Neuromuscular Scoliosis

Neuromuscular scoliosis is a sideways curve of the spine that develops in children who have conditions affecting their nerves and muscles. Unlike other forms of spinal curvature, this type often appears early in childhood and tends to worsen over time, affecting how children sit, stand, and move.

Table of contents

• What is neuromuscular scoliosis?
• What causes this condition?
• How common is it?
• Signs and symptoms
• How doctors diagnose the condition
• Treatment options
• Understanding progression

What is neuromuscular scoliosis?

Neuromuscular scoliosis is a type of spinal curve that happens when the spine bends sideways in a C or S shape. Instead of standing straight down the middle of the back, the small bones of the spine, called vertebrae, tilt and rotate slightly off-center^[1].

This condition is different from the most common type of scoliosis because it develops as a result of other medical problems that affect the nervous system or muscles. When children have conditions that weaken their muscles or affect how they control them, the support around their spine weakens. Without proper muscle support, the spine begins to curve as the child grows^[2].

The curves seen in neuromuscular scoliosis are typically long and involve the entire spine, including the lower part that connects to the pelvis. This is different from other types of scoliosis where curves usually affect only smaller sections of the spine^[3].

What causes this condition?

An underlying medical condition that affects the child’s nervous system, muscles, or both causes neuromuscular scoliosis. Children with these conditions may not be able to move or control certain muscles in their body properly. This muscle weakness or lack of control can weaken the area around the spine, causing a curve to form^[1].

The most common conditions associated with neuromuscular scoliosis include:

• Cerebral palsy – a group of disorders that affect movement and muscle tone
• Muscular dystrophy, particularly Duchenne muscular dystrophy – a genetic condition that causes progressive muscle weakness
• Spina bifida – a birth defect that affects the spine
• Spinal muscular atrophy – a condition that results in the loss of nerve cells controlling muscles
• Paralysis from spinal cord injury
• Polio

The condition is especially common in children who use wheelchairs. In some neuromuscular conditions, a child may be able to walk when younger but may need to use a wheelchair when they reach adolescence. Because adolescence often coincides with major growth spurts, this is a particularly vulnerable time for spinal curve development^[3].

How common is it?

Neuromuscular scoliosis is the second most common form of scoliosis after idiopathic scoliosis^[2]. How often it occurs depends on the underlying condition causing it.

The likelihood and severity of the curves tends to increase with the degree of neuromuscular involvement. An estimated 90% of people diagnosed with Duchenne muscular dystrophy and 80% of people diagnosed with spinal muscular atrophy develop scoliosis. Among people diagnosed with cerebral palsy, scoliosis affects between 20% and 70%^[1].

Other conditions show varying rates. About 80% of people with cerebral palsy affecting all four limbs develop scoliosis, compared to 25% of those with only two limbs involved. Nearly all children with high-level spinal injuries that occur before age 10 develop scoliosis^[4].

Signs and symptoms

Signs of neuromuscular scoliosis often appear early in a child’s life, sometimes before adolescence. Parents, doctors, or caregivers will most likely notice the spinal curve through a change in the child’s overall body position or when they start having trouble sitting in a chair^[2].

The visible signs of neuromuscular scoliosis include:

• Uneven shoulders – one shoulder appears higher than the other
• Ribs that stick out on one side
• Tilted hips and waist
• Uneven shoulder blades
• Head positioned off-center from the rest of the body

Among children who use a wheelchair, you may notice:

• Slouching or leaning to one side
• A slanted pelvis
• Difficulty sitting upright without using hands or arms for support
• Pressure sores developing on one side

Sitting up straight becomes a constant challenge for these children. It’s not that they are ignoring reminders to sit properly – the task is genuinely difficult or even uncomfortable for them^[1].

In addition to the sideways spine curve, children may also have other types of curves. Kyphosis is a front-to-back curve that creates a hunched appearance, while lordosis (also called swayback) curves in the opposite direction^[1].

As the curve progresses, children may experience symptoms including:

• Back pain
• Discomfort when sitting
• Muscle weakness
• Numbness in the arms and legs
• Limited range of motion
• Difficulty with balance and coordination of the head, trunk, and neck

Children with neuromuscular scoliosis usually do not experience pain from the condition itself in the early stages. However, most children have poor balance and poor coordination of their trunk, neck, and head^[4].

As the curve becomes more severe, it can lead to additional problems with seating and hygiene. In very severe cases, the curve may reduce space in the chest and cause breathing problems^[4].

How doctors diagnose the condition

Doctors use medical and family histories, physical examinations, and diagnostic tests to determine the nature, extent, and impact of the scoliosis. They will also evaluate the child’s underlying neuromuscular disease^[2].

