Scoliosis Health Article

Definition

Scoliosis is a side-to-side curvature of the spine of 10 degrees or greater.

Description

When viewed from the rear, the spine usually appears to form a straight vertical line. Scoliosis is a lateral (side-to-side) curve in the spine, usually combined with a rotation of the vertebrae. (The lateral curvature of scoliosis should not be confused with the normal set of front-to-back spinal curves visible from the side.) While a small degree of lateral curvature does not cause any medical problems, larger curves can cause postural imbalance and lead to muscle fatigue and pain. More severe scoliosis can interfere with breathing and lead to arthritis of the spine (spondylosis).

Four out of five cases of scoliosis are idiopathic, meaning the cause is unknown. Children with idiopathic scoliosis appear to be otherwise entirely healthy, and have not had any bone or joint disease early in life. Scoliosis is not caused by poor posture, diet, or carrying a heavy bookbag exclusively on one shoulder.

Idiopathic scoliosis is further classified according to age of onset:

• Infantile. Curvature appears before age three. This type is quite rare in the United States, but is more common in Europe.
• Juvenile. Curvature appears between ages three and 10. This type may be equivalent to the adolescent type, except for the age of onset.
• •Adolescent. Curvature appears between ages of 10 and 13, near the beginning of puberty. This is the most common type of idiopathic scoliosis.
• Adult. Curvature begins after physical maturation is completed.

Causes are known for three other types of scoliosis:

• Congenital scoliosis is due to congenital birth defects in the spine, often associated with other structural abnormalities.
• Neuromuscular scoliosis is due to loss of control of the nerves or muscles that support the spine. The most common causes of this type of scoliosis are cerebral palsy and muscular dystrophy.
• Degenerative scoliosis may be caused by degeneration of the discs that separate the vertebrae or arthritis in the joints that link them.

Genetic profile

Idiopathic scoliosis has long been observed to run in families. Twin and family studies have consistently indicated a genetic contribution to the condition. However, no consistent pattern of transmission has been observed in familial cases. As of 2000, no genes have been identified which specifically cause or predispose to the idiopathic form of scoliosis.

There are several genetic syndromes that involve a predispostion to scoliosis, and several studies have investigated whether or not the genes causing these syndromes may also be responsible for idiopathic scoliosis. Using this candidate gene approach, the genes responsible for Marfan syndrome (fibrillin), Stickler syndrome, and some forms of osteogenesis imperfecta (collagen types I and II) have not been shown to correlate with idiopathic scoliosis.

Attempts to map a gene or genes for scoliosis have not shown consistent linkage to a particular chromosome region.

Most researchers have concluded that scoliosis is a complex trait. As such, there are likely to be multiple genetic, environmental, and potentially additional factors that contribute to the etiology of the condition. Complex traits are difficult to study due to the difficulty in identifying and isolating these multiple factors.

Demographics

The incidence of scoliosis in the general population is 2-3%. Among adolecents, however, 10% have some degree of scoliosis (though fewer than 1% have curves which require treatment).

Scoliosis is found in both boys and girls, but a girl's spinal curve is much more likely to progress than a boy's. Girls require scoliosis treatment about five times as often. The reason for these differences is not known, but may relate to increased levels of estrogen and other hormones.

Signs and symptoms

Scoliosis causes a noticeable asymmetry in the torso when viewed from the front or back. The first sign of scoliosis is often seen when a child is wearing a bathing suit or underwear. A child may appear to be standing with one shoulder higher than the other, or to have a tilt in the waistline. One shoulder blade may appear more prominent than the other due to rotation. In girls, one breast may appear higher than the other, or larger if rotation pushes that side forward.

Curve progression is greatest near the adolescent growth spurt. Scoliosis that begins early on is more likely to progress significantly than scoliosis that begins later in puberty.

More than 30 states have screening programs in schools for adolescent scoliosis, usually conducted by trained school nurses or gym teachers.