Developmental Disorders

Sacral Agenesis
Scheuermann's Kyphosis
Scoliosis

Developmental disorders of the lower back are caused by abnormalities in the formation and growth of the skeleton. Scoliosis is one example of a developmental disorder that can be caused by several different congenital abnormalities of the spinal column, and that also occurs during periods of accelerated growth, like puberty. Many of these conditions need to be followed closely during development so that they can be treated accordingly. Although the treatment for many of these conditions is conservative, surgery may be required to keep some disorders from worsening, and in order to prevent long-term disability and or deformity. The following is an explanation of the causes and treatment of some of the more common developmental disorders of the spine.

Sacral Agenesis
Sacral Agenesis is a term that applies to a wide range of developmental disorders of the lower portions of the spinal column and pelvis. This term indicates that some portion of the lumbar spine, sacrum, or pelvis is incompletely or incorrectly formed at the time of birth. These disorders are usually quite serious, as patients often lack any useful motor functioning below the last normally formed level of the spine.

Fortunately, these are very rare abnormalities, affecting approximately 1 in 25,000 children. Girls and boys are affected equally, and the causes of these disorders are not completely understood. The majority of cases involve a complete or partial absence of the sacrum, and often a portion of the lumbar spine as well.

The diagnosis and treatment of sacral agenesis is often initiated soon after birth, since the majority of patients with this disorder are recognized as having something wrong with their lower lumbar spine or pelvis during their first physical examination. When an infant is found to have evidence of sacral agenesis, the diagnosis is usually confirmed with a radiographic examination of the spine and pelvis. At this point, several other consultants, including pediatric orthopaedic surgeons, neurosurgeons, neurologists, and developmental experts, are often asked to provide opinions regarding the prognosis and treatment of the condition.

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Scheuermann's Kyphosis
Scheuermann's disease is a developmental disorder that causes patients to have a stooped forward or bent-over posture as a result of excessive kyphosis of the thoracic spine. This condition affects between 0.5% and 8% of the general population, and is more common in boys than in girls. Scheuermann's disease is caused by more than bad posture, and there are several clinical and radiographic findings that are typical in this disease that help to differentiate Scheuermann's kyphosis from postural kyphosis.

The above illustration shows a patient with postural kyphosis. When he bends forward, his spine forms a smooth curve. Patients with postural kyphosis can generally correct the kyphosis by making a conscious effort to do so.

This illustration shows a patient with structural kyphosis. When he bends forward, the angular gibbus can be seen. The patient cannot consciously correct his posture.

Doctors believe that irregularities in the endplates of the vertebral bodies can prevent the anterior part of the vertebral body from growing normally, which results in vertebral body wedging and produces a kyphotic curve that can be quite rigid. The apex of the curve is usually located in the upper thoracic spine, and X-rays of the spine often demonstrate the characteristic vertebral body wedging, endplate abnormalities, and Schmorl's nodes that are present in this disease. In contrast, a patient who is stooped forward and has excessive thoracic kyphosis as a result of bad posture will have none of these radiographic findings.

Patient position for hyperextension X-ray film. A bolster is placed under the apex of the curve to allow it to bend out as much as possible, and a lateral X-ray is taken.

Diagnosis
The diagnosis of Scheuermann's disease is made on the basis of a physical examination and radiographs of the spine. A physical examination is used to determine where the apex of the curve is located, where the patient is experiencing back pain, how flexible the curve is, and whether or not there are any other related findings. Currently, the most commonly accepted criteria for the radiographic diagnosis of Scheuermann's disease is the presence of at least 5 degrees of vertebral body wedging over three adjacent levels. Radiographs are also used to determine more precisely the relative percent correction that is possible by attempting to reverse the kyphotic curve with a bolster or a pillow placed at the apex of the curve while the patient is lying down.

Treatment
The treatment of Scheuermann's disease depends upon several factors, including the age of the patient, the severity of the curve, the presence or absence of back pain, and whether or not the lungs are developing and functioning normally.

