(3) Dysplasias Flashcards
What is the most common congenital dwarfism?
achondroplasia
What is the inheritance of Achondroplasia?
Autosomal dominant
(spontaneous mutation in 80% of cases)
What type of dwarfism is achondroplasia?
rhizomelic (root of limbs; causing short stature)
What type of ossification is affected by Achondroplasia?
- endochondral: disturbance of epiphyseal chondroblastic growth & maturation
- normal intramembranous ossification
What are the clinical features of the head in Achondroplasia?
- large head, prominent forehead
- depressed nasal ridge
- small foramen magnum
What are the clinical features of the trunk in Achondroplasia?
- Normal sized torso/spine
- thoracolumbar kyphosis
- lumbar hyperlordosis
- protuberant abdomen
- prominent buttocks (UH BUHBAYUM)
What is the life expectancy of patients with Achondroplasia?
normal
Stenosis of the vertebral foramen is a major concern in what conditions?
Achondroplasia
What is the average height of patients with Achondroplasia?
50 inches
What are the imaging features of Achondroplasia in the spine?
- posterior body scalloping
- narrow interpedicular distance
- short, thick pedicles
- bullet vertebrae
- thoracolumbar gibbous
What are the differentials for posterior body scalloping?
- NF1
- acromegaly
- achondroplasia
- marfan syndrome
What is the most clinically significant implication of achondroplasia?
(congenital) spinal stenosis
What causes posterior body scalloping in achondroplasia?
^CSF pulse pressure
What is a potential complication of a small foramen magnum in achondroplasia?
small foramen magnum can lead to hydrocephalus, OR death in infants (pressure on brainstem affecting respiratory centers)
What are the imaging features of Achondroplasia in the pelvis?
- champagne glass pelvis
- small pelvis
- paddle-shaped ilia (short, flat)
- horizontal acetabulum
- short femoral necks
- horizontally oriented sacrum (can’t see distal sacrum on AP view)
What are the imaging features of Achondroplasia in the hand?
- trident configuration (^space between 3rd & 4th digits)
- shortened fingers
What are the potential complications of Achondroplasia?
- spinal stenosis, ^cauda equina syndrome
- basilar impression (brainstem compression, sleep apnea, sudden death in infants)
What is the inheritance of cleidocranial dysplasia (CCD)?
autosomal dominant
What type of ossification is affected by CCD?
intramembranous > endochondral
What are the clinical features of CCD?
- large head, small face
- abnormal dentation ( persistent metopic suture)
- drooping hypermobile shoulders
- multiple midline defects (eg. cleft palate)
- reduced height (not dwarfs)
- narrow cone-shaped thorax
What are the imaging features of cleidocranial dysplasia in the skull?
- wormian bones
- wide, persistent metopic suture
- hot cross bun appearance
- brachycephaly
- small face
- midline defects (cleft palate)
What are the imaging features of cleidocranial dysplasia in the thorax?
- absent or hypoplastic clavicles, wide AC joints
- pseudoarthrosis of clavicle (mid portion missing)
- small, winged, elevated scapulae
- narrow, cone-shaped thorax
What are the imaging features of cleidocranial dysplasia in the pelvis?
- hypoplastic bones
- midline defects (pubic symphysis diastasis/agenesis)
- coxa vara or valga
What type of gait might a patient with CCD have?
A-frame gait
(pushes femurs inward for stability)
What are the imaging features of cleidocranial dysplasia in the spine?
- multiple SBOs
- hemivertebrae
What are the imaging features of cleidocranial dysplasia in the hands?
- supernumerary epiphysis
- hypoplastic, tapered distal phalanges
What is the lifespan of patients with CCD?
normal
What are the potential complications of CCD?
- deafness
- blindness
- severe dental problems
- dislocations (hip & shoulder)
- respiratory distress in children
- scoliosis
What is another name for chondrodysplasia punctata?
congenital stippled epiphysis
What is chondrodysplasia punctata?
punctate or stippled calcification of multiple epiphyseal centers
When does congenital stippled epiphysis occur?
1st year of life
What are the 2 forms of congenital stippled epiphysis?
- autosomal dominant
- autosomal recessive
What is the name for the autosomal dominant form of congenital stippled epiphysis?
Conradi-Hunermann syndrome
Which form of congenital stippled epiphysis is fatal in the first few years?
autosomal recessive
Congenital stippled epiphysis has similar clinical features to what other condition?
achondroplasia
What are the imaging features of Conradi-Hunermann syndrome?
