Find information on thousands of medical conditions and prescription drugs.

Infantile spinal muscular atrophy

Spinal Muscular Atrophy (SMA) is a term applied to a number of different disorders, all having in common a genetic cause and the manifestation of weakness due to loss of the motor neurons of the spinal cord and brainstem. more...

ICF syndrome
Ichthyosis vulgaris
Imperforate anus
Inborn error of metabolism
Incontinentia pigmenti
Infant respiratory...
Infantile spinal muscular...
Infective endocarditis
Inflammatory breast cancer
Inguinal hernia
Interstitial cystitis
Iodine deficiency
Irritable bowel syndrome


Caused by mutation of the SMN gene

The most common form of SMA is caused by mutation of the SMN gene, and manifests over a wide range of severity affecting infants through adults. This spectrum has been divided arbitrarily into three groups by the level of weakness.

  • Infantile SMA - Type 1 or Werdnig-Hoffmann disease (generally 0-6 months). SMA type 1, also known as severe infantile SMA or Werdnig Hoffmann disease, is the most severe, and manifests in the first year of life with the inability to ever maintain an independent sitting position.
  • Intermediate SMA - Type 2 (generally 7-18 months). Type 2 SMA, or intermediate SMA, describes those children who are never able to stand and walk, but who are able to maintain a sitting position at least some time in their life. The onset of weakness is usually recognized some time between 6 and 18 months.
  • Juvenile SMA - Type 3 Kugelberg-Welander disease (generally >18 months). SMA type 3 describes those who are able to walk at some time. It is also known as Kugelberg Welander disease.

Other forms of SMA

Other forms of spinal muscular atrophy are caused by mutation of other genes, some known and others not yet defined. All forms of SMA have in common weakness caused by denervation, i.e. the muscle atrophies because it has lost the signal to contract due to loss of the innervating nerve. Spinal muscular atrophy only affects motor nerves. Heritable disorders that cause both weakness due to motor denervation along with sensory impairment due to sensory denervation are known by the inclusive label Charcot-Marie-Tooth or Hereditary Motor Sensory Neuropathy. The term spinal muscular atrophy thus refers to atrophy of muscles due to loss of motor neurons within the spinal cord.

  • Hereditary Bulbo-Spinal SMA Kennedy's disease (X linked, Androgen receptor)
  • Spinal Muscular Atrophy with Respiratory Distress (SMARD 1) (chromsome 11, IGHMBP2 gene)
  • Distal SMA with upper limb predominance (chromosome 7, glycyl tRNA synthase)


The course of SMA is directly related to the severity of weakness. Infants with the severe form of SMA frequently succumb to respiratory disease due to weakness of the muscles that support breathing. Children with milder forms of SMA naturally live much longer although they may need extensive medical support, especially those at the more severe end of the spectrum.

Although gene replacement strategies are being tested in animals, current treatment for SMA consists of prevention and management of the secondary effect of chronic motor unit loss. It is likely that gene replacement for SMA will require many more years of investigation before it can be applied to humans. Due to molecular biology, there is a better understanding of SMA. The disease is caused by deficiency of SMN (survival motor neuron) protein, and therefore approaches to developing treatment include searching for drugs that increase SMN levels, enhance residual SMN function, or compensate for its loss. The first effective specific treatment for SMA may be only a few years away, as of 2005.


[List your site here Free!]

From Gale Encyclopedia of Alternative Medicine, 4/6/01 by Paula Ford-Martin


Scoliosis is a side-to-side or front to back curvature of the spine.


When viewed from the rear, the spine usually appears perfectly straight. 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).

Approximately 10% of all adolescents have some degree of scoliosis, though fewer than 1% have curves which require medical attention beyond monitoring. 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.

Causes & symptoms

Four out of five cases of scoliosis are idiopathic, meaning the cause is unknown. While idiopathic scoliosis tends to run in families, no responsible genes had been identified as of 1997. 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 book-bag 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 organ defects.
  • Neuromuscular scoliosis is due to loss of control of the nerves or muscles which 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 which separate the vertebrae or arthritis in the joints that link them.

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.


Diagnosis for scoliosis is typically continued by an orthopedist. A complete medical history is taken, including questions about family history of scoliosis. The physical examination includes determination of pubertal development in adolescents, a neurological exam (which may reveal a neuromuscular cause), and measurements of trunk asymmetry. Examination of the trunk is done while the patient is standing, bending over, and lying down, and involves both visual inspection and use of a simple mechanical device called a scoliometer.

If a curve is detected, one or more x rays will usually be taken to define the curve or curves more precisely. An x ray is used to document spinal maturity, any pelvic tilt or hip asymmetry, and the location, extent, and degree of curvature. The curve is defined in terms of where it begins and ends, in which direction it bends, and by an angle measure known as the Cobb angle. The Cobb angle is found by projecting lines parallel to the vertebrae tops at the extremes of the curve; projecting perpendiculars from these lines; and measuring the angle of intersection. To properly track the progress of scoliosis, it is important to project from the same points of the spine each time.