If a patient is young, has a mild curve, no back pain, and normal pulmonary function, then continued observation by a doctor is usually prescribed, with repeat clinical examinations and radiographs at regular intervals (often every year). Many doctors will advise patients with kyphosis to participate in activities that strengthen the muscles that support the spine, stretch the hamstrings, and improve cardiovascular fitness. This type of therapy is considered an important part of ensuring the curve stays as flexible as possible, and that the muscles of the back are as strong as possible in an effort to prevent further progression.

Other forms of treatment, including bracing and surgery, are considered when there is a rapid increase in the size of the curve; worsening of the vertebral body wedging, back pain that will not improve with conservative measures, and difficulties with pulmonary function that are related to the kyphotic deformity. The decision about when and how to brace the spine of a patient with Scheuermann's disease, or to perform surgery, is made on an individual basis. Your doctor will be able to explain all of the options for the treatment of this disease if conservative measures are no longer working.

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Scoliosis
Scoliosis is not a disease - it is a descriptive term. All spines have curves. Some curvature in the neck, upper trunk and lower trunk is normal. Humans need these spinal curves to help the upper body maintain proper balance and alignment over the pelvis. However, when there are abnormal side-to-side (lateral) curves in the spinal column. This is referred to as scoliosis.

Congenital Scoliosis
Congenital scoliosis is defined as a curvature of the spine that is the result of malformations of the vertebral elements. The fact that the spine and spinal column ever form correctly is amazing given the complexity of the process from the embryological standpoint. Most of this development happens during the 3rd-6th week in utero (after conception). In spite of the opportunities for error, congenital malformations are relatively rare.

Doctors categorize congenital scoliosis into three groups: failures of formation, failures of segmentation, and combinations of these defects. The most common failure of formation is called a hemivertebra. Hemivertebra produce a growth imbalance in the spine and, therefore, result in the spine growing crooked. Failures of segmentation include block vertebra and unilateral bars, which produce a growth tether of the spine. Finally, when these occur in combination, such as a hemivertebra on one side and a bar on the other, the scoliosis can progress in very rapid manner.

Idiopathic
Idiopathic scoliosis is the most common form of scoliosis in North America, affecting up to 2% of the population. It's usually caused by an adolescent growth spurt. In order for a physician to diagnose and treat idiopathic scoliosis, he or she must first rule out all other causes of scoliosis. Most idiopathic curves present in adolescence are painless, gradual, have a typical curve pattern (for example, a right thoracic curve), and the neurological exam is normal. Idiopathic scoliosis is much more common in females.

Kyphosis
Kyphosis or hunching over is normal in the thoracic spine. When the doctor measures it on an x-ray, the normal range for kyphosis is quite broad, between 20-50 degrees. However, when kyphosis is greater than 50 degrees, it becomes easy to see and is considered abnormal.

There are two common forms of kyphosis encountered in the teenage population: Scheuermann's kyphosis and postural roundback. Scheuermann's kyphosis is most common in teenage boys. It is characterized by a short, sharp kyphosis in the middle part of the upper spine, and may be associated with aching back pain. The kyphosis tends to be rigid on clinical examination. There are x-ray criteria that establish a diagnosis of Scheuermann's kyphosis that can be seen on the x-ray. A mild degree of scoliosis is common in adolescents with Scheuermann's kyphosis.

Postural roundback is noted by a smooth, flexible kyphosis that is not typically associated with pain. The curve is easily corrected by asking the child to stand up straight. Radiographically, the criteria for the diagnosis of postural roundback are kyphosis greater than 50 degrees, but without the other x-ray findings seen with Scheuermann's kyphosis. These curves tend to be mild in severity and extend over a longer number of vertebral segments when compared to Scheuermann's kyphosis.

Neuromuscular Scoliosis
The term "neuromuscular scoliosis" is used to describe curvature of the spine in children with any disorder of the neurological system. Common categories include cerebral palsy, spina bifida, muscular dystrophies, spinal cord injuries and so forth. Most of these children have as a unifying feature weakness of the trunk. As they grow and their trunk gets weaker, there is a progressive, collapsing deformity of the spine producing a long, c-type curve. These curves tend to be progressive, with the rate of progression becoming worse during rapid growth. For children confined to a wheel chair, progressive curves may affect the child's ability to be seated comfortably, thereby affecting their quality of life and function.

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