Neuromuscular Scoliosis

Neuromuscular scoliosis is a condition that affects children with neuromuscular disorders and is characterized by one or more abnormal spinal curvatures. This curvature causes the spinal column to bend to the left or right, forming an S or C shape.

Because there is such a wide variety of diseases that may cause neuromuscular scoliosis, the clinical presentation and severity of this condition are highly variable. However, most children with this disease have poor balance and poor coordination of their trunk, neck, and head.

There is also a high frequency of concurrent kyphosis, which is an abnormal forward-bending curve of the spine. The condition is generally classified into two categories based on the type of disease the child suffers from and the cause of the abnormal curve:

• Neuropathic scoliosis involves diseases that are primarily afflictions of the nervous system, such as cerebral palsy or spinal cord trauma.
• Myopathic scoliosis involves muscular disorders, like muscular dystrophy or arthrogryposis.

Unlike other types of scoliosis, treatment of neuromuscular scoliosis is highly unpredictable, largely because the abnormal spine curves are unpredictable.

Basic Facts About Neuromuscular Scoliosis

• Scoliosis is technically defined by the presence of a curvature in the spine of >10 degrees deviation from straight upright.
• The earlier the curve develops in neuromuscular scoliosis, the more likely it is to progress to a more severe curve. Likewise, the more severe a curve is when it is first detected, the faster it will progress, on average.
• Unlike most cases of idiopathic scoliosis, in which the curves occur in a limited region of the spinal column and are relatively short, so to speak, neuromuscular scoliosis is associated with long curves that often extend to the bottom of the spinal column.
• Neuromuscular curves are often associated with a condition known as pelvic obliquity, in which the child’s pelvis is unevenly tilted, with one side positioned higher than the other side.
• Children with neuromuscular scoliosis usually do not experience any pain from the condition.

What Causes Neuromuscular Scoliosis?

Unlike idiopathic scoliosis, which is the most common type of scoliosis and does not have an established cause, neuromuscular scoliosis is generally quite well understood with regard to causation. In all cases, the underlying neuromuscular condition is considered the trigger for scoliosis development.

In neuropathic scoliosis, defects or abnormalities in the central nervous system (i.e., the brain and spinal cord) lead to altered proprioception, or diminished control of the paraspinal muscles. As a result, abnormal forces will be transmitted upon the vertebral units of the spine, either because the muscles show increased motion (termed spasticity, as seen in cerebral palsy), decreased motion (also referred to as flaccidity, as occurs in Friederich’s ataxia), or motion that is out-of-sequence (called dyskinesia, also seen in cerebral palsy).

Myopathic scoliosis is caused in a similar fashion, but through the direct effects of various diseases upon the muscles themselves, despite a normal nervous system. In many of these conditions, the most common of which is muscular dystrophy, the muscles undergo atrophy, or gradual wasting of the muscle tissue. Because muscles atrophy at different rates, scoliosis can result when the paraspinal muscles or other trunk muscles waste more quickly or significantly on one side of the body than the other, even in a very small section of the spine. This disrupts the stability of the spinal column and leads to the curvatures seen in scoliosis.  

Other muscle diseases, such as arthropryposis, cause contractures, meaning the muscles are excessively flexed and remain fixed in a contracted position due to fibrosis. This can occur in trunk and paraspinal muscles, obviously transmitting abnormal lateral forces on the normally symmetrical spine.

Because the neuromuscular changes in many of these diseases arise in childhood, the spine is still growing when it experiences these abnormal forces, which generally worsen curves during growth spurts.

How Is It Diagnosed?

Neuromuscular scoliosis is usually first detected during a standard physical examination by a pediatrician, noticed by a child’s parents, or during a full workup for the child’s neuromuscular condition. The physical will be followed by a series of X-rays, which allow for a more precise measurement of the possible presence and severity of one or more curves. As previously mentioned, this requires at least 10 degrees of curvature to be diagnosed with scoliosis.

A full neurologic exam of the back and extremities will be performed to ensure that no other spinal conditions are present and that the spinal cord is not affected by the abnormal curvature, if it is not already affected by the underlying condition. Occasionally, a spinal MRI, another radiological imaging technique, will be done in addition to the spinal x-rays.

How Is It Treated?

Decisions regarding the appropriate treatment for neuromuscular scoliosis depend on the severity of the spinal curvature at the time of diagnosis, the patient's age, and the symptoms of the underlying neurological or muscular disorder. The curves in almost all of the predisposing diseases have a high rate of progression, and almost all children will therefore require surgery at some point. However, in some instances, bracing, though not a definitive treatment, will be used to slow the progression of the curve until a later time when surgery can be safely performed.

Bracing treatment usually involves wearing an external brace when the child is upright, but not when they are sleeping or lying flat. Though there are a number of braces available for the treatment of scoliosis, the semi-rigid molded TLSO brace (thoraco-lumbo-sacral orthosis) is the preferred design because it is effective when worn periodically and does not significantly constrict breathing, as might occur with some other designs. This is typically the brace used for patients in wheelchairs. In ambulatory patients, the more traditional TLSO may be used.  

In general, the brace should improve a patient’s ability to sit or stand, as well as to perform certain functions that would otherwise be impossible. The brace should be worn for only a few years, or until the decision to pursue surgical treatment has been made. Wheelchair seating adaptations also exist that can act similarly to bracing, and may be appropriate for some patients.

Surgeries for neuromuscular scoliosis are relatively complex because of the other biological effects that are common in underlying neuromuscular diseases, such as respiratory difficulties, weak bones, and poor nutrition.  

Operations generally consist of:

• Instrumentation, in which metal rods are attached to the spine to maintain curve correction.
• Spinal fusion, in which two or more of the vertebrae are fused together with bone bridges made of bone grafts.
• Fusion between the spine and the pelvis may also be necessary in cases of pelvic obliquity, particularly in children with muscular dystrophy.  

Because of the stability and effectiveness of the devices used in these spine operations today, patients usually do not require bracing after surgery, and hospital stays are typically limited to 3-5 days.  

The type of surgery depends on the severity of the curve and the patient's age. If the patient is younger, a growing rod type of technique may be used.  If the patient is older, then a spinal fusion and instrumentation is most likely what will be recommended.

Please find more information below on each of these methods:

• Growing Rods – VEPTR - MAGEC
• Spinal Fusion and Instrumentation

Coping With Neuromuscular Scoliosis

The development of scoliosis on top of an existing neuromuscular condition can be a difficult challenge for children and their parents alike. Surgery at a young age, if necessary, can seem somewhat daunting as well. However, because of the effects that scoliosis can have if left untreated, it is imperative that parents promptly seek out diagnosis and management of the condition by an orthopaedic surgeon. Surgical treatment of neuromuscular scoliosis is generally quite successful in reducing curves and improving patients' quality of life.

Our Pediatric Orthopedic group here at the Children’s Hospital of New York is dedicated not only to the outcome of the treatment steps along the way, but also to the end goal of making your child’s present and future life as comfortable, happy, and fulfilling as possible.