drkbravva
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09.12.05 (3 years ago)
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Osteogenesis imperfecta
Causes: Osteogenesis is an inherited disorder.
Type I is autosomal dominant.
Type II is autosomal dominant with new mutation.
Type III is autosomal dominant with new mutation. Rarely, recessive forms also are observed.
Type IV is autosomal dominant.
Age: Age of onset of symptoms (ie, fractures) varies depending on the type, as follows:
Type I - Infancy
Type II - In utero
Type III - Half the cases in utero, and other half in the neonatal period
Type IV - Usually in infancy
Physical: Physical examination can vary depending on the type. It forms the basis for Sillence classification.
Type I
A: Dentinogenesis imperfecta is absent.
B: Dentinogenesis imperfecta is present.
Symptoms of both subtypes include the following:
Blue sclera present (However, blue sclera also may occur in other disorders, such as Turner syndrome, Paget disease, or osteopetrosis.)
In utero fractures - 10% (Fractures are more common during infancy.)
Mild-to-moderate bone fragility (Frequency of fractures decreases after puberty.)
Kyphoscoliosis
Hearing loss
Premature arcus senilis
Easy bruising
Mild short stature
Type II
Dentinogenesis imperfecta
Blue sclera may be present.
Hearing loss is not applicable to type II OI.
Perinatal lethality
Small nose, micrognathia
Connective tissue fragility
In utero fractures are present in 100% cases
Short trunk
Type III
Dentinogenesis imperfecta
Sclera of variable hue
No hearing loss
In-utero fractures in 50% of cases (The remaining half of cases have fractures in neonatal period.)
Limb shortening and progressive deformities
Triangular facies with frontal bossing
Pulmonary hypertension
Type IV
Subtype A: Dentinogenesis imperfecta is absent.
Subtype B: Dentinogenesis imperfecta is present.
Symptoms of both subtypes include the following:
Normal sclera
Normal hearing
Fractures that begin in infancy (In utero fractures are rare.)
Mild angulation and shortening of long bones
No bleeding diathesis
Imaging Studies:
Postnatal x-ray: Obtain skull, chest, long bones, and pelvis x-ray films.
Type I
Tam O'Shanter skull - Flattening in vertical axis and widening in transverse axis
Thin bones
Multiple wormian bones
Fractures with deformities
Osteopenia
Platyspondylia
Type II
Beaded ribs
Broad bones
Fractures with deformities
Osteopenia
Platyspondylia
Type III
Cystic metaphyses (popcorn appearance)
Normal or broad bones early on; thin bones later
Fractures with deformities
Osteopenia
Type IV
Thin bones
Fractures with deformities
Osteopenia
Prenatal ultrasound
Prenatal ultrasound can be used to detect limb length abnormalities at 15-16 weeks' gestation.
Limb abnormality can be detected by 15-18 weeks' gestation. Mild forms may have normal sonogram findings.
Features
Supervisualization of intracranial contents caused by decreased mineralization of calvarium (also calvarial compressibility)
Long bones bowing, decrease in length (especially the femur)
Multiple rib fractures
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