Download What you need to know - Society for Pediatric Radiology

Scoliosis:
What you need to know
Nancy A. Chauvin, MD
Assistant Professor of Radiology
Director of Musculoskeletal Imaging
The Children’s Hospital of Philadelphia
University of Pennsylvania, Perelman School of Medicine
IPR, 2016
Learning Objectives
• Review pathophysiology and classification of scoliosis
• Discuss an imaging Algorithm and approach to
interpretation
• Explore indications for MRI
• Describe treatment options
• Evaluate the use Digital Slot Scanning
Scoliosis
15°
Lateral curvature of the spine > 10 ° as
measured by the Cobb method on a
standing radiograph
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
11°
15 year old girl
Spinal Asymmetry
• Curves less than 10 °
Clinical follow - up
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
Curve Development
Hueter-Volkman law – growth is retarded by
mechanical compression on the growth plate
and accelerated by growth plate tension
Curves progress during periods of
rapid spinal growth
Kim et al. Radiographics 2010; 30: 1823-1812
Primary (Idiopathic) vs Secondary Scoliosis
• Primary (Idiopathic)
• Classified according to age
80%
• Secondary
• Congenital
• Neuromuscular
• Developmental/Syndromic
• Tumor associated
Kim et al. Radiographics 2010; 30: 1823-1812
10%
10%
Congenital Scoliosis
• 2nd most common type
• Maldevelopment of vertebral
elements (bone and neural tissue)
• May not become apparent until
later in childhood
• Most common
• Hemivertebra ~ 40%
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
Anterior
Congenital Scoliosis
• Curve progression is related
to the vertebral abnormality
Posterior
• Poorest prognosis –
unilateral unsegmented bars
with contralateral
hemivertebrae
Birth
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
9 month-old
www.rad.washington.edu
Neuromuscular Scoliosis
• Neurologic disorders
• e.g. CP, spinocerebellar degeneration
• Myopathic causes
• e.g. Muscular dystrophies
Lack of muscular support of the spinal
column – gravity & posturing cause
deformity
• Characteristic long C-shaped curve
• Less commonly S-shaped patterns
• Often with severe kyphosis or lordosis
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
9 year-old girl with Rett syndrome
Idiopathic Scoliosis
Largest subset 0.5-3/100 children
Diagnosis of exclusion -Based on age
Type
Infantile
Age (years)
0-3
Incidence (%)
0.5
Juvenile
4-10
10.5
Adolescent
11-17
89
Age at onset has prognostic significance
Early Onset < age 8 years
Late Onset > 8 years
Riseborough EJ et al. J Bone Joint Sug Am 1973; 55: 974-982
Infantile Idiopathic Scoliosis
Male, left sided thoracic curve
75% of curves resolve spontaneously
25% progress rapidly
Spine growth
Most rapid during the 1st 5 years (2.2 cm/year)
Slows 5 – 10 years
Peaks again at puberty (1.8 cm/year)
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
17 month-old boy
Juvenile Idiopathic Scoliosis
Higher rate of cardiopulmonary complications in
children who develop large curves before the age
of 5
32 °
Alveoli development upto age 7 - 8 years
Typically slow progression until age 10, period of
accelerated growth
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Kim et al. Radiographics 2010; 30: 1823-1812
10 year-old girl
Adolescent Idiopathic Scoliosis
• Risk of progression?