Occasionally, magnetic resonance imaging (MRI) is used, primarily to look more closely at the condition of the spinal cord and nerve roots extending from it if neurological problems are suspected.


Although important for general health and strength, exercise has not been shown to prevent or slow the development of scoliosis. It may help to relieve pain from scoliosis by helping to maintain range of motion. Good nutrition is also important for general health, but no specific dietary regimen has been shown to control scoliosis development. In particular, dietary calcium levels do not influence scoliosis progression.

Chiropractic treatment may relieve pain, but it cannot halt scoliosis development, and should not be a substitute for conventional treatment of progressing scoliosis. Acupuncture and acupressure may also help reduce pain and discomfort, but they cannot halt scoliosis development either.

Other movement therapies (yoga, t'ai chi, qigong, and dance) improve flexibility and are useful when used with movement education therapies such as Feldenkrais, the Rosen method , the Alexander technique , and Pilates.

Allopathic treatment

Treatment decisions for scoliosis are based on the degree of curvature, the likelihood of significant progression, and the presence of pain, if any.

Curves less than 20° are not usually treated, except by regular follow-up for children who are still growing. Watchful waiting is usually all that is required in adolescents with curves of 20-30°, or adults with curves up to 40° or slightly more, as long as there is no pain.

For children or adolescents whose curves progress to 30°, and who have a year or more of growth left, bracing may be required. Bracing cannot correct curvature, but may be effective in halting or slowing progression. Bracing is rarely used in adults, except where pain is significant and surgery is not an option, as in some elderly patients.

Two general styles of braces are used for daytime wear. The Milwaukee brace consists of metal uprights attached to pads at the hips, rib cage, and neck. The underarm brace uses rigid plastic to encircle the lower rib cage, abdomen, and hips. Both these brace types hold the spine in a vertical position. Because it can be worn out of sight beneath clothing, the underarm brace is better tolerated and often leads to better compliance. A third style, the Charleston bending brace, is used at night to bend the spine in the opposite direction. Braces are often prescribed to be worn for 22 to 23 hours per day, though some clinicians allow or encourage removal of the brace for exercise.

Bracing may be appropriate for scoliosis due to some types of neuromuscular disease, including spinal muscular atrophy, before growth is finished. Duchenne muscular dystrophy is not treated by bracing, since surgery is likely to be required, and since later surgery is complicated by loss of respiratory capacity.

Surgery for idiopathic scoliosis is usually recommended if:

  • The curve has progressed despite bracing.
  • The curve is greater than 40-50° before growth has stopped in an adolescent.
  • The curve is greater than 50° and continues to increase in an adult.
  • There is significant pain.

Orthopedic surgery for neuromuscular scoliosis is often done earlier. The goals of surgery are to correct the deformity as much as possible, to prevent further deformity, and to eliminate pain as much as possible. Surgery can usually correct 40-50% of the curve, and sometimes as much as 80%. Surgery cannot always completely remove pain.

The surgical procedure for scoliosis is called spinal fusion, because the goal is to straighten the spine as much as possible, and then to fuse the vertebrae together to prevent further curvature. To achieve fusion, the involved vertebra are first exposed, and then scraped to promote regrowth. Bone chips are usually used to splint together the vertebrae to increase the likelihood of fusion. To maintain the proper spinal posture before fusion occurs, metal rods are inserted alongside the spine, and are attached to the vertebrae by hooks, screws, or wires. Fusion of the spine makes it rigid and resistant to further curvature. The metal rods are no longer needed once fusion is complete, but are rarely removed unless their presence leads to complications.

Spinal fusion leaves the involved portion of the spine permanently stiff and inflexible. While this leads to some loss of normal motion, most functional activities are not strongly affected, unless the very lowest portion of the spine (the lumbar region) is fused. Normal mobility, exercise, and even contact sports are usually all possible after spinal fusion. Full recovery takes approximately six months.

Expected results

The prognosis for a person with scoliosis depends on many factors, including the age at which scoliosis begins and the treatment received. More importantly, mostly unknown individual factors affect the likelihood of progression and the severity of the curve. Most cases of mild adolescent idiopathic scoliosis need no treatment and do not progress. Untreated severe scoliosis often leads to spondylosis, and may impair breathing.


There is no known way to prevent the development of scoliosis. Progression of scoliosis may be prevented through bracing or surgery.

Key Terms

Cobb angle
A measure of the curvature of scoliosis, determined by measurements made on x rays.
A tool for measuring trunk asymmetry; it includes a bubble level and angle measure.
Arthritis of the spine.

Further Reading

For Your Information


  • Neuwirth, Michael, and Kevin Osborn. The Scoliosis Handbook. New York: Henry Holt & Co., 1996.


  • National Scoliosis Foundation. 72 Mount Auburn St., Watertown, MA 02172. (617) 926-0397.
  • The Scoliosis Association. PO Box 811705, Boca Raton, FL 33481-0669. (407) 368-8518.
  • Scoliosis Research Society. 6300 N. River Rd., Suite 727, Rosemont, IL 60018-4226. (708) 698-1627.

Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.

Return to Infantile spinal muscular atrophy
Home Contact Resources Exchange Links ebay