Role of Medical Imaging in Achondroplasia

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Role of Sonographic imaging in achondroplasia

• Dr. Muhammad Bin Zulfiqar
• PGR IV FCPS Services Institute of Medical
  Sciences / Hospital
• radiombz_at_gmail.com

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Aims

• To look for Antenatal US imaging in
  Achondroplasia.
• To differentiate between homozygous /
  heterozygous achondroplasia
• Role of plain radiography , CT and MRI

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Achondroplasia

• Rhizomelic micromelia associated with frontal
  bossing and low nasal bridge.
• Types
• HeterozygousCompatible with life
• HomozygousIncompatible with life

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Heterozygous Achondroplasia

• Prototype of rhizomelic dwarfism
• Autosomal dominant I sporadic (80) disease with
  quantitatively defective endochondral bone
  formation
• Related to advanced paternal age
• Epiphyseal maturation ossification unaffected

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OB-US (diagnosable gt21-27th week GA)

• Shortening of proximal long bones femur length
  lt99th percentile between 21 and 27 weeks MA
• Increased BPD, HC, HC AC ratio
• Decreased FL BPD ratio
• Normal mineralization, no fractures
• Normal thorax normal cardiothoracic ratio
• Three-pronged( trident) hand 2nd 3rd 4th
  finger of similarly short length without
  completely approximating each other(
  PATHOGNOMONIC)

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Case1heterozygous Achondroplasia
Yuliya Burmagina, MD Ekaterina Kaloyanova, MD.
20087-06-16-21 Achondroplasia  Burmagina www.thef
etus.net/

• Mrs. M., 34 years old, housewife, G7P5, with no
  consanguinity, was admitted at 33 weeks of
  gestation to antenatal ward for evaluation of
  fetus in view of tense polyhydramnios.

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• Frontal Bossing
• Flattened Nasal Bridge

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• Abnormal head shape brachycephaly with starting
  craniosynostosis.

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• Characteristic profile and head shape (prefrontal
  edema, frontal bossing, typical appearance of
  nasal bridge (midface hypoplasia) and short
  cranial base).

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•  Bell-shaped" trunk (narrow thorax and distended
  abdomen), frontal bossing. Note the
  polyhydramnios.

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• Note the significant difference in circumferences
  of abdomen and thorax (along with relative
  cardiomegaly)

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• Normal kidney size and sonographic pattern
  (enabling better differential diagnosis).

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• Absence of polydactyly (helping to differentiate
  the condition).

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•  Short femur length58 mm, lt5centile, fibula
  tibia. Humerus (52 mm, lt 2centile).

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• Note shortened arm (ulna51 mm, lt5 centile).

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• X-ray study few days after birth Narrow chest,
  shortened long bones (no evidence of
  platyspondyly).

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Case2heterozygous Achondroplasia

• A 21-year-old G2P1 at 36 weeks of pregnancy of
  gestation. Her husband has some family history
  of achondroplasia. 

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• 36 weeks of pregnancy the image 1 shows a normal
  head circumference corresponding to 363 weeks of
  pregnancy. The image 2 shows a short fetal
  femur corresponding only to 263 weeks of
  pregnancy. 

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•  36 weeks of pregnancy the images show short
  long bones of the fetus corresponding to 27 weeks
  (humerus image 3) and 30 weeks of pregnancy
  (tibia image 4).

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• 3D image of the fetal face with the low nasal
  bridge and midface hypoplasia.
• The images compare the prenatal 3D image and
  postnatal appearance of the baby.

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• Radiography
• CT Scan
• MRI

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heterozygous AchondroplasiaSkull

• Large calvarium with frontal bossing
• Depression of nasion
• Broad mandible
• Constricted basicranium small foramen magnum
• Communicating hydrocephalus caused by obstruction
  of basal cisterns aqueduct

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• Image shows an enlarged calvaria with a shortened
  skull base and frontal bossing. Note the midface
  hypoplasia.

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• Enlarged calvaria. Note the enlarged mandible.

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• Typical findings of skull base achondroplasia Lar
  ge skull vault with small skull base, narrow
  foramen magnum, prominent forehead, depressed
  nasal bridge, dilated suprasellar
  cistern, vertical straight sinus and dilated
  supratentorial ventricular system with normal 4th
  ventricle.

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• There is evidence of stenosis of the foramen
  magnum.

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• Achondroplasia. Sagittal section of the cervical
  spine on a T2-weighted magnetic resonance image
  in a 6-year-old patient who presented with a
  neurologic deficit. This image shows narrowing of
  the foramen magnum at the C1 canal, effacement of
  the subarachnoid spaces at the cervicomedullary
  junction, and abnormal intrinsic cord signal
  intensity.

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heterozygous AchondroplasiaChest

• Anteroposterior narrowing of chest
• Short anteriorly flared concave ribs
• Squaring of inferior scapular margin

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• Shortened ribs.

