What is Spinal Cord Compression?
Spinal cord compression can happen due to several reasons, both because of injuries (traumatic) and naturally occurring changes (atraumatic). The spinal column, made up of many soft tissue and bones, is designed to provide support to our body and protect the spinal cord and nerve roots. Despite this protection, the spinal cord remains at risk of compression from various factors like swelling from blood products, growth of cancerous cells (neoplastic disease), infections, or bulging of bones or intervertebral disc within a restricted area filled with fat referred to as the spinal epidural space (the space between spinal cord and spinal column) and meninges (protective membranes covering the spinal cord).
Here’s a simplified explanation of our spinal anatomy:
Our spine is made up of 33 bones or vertebrae: 7 in the neck (cervical), 12 in the chest area (thoracic), 5 in the lower back (lumbar), 5 in the pelvic region (sacral; fused to form one bone), and 4 at the bottom (coccygeal; also fused). These bones are separated by cushion-like structures (cartilaginous intervertebral disks) and strengthened by bands of tissue (ligaments), including the front (anterior longitudinal ligament) and back (posterior longitudinal ligament). Each nerve root (where nerves exit the spinal cord) is enclosed by a bone (a pedicle), a disc space below, joints at the back (facet joints), and the body of the vertebra at the front.
The spinal cord, about 40 cm long, runs from the large hole at the base of the skull (foramen magnum) to the L1-L2 vertebrae. Specific parts of the spinal cord responsible for signaling to the arms and legs (cervical and lumbar enlargements) span from C5-T1 and L2-S3, respectively. The spinal cord then narrows to a tip (the conus medullaris) between T10-L1, after which non-neural strands continue down to the S2 vertebra. Paired nerves then extend down, forming the bundle of nerves called the cauda equina until they exit the spine at their respective holes (foramina).
The blood supply to the spinal cord comes from the anterior spinal artery (supplied by the vertebral arteries) and two posterior spinal arteries. The anterior spinal artery provides about two-thirds of the blood to the spinal cord, with the rest supplied by the posterior ones. These arteries also receive more blood from smaller branching arteries, the largest being the artery of Adamkiewicz, originating from the aorta, usually situated between T8-L4 levels, predominately on the left side.
The space around the spinal cord, the spinal epidural space, is bounded at the front by the body of the vertebra and the back by a tough outer layer (dura mater). This space contains fat, arteries, and a network of veins (venous plexus). It is larger along the thoracic and lumbar spine, meaning there’s a higher likelihood of abscesses (collections of pus as a result of infection) in this region.
What Causes Spinal Cord Compression?
The spinal cord can be compressed or pressed upon due to various reasons. This article discusses non-injury related causes of spinal cord compression. These include certain conditions such as:
– Degenerative spondylosis with myelopathy: This is a condition where the spinal cord becomes damaged due to wear and tear of the spinal disks over time.
– Metastatic disease of the spine: This is when cancer from another part of the body has spread to the spine.
– Primary spinal cord malignancy: This is a rare case where the cancer starts in the spinal cord itself.
– Spinal epidural abscess: This is a pocket of pus that forms between the spinal cord and the outer covering of the spine, often caused by a bacterial infection.
– Spontaneous or iatrogenic spinal epidural hematoma: This is a condition where blood collects between the spinal cord and its outer covering. It can happen spontaneously (without a known cause) or iatrogenically (as a result of a medical procedure).
Risk Factors and Frequency for Spinal Cord Compression
Myelopathy, which is a neurological problem due to a disease of the spinal cord, is usually a result of wear-and-tear changes involving the spinal discs, facet joints, or the vertebral bodies. This leads to a narrowing of the spinal canal in the neck or lower back area. The most common cause of myelopathy in adults over 55 is cervical spondylosis, and about 5% to 10% of people with this condition will develop myelopathy.
Spinal cord compression due to cancer metastasis occurs in 2.5% to 5% of patients who die from cancer, but the frequency varies depending on the type of primary cancer. A 2011 analysis revealed that lung cancer, prostate cancer, and multiple myeloma were the main causes of hospitalizations related to this condition.
Although it’s not common, the frequency of spinal epidural abscess, which is a collection of pus between the outer covering of the spinal cord and the bones of the spine, has risen over the past several decades. This increase is thought to be due to better detection methods, increased illegal drug use related to the opioid crisis, and a rise in the number of invasive spinal procedures in the United States.
