Fact-sheet: Achondroplasia
Updated on 03/29/2021 at 10:17 AM
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Definition
Achondroplasia belongs to the osteochondrodysplasias with micromelia.
Constitutional disease, the most common cause of disharmonic dwarfism.
Autosomal dominant inheritance.
Prevalence: 1/10,000 to 50,000
Clinical features
Birth length is minimally affected.
Dwarfism marked by shortening of the proximal limb segments (rhizomelic), becoming apparent during growth.
Characteristic facial dysmorphism
Hand malformation with widening of the gap between the 3rd and 4th fingers
Risk of nerve compression due to spinal canal narrowing
ENT and respiratory problems.
Radiography
Excessive development of the skull vault with a small skull base
Narrow spinal canal
Short ribs, square scapulae
Pelvis with "squared-off" iliac wings: small and squat.
Shortening of the long bones (humerus and femur ++)
Square-shaped pelvis
Horizontalization of the acetabular roof
Hypertrophy of the greater and lesser trochanters
Reduced pelvic height,
Horizontalized sacrum, narrow internal margins, cranio-caudal flattening
Thoracolumbar kyphosis
Ultrasound
Prenatal diagnosis is possible by ultrasound: it must then be confirmed by genetic testing for the mutation.
MRI
Brain and cervical spine MRI is systematically indicated at 6 months of age to look for cervical canal stenosis that may lead to neurological disorders.
A search is also made for pathological FLAIR hyperintensity, found in 20% of subjects, even asymptomatic ones.
Management
Regular radiological and clinical follow-up:
- pediatrician
- orthopedist
- ENT specialist
- radiologists