Paediatric cervical spine injuries: A pictorial review

Transcription

1 Paediatric cervical spine injuries: A pictorial review Poster No.: C-2863 Congress: ECR 2010 Type: Educational Exhibit Topic: Pediatric Authors: L. L. Wang, W. Thomas, K. Ng, C. C. Hiew ; Randwick/AU, Campsie/AU, Westmead/AU Keywords: Pediatric neuroradiology, Trauma, Cervical spine DOI: /ecr2010/C-2863 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 40

2 Learning objectives 1.To review normal and developmental anatomy of the cervical spine. 2.To illustrate common pattern of common paediatric cervical spine injury. 3.To recognise common pitfalls in diagnosis. Background Compared with adults, cervical spine trauma in children produces a different spectrum of injuries. The consequences of these injuries tend to be more devastating. Cases of C-spine injury presenting to Sydney Children's Hospital over the last decade illustrate these patterns unique to children, which relates to differences in anatomy and biomechanics. Characteristic patterns of spinal injury occur in infants and young children as a result of relatively little force. The upper cervical spine is particularly vulnerable. Up to 8 years of age, 70% of fractures and dislocations occur above the C3 level. Avulsions and epiphyseal separations occur commonly, rather than true fractures. After 8-10 years the C-spine assumes adult proportions. After years the pattern of spinal injury is similar to adults, typically lower cervical wedge compression fractures and anterior subluxation or dislocation resulting from axial loading and hyperextension. These patterns are due to anatomic and biomechanical factors including: Cervical musculature - relatively weak. Ligamentous structures - supple and permit a high degree of spinal mobility. Articular facets - more horizontally orientated than in the adult spine. Occipital condyles - relatively hypoplastic. Head size - relatively large. Composition of infant spine - primarily cartilaginous, ossifies progressively. Flexion-extension fulcrum - C2/3, moves caudally with age (C5/6 in adult). Images for this section: Page 2 of 40

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4 Fig. 1: Normal pediatric lateral cervical spine radiograph taken in flexion. Page 4 of 40

5 Imaging findings OR Procedure details Developmental Anatomy of C-Spine C1 and C2 have unique development, while C3-7 develop in a similar fashion. C1 Fig.: C1 has three ossification centres: anterior arch (1) and two neural arch halves (2). The neural arches fuse posteriorly by 3-4 years and the anterior arch fuses with the neural arch by 7 years. C2 Page 5 of 40

6 Fig.: At least four ossification centres are present at birth: body (1), two neural arch halves (2), and odontoid process (3). The neural arches fuse posteriorly by 2-3 years and the body fuses with the neural arch by 3-6 years. The os terminale (4) is a secondary ossification centre at the tip of the dens which appears at 3-6 years and fuses by 12 years. Page 6 of 40

7 Fig.: The dens is separated from the lateral masses by the neurocentral synchondroses (5) and from the centrum of the axis body by the subdental synchondrosis (6). All fuse between the 3rd and 6th years. The subdental synchondrosis shows as a transverse lucent defect separating the axis centrum from the base of the dens. This gradually decreases in width, but may persist into adolescence as a thin radiolucent stripe with densely sclerotic margins (not to be confused with a fracture). C3-7 Page 7 of 40

8 Fig.: These vertebrae have similar development with three ossification centres at birth: centrum (1), and two neural arch halves (2). The neural arches fuse posteriorly by 2-3 years and the body fuses with neural arch by 3-6 years. Five secondary ossification centres appear around puberty (two upper and lower annular epiphyses, transverse processes and spinous process) and fuse with the rest of the bone by about 25 years. Interpreting the Lateral View Page 8 of 40

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10 Fig.: Normal C-spine radiograph taken in flexion Several features are important to recognise on the lateral radiograph of the paediatric C-spine. 1. Pseudosubluxation This refers to the apparent anterior displacement of C2 on C3 which is a physiological phenomenon in children under 7. It is related to the location of the fulcrum at C2/3, ligamentous laxity and horizontally orientated facets. Page 10 of 40

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12 Fig. 2. Posterior cervical line of Swischuk Can differentiate C2/3 displacement due to fracture vs. physiological subluxation. A line drawn from the anterior aspect of the C1 spinous process to the same point on C3 normally passes within 1.5mm of C2. If the line misses C2 by #2mm then pathological dislocation is present, resulting from a hangman's or bilateral C2 pars fracture. This line can only be applied where there is anterior displacement of C2 on C3. A normal line excludes hangman's fracture but not a pure ligamentous injury. Page 12 of 40

