While the most common form of scoliosis is adolescent idiopathic scoliosis (AIS), the second most common form of the condition is neuromuscular scoliosis (NMS); in this form, the scoliosis is a secondary complication of a serious nerve or muscular system disorder. Neuromuscular conditions involve a disconnect between the brain and the muscles/connective tissues that support the spine. Cerebral palsy, muscular dystrophy, spina bifida, and trauma to the spinal cord are common causes of NMS development.
Before we move on to defining neuromuscular scoliosis and exploring its development, symptoms, and treatment options, let’s first take a look at where it fits amongst other causes of scoliosis.
One of the reasons scoliosis is so often described as a ‘complex condition’ is because even though it’s been around for hundreds of years, there is still so much we don’t know about it.
While we most certainly know how to treat it effectively and manage its progression, we still can’t completely cure it, nor do we know what causes its development in its most common form: adolescent idiopathic scoliosis (AIS).
We know that growth is the big trigger for progression, so it’s likely that growth/ development and spinal tension are connected to its causation, but we can’t pinpoint one single known cause.
As a result, AIS is considered ‘multifactorial’, meaning its development is thought to be caused by a combination of multiple factors that can vary from person to person.
Different Forms of Scoliosis
Another reason scoliosis is described as complex is because there are so many forms of the condition. By far, its most common form is AIS, diagnosed between the ages of 10 and 18, accounting for 80 percent of known diagnosed cases in the United States.
The other 20 percent include forms with known causes such as congenital, degenerative, traumatic, and neuromuscular.
Congenital Scoliosis: congenital scoliosis develops as a result of a bone malformation that was present at birth.
The spine is made up of bony vertebrae that are stacked on top of one another like bricks.
If you picture one of the vertebrae of the spine as triangular-shaped, you can see how that could shift the spine out of alignment and cause an abnormal spinal curvature to develop.
Degenerative Scoliosis: degenerative scoliosis is the most common cause of scoliosis developing in adults.
This form of the condition develops as a result of degenerative changes affecting the spine, commonly involving disc degeneration. This form is most common in adults over the age of 40.
Traumatic Scoliosis: a less common form of the condition, traumatic scoliosis develops because the spine has experienced an extreme trauma and sustained injury, such as in a serious fall or car accident.
Also, tumors can be a driving force behind the development of scoliosis as they press against the spine and force it out of alignment.
Neuromuscular scoliosis is the second most common form of the condition. It develops because there is another disorder affecting the body, such as cerebral palsy, muscular dystrophy, or spina bifida. These disorders commonly affect the spinal cord, brain, and muscular system. Depending on the disorder and its severity, one or more of these areas can be affected.
As the brain and spinal cord work together to facilitate communication and transmit signals throughout the body, when a disorder affects these systems, the muscles and nerves surrounding the spine are impaired and unable to properly balance the spine and trunk.
There are many neuromuscular disorders capable of causing scoliosis to develop. Following are some of the most common.
Cerebral Palsy: cerebral palsy affects the body’s musculoskeletal system and the ability to move and balance itself.
Often caused by damage to the brain that occurs in utero, cerebral palsy can range in severity and is often diagnosed in children around preschool age.
This inability to balance the body and control the nerves and muscles surrounding the spine can cause it to develop an abnormal curvature.
Muscular Dystrophy: there are many different forms of muscular dystrophy (MD) that shape the occurrence of scoliosis within the disorder.
In fact, muscular dystrophies form a group of 30 genetic diseases that involve weakening and degenerating skeletal muscles that control movement and balance.
Some forms of MD are present at birth, while others can appear in infancy or adolescence.
Spina Bifida: Spina bifida is one of the most common birth defects. It develops in utero as the embryo’s neural tube (which later develops into the brain and spinal cord) does not close properly.
This causes a malformation of the spinal cord, its coverings, and/or the vertebrae of the spine.
In addition to the aforementioned neuromuscular conditions, there are many others such as Myelodysplasia, spinal muscle atrophy, Friedrich ataxia, and Myelodysplasia.
Any condition that affects the brain and/or spinal cord can produce a wide variety of symptoms as they play a role in virtually every working system within the body.
Cases of NMS can vary greatly as its progressive rate and severity is determined by the amount of muscle and nerve involvement related to the individual’s condition.
While not every person with a neuromuscular disorder is guaranteed to develop scoliosis, it is a common related complication.
Generally speaking, the more a person’s neuromuscular condition impairs their movement and balance, the more likely they are to develop scoliosis as a result; people who are wheelchair-bound (non-ambulatory) are more likely to develop scoliosis as a related complication.
The development of neuromuscular scoliosis is more common in children and adolescents than in adults, just as the development of idiopathic scoliosis is far more prevalent in children and adolescents.
Neuromuscular Scoliosis in Children
In children with neuromuscular conditions, if scoliosis doesn’t develop earlier in life, they are most likely to develop it in adolescence; this is because, as previously mentioned, growth is the number-one trigger for scoliosis development and progression.
As an adolescent enters into the puberty stage of rapid growth and development (when scoliosis is most commonly diagnosed in otherwise healthy adolescents), when paired with a pre-existing neuromuscular condition, they are at a much higher risk for developing scoliosis.
Symptoms of NMS
For people with neuromuscular conditions and are not wheelchair-bound, their symptoms of neuromuscular scoliosis present similarly to adolescent idiopathic scoliosis and can include:
For those whose neuromuscular conditions have caused impairment to the point of being wheelchair-bound (ambulatory), in addition to the above symptoms, they are also likely to experience:
The changes associated with neuromuscular scoliosis can be extreme and can greatly impact a person’s independence. Especially for those needing wheelchairs, they will need assistance with basic every-day routines such as cleaning, eating, sitting comfortably, and bathing.
