In medicine, ACHONDROPLASIA is known as being undersized, or less than 50in. in
height. Having short limbs, a normal sized trunk, large head with a depressed
nasal bridge and small face. This is a result of a disease in the thyroid gland.
It can also be caused by Down syndrome or absorption, a cartilaginous tissue
during the fetal stage. Hypochondroplasia, a mild form of dwarfism. Spinal
tuberculosis and the deficiency of the pituitary gland secretions. Treatment
with thyroxin or thyroid extract early in childhood results in normal growth and
development. Somatrophin, also known as the human growth hormone is secreted by
the anterior pituitary. Respiratory problems start to occur in infants. Symptoms
of problems include snoring and sleeping with neck in a hyperextended condition.
The limbs have rhizometic shortening. The legs are straight in infantry but when
a child. He begins walking they develop a knock-knee position. When the child
continues to walk legs begin to have a bowed-leg look. Occasionally, these
curvatures are fixed. As the child continues to walk the kyphosis disappears and
the back assumes a lordotic posture. If a delay in child’s walking occurs, the
spine should be monitored closely for signs of gibbous formation. In infancy,
hypercephalus can occur. Infants head circumference should be monitored close .
Monthly checks of head circumference must be monitored. Radiologic studies are
indicated if head circumference raises to disproportionately, or if symptoms of
hydrocephalus. Child’s pediatrician should have a copy of head circumference
curves for children with achondroplasia. Radiologic procedures for dwarfism
include head ultrasound, C-T scan, or MRI of the head. If intervention is
necessary, a ventriculoperitoneal shunt is placed relieving the pressure.
Infants should also be monitored for foramen magnum compression. It is the
opening at the base of the skull in which the brain stem and cervical spinal
cord exit. When you have achondroplasia the foramen magnum is compressing the
brain stem and spinal cord. Symptoms of narrowing include apnea the cessation of
breathing and cervical myleopathy. C-T scans and MRI scans are done to examine
the size of the infectious foramen magnum. A neurosurgical procedure called a
foramen magnum decompression is executed to alarge foramen and alleviate further
symptoms. Adolescents are at risk of getting lumbosacral spinal stenosis. The
lumber spinal cord or nerve roots become compressed producing nerosurgical
symptoms. Initial symptoms including weakness, tingling, and pain of the legs.
Pain usually alleviated by assuming a squatting position. When condition
worsens, pain in lower buttocks occurs. Diagnosis made by neurosurgical
procedure called a lumber laminectomy. Dwarfism is an autosomal dominant
condition. This means a person with achondroplasia has a 50% chance of passing
it to his children. 75% of individuals with achondroplasia are born to normal
size parents. The gene for Dwarfism, fibroblast growth factor receptor 3 (FGFR3)
is acquired when one undersized individual and a normal sized individual produce
a child. Couples at risk of having a child with 2 copies of the changed gene. A
DNA test is now also available to detect double homozygosity.
Bibliography
The Merck Manual of Medical Information. P 295, Merck & Co, Inc.
Whitehouse Station, NS 1997 Hunter, AGW, et. al. Standard weight for height
curves in achondroplasia. Am J Med Genet, 1996, 62:255-261 Science Publishing
Inc., Disease Volume 7, p 73 “Dwarfism”,”Microsoft (R) Encarta (R) 98
Encyclopedia (c) 1993-1997 Microsoft Corporation.