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14 Fig. 3. C3 wedging This apparent deformity of the anterosuperior corner of the vertebral body is usually normal (a true compression fracture of C3 is very rare). It probably results from normal hypermobility of upper C-spine causing chronic subclinical trauma and transient impairment of ossification of this region. Page 14 of 40

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16 Fig. 4. Prevertebral soft tissue thickening Apparent thickening may be seen if the film is taken during expiration and flexion (ideal position is mild extension, in inspiration). True prevertebral soft tissue thickening (i.e. #7mm above the glottis and #14mm below the glottis) is not always present in trauma, particularly in the absence of anterior ligament or vertebral body injury. Page 16 of 40

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18 Fig. 5. Predental space (atlantodental interval, ADI) A distance of up to 5mm can be normal in children. Abnormal widening may be seen with: disruption of transverse ligament, ligamentous laxity, C1 fractures (Jefferson/burst), rotatory subluxation, chronic juvenile arthritis, and congenital dens hypoplasia. Page 18 of 40

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20 Fig. 6. Absence of cervical lordosis This may be observed in 14% of normal children. 7. Interspinous distance (ISD) This should normally be #1.5 x ISD one segment above or below. The exception is at C1-C2 which often appears unusually wide in flexion, probably due to tight C1-occiput ligamentous attachments Page 20 of 40

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22 Fig Common Paediatric C-Spine Injuries Torticollis & Atlanto-Axial Rotatory Fixation Torticollis may occur due to either: 1. Disorders limiting neck rotation, without primary involvement of the atlanto-axial joint -Inflammation -Cervical cord tumour -Fibromatosis colli 2. Disorders of rotation at the atlanto-axial joint. Fig.: Lateral and frontal radiograph is difficult to interpret due to head tilt. Open mouth view shows asymmetry of the C1 lateral mass to dens distance (arrows). Page 22 of 40

23 Atlanto-Axial Rotatory Fixation Defined as an irreducible C1/2 rotatory deformity. This may occur either spontaneously or following trauma. Fixation usually occurs within the physiological range of motion, however true subluxation or dislocation can occur in rare cases. Fixation is optimally evaluated using 'dynamic' CT (i.e. scans repeated with rotation of head to the opposite side), where C1 and C2 move as a single unit rather than independently as normal. Fig.: Axial CT shows anterior displacement of the right lateral mass of C1 relative to C2. Page 23 of 40

24 Fig.: 3-year-old female with fixed torticollis following a motor vehicle accident. Axial CT and 3D reformat demonstrates atlanto-axial rotatory subluxation with C2 fractures. Atlanto-Occipital Disruption This injury is often fatal or results in severe neurological deficit. It is more common in children as the articulation is less stable. Page 24 of 40

25 Several methods of cranio-cervical evaluation using the lateral radiograph have been described -Powers ratio, Wackenheim clivus line, X-line method. -In children however, the most reliable technique is measurement of the atlanto-axial joint space. -As described by Kaufman et al (1982), separation of more than 5mm between the occipital condyle and the condylar surface of C1 is abnormal. Fig.: Lateral radiograph and CT coronal and 3D reformations showing separation at the atlanto-occipital joint with anterior displacement of occipital condyle relative to C1. Page 25 of 40

26 Fig.: Sagittal T2W MR, 14-month-old. Deceleration injury has caused disruption of all anterior and posterior ligamentous structures at the cranio-cervical junction including the anterior and posterior atlanto-occipital ligaments, tectorial membrane, apicalcruciate ligament complex and an avulsion fracture of the odontoid. Additional findings include cord and soft-tissue oedema and haemorrhage. This injury was fatal. Atlanto-Axial Subluxation Page 26 of 40

27 Isolated injury of the transverse ligament without associated fracture of the odontoid is uncommon in children. Chronic atlanto-axial subluxation may occur in children with -Down's syndrome -Skeletal dysplasias -Juvenile chronic arthritis -Anatomic anomalies (e.g. os odontoideum) Fig.: 7-year-old with Down's syndrome. Flexion and extension radiographs show widening of the ADI in flexion in keeping with atlanto-axial subluxation due to ligamentous laxity. C1 Fractures Fractures of C1 may be single or multiple. A Jefferson burst fracture occurring as a result of axial compression is relatively uncommon in children. Page 27 of 40