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heterozygous AchondroplasiaSpine

• .Hypoplastic bullet / wedge-shaped vertebra
• Rounded anterior beaking of vertebra in upper
  lumbar spine (DDx Hurler disease)
• Decreased vertebral height
• Scalloped posteriorly concave vertebral margin
• Scoliosis
• Thoracolumbar angular kyphosis (gibbus)
• Exaggerated sacral lordosis

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heterozygous AchondroplasiaSpine

• Stenosis of lumbar spine
• Narrowing of interpedicular space due to laminar
  thickening
• Ventrodorsal narrowing of spine due to short
  pedicles
• Bulging / herniation of intervertebral disks
• Wide intervertebral foramina

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• Image shows progressive narrowing of the lumbar
  spinal canal, bullet-nose vertebrae, Note the
  shortened ribs

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• Image shows progressive reduction in vertebral
  interpediculate distance in the caudal direction.

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• The spine is often affected in achondroplasia.
  Features include interpediculate narrowing and
  thickened pedicles.

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• Disk herniation is common. Changes in the spine
  can result in stenosis of the spinal canal,
  particularly in the lumbar region.

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• Image shows a decreased lumbar interpedicular
  distance. Note the scoliosis.

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• short pedicles
• posterior vertebral scalloping
• thoracolumbar kyphosis
• tombstone iliac wings

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heterozygous AchondroplasiaPelvis

• Square flattened iliac bones Tombstone
  configuration
• Champagne glass"-shaped pelvic inlet
• Lack of flaring of iliac wings
• Horizontal acetabula( flat acetabular angle)
• Small sacrosciatic notch

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• short pedicles
• posterior vertebral scalloping
• thoracolumbar kyphosis
• tombstone iliac wings

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• Champagne-glass pelvis with squared iliac wings,
  a narrow sacroiliac notch, and a reduced
  acetabular angle.

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• Image shows progressive narrowing of the
  interpediculate distance with a champagne-glass
  pelvis. Note that the legs are straight in
  infancy.

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heterozygous AchondroplasiaExtremities

• Predominantly rhizomelic micromelia of long bones
  (femur, humerus)
• Trumpet" appearance of long bones shortening
  with disproportionate metaphyseal flaring
  (actually normal width of metaphysis)
• Short femoral necks
• Limb bowing

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heterozygous AchondroplasiaExtremities

• Ball-in-socket" epiphysis broad V-shaped distal
  femoral metaphysis in which epiphysis is
  incorporated
• High position of fibular head(
  disproportionately long fibula)
• Short ulna with thick proximal slender distal
  end
• Brachydactyly (short tubular bones of hand
  feet), especially short proximal middle
  phalanges

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• Image shows inverted femoral physis (inverted V
  configuration), which contributes to a waddling
  gait.

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• Genu varum. Image shows rhizomelic shortening of
  the bilateral femurs with metaphyseal flaring.
  The bones are wide because of unaffected
  appositional growth.

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• Image shows rhizomelic shortening of the humerus
  with posterior bowing and an incomplete glenoid
  fossa.

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• Image shows posterior bowing of the humerus, the
  principal cause of the loss of elbow extension.
  Posterior dislocation of the radial head may also
  contribute.

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• Trident hands. Image shows widely opposed fingers
  of equal length.

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• Trident hands.

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Complications of achondroplasia

• (1) Hydrocephalus syringomyelia (small foramen
  magnum)
• (2) Recurrent ear infection (poorly developed
  facial bones)
• (3) Neurologic complications (compression of
  spinal cord, lower brainstem, cauda equina, nerve
  roots) apnea and sudden death
• (4) Crowded dentition malocclusion

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Homozygous Achondroplasia

• Hereditary autosomal dominant disease with severe
  features of achondroplasia (disproportionate limb
  shortening, more marked proximally than distally)
• Risk marriage of two achondroplasts to each
  other

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Homozygous Achondroplasia

• Skull
• Large cranium with short base small face
• Flattened nose bridge
• Short ribs with flared ends
• Vertebra
• Hypoplastic vertebral bodies
• Decreased interpedicular distance

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Homozygous Achondroplasia

• Pelvis
• Short squared innominate bones
• Flattened acetabular roof
• Small sciatic notch
• Limb Bones
• Short limb bones with flared metaphyses
• Short, broad, widely spaced tubular bones of hand

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Indices depicting fatal outcome

• FL / AC ratio lt0.16---Lethal outcome
• FL / AC ratio gt0.16---Non lethal outcome
• Normal thoracic / abdominal circumference ratio
  is 0.89-1.0
• TC /AC ratio of lt 0.8 is associated with
  Pulmonary hypoplasia and lethality.