Lastly, Spontaneous spinal epidural hematoma, which is a rare occurrence, where blood collects between the outer covering of the spinal cord and the spine. With an occurrence rate of 0.1 per 100,000 and 600 reported instances in medical literature. It typically affects people in their 40s and 50s. In recent years, there is more focus on this because of the use of oral anticoagulants and vitamin K antagonists for treating conditions like non-valvular atrial fibrillation and clot formation in deep veins or lungs. Our current understanding of this condition mainly comes from experience with related epidural analgesia procedures.
Signs and Symptoms of Spinal Cord Compression
Back pain can sometimes be a “red flag” that indicates severe medical conditions such as spinal cord compression. Some general warning signs that suggest the need for specialized spine imaging include: being over 65 years old, difficulty walking, bladder or bowel incontinence, using corticosteroids, pain along the midline of the back, and any signs of bruising on the spine, particularly after a traumatic event.
These signs can overlap with symptoms of cervical spondylotic myelopathy, a type of neck-related disease that can varyingly cause muscle weakness in arms, legs, or both. Sensory loss at the neck or chest level, bladder and rectal problems, and other motor control issues can also occur. A physical examination may reveal decreased reflexes or difficulty with complex hand movements, but increased reflexes and abnormal response in the feet. Trouble with walking can often be an early sign, along with an “electric shock” sensation along the spine or arms during neck movement. If these symptoms appear suddenly after a strong neck movement, medical imaging of the neck should be performed.
When considering metastatic spinal cord compression (MSCC), a condition where cancer has spread to the spine, the most important red flag is prior history of cancer. Common symptoms include back pain, especially at night and when coughing or sneezing, and potential shooting nerve pain in advanced cases. Motor difficulties can occur from 35% to 75% of patients at diagnosis. In severe cases, symptoms can mimic a condition called cauda equina syndrome, which may include bladder and bowel problems, leg weakness, sensory deficits, and walking abnormalities.
- Prior history of cancer
- Back pain, especially at night and when coughing or sneezing
- Shooting nerve pain in advanced stages
- Motor difficulties
- Symptoms mimicking cauda equina syndrome
Spinal epidural abscess (SEA) can sometimes present with a trio of symptoms such as fever, back pain, and specific neurological deficits, though this is more common in late stages. Any combination of fever and localized back pain, especially if touch worsens the pain, should warrant further investigation. However, lack of fever does not necessarily rule out SEA, as many patients are often seen multiple times before a diagnosis is made.
Finally, symptoms for spinal epidural hematoma (SEH), a condition where a blood clot forms in the spine, can include acute back pain, muscle weakness, and changes in bowel or bladder function. Nerve pain shoot towards the arms or legs is uncommon. Risk factors such as receiving certain types of pain relief and taking blood thinners should prompt further investigation if these symptoms are present.
Testing for Spinal Cord Compression
If there are concerns that you might have spondylotic myelopathy, a form of spinal cord dysfunction, your doctor will likely order MRI (Magnetic Resonance Imaging) scans. Another option, though less common, is a CT (Computed Tomography) myelography which quantitatively examines spinal canal narrowing and gives more detail on bones and soft tissue. However, MRI is less invasive and provides better details of the spinal cord, making it the preferred choice, especially for those presenting with signs of sudden myelopathy (spinal cord disease).
The most effective way to diagnose MSCC (a condition where a mass presses on the spinal cord, often due to cancer spread) is through MRI with a special dye known as gadolinium contrast-enhanced – this is the gold standard. This method has shown a 93% sensitivity (ability to correctly identify positive cases) and a 97% specificity (ability to correctly reject negative cases). Because of the high potential for disease spread, it’s advised to image the entire spine.
CT myelography can be considered if MRI is not suitable for the patient; x-ray imaging is not recommended as it’s not sensitive enough for tracking the spread of cancer and doesn’t provide adequate details of soft tissue.
Your doctor might conduct a routine laboratory test if SEA, a type of spinal infection, is suspected, although it’s not always helpful. Lack of leukocytosis, a high number of white blood cells, doesn’t necessarily mean SEA isn’t present – only about two-thirds of patients with SEA have demonstrated leukocytosis. Two other tests, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), have been used to identify patients at risk of SEA. Should these tests yield abnormal results, your doctor might proceed to imaging evaluation with MRI or CT myelography, as suitable.
