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.
Understanding Scoliosis Causation
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.
In addition to different severity levels, there are also different condition types with their own unique characteristics and treatment needs.
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.
Now, in cases of typical idiopathic scoliosis, the scoliotic curve bends to the right (dextroscoliosis), away from the heart, so when I see a scoliotic curve bending to the left, towards the heart (levoscoliosis), this is a red flag for me that there is an underlying pathology.
When I see a levoscoliosis, I know that this is an atypical form such as congenital, neuromuscular, or traumatic scoliosis, and that the treatment process will be more complex than in typical cases.
Congenital Scoliosis
Congenital scoliosis develops as a result of a bone malformation that was present at birth and is a rare form, affecting approximately 1 in 10,000.
A healthy spine is made up of bony vertebrae that are rectangular in shape and are stacked on top of one another like bricks, in a straight and neutral alignment.
If you picture one of the vertebrae as more triangular-shaped, you can see how that could shift the spine out of alignment and cause an abnormal spinal curvature to develop.
Congenital scoliosis can also develop when vertebral bodies fail to form into distinct and separate structures, instead becoming fused together into one solid bone (boney bar); when this happens, the spine doesn’t continue growing on one side after the infant is born, and the spinal curve increases as the child grows.
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 and is more common in women due to bone density and hormone changes related to menopause.
While there is a natural amount of spinal degeneration to be expected with age, the cumulative effect of certain lifestyle choices can increase or decrease the rates of spinal deterioration: carrying excess weight, chronic poor posture, repeatedly lifting heavy objects incorrectly, and leading a sedentary lifestyle.
While scoliosis is commonly regarded as a child and adolescent condition, the actual rate of scoliosis in adolescents is estimated at around 2 to 4 per cent, while one study looking at the incidence of scoliosis in healthy adults over the age of 60 detected a rate of 68 per cent.
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, and cancer treatment such as chemotherapy and radiation can also weaken the bones of the spine, making it vulnerable to develop a variety of spinal conditions.
Neuromuscular Scoliosis
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.
What Causes Neuromuscular Scoliosis?
Neuromuscular scoliosis is caused by the presence of a larger neuromuscular condition and/or a degenerative muscular condition such as cerebral palsy, spina bifida, and muscular dystrophy.
While not everyone with a neuromuscular condition will develop scoliosis, it is a common complication, and it’s said that the more nerve involvement there is, the more severe the condition is likely to be, and the more noticeable its effects are going to be.
Neuromuscular scoliosis is diagnosed in a small percentage of patients, compared to typical idiopathic scoliosis cases that make up 80 percent of known cases; neuromuscular scoliosis falls within the remaining 20 percent of scoliosis cases associated with known causes, along with degenerative scoliosis and congenital scoliosis.
In cases of neuromuscular scoliosis, the scoliosis has developed as a secondary complication of a larger medical issue, and neuromuscular conditions involve a disconnect between the brain and the connective tissues/muscles that support the spine, and this disrupts the spine’s ability to maintain its natural curve and alignment.
Neuromuscular scoliosis also disrupts the ability of the spine’s surrounding muscles to optimally support and stabilize the spine, which is why physical therapy and scoliosis-specific exercises are such a key part of treatment by working towards helping patients increase their core strength and stability.
How is Neuromuscular Scoliosis Diagnosed?
Neuromuscular scoliosis is diagnosed the same as other types of scoliosis: through a combined physical examination and X-ray results.
A physical examination commonly includes taking the patient’s family/medical history, with a focus on the prevalence of spinal/neuromuscular conditions in the family.
I generally perform an Adam’s forward bend test as part of a scoliosis screening exam, and this involves patients standing in front of me and bending forward at the hips as if they are trying to touch their toes; in this position, the spine is highly visible, as are any trunk asymmetries caused by the condition.
If an Adam’s test shows indicators of scoliosis, this warrants further testing, and a scoliosis X-ray is ordered to truly see what’s happening in and around the spine, and to confirm a patient’s Cobb angle measurement to reach a diagnosis of scoliosis and classify the condition based on severity; mild, moderate, severe, or very severe.
The more severe scoliosis is, the more likely it is to continue progressing, the more likely it is to have a fast rate of progression and cause complications, and the more in need of treatment the patient is.
What are the Symptoms of Neuromuscular Scoliosis?
My neuromuscular scoliosis patients are among the most challenging to treat, and this is because the scoliosis is secondary to a larger medical condition, and this complicates the treatment process as the underlying neuromuscular condition has to be the focus of treatment
In addition, because neuromuscular scoliosis cases tend to be severe, I can’t offer these patients the same types of prognoses as I can in cases of typical idiopathic scoliosis.