- stippling at end of long bones
- can be seen at endplates & ribs
- can lead to ASx limb shortening
What is another name for Dysplasia epiphysealis hemimelica?
Trevor disease
What is Trevor disease?
focal osteocartilaginous overgrowth of a portion of the epiphysis (intra-articular osteochondroma)
What are the 3 forms of Trevor disease?
- monostotic
- polyostotic
- generalized
What demographic is affected by Trevor disease?
- present during first decade of life
- M>F (3:1)
What is the clinical presentation of Trevor disease?
- altered jt biomechanics
- reduced ROM
- pain
- typically only 1 limb affected in LE
What causes Marfan syndrome?
failure to produce normal fibrillin-1 (component of most CT and osteoid)
What is the inheritance of Marfan syndrome?
autosomal dominant
(50% chance of marfan pt having child w/ marfan)
75% have familial incidence, 25% spontaneous mutation
What assessment tools are used to screen for Marfan syndrome?
- Beighton questionnaire (not specific to Marfan)
- Beighton score (not specific to Marfan)
- Marfan score
What result on the Beighton questionnaire gives a high probability of hypermobility?
2 or more yes answers
What Beighton score indicates probable hypermobility?
4 or more (of 9)
What systems may be involved in Marfan syndrome?
anything w/ CT
- skeletal (mainly extremities)
- ocular
- cardiovascular
What is the life expectancy of Marfan syndrome?
halved if untreated/monitored
What is the most common cause of death in patients with Marfan syndrome?
congenital heart disease
What is the most common congenital heart disease in patients with Marfan syndrome?
atrial septal defect
What are the potential cardiovascular complications of Marfan syndrome?
- congenital heart disease
- aortic dissection & rupture
- pulmonary artery rupture
- aortic valve incompetence
- mitral valve prolapse
What are the potential ocular complications of Marfan syndrome?
- lens dislocation (50%)
- macular detachment
What are the imaging features of Marfan syndrome?
- arachnodactyly
- thin gracile long bones
- thin cortices
- delicate trabecular pattern
- scoliosis (>50%)
- acetabular protrusion (50% of pts)
- pectus excavatum/carinatum
- dislocations (jt laxity)
What are the imaging features of Marfan syndrome in the spine?
- tall vertebrae
- kyphoscoliosis
- double major or right thoracic scoliosis (develops in childhood)
- widened spinal canal (50% of cases)
- posterior body scalloping
- thinning of pedicles
What are the potential complications of Marfan syndrome?
- cardiac abnormalities
- aneurysms
- dental problems
- slipped capital epiphysis
- transverse lig rupture (contraindication to HVLA)
If you determine your patient has Marfan syndrome, what is your next step prior to treatment of the cervical spine?
flexion & extension x-rays
If you discover your patient with Marfan syndrome has anterior translation of C1 on flexion radiographs, what complication may have occurred? What is your next step?
- transverse ligament rupture
- neurosurgical referral
What is the inheritance of Osteogenesis imperfecta?
autosomal dominant
What is the cause of Osteogenesis imperfecta?
defect in quality & quantity of type I collagen (component in osteoid)
What is the clinical diagnostic criteria for Osteogenesis imperfecta?
Presence of at least 2:
- osteoporosis & skeletal fragility
- blue sclerae (faint blue-gray sheen)
- dentinogenesis imperfecta (^cavities & dental abscesses)
- premature otosclerosis
What are the 2 classifications (phenotypes) of Osteogenesis imperfecta?
- Osteogenesis imperfecta congenita
- Osteogenesis imperfecta tarda
Which form of Osteogenesis imperfecta has a high rate of stillbirths?
Osteogenesis imperfecta congenita
What is the life expectancy of Osteogenesis imperfecta tarda?
often normal
What are the clinical features of Osteogenesis imperfecta congenita?
- osseous Fx & deformity in utero
- paper thin skull
- death in utero or shortly after birth (<2yrs)
What are the clinical features of Osteogenesis imperfecta tarda?
- less severe
- Fx’s following trivial trauma
- blue sclerae
- kyphoscoliosis
- deformities
- deafness (conductive) d/t sclerosis of ossicles
What are the imaging features of Osteogenesis imperfecta?
- diffuse osteopenia
- pencil-thin cortices
- multiple Fx’s in various stages of healing
- deformities
- wormian bones