Interesting findings from a 2011 study showed that where ESR and CRP testing was incorporated into a diagnostic process, less diagnostic delays and reduced motor deficits at the time of SEA diagnosis were reported. However, these findings haven’t been validated externally.
An MRI with gadolinium contrast enhancement is also the gold standard for diagnosing SEA. In order to identify any “skip lesions” (areas of the spine unaffected by disease located between affected areas), it might be necessary to image the entire spine. Certain risk factors such as symptoms persisting for seven or more days, ESR exceeding 95 mm/h, and infections outside of the spine could predict the presence of skip lesions.
Treatment Options for Spinal Cord Compression
Cervical spondylotic myelopathy, a condition that affects the neck, is generally managed conservatively in its early stages. This means the initial approach is to manage symptoms and slow down the disease progression. This might include physical therapy, avoiding risky physical activities, and controlling pain with over-the-counter anti-inflammatory drugs or muscle relaxants. In some cases, patients may also get epidural steroid injections, which are shots into the spine to help relieve pain.
Regular check-ups and imaging tests may be needed to monitor the disease progress. Surgery to relieve pressure on the spinal cord is considered if the condition worsens despite these treatments. However, the type of surgery varies according to the severity of the condition and any worsening symptoms.
In some cases, oral steroid medication, like dexamethasone, may be prescribed to reduce swelling in the spinal cord. Steroid therapy has been shown to enhance pain relief and improve nerve function. However, high doses of these medications can have side effects like psychosis and stomach ulcers, so doctors usually give the lowest effective dose.
For a condition called metastatic spinal cord compression (MSCC), treatments often involve surgery and radiation. Several factors, such as the stability of the spine, the presence of neurological deficits, and overall health prognosis, are considered when deciding whether to opt for surgery.
Surgical management can include various techniques, like kyphoplasty and vertebroplasty which strengthen a damaged vertebral body, as well as decompression and spine stabilization procedures. Radiation therapy alone is typically selected for patients with a stable spine, no neurological deficits, and tumors that are sensitive to radiation.
If a severe bone infection (vertebral osteomyelitis) is confirmed, intravenous antibiotics are generally given. Surgical intervention, often involving decompression, is typically included in the management. Some patients may be suitable for non-surgical treatment with IV antibiotics and close monitoring. However, this must be decided on case by case basis and with careful consultation with a neurosurgeon.
Variety of surgical methods are available based on where the disease is located in the spine. For issues in the neck region, surgeries can be accessed from the front (anterior) or the back (posterior) of the neck. Lower back (lumbar) issues are usually dealt with through posterior access. Depending on the specific condition and location, surgeons may use an anterior, lateral (side), or posterior approach to the thoracic (chest level) and lumbar spine.
The decision for the surgical approach depends on the location and type of the issue, the surgeon’s skills and experience, and the patient’s general health. In any case, the safest approach is often the best.
What else can Spinal Cord Compression be?
People suffering from spinal cord compression may experience back pain and other nerve-related symptoms. There might be various reasons for these symptoms, which are not limited to those discussed in this article. Some of these include:
- Spinal cord infarction (damage or obstruction of the blood vessels supplying the spinal cord)
- Transverse myelitis (inflammation of the spinal cord)
- Subarachnoid hemorrhage (bleeding in the space surrounding the brain)
- Conditions related to the aorta such as a tear (dissection) or a bulge (aneurysm)
- Heart attack (acute myocardial infarction)
For people showing signs of cauda equina syndrome – a serious condition that affects the nerves at the bottom of the spine – other potential conditions to consider include:
- MSCC (metastatic spinal cord compression)
- Leptomeningeal carcinomatosis (cancer that has spread to the membranes surrounding the brain and spinal cord)
- Intervertebral disc extrusion (a slipped disc)
- Osteoporotic fracture (a break in the bone due to osteoporosis)
If a patient is suffering from sudden neurological deficits and the doctor has ruled out any disorders causing pressure on the spinal cord after examining MRI or CT scans, other disorders that may be causing these symptoms should be considered. These might include:
- Amyotrophic lateral sclerosis (ALS – a disease that affects nerve cells in the brain and spinal cord)
- Guillain-Barre syndrome (a condition in which the body’s immune system attacks the nerves)
- HIV myelopathy (spinal cord disease in people with HIV)
- Botulism (a type of poisoning affecting the nerves)
- Multiple sclerosis (a disease that affects the brain and spinal cord)
- Transverse myelitis (inflammation across a section of the spinal cord)
These conditions need further examination by a neurologist and additional tests, such as a lumbar puncture to get a sample of cerebrospinal fluid or an electromyography (a test to evaluate the health of muscles and the nerve cells that control them).
