What is Spinal Epidural Abscess?
A spinal epidural abscess (SEA) is a type of serious infection that happens in the space between the protective covering of your spine and the hard shell surrounding your vertebrae. This condition was first documented by Giovanni Morgagni in 1761.
People with SEA often experience symptoms like back pain in the middle of their back, fever, and trouble with their nerves like numbness or weakness. However, the symptoms can vary greatly from person to person. It can be hard to identify SEA unless the doctor strongly suspects it, because the symptoms can be quite general.
If it’s not treated, SEA can actually be life-threatening or cause serious health issues. So, if there’s any concern that a person might have SEA, it’s very important to get it checked out and treated as soon as possible.
Diagnosing and treating SEA has been greatly improved with new technology. Now, doctors can use imaging techniques like CT scans and MRIs to help find and treat SEA. These tools provide clear images of the spinal area, which can help your doctor make a precise diagnosis and plan effective treatment.
What Causes Spinal Epidural Abscess?
Spinal epidural abscess is a condition where bacteria infiltrates and infects the space around your spinal cord. This bacterial invasion is most commonly caused when bacteria spread through the bloodstream. When these bacteria reach the space around spinal cord, they cause an infection which leads to pus formation.
There are certain factors that can make a person more susceptible to developing a spinal epidural abscess. These can include having a weaker immune system due to conditions like diabetes, alcoholism, cirrhosis, terminal kidney disease, or HIV infection. Other contributing factors can include using drugs through veins, medical procedures which directly access the spine (like acupuncture, spinal or epidural injections, lumbar puncture, or brain and spine surgery), and bacteremia, which is when bacteria are present in your blood.
Diabetes is the most common condition that increases the risk of developing a spinal epidural abscess. However, using drugs intravenously and having an epidural catheter placed (which is a tube inserted into the space around the spinal cord) are becoming more and more common as risk factors for this condition.
Risk Factors and Frequency for Spinal Epidural Abscess
Spinal Epidural Abscess (SEA) is a rare condition. It’s seen in about 2 to 8 in every 10,000 hospital admissions. However, it’s becoming slightly more common due to the rise of invasive spinal procedures, aging population, and increased usage of intravenous drugs.
A study that reviewed information from 12 different studies and 1099 patients found some common patterns:
- The average age of people affected was 57.2 years.
- There were more men affected than women, with a ratio of 1.66:1.
- The most common risk was intravenous drug abuse, found in 22% of cases.
- Diabetes was the most frequently associated medical condition, found in 27% of cases.
- Staphylococcus aureus was the most common culprit, causing the problem in 63.6% of cases.
- The lumbar spine was the most common area of involvement, in 48% of cases.
- The most common symptoms were back pain (67% of cases) and weakness in the muscles (52% of cases).
- 60% of patients ended up needing surgery to manage their condition.
Signs and Symptoms of Spinal Epidural Abscess
Spinal epidural abscess (SEA) is a serious condition that unfortunately often goes undetected, with the three key symptoms – back pain, fever, and neurological issues – appearing in just 8 to 15% of cases. Back pain is the most common symptom, appearing in around two-thirds of cases. This can often be identified when pressure or touch is applied to the spine. Pain may also be felt when a leg is raised, due to pressure on the spinal nerve roots. If the disease continues to develop without treatment, patients may experience more serious symptoms, such as an inability to control the bladder or bowel, loss of sensation in the saddle and perianal areas, muscle weakness, or even paralysis.
SES typically progresses through four stages:
- Stage 1 – Back pain, fever, or tenderness in the spine
- Stage 2 – Severe, shooting pain and stiffness in the neck
- Stage 3 – Neurological issues
- Stage 4 – Paralysis
Worryingly, about 34% of patients reach the final, most severe stage. Other telling signs or “red flags” for SEA include unexplained fever, neurological problems, and an ongoing infection.
Several major risk factors can increase the likelihood of developing a SEA:
- Diabetes
- Injection drug use
- Having a catheter placed inside a blood vessel
- Having recently undergone spinal treatment
- Being immunocompromised
- Having an infection in another part of the body
A study identified key indicators for SEA, including age, fever, using antibiotics within the past 30 days, back or neck pain, and a history of drug abuse. If back pain is accompanied by fever or any of these risk factors, and blood tests show a high level of inflammation, a contrast MRI of the spine is generally recommended.