The majority of scoliosis cases, approximately 80 percent have no known cause, so idiopathic scoliosis is considered typical, and in typical cases of scoliosis, the unnatural spinal curve bends to the right (dextroscoliosis), away from the heart, but in atypical cases with known causes, it can bend to the left, towards the heart.
When I see a left-bending curve (levoscoliosis), this is a red flag that there is an underlying pathology at play, and I know it’s likely that a patient’s symptoms are going to be severe, as is the condition in general.
Neuromuscular scoliotic curves tend to be more rigid, and because there is such an overt disconnect in brain-body communication, the condition often has a faster rate of progression.
Many cases of neuromuscular scoliosis can involve patients becoming wheelchair dependent because they are no longer able to walk on their own.
In addition to postural changes such as uneven shoulders, hips, and the development of a rib arch, additional symptoms of neuromuscular scoliosis can include:
- Pelvic obliquity (excessively-tilted pelvis)
- Pressure sores
- Difficulty sitting
- Slouching posture
- Prominent lean to one side
Some cases of neuromuscular scoliosis will require surgery because of their atypical, complex, severe, and progressive nature.
Scoliosis Neurological Symptoms
When it comes to the symptoms of scoliosis, no two cases are the same as symptoms are shaped by a number of patient/condition factors, especially when it comes to neurological symptoms.
All types of scoliosis can carry neurological symptoms because the spinal cord within consists of 31 pairs of spinal nerves, and if scoliosis is causing one or more of those nerves to become compressed, irritated, inflamed, and/or impinged, neurological symptoms will develop.
As scoliosis doesn’t become a compressive condition until skeletal maturity has been reached, neurological symptoms are more common in adult scoliosis and/or in severe forms with a large degree of nerve involvement, as is common in neuromuscular scoliosis.
Neurological symptoms can involve both movement and sensation, particularly if a mixed nerve containing both sensory and motor fibers is exposed to uneven pressure.
Neurological symptoms can involve nerve pain and discomfort that can cause zapping sensations anywhere along an affected nerve’s pathway, shooting pains, tingling, numbness, and weakness.
When left untreated, neurological symptoms tend to get worse because as a progressive condition, the size of a scoliotic curve is virtually guaranteed to increase over time, and this increases the condition’s uneven forces, and their effects, which includes nerve compression.
If nerve compression is left untreated, nerves can become permanently damaged and lose their ability to function properly; once this level of nerve damage has occurred, it can be difficult, if not impossible, to reverse the damage.
If scoliosis is left untreated, particularly severe forms, additional complications can develop such as cardiac issues, lung impairment, and digestive issues; the best way to minimize the condition’s effects and manage its progression is to treat it proactively, and when it comes to neuromuscular scoliosis, this means addressing the larger neuromuscular condition first.
Neuromuscular Disorders
There are many neuromuscular disorders capable of causing scoliosis to develop. Following are some of the most common.
Cerebral Palsy and Neuromuscular Scoliosis
Cerebral palsy affects the body’s musculoskeletal system and the ability to move and balance itself.
Cerebral palsy is caused by damage that occurs as the brain develops, most commonly, in utero, and signs and symptoms of cerebral palsy can appear during infancy, or when a child reaches preschool age.
Symptoms of Cerebral Palsy can include:
- Irregular muscle tone
- Stiff muscles
- Exaggerated reflexes
- Stiff muscles with normal reflexes
- Ataxia (lack of muscle coordination)
- Athetosis (slow movements)
- Seizures
- Tremors
- Involuntary movements
- Difficulty walking
- Overusing one side of the body
- Paraplegia (leg paralysis)
- Difficulty speaking
- Difficulties with eating/swallowing
- Difficulties with fine motor muscle control
While the symptoms of cerebral palsy can vary widely, it’s most often movement and coordination that are affected, and in most cases, symptoms of cerebral palsy don’t change over time, so worsening symptoms with age is not a common characteristic of the condition; however, if left untreated, increasing muscle rigidity and shortening can worsen if left untreated.
The way cerebral palsy affects the body’s overall function can vary widely with some cerebral palsy patients being able to walk, while others can’t, and in addition, some individuals with cerebral palsy will have normal intellectual development, while others can experience delays or intellectual impairment.
The inability to balance the body and control the nerves and muscles surrounding the spine can cause it to develop an unnatural scoliotic curvature: NMS.
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.
Diagnosing Neuromuscular Scoliosis in Children
In order to diagnose neuromuscular scoliosis in children, the process starts with a physical examination conducted by a medical professional.
A physical examination commonly includes the child’s doctor taking the family’s medical and genetic history, and enquiring as to what symptoms are present and when they started.
During the physical exam, the doctor will comprehensively examine the child’s spine and back and will assess any issues with balance, movement, skin breakdown, and the presence of any functional deficits.