 Antenatal Detection of Skeletal Dysplasias 
Barbara V. Parilla, MD, Elizabeth A. Leeth, MS,
Michelle P. Kambich, MS, Patricia Chilis, RDMS
and Scott N. MacGregor, DO . Division of
Maternal-Fetal Medicine, , Northwestern
University Medical School, Evanston, Illinois
USA. J Ultrasound Med 22255-258
0278-4297. Johnson A, Callan NA, Bhutani VK,
Colmorgen GH, Weiner S, Bolognese RJ. Ultrasonic
ratio of fetal thoracic to abdominal
circumference an association with fetal
pulmonary hypoplasia. Am J Obstet Gynecol 1987
157764769.
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Thoracic Circumference

• Preparation Full bladder for TA imaging in first
  and second trimester
• Method excluding the skin and subcutaneous
  tissues at the level of four chamber view of the
  heart.
• Normal thoracic / abdominal circumference ratio
  is
• 0.89-1.0
• TC /AC ratio of lt 0.8 is associated with
  Pulmonary hypoplasia and lethality.

Johnson A, Callan NA, Bhutani VK, Colmorgen GH,
Weiner S, Bolognese RJ. Ultrasonic ratio of fetal
thoracic to abdominal circumference an
association with fetal pulmonary hypoplasia. Am J
Obstet Gynecol 1987 157764769.
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DD between Achondroplasia

• At 26 weeks BPD age
• Homozygous fetuses never had a femoral length
  that exceeded 34 mm. (progressive decrease in
  relative femoral length in the second trimester)
• Heterozygous fetuses always had a femoral length
  that exceeded 34 mm.
• Fetal femoral growth curves therefore allows the
  distinction between homozygous, heterozygous and
  unaffected fetus in the second trimester.
•  
•  

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• Cases

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• Right. US scan of a homozygous achondroplastic
  fetus at 17.0 weeks gestational age shows a
  morphologically normal femur (cursors).
• Left. US scan of a different homozygous
  achondroplastic fetus at 34.0 weeks gestational
  age shows an obviously short and thick femur with
  metaphyseal flaring (cursors).

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• Short ribs with flared ends, hypoplastic vertebral
  bodies (platyspondyly), flat acetabular roof and
  small sciatic notches favor Homozygous
  Achondroplasia

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CaseAchondroplasia

• 19 years male

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• short pedicles
• posterior vertebral scalloping
• thoracolumbar kyphosis
• tombstone iliac wings

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• short pedicles
• posterior vertebral scalloping
• thoracolumbar kyphosis
• tombstone iliac wings

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CaseAchondroplasia

• Three month old child

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• Foramen magnum stenosis with significant
  compression of the cervico-medullary junction.

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CaseAchondroplasia

• Two Years Female Child

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CaseAchondroplasia

• Three month old child

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CaseAchondroplasia

• 50 years female

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• Bilateral knee x-rays show metaphyseal flaring
  typical of achondroplasia.

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CaseAchondroplasia

• 14 Years Male

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• Rhizomelic dwarfism, with relatively short femora
• Bilateral genu vara.
• Metaphyseal flaring, most evident at the lower
  femora, giving trumpet bone type appearance
• Relatively long fibulae.
• V shaped growth plates, most evident at the upper
  tibiae

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CaseAchondroplasia

• 1 Years Male

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• Shortened long bones of the upper and lower limbs
  with metaphyseal flaring.
• Anterior Flaring of the ribs. 
• Small pelvis (trident pelvis).

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• Shortened long bones of the upper and lower limbs
  with metaphyseal flaring.
• Anterior Flaring of the ribs. 
• Small pelvis (trident pelvis).

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• Typical findings of skull base achondroplasia Lar
  ge skull vault with small skull base, narrow
  foramen magnum, prominent forehead, depressed
  nasal bridge, dilated suprasellar
  cistern, vertical straight sinus and dilated
  supratentorial ventricular system with normal 4th
  ventricle.

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CaseAchondroplasia

• 3 Years Male

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• stenosis of the foramen magnum with a large skull

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• trident hands

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• metaphyseal flaring giving a trumpet bone type
  appearance
• the femora and humeri are particularly shortened
  (rhizomelic shortening)
• the acetabular roof is horizontal, the iliac
  wings have a tombstone appearance
• horizontal sacrum

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• progressive decrease in interpedicular distance
  in lumbar spine

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• Role of CT

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• CI axial section images of the foramen magnum of
  four patients with achondropbasia. (a)
  Four-month-old patient (b) 8-monthold
• patient (c) il-month-old patient (d) 2-year-old
  patient. The contour of the posterior two-thirds
  of the foramen magnum varies, whereas
• the anterior third maintains a constant and
  symmetric shape.