The evaluation includes assessment of:

• Nutritional status
• Lung and heart function
• Functional level
• Joints and extremities (checking for contractures, which are permanent tightening of muscles or joints)
• Balance and ability to walk

X-ray images taken from the front and side are the main tool for confirming neuromuscular scoliosis and measuring the severity of the curve. Often, children who cannot stand have these images taken in a seated position^[2].

Doctors can often predict the likely progression of a child’s scoliosis by assessing the severity of the existing curve and comparing that to the child’s stage of growth. Mild or moderate curves can become more pronounced during growth spurts. Children at a later stage of growth may be less prone to further spinal deformity^[2].

Additional tests may be ordered to evaluate the underlying condition associated with the scoliosis:

• Magnetic resonance imaging (MRI) – uses magnets and radio waves to create detailed images of soft tissues
• Computed tomography (CT) scan – creates three-dimensional images using X-rays
• Blood tests
• Ultrasound
• Bone scans and bone density scans
• Muscle biopsy – removal of a small sample of muscle tissue for examination
• Pulmonary function tests – measure how well the lungs are working
• Electromyogram (EMG) and nerve conduction studies – test muscle and nerve function

Treatment options

Treatment for neuromuscular scoliosis involves a team of doctors and health professionals from different medical specialties working together. Because children with this condition can have a range of medical issues in addition to the spinal curve, this multidisciplinary approach is essential^[3].

Non-surgical treatments

Non-surgical treatments should be prescribed and managed by a multidisciplinary team to ensure that all clinical areas receive proper treatment, including pulmonary, neurologic, orthopedic, nutritional, and gastroenterologic care^[4].

Non-surgical options include:

Bracing: For some children, braces may be recommended to help achieve sitting balance and provide support. However, unlike in other types of scoliosis where bracing can help prevent progression of curves, bracing for neuromuscular scoliosis is mainly used for comfort or as a functional aid. Most curves from neuromuscular scoliosis do not benefit from bracing in terms of stopping curve progression^[4].

Wheelchair modifications: For children who do not walk, wheelchair modifications can improve function and seating comfort. Custom seating systems can help accomplish sitting balance, freeing the arms for other activities^[4].

Physical therapy: Exercise programs can help maintain flexibility, muscle strength, and functional abilities^[2].

Environmental adaptation: Changes to the home and school environment can help children adapt to everyday settings and improve their mobility^[2].

Surgical treatment

In many cases of neuromuscular scoliosis, surgery is needed to correct the curvature and stabilize the spine. Surgery should be considered when there is significant impact on the patient’s quality of life, which is usually due to poor sitting balance, back pain, breathing complications, or problems with self-care and feeding^[5].

The surgical goals are to:

• Prevent curve progression
• Improve sitting balance and tolerance (in children who do not walk)
• Reduce the need for repositioning
• Reduce pain

The most common surgical procedure is spinal fusion, which involves permanently joining two or more vertebrae to straighten the spine and prevent further curvature. Modern modular posterior instrumentation systems using metal rods, screws, and bone grafts allow effective deformity correction^[5].

The type of spinal stabilization depends on the age of the patient, whether they can walk, and their underlying condition. Surgery can achieve good curve correction and results in high levels of satisfaction from patients and their caregivers^[5].

However, patients with neuromuscular spinal deformity are among the most challenging due to the number and complexity of medical comorbidities that increase the risk for severe complications during or after surgery. Meticulous preoperative assessment is required, and involvement of the family at all stages of decision-making is essential to balance the risks and anticipated benefits^[5].

Understanding progression

Neuromuscular scoliosis is progressive, meaning that the curve in the spine gets worse over time. Since the curve is often present in early childhood, it may quickly worsen when the child has a growth spurt. Spine curves may continue to progress even into adulthood^[1].

This is different from other types of scoliosis. Children with curves less than 45 degrees from the most common type of scoliosis (idiopathic scoliosis) generally do not have continued curvature progression once they reach their adult height. In contrast, children with neuromuscular scoliosis continue to be at risk for progression of their deformities throughout their lives^[3].

Curve progression and trunk imbalances are more severe in patients who are not able to walk. The development of spinal deformity can affect the ability to function and impact quality of life, as well as compromise provision of nursing care^[4].

In some cases, untreated large spinal deformities may be associated with pain and breathing or heart problems over time. Progressive deformity may limit mobility and seating status^[5].

Recent changes in medical management of some underlying diseases appear to alter the natural history of certain neuromuscular conditions. In the case of patients with Duchenne muscular dystrophy, advances in treatment have significantly diminished the incidence of spinal deformity^[5].