What to expect with Spinal Cord Compression
If cervical spondylotic myelopathy is left untreated, it may slowly lead to worsening of walking ability, weakness in the upper and lower body, sensory loss, and pain. Even a minor neck injury can cause sudden changes in neurological symptoms in people suffering from cervical spondylosis, warranting an urgent examination.
Following surgery to relieve pressure on the spinal cord, around half to 80% of patients report symptom improvement, but in 5–30% of cases, symptoms may worsen.
Proper and prompt identification of MSCC (metastatic spinal cord compression) is key to maintaining neurological function. Studies have shown that the level of neurological deficits before treatment and how long the symptoms have persisted can predict the ability to walk after treatment. Hence, severe weakness and an inability to walk more than 48 hours just before diagnosis can lead to poor neurological outcomes.
Thankfully, awareness and recognition of new-onset back pain in walking cancer patients as being potentially serious and needing immediate attention have led to earlier diagnosis of MSCC.
Approximately 5% of patients with SEA (spinal epidural abscess) die from sepsis (serious body response to infection) or other complications, and irreversible paralysis may occur in up to 22% of patients. A study involving 97 patients discharged from two large urban hospitals following SEA treatment revealed a 90-day readmission rate of 37.1%, where 36.1% was due to persistent infection.
Risk factors for readmission were a weakened immune system to begin with, excessive alcohol consumption, and chronic hepatitis. Interestingly, the readmission rate did not increase with a selection of treatment option, whether it was surgical intervention or “watch and wait” approach.
Possible Complications When Diagnosed with Spinal Cord Compression
One of the most alarming complications of neglected spinal cord compression, no matter the cause, is permanent nerve damage. This can include paralysis, trouble walking, loss of sensation, and loss of bladder and bowel control.
There can be different complications from surgical treatment to relieve pressure on the spinal cord. These can include unintended injury to the spinal cord or nerve roots during surgery, tearing of the tough membrane around the spinal cord which can lead to leaking of cerebrospinal fluid, a buildup of blood in the epidural space, infection in the wound, and failure of the vertebral bones to grow together. It’s important to consider these potential complications along with the potential benefits of surgery, and tie these in with the patient’s age, existing health conditions, and the length and intensity of their symptoms.
For patients undergoing non-surgical treatment, there’s a risk of sudden paralysis because of gradual blockage of the blood vessels that feed the spinal cord. This is a bigger concern for older patients with hardened arteries.
Common Side Effects:
- Permanent nerve damage
- Paralysis
- Trouble walking
- Loss of sensation
- Loss of bladder and bowel control
- Unintended injury to the spinal cord or nerve roots during surgery
- Tearing of the tough membrane around the spinal cord
- Leaking of cerebrospinal fluid
- A buildup of blood in the epidural space
- Infection in the wound
- Failure of the vertebral bones to grow together
- Sudden paralysis from gradual blockage of blood vessels
Preventing Spinal Cord Compression
Back pain is one of the most common reasons people unexpectedly go to the emergency room and can cause people to be temporarily or long-term disabled. When in pain, usually the top priority for patients is to find a way to relieve it. Medical imaging, like X-rays or MRIs, often doesn’t help if you just recently started experiencing back pain, unless there are specific high-risk health factors (called “red flag” risk factors).
The use of medical imaging wouldn’t change the treatment plan for a patient if the doctor’s examination doesn’t show any neurological problems (issues relating to the nervous system, including the brain and nerves). So, when treating someone with recent back pain, the doctor will explain the usefulness (or potential lack of it) of medical imaging and why they may or may not recommend it.
If a patient’s condition is stable enough for them to go home, and there are plans for them to see their doctor for further check-ups, they should be well-informed about any symptoms that might mean their back pain has serious or surgical causes. These symptoms could include experiencing problems in both arms or legs, feeling weak, losing sensation, having difficulty controlling their bladder or bowel, having trouble walking, or experiencing worsening back pain in the middle of their back, especially if they have a history of cancer.