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• The posterior margin of the foramen magnum
  extends anteriorly (arrow) beyond the posterior
  arch of C1 and impinges on the posterior surface
  of the bower medulla oblongata and the upper
  cervical cord.
• The posterior margin of the foramen magnum
  protrudes inferiorly (arrow) and extends ventral
  to the posterior arch of C-1, further decreasing
  the AP diameter of the spinal canal.

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• Coronal reformatted CT image shows the thickened,
  deformed left lateral margin of the foramen
  magnum (arrow) compressing the neural tissue. The
  subarachnoid space was opacified with intrathecal
  metrizamide (arrowhead) (metrizamide was black on
  the negative image display).
• The mid-sagittal view shows kinking and narrowing
  of an hourglass deformity of the cord at the
  cervicomedullary junction (arrow) with a thin
  layer of CSF interposed between the cervical cord
  and the posterior margin of the foramen magnum.

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• MR sagittal image (0.5 1) of the craniocervical
  junction with SE 538/38 (repetition time m
  sec/echo time m sec) the margin of the foramen
  magnum is not clearly defined.
• However, the brain stem cord outline is well
  delineated note the abnormal focal cord
  narrowing from C-i to C-2 bevel

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Cardiaothoracic and HC / AC ratio

• HC / AC 1.207 at 14 week's but decreased slowly
  until 30 week's when the ratio was 1.110
  thereafter there was a rather sharp fall in the
  mean ratio 1.010 at 36 weeks and 0.967 at 40
  weeks and then the variability decreases. 

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DD Ellis Van Crevald Syndrome
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• Ellis-van Creveld (EVC) syndrome is a
  differential diagnosis of short-limb dwarfisms.
  It is also known as chondroectodermal dysplasia.
  This autosomal recessive disease involves
  chromosome 4p16. The hands demonstrate
  polydactyly in almost all patients, whereas the
  feet demonstrate polydactyly in only 10. Note
  the broad hands with short middle phalanges and
  hypoplastic distal phalanges. The carpal bones
  are malformed, with fusion of the capitate and
  hamate. Extracarpal bones might also be present.
  The ends of the ulna and radius are enlarged.

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• Ellis-van Crevald (EVC) syndrome. (See the
  previous image.)

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• The knees of patients with Ellis-van Creveld
  (EVC) syndrome develop a genu valgus deformity,
  and the long bones are short. Hypoplasia of the
  proximal tibia is also present. (See the previous
  2 images.)

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• The knees of patients with Ellis-van Creveld
  (EVC) syndrome develop a genu valgus deformity,
  and the long bones are short. Hypoplasia of the
  proximal tibia is also present. (See the previous
  3 images.)

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• The thoracic cavity of this patient with
  Ellis-van Creveld (EVC) syndrome is small and
  narrow, with short ribs. About 60 of patients
  have cardiac anomalies, and most patients
  ultimately die from respiratory illness.

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• In Ellis-van Creveld (EVC) syndrome, the teeth
  are hypoplastic, as are the nails. The teeth are
  small and cone shaped, with irregular spacing.
  Other facial anomalies include a partial harelip.

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• Metaphyseal chondroplasia (Schmid type) is a
  differential diagnosis of achondroplasia, with
  metaphyseal flaring of the ulna and radius as
  well as bowing of the shaft. Note no hand
  involvement with metaphyseal chondroplasia,
  unlike achondroplasia.

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• Metatrophic dwarfism II, or Kniest syndrome, is a
  differential diagnosis. Skeletal dysplasia
  results in short limbs and a proportionally long
  trunk however, the head and face appear normal.
  With time, severe kyphoscoliosis produces marked
  shortening of the trunk, which can make body
  proportions deceiving.

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CaseAchondroplasia

• TWO YEARS MALE

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• The skull vault is enlarged, with small skull
  base.
• There is exacerbation of the lumbar-sacral angle
  and the interpedicular distance gradually
  diminishes in the lumbar spine. The iliac wings
  are vertical.
• The limbs demonstrate normal density with marked
  shortening of the long bones. 

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• The skull vault is enlarged, with small skull
  base.
• There is exacerbation of the lumbar-sacral angle
  and the interpedicular distance gradually
  diminishes in the lumbar spine. The iliac wings
  are vertical.
• The limbs demonstrate normal density with marked
  shortening of the long bones. 

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• There is evidence of stenosis of the foramen
  magnum.

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CaseAchondroplasia
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• There is a relatively large cranial vault with
  small skull base. There is a prominent forehead
  with depressed nasal bridge. The foramen magnum
  is narrowed, and there is a cervicomedullary
  kink. Relative elevation of the brainstem gives
  rise to a large suprasellar cistern and a
  vertically-oriented straight sinus.

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Take Home Message

• Antenatal Diagnosis is possible with confident.
• Antenatal Differentiation between lethal and non
  lethal dysplasia is possible.
• Radiography, CT and MRI are helpful in
• Postnatal workup
• to look for complications.

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• THANK YOU