• Skeletal maturity
• Gender (girls more likely to progress & require treatment
• Curve magnitude (increases with skeletal growth)
Progresses during growth and ceases when skeletal
maturity is reached (provided the curve is not severe)
Curves greater than 20 ° in skeletally immature
children are at greatest risk for progression
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Kim et al. Radiographics 2010; 30: 1823-1812
12 year-old girl
Terminology
Apex
Vertebra or disk with the greatest
rotation or farthest deveiation from the
center of the vertebral column
15 year-old girl
Kim et al. Radiographics 2010; 30: 1823-1812
Terminology
End Vertebrae
Maximal tilt toward the apex of the curve
Used to measure the Cobb angle
Kim et al. Radiographics 2010; 30: 1823-1812
Terminology
Neutral Vertebrae
No evidence of rotation
Pedicles in normal, symmetric position
Kim et al. Radiographics 2010; 30: 1823-1812
Terminology
Stable Vertebrae
Farthest cephalad that are bisected or nearly
bisected by the central sacral vertical line (CSVL)
CSVL – Roughly vertical line that is drawn
perpindicular to an imaginary tangential line
drawn across the top of the iliac crests
(bisects the sacrum)
Kim et al. Radiographics 2010; 30: 1823-1812
Cobb Angle
Angle formed by the intersection of 2 lines, one parallel to the endplate of the
superior end vertebra & other parallel to the endplate of the inferior end vertebra
Kim et al. Radiographics 2010; 30: 1823-1812
Goal is to create the largest angle possible
Cobb Angle
Superior endplate of the most
angulated upper body endplate
41 °
Inferior endplate of the most
angulated lower body endplate
Major & Minor Curves
Major curve – “primary curve” largest
abnormal curves in the scoliotic spine
& first to develop
Minor curve – “secondary curve”
develops afterward, to compensate for
perturvation of balance
Kim et al. Radiographics 2010; 30: 1823-1812
14 year-old girl
Structural vs Non-Structural Curves
Structural Curve
Not correctable with
ipsilateral bending
70 °
50 °
Cobb angle > 25 ° on
ipsilateral side-bending
radiographs
Rightward bending
Kim et al. Radiographics 2010; 30: 1823-1812
Lenke LG et al. J Bone Joint Surg Am 2001; 83-A: 1169-1191
AP standing
12 year-old girl
Structural vs Non-Structural Curves
Non-structural
correctable with bending
Usually does not progress unless
ligament shortening results from
growth retardation on the concave
side of the curvature
Becomes important when selecting
the appropriate level for fusion
Kim et al. Radiographics 2010; 30: 1823-1812
29 °
Levocurvature is fully corrected
with rightward bending
Cobb Angle Pitfalls
www.clker.com
• Diurnal variation of 5 degrees – increasing in the afternoon
• Vertebral rotation – may underestimate angle on frontal
radiographs
• Prone positioning – decreased / anesthesia, postoperative
rebound effect
• Radiographic acquisitions/measurement error – 2 to 7 °
• Same endpoints should be used each time
• Intraobserver variation – 5 to 10 °
Kim et al. Radiographics 2010; 30: 1823-1812
Vertebral Alignment & Balance
Plumb line – vertical line drawn downward from
the center of C7 parallel to the lateral edges of
the radiograph
Coronal balance
Distance between the CSVL and plumb line
• Plumb line to the right - Positive
• Plumb line to the left – Negative
> 2 cm, is abnormal
Kim et al. Radiographics 2010; 30: 1823-1812
Vertebral Alignment & Balance
Plumb line – vertical line drawn downward from the center of
C7 parallel to the lateral edges of the radiograph
Sagittal balance
Distance between the posterosuperior aspect of S1 and
the plumb line
• Plumb line anterior – Positive
• Plumb line posterior - Negative
> 2 cm, is abnormal
Kim et al. Radiographics 2010; 30: 1823-1812
Imaging Goals
• Detect & characterize type of curve &
severity
• Identify vertebral anomalies
• Track curve progression
• Monitor treatment related changes
www.nhs.uk
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251
Radiography
• PA radiograph of the entire spine
• Cervicothoracic junction – pelvis
• Standing if possible (seated or supine)
Feet placed shoulder width apart, looking
straight ahead
Elbows bent & knuckles in the supraclavicular
fossae
Khanna G. Pediatr Radiol 2009; 39 (Suppl 2): S247-251.