28 Radiograph interpretation is complicated by the wide range of ossification patterns and normal variants. Fig.: A. Axial CT through C1 shows a fracture adjacent to the left synchondrosis in a 3year-old. B. Axial CT shows a fracture through the left synchondrosis of C1 in a 5-yearold. C. Axial T2W MR. Undisplaced fracture of the C1 anterior arch with high signal adjacent to the left synchondrosis of C1 (arrow). D. Axial CT. Congenital incomplete development of the C1 anterior arch which may mimic a fracture. C2 Fractures In children C2 fractures involving the body and neural arch are less common than fractures of the odontoid. Odontoid fractures occur most commonly through the cartilaginous subdental synchondrosis in children under 7 years. Page 28 of 40

29 Fig.: Lateral radiograph and axial CT showing a fracture through the subdental synchondrosis with anterior displacement of the dens. Page 29 of 40

30 Fig.: T2W MR (different patient) illustrates abnormal high signal within the synchondrosis and adjacent soft tissues resulting from a similar injury. Axial CT and coronal reformation. Fractures through the right synchondrosis and left lateral mass of C2 are present. Lower C-spine Injuries Sub-axial injuries of the C-spine are more common in older children. These are often related to sporting and motor vehicle accident injuries. Page 30 of 40

31 Fig.: Axial CT and coronal reformation shows a teardrop fracture of C5. Page 31 of 40

32 Fig.: Rugby injury in 15-year-old. Axial CT shows bilateral C6/7 facetal dislocation. Page 32 of 40

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34 Fig.: Sagittal T2W MR illustrating a C5 compression fracture and central canal stenosis without cord oedema. Spinal Cord Injury Without Radiographic Abnormality Spinal cord injury without radiographic abnormality (SCIWORA) describes a syndrome of neurological injury with no evidence of fracture or malalignment on radiograph or CT. It probably occurs as the result of a hypermobile spine allowing excessive intersegmental displacement causing cord compression or distraction, with spontaneous vertebral realignment. An alternative mechanism may be cord ischaemia. MRI findings may be classified as neural (cord oedema or haemorrhage) and extraneural (ligament or disc injury). Page 34 of 40

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36 Fig.: 7-year-old with severe neurological deficit following MVA. Lateral radiograph shows prevertebral soft tissue swelling only. Sagittal T2W and axial GE MR demonstrates cord oedema and haemorrhage, and paravertebral soft tissue oedema. Images for this section: Page 36 of 40

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38 Fig. 1: Normal pediatric lateral cervical spine radiograph taken in flexion. Page 38 of 40

39 Conclusion Paediatric C-spine injury patterns are different from adults. Imaging and accurate diagnosis of these injuries play a major rule in the management of these patients The cervial spinal injuries in children tend to be concentrated in the upper Cspine and at the craniocervical junction. Avulsions and epiphyseal separations occur commonly, rather than true fractures. Personal Information 1 Lily L. Wang BSc(med) MBBS MPH, 2 Warwick Thomas BSc(med) MBBS FRANZCR, 3 Kevin Ng MBBS FRANZCR, 1 Chee-Chung Hiew MBBS FRANZCR, 1 Department of Medical Imaging, Sydney Children's/The Prince of Wales Hospitals, Randwick, Australia 2 Campsie Medical Imaging, Campsie, Australia 3 Department of Radiology, Westmead Hospital, Westmead, Australia References Grabb PA, Pang D. Magnetic resonance imaging in the evaluation of spinal cord injury without radiographic abnormality in children. Neurosurgery 1994; 35: Kaufman RA, Dunbar JS, Botsford JA, McLaurin RL. Traumatic longitudinal atlanto-occipital distraction injuries in children. AJNR 1982; 3: Lee C, Woodring JH, Goldstein SJ, Daniel TL, Young AB, Tibbs PA. Evaluation of traumatic atlantooccipital dislocations. AJNR 1987; 8: Lustrin ES, Karakas SP, Ortiz AO, Cinnamon J, Castillo M, Vaheesan K, Brown JH, Diamond AS, Black K, Singh S. Pediatric cervical spine: normal anatomy, variants, and trauma. Radiographics 2003; 23: Page 39 of 40

40 Maves CK, Souza A, Prenger EC, Kirks DR. Traumatic atlanto-occipital disruption in children. Pediatr Radiol 1991; 21: Roche C, Carty H. Spinal trauma in children. Pediatr Radiol 2001; 31: Roche CJ, O'Malley M, Dorgan JC, Carty HM. A pictorial review of atlantoaxial rotatory fixation: key points for the radiologist. Clin Radiol 2001; 56: Swischuk LE. Emergency imaging of the acutely ill or injured child. In: The spine and spinal cord. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2000; Swischuk LE, Swischuk PN, John SD. Wedging of C-3 in infants and children: usually a normal finding and not a fracture. Radiology 1993; 188: Page 40 of 40