In severe cases of neuromuscular scoliosis with large scoliotic curves, respiratory impairment can also become an issue as it can compress the chest, lungs, and heart.
Some of these extreme cases necessitate chest-expansion surgery to relieve the pressure and improve the patient’s ability to inhale/exhale deeply.
In cases of NMS, the treatment prognosis is not as positive as in treating average cases of idiopathic scoliosis.
This is because in treating the condition’s most common form, we can address and treat the underlying structural nature of the scoliosis; in NMS, the scoliosis has developed as a secondary complication of a more serious neuromuscular condition. In this regard, when treating the scoliosis, we are treating a symptom of another underlying condition.
Another added complication of treating NMS is that in average cases of adolescent idiopathic scoliosis, progression tends to slow or stop after skeletal maturity has been reached; in neuromuscular scoliosis, curvature progression tends to be faster and often continues after skeletal maturity has been reached and well into adulthood.
There are two main treatment approaches when dealing with NMS: nonsurgical (conservative) and surgical.
Conservative Treatment for Neuromuscular Scoliosis
With NMS, because the scoliosis has developed, in part, due to a condition affecting the brain/spinal cord, and because there is also no cure for scoliosis, no treatment approach can permanently stop a patient’s NMS from progressing.
Here at the Scoliosis Reduction Center, our treatment goal for NMS patients is to effectively stall its progression and improve their quality of life.
We do our best to address the underlying cause of the scoliosis, which in these cases, is the neuromuscular condition that contributed to its development. We do this by adjusting our treatment plan to ensure the underlying condition is the guiding force behind the chosen treatment approach.
We treat the scoliosis by integrating multiple treatment forms such as bracing and rehabilitation; however, bracing is not always successful in severe cases of NMS, and scoliosis-specific exercises have to be modified to address the characteristics of NMS.
Treating patients with NMS are among the most difficult cases because the underlying neuromuscular condition places so many additional limitations on the patient’s function, mobility, and overall health.
Patients whose neuromuscular deficits have landed them in a wheelchair are even more difficult to treat as many of these conditions are unresponsive to bracing, and there are so many additional complications to being immobile, including spinal rigidity.
As there is no curing or resolving these types of cases, treatment is aimed at slowing the curvature’s progression as much as possible, for as long as possible, in the hopes of improving the patient’s quality of life.
Surgical Treatment for Neuromuscular Scoliosis
In severe cases of NMS, surgical treatment (spinal fusion), is often recommended. As with AIS, surgery carries heavy risks and side effects and should be considered as a last resort after other noninvasive treatment methods have been attempted.
The types of cases recommended for surgery are generally those with extreme spinal curvatures of more than 50 degrees, those who are progressing rapidly, those who have continued to progress into adulthood, are experiencing a lot of pain, have difficulty sitting, or are experiencing related functional deficits such as heart and lung impairment.
For NMS patients, because of their underlying condition, surgery is even more complicated a choice than for other patients with scoliosis.
Any treatment plan for NMS cases has to first address the underlying neuromuscular condition, and not just the scoliosis.
For young people with NMS, surgical options are complicated because the spine is still growing, and that growth has to be factored into any treatment plan, especially as growth is the big trigger for curvature progression.
For adults with NMS, surgical options are also complicated because while every surgery has risks, as a person gets older, those risks only get higher and recovery tends to take longer. Also, younger people, and patients whose scoliosis has not progressed into adulthood, have more flexibility in their spines, making treatment easier.
The danger with surgical treatment for young NMS patients is that even if it successfully stabilizes the spine, it can halt growth in the fused section; while an innovative response to this is to use growing rods that can be lengthened as the patient grows, this does mean subsequent procedures done periodically, and facing the risks that go along with them repeatedly.
One of the major side effects to spinal fusion is a loss of mobility. As the vertebrae of the curvature are fused together into one solid bone, movement in that area is impaired. While this can work to stop further progression, there is still no guarantee that it will do so every time.
For patients with an average form of scoliosis and have undergone spinal fusion, some report that although they have lost mobility in the fused section of their spine, the rest of the spine still has enough flexibility; with NMS patients, the whole spine is often involved, especially in non-ambulatory cases, so a further reduction in mobility can produce significant functional deficits.
Scoliosis surgery for any form of the condition is still considered extremely invasive. There isn’t a lot of data on long-term effects, and in addition to the high price tag that comes with the surgery and recovery time spent in hospital, there are significant risks to consider:
I have treated numerous forms of scoliosis throughout my career. Some have been very typical cases, and some have been extremely challenging.
Some of the most difficult cases have been those with neuromuscular scoliosis because the prognosis can’t be as positive as with other forms of the condition. In cases of idiopathic scoliosis where there is no other underlying condition to address, the treatment plan can focus on achieving a curvature reduction by addressing the structural nature of the scoliosis, first and foremost.
In treating NMS, I have to be clear with my patients that our treatment can only go so far. We can do our best to tweak our treatment plans to address the underlying neuromuscular condition, but due to the additional impairments and mobility restrictions caused by it, the ultimate prognosis is rarely as positive as with more typical cases of AIS.
My approach is to be 100-percent honest with every prognosis for an NMS patient. I want to ensure that every patient’s treatment expectations are aligned with realistic treatment outcomes.
For those considering scoliosis surgery, I educate them on the risks involved and advise they first attempt a more conservative and less invasive approach to managing their condition.