O’Brien et al. Medtronic Sofamor Denek
Arms places at 30 – 45 °
Radiography
PA radiograph should
include iliac crests &
triradiate cartilage
4 year-old boy with scoliosis
Skeletal Maturity – Risser Stage
Patients with significant growth potential
possess a greater potential for curve
progression
1936; used despite a lack of consensus of reliability
Kim et al. Radiographics 2010; 30: 1823-1812
Reem et al. near perfect agreement of Risser
stage rating intra-observer raliability (n=100) &
substantial inter-observer agreement
Other markers: Rib epiphyses, proximal humeri, closure of triradiate cartilage
Reem et al. Skeletal Radiol (2009) 38: 371-375
Risser Stage
Risser stage 0 -1: Risk of curve progression is up
to 60-70%
Risser stage 3: Risk of curve progression is 10%
12 year-old girl
Triradiate cartilage usually closes before the
iliac crest apophyses appear
4 year-old boy
Radiography
Lateral radiograph not required at screening - used to assess
sagittal balance
Normal Thoracic Kyphosis
20 – 50 ° between T1 – T12
Stitch/ Motion Artifacts
Digital methods
Separate imaging of the thoracic and
lumbar spine are acquired
Can result in false diagnosis if the
source images are not evaluated
Supakul et al. 16% of studies had
stitching errors that could result in
false diagnosis (n = 86)
Patient moved between exposures
Supakul et al. Pediatr Radiol 2012; 42: 584-598
Stitch/ Motion Artifacts
Digital methods
Separate imaging of the thoracic and
lumbar spine are acquired
Can result in false diagnosis if the
source images are not evaluated
Supakul et al. 16% of studies had
stitching errors that could result in
false diagnosis (n = 86)
Patient moved between exposures
Supakul et al. Pediatr Radiol 2012; 42: 584-598
Stitch Artifact
Stitched incorrectly, simulating a vertebra plana
MRI – Indications for Presumed Idiopathic Scoliosis
Age < 10 years
Onset between 4 – 12 years, 26 % had abnormal MRIs*
Chairi I with syrinx most common
Increase Cobb angle by more than
1° / month
* Evans et al. J Bone Joint Surg Am 1996; 78: 314-317.
Abnormal neurologic examination
Foot deformity
Rapid progression
Back pain, neck pain, head
Not ‘generalized’ back pain
560/2442 idiopathic scoliosis, 9% had underlying
pathologic condition**
**Ramirez et al. J Bone J Surg Am 1997; 79(3): 364-368.
Kim et al. Radiographics 2010; 30: 1823-1812
MRI – Indications for Presumed Idiopathic Scoliosis
Curve type commonly associated with neuropathy
(left thoracic, double thoracic, triple major, short segment, long right
thoracic curve, severe curvature after skeletal maturity)
Wide spinal canal, thin pedicle, wide neural foramina, features of lesion
Kim et al. Radiographics 2010; 30: 1823-1812
25 °
18 °
Chiari I and syrinx
8 year-old boy with early onset idiopathic scoliosis
Congenital Scoliosis
Osteoid Osteoma
Asymmetric location of the lesion within the neural arch is the
most significant factor that leads to scoliosis
For scoliosis to develop, muscle spasm must be unilateral
Davies et al. Skeletal Radiol 2009; 38: 207-223
Scoliosis with
abnormal sagittal
balance on exam
7 year-old boy
Osteoblastoma
40% of all osteoblastomas are located within the spine
2/3 cause cortical destruction
Davies et al. Skeletal Radiol 2009; 38: 207-223.
Osteoblastoma
40% of all osteoblastomas are located within the spine
2/3 cause cortical destruction
Davies et al. Skeletal Radiol 2009; 38: 207-223.
Aneurysmal Bone Cyst
Posterior elements are always involved with
frequent extension to the vertebral body or rib(s)
9 year old girl
Scoliosis associated with ABCs is from unilateral vertebral collapse
Davies et al. Skeletal Radiol 2009; 38: 207-223
Langerhans Cell Histiocytosis
12 year-old girl with scoliosis and back pain
Davies et al. Skeletal Radiol 2009; 38: 207-223
Most common cause of vertebra plana in
children
Neurofibromatosis
8 year-old boy
9 year-old boy with Neurofibromatosis
Chronic
Non-bacterial
Osteomyelitis
14 year-old boy with scoliosis and
intermittent back pain
Treatment – Idiopathic Scoliosis
Surgeon preference
Curve severity
Likelihood of curve progression over time
Patient’s perception of deformity & symptoms
Observation
Adolescent Idiopathic Scoliosis
Skeletally immature - Cobb angle < 20 - 25 ° (Risser 0-1)
Skeletally mature - Cobb angle < 30 ° (Risser 3)
Follow-up at 4 to 12 month intervals
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Kim et al. Radiographics 2010; 30: 1823-1812
Bracing
Adolescent Idiopathic Scoliosis
Goal – to avoid surgery