Observing how a child walks is also important; I can tell a lot about patients’ conditions by how their posture and gait.
For example, if an adolescent child with cerebral palsy is wheelchair bound and has a large scoliotic curve that bends to the left, this can cause a pelvic tilt, which is associated with sitting imbalance and the development of sitting sores.
X-ray imaging is also a big part of assessing and diagnosing neuromuscular scoliosis.
A patient’s Cobb angle is measured during X-ray and is known as the orthopedic gold standard in the assessment of scoliosis, tells me how far out of alignment a scoliotic spine is, and places conditions on a severity scale:
- Mild scoliosis: Cobb angle measurement of between 10 and 25 degrees
- Moderate scoliosis: Cobb angle measurement of between 25 and 40 degrees
- Severe scoliosis: Cobb angle measurement of 40+ degrees
- Very-severe scoliosis: Cobb angle measurement of 80+ degrees
Magnetic resonance imaging (MRI) scans can also help further assess NMS by providing clear images of soft tissues to help evaluate the overall health of the spinal cord.
Symptoms of Neuromuscular Scoliosis
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
Neuromuscular scoliosis is a type of scoliosis that can affect children who have underlying medical conditions that impact their ability to control the muscles that provide the spine with support.
There are many different medical conditions associated with the development of NMS in children, some of the most common being muscular dystrophy, cerebral palsy, and spina bifida.
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.
Children with NMS often have a number of medical issues in addition to the unnatural spinal curve, and scoliosis progresses during noticeable times of growth and development, such as puberty.
Scoliotic curves characteristic of idiopathic and congenital scoliosis typically affect certain sections of the spine and stop progressing when skeletal maturity has been reached, or at least slow down; conversely, NMS curves tend to develop at a younger age than in idiopathic scoliosis, and NMS curves tend to be long and affect the entire spine.
NMS curves also tend to progress more rapidly and can continue to progress into adulthood.
Causes of Neuromuscular Scoliosis in Children
Again, neuromuscular scoliosis is caused by the presence of a larger underlying medical condition that impairs the body’s neurological system, muscular system, or both.
While not all children with neuromuscular conditions are guaranteed to develop NMS, it is particularly common in children who are wheelchair-bound.
In some neuromuscular conditions, children can walk when they are younger, but need a wheelchair in adolescence, and this is because the major growth spurts associated with adolescence can trigger the development of NMS or an existing curve to progress.
Whether or not a child will develop neuromuscular scoliosis is determined by the degree of nerve and muscle involvement associated with the underlying neuromuscular condition.
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:
- Uneven shoulders where one shoulder blade protrudes more prominently than the other
- A rib arch where the rib cage protrudes more prominently on one side of the body
- An uneven waistline
- One hip that appears to sit higher on one side
- An overall asymmetrical appearance to the body
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:
- A tilted pelvis (pelvic obliquity)
- Pressure sores from imbalance and pelvic obliquity
- Difficulty with sitting due to the imbalance
- Slouching posture with extreme leans to one side
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 addition, children with neuromuscular scoliosis often present with other types of unnatural spinal curves: excessive kyphosis and/or lordosis.
Kyphosis refers to the spine’s outward curve, that bends away from the body’s center in a reverse ‘C’ shape at the thoracic level, while lordosis refers to the spine’s inward curves, that bends towards the body’s center in a standard ‘C’ shape at the cervical and lumbar sections.
Large scoliotic curves in the thoracic spine and/or hyperlordotic curves (excessive lordosis) can reduce the space available in the chest, affecting the ability of the lungs to fully inhale/exhale and can lead to breathing problems.
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.
Treatment Options for Neuromuscular Scoliosis
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.
Side Effects of Spinal Fusion Surgery for Neuromuscular Scoliosis
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:
- Infection
- Excessive bleeding
- Neurological damage
- Hardware failure
- Adverse reaction to the hardware
- Loss of mobility
- Need for subsequent surgeries
- Continued progression
- Post-surgical pain
- Adverse psychological effects
The reality of spinal fusion research and data is that there is a significant gap in the procedure’s long-term effects, and by long-term effects, I’m talking about 20, 30, 40 years down the road; after all, the hardware used in the procedure can’t last forever, and if it does fail or reach its natural expiration, the only recourse is subsequent surgery, which only gets riskier with age.
Many patients report an increase in post-surgical pain due to the increased stiffness in the fused section of the spine, and this can also affect the spine’s surrounding muscles.
The psychological effect of living with a fused spine is often underestimated or overlooked, but for many who have undergone spinal fusion, quality of life is impacted as the knowledge that a fused spine is more vulnerable to injury can make people fearful of trying new things, and/or participating in once-loved activities.
Conclusion
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.
