Three common types of scoliosis are found in children and adolescents: Congenital scoliosis is present at birth. Idiopathic scoliosis (the most common form) has no identifiable cause. The third, neuromuscular scoliosis, is a direct consequence of another underlying muscular or neurological condition.
This form of scoliosis (a sideways curvature of the spine) results from a lack of muscular control caused by a neurological or degenerative muscular condition, such as cerebral palsy or muscular dystrophy.
Neuromuscular scoliosis represents only a small segment of the total number of scoliosis cases diagnosed each year. However, the underlying disorders associated with this form of scoliosis often result in some of the more complex and extensive curves seen by pediatric orthopedic surgeons and present a unique set of treatment challenges.
Neuromuscular scoliosis is caused by muscle weakness, paralysis or neurological issues related to an underlying condition, including:
As with idiopathic scoliosis, neuromuscular scoliosis is diagnosed when there is the presence of a curve in the spine that measures greater than 10 degrees. In contrast to patients with idiopathic scoliosis, in which the curve pattern is restricted to smaller segments of the spine [see Figure 1], children with neuromuscular scoliosis develop long, sweeping S- and/or C-shaped curves that involve the entire spine, including the sacrum (the vertebrae that form part of the pelvis) [see Figure 2]. The curves seen in children with neuromuscular scoliosis are also much more likely to progress than those seen in idiopathic scoliosis.
Roger F. Widmann, MD, Chief of Pediatric Orthopedic Surgery at Hospital for Special Surgery (HSS) explains, Children with neuromuscular scoliosis continue to be at risk for progression of their deformities into adulthood." Children with idiopathic scoliosis with curves that are less than 45 degrees generally do not progress once they reach their adult height.
As with other forms of scoliosis, X-rays of the spine are key tools in the diagnosis of neuromuscular scoliosis. Often, these patients are unable to stand and have radiographic images while seated so that the pediatric orthopedist may assess curve progression.
Wearing a special brace, and other nonsurgical treatments may help some patients with balance problems, but only spinal fusion surgery with stop the progression of the curvature in the spine. (Find a doctor at HSS who treats scoliosis.)
For some patients, braces may be recommended to help achieve sitting balance, thereby freeing the arms for other activities. Custom seating systems can also help accomplish this goal. John Blanco, MD, Associate Attending Orthopedic Surgeon at Hospital for Special Surgery (HSS) notes, "It is important to understand that brace treatment will not slow the progression of the curve as it can in some other forms of scoliosis."
Surgical treatment of neuromuscular scoliosis is performed to stop the progression and correct the curve. As a patient’s pelvis is brought back to a more level position, it provides a stable platform for sitting.
Computer navigation assistance enables the pediatric orthopedic surgeon to place rods and bone graft along the vertebral column to straighten, fuse, and maintain the spinal curve correction. "For these patients, we almost always use allografts (freeze-dried, irradiated donor bone) with excellent results," says Dr. Widmann. Patients with neuromuscular scoliosis often have poor bone density, therefore, a variety of techniques are used to fix the rod in place, including hooks, pedicle screws, and wires.
Timing of the surgery varies and may be dictated by the underlying disorder. "In the presence of muscular dystrophy, for example, we consider surgical intervention once the child is wheelchair-bound, since curve progression seems to be related to loss of ambulatory ability," Dr. Blanco explains.
A curve less than 40 degrees may also require surgery in patients with muscular dystrophy since the curve is expected to progress in a predictable manner. In the presence of cerebral palsy, surgery may not be recommended until there is documented progression of the curve to 45 or 50 degrees and/or the child develops difficulty sitting or maintaining his/her balance.
Children who are surgical candidates must be screened carefully. At HSS, our multidisciplinary team of health care professionals ensures that children have optimal breathing function. Safeguards are in place to prevent pneumonia and any potential difficulties with swallowing − risks that may be associated with the underlying disorder.
Patients with neuromuscular scoliosis have an increased risk of blood loss during surgery. Multiple precautions are taken to address this, including the use of cell savers (machines that filter the blood so that it may be given back to the patient), designated donor blood, or autologous blood (blood that the patient donates in advance of the surgery), if needed.
Following surgery (usually one to two days), many children with neuromuscular scoliosis remain in the pediatric intensive care for acute respiratory management. In most cases, one surgery is performed for correction of the curve, although, Drs. Blanco and Widmann note, some patients with very large curves may require a second procedure for additional releases and fusions.