Cobb angle of 20 – 45 degrees
For curves 20 – 30 degrees, bracing commenced only when progression of
5 degrees or more between 2 consecutive visits
Skeletally immature (Risser grade 2 or lower) initial presentation with
curve of 30 – 45 °
~ 75% success rate reducing curve progression
Artlet et al. Neurosurg Clin Am 2007; 18: 255-259
Kim et al. Radiographics 2010; 30: 1823-1812
Braces
Thoracolumbosacral orthosis (TLSO)
www.hangerclinic.com
Boston Brace
www.sunshinepando.com
Charleston Brace
www.sunshinepando.com
Providence Brace
Cosmetic deformity is unlikely to improve
Surgery
Adolescent Idiopathic Scoliosis
Goal – to prevent curve progression by achieving solid bone
fusion of involved segments
Avoid any neurologic complication
Curve correction
Trunk balance restoration
Sagittal contour preservation
Leaving as many mobile segments in the lumbosacral spine as
possible
Curves greater than 45 ° who are Risser < 2
Curves greater than 50 ° who are Risser > 3
Artlet et al. Neurosurg Clin Am 2007; 18: 255-259
Kim et al. Radiographics 2010; 30: 1823-1812
Each lumbar vertebra provides 15° of flexion & extension –
preserving distal motion is critical to maintaining function
Treatment – Early Onset
Goal – Stop progression of spine deformity & allow for
continued growth of the spine, thoracic cavity and lungs
Observation
Non-surgical treatment with bracing,
serial casting
Growth-friendly surgery
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Surgery - Early Onset
Goal – Based on the underlying cause
Restore seating balance
Ease wheelchair use
Control pain
Support trunk to reinforce respiratory function
Growth friendly options to avoid pulmonary insufficiency
syndrome/restrictive lung disease
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
Kim et al. Radiographics 2010; 30: 1823-1812
Surgery - Early Onset
Complication rates are high!
4 year-old girl
Spinal growing rods
Spine-based distraction
El-Hawary et al. Pediatr Clin N Am 2014; 61: 1223-1241
1 year-old girl
Rib based distraction
VEPTR
Surgery - Early Onset
Magnetic Controlled Growing Rods (MCGRs)
Non-invasive lengthening via
magnet system
External remote controller in
outpatient setting without need for
anesthesia or sedation
www.ellipse-tech.com
www.eandt.theiet.org
Teoh KH et al. The Spine Journal, Accepted 12/28/2015
Biplanar Digital Slot-Scanning
Acquisition of concurrent orthogonal
radiograph images
Narrow radiograph fan beam (no grid needed)
Patient stands in the center of the scanner
PA and lateral images taken at the same time,
so no change in patient position
Exposure is ~ 15 seconds – remain still with
single breath hold
Hull et al. AJR 2015; 205: W124-132
Blumer et al. Pediatr Radiol 2014; 44: 871 – 882
EOS Imaging Operator Manual
Biplanar Digital Slot-Scanning
Advantages
Lower radiation dose (50-60% dose reduction in ED*)
Better total spine visualization (obese patients)
No geometric magnification
Improved work-flow (one expsure without need for stitching)
Calculation applications – considering pelvic rotation for Cobb
angle calculations
Ability to create 3D images (standing position)
*Hull et al. AJR 2015; 205: W124-132
Blumer et al. Pediatr Radiol 2014; 44: 871 – 882
10 year-old girl with 32 ° levocurvature
Biplanar Digital Slot-Scanning
Disadvantages
Extensive post-processing (90-120 minutes)
Artifacts due to relatively long acquisition times (15 sec)
(motion artifacts, edge enhancement, off-center artifact)
Cost
(Machine with set-up training: $400,000-600,000*)
*Hull et al. AJR 2015; 205: W124-132
Blumer et al. Pediatr Radiol 2014; 44: 871 – 882
Cardiac Pulsation Artifact
EOS scoliosis image
Conventional scoliosis image
Incorrect Centering
Artifact
EOS scoliosis image
Conventional scoliosis image
Respiratory Motion Artifact
Conventional scoliosis image
EOS scoliosis image
Pseudopneumopericardium Artifact
EOS scoliosis image
Motion
Wavy Fusion Rod
Artifact
EOS scoliosis image
Conventional scoliosis image
Motion
Wavy Fusion Rod
Artifact
EOS scoliosis image
Conventional scoliosis image
Take Home Points
• Scoliosis is a common problem in pediatric patients
• Cobb angles, vertebral alignment & balance, congenital osseous
abnormalities and skeletal maturity should be described
• The underlying cause of scoliosis has tremendous impact on
prognosis and treatment options
• Radiologists should be aware of the indications for advanced imaging
• EOS is a low dose technique with very good quality; radiologists
should be aware of common artifacts