, or MRI
    • anterior discectomy for removal of extruded disc material before posterior interspinous wiring and fusion recommended

Fractures of vertebral body

  • range from stable compression fractures to highly unstable burst fractures with significant neurologic injury
  • most result from axial loading and flexion

Denis’s three column theory

1. Compression #

  • anterior height of a vertebral body 3 or more mm less than the posterior height
  • without posterior element fracture, ligament disruption, facet dislocation, or neurologic injury
  • stability verified by the criteria of White and Panjabi
Element Point Value
Anterior elements destroyed or unable to function 2
Posterior elements destroyed or unable to function 2
Relative sagittal plane translation >3.5 mm 2
Relative sagittal plane rotation >11 degrees 2
Positive stretch test 2
Medullary (cord) damage 2
Root damage 1
Abnormal disc narrowing 1
Dangerous loading anticipated 1
*Total of 5 or more = unstable

Rx

  • heal with 8 to 12 weeks of external cervical orthotic immobilization

2. Burst fractures

  • unstable injuries
  • more common in the thoraco-lumbar spine
  • posterior element disruption and incompetent posterior ligaments

Dg

  • displacement of posterior fragments into the spinal canal - spinal cord injury
  • CT or tomography should be done

Rx

Conservative

  • longitudinal skull traction to realign the spinal canal
    • intact soft tissue structures to pull retro-pulsed bone fragments into more acceptable alignment and decrease cord compression
  • not to overdistract the cervical spine –> lateral cervical roentgenograms mandatory

Operative

  • decompression of the cord through an anterior approach
  • posterior stabilisation may be required
  • postoperative immobilisation - 12/52 in a halo vest or a rigid cervical thoracic brace

3. Teardrop fracture

  • specific form of burst fracture
  • characteristic triangular or quadrilateral fragment from the anterior inferior margin of the vertebral body (teardrop)
  • with more severe injuries the fracture is accompanied by a posterior dislocation, widening of the interspinous distance, and disruption of the facet joints
  • usually accompanied by a spinal cord injury
  • in 50% a vertical, sagittal split seen in the vertebral body, either on the plain AP film or by CT or tomography

Fractures of the Posterior Elements

1. Fracture of the spinous process

  • clay shoveler’s fracture

2. Fractures of the articular pillars & facets

Fractures of the spondylotic or arthritic cervical spine

  • in patients over 40 years of age with degenerative arthritis
  • hyperextension from lower impact forces
  • central cord syndrome

Spinal Cord Injury without radiologic abnormality (SCIWORA)

  • 10% of spinal cord injuries have no evidence of fracture or dislocation
  • in older individuals with spondylosis
  • may also occur in individuals with relative narrowing of the spinal canal
    • normal AP diameter of the cervical spinal canal 12 to 21 mm
      • if < 12 mm in the midcervical spine - relative stenosis
    • comparing the AP width of the canal with that of the vertebral body
      • generally, these widths approximately equal
      • when the canal measures < 80% of the width of the vertebral body - relative stenosis
  • an acute ruptured disc will cause a spinal cord injury, and of course the plain films will be normal