Testing for Spinal Epidural Abscess
If your doctor suspects you might have spinal epidural abscess (SEA), a condition marked by localized infection near the spine, they may use different types of tests to confirm it. MRI scans, especially those using a special substance called gadolinium which highlights any areas of concern, are the most reliable way to find out if you have SEA. In particular, looking for swelling in the paraspinal area (near the spine) and in the bone marrow can provide a strong hint of SEA.
Your doctor might also spot other signs on the MRI, like stretching of the infection over multiple spine segments, or even across the entire spine. Despite the complexity, MRI is still preferred because it can clearly show the affected area. It’s also very good at distinguishing SEA from other similar conditions- with a success rate of over 90%!
Considering other tests, plain X-rays or CT scans can sometimes show narrowing of the discs in your spine, and bone loss. These tests could also show a certain pattern of SEA, which looks like a ring because the necrotic (dead) center of the growth isn’t getting a blood supply.
Blood tests can help, too. For instance, a measurement of your ESR (erythrocyte sedimentation rate) or CRP (C-reactive protein) levels. If your ESR is greater than 30 mm/hr or your CRP is greater than 10 mg/L, there is a more than 95% chance that you have SEA.
Examining your cerebrospinal fluid (CSF), which surrounds your brain and spinal cord, could also help in diagnosis. Although it can only show signs of inflammation near the meninges (the coverings of your brain and spinal cord), like increased proteins and an increased number of cells (pleocytosis).
Some newer tests such as Indium-biotin scans and fluorodeoxyglucose-positron emission tomography (_F_-FDG PET) can show more details in cases of SEA.
While culturing CSF can detect the infection causing SEA, it’s only successful about 25% of the time. Plus, it comes with risks like meningitis and subdural infections (infections in or around the brain). So, it’s not recommended unless needed for a different procedure called myelography, which isn’t used for SEA anymore.
Blood cultures (growing any bacteria present in your blood in a lab), or taking a sample from the infected area using a needle under CT guidance might be more successful. Importantly, if your CSF culture is positive, your blood culture will almost always also be positive.
If surgery is performed, either open or minimally invasive, cultures from the procedure have a high rate of success, finding the infection causing SEA in about 78.8% to 90.5% cases.
Treatment Options for Spinal Epidural Abscess
The timeline for the progression from one stage of disease to another can vary greatly, with a shift from stage III to IV typically happening quite rapidly, usually within a day.
The widely agreed-upon treatment for this condition involves surgery, specifically decompressive laminectomy and débridement, along with systemic antibiotics. Surgery should ideally be performed early on to obtain the best results.
A decompressive laminectomy is a surgical procedure aimed at relieving pressure on the spinal cord or nerves, while débridement is the medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. The first successful decompressive laminectomy was done in 1901 for a thoracic abscess. Nowadays, this surgical intervention combined with systemic antibiotics is the gold standard for treating patients who show neurological deterioration, spinal instability, or whose infection persists despite antibiotic treatment.
Children with the disease can undergo an alternative surgery called laminotomy. There is also an option to use spinal instrumentation, which involves the use of medical devices to maintain spinal stability, as this option has been observed to be safe and devoid of significant infective complications.
The specific antibiotics used as part of the treatment depend on the results of culture reports that identify the type of bacteria causing the infection. Some examples include penicillin and first or second-generation cephalosporins for staphylococcal infections, vancomycin for Methicillin-resistant Staphylococcus aureus (MRSA), and third or fourth-generation cephalosporins for gram-negative bacilli.
In some cases, only medical management might be necessary. This approach is suggested in situations where the patient displays little or no neurological deficits, the cause of the infection is clearly identified, and the patient is closely monitored. This can also be suitable for high-risk patients who do not consent to surgery, patients who present late with paralysis, and in scenarios where the infection is seen throughout the spinal cord (panspinal).
Nowadays, a higher percentage of patients are managed medically compared to previous years. This is largely due to earlier diagnoses, with patients typically presenting with back pain and fever, and often with little or no neurological deficiencies.
Medical management generally involves administering antibiotics for a duration of four to eight weeks, considering the concurrent risk of osteomyelitis (bone infection). Intravenous therapy is used to ensure better absorption of the drug and adherence to the treatment schedule. Removal of implanted devices, such as a spinal cord stimulator system, is often required if they have become infected.
However, medical management alone can often fail (more than 40% of cases) and can lead to higher morbidity (up to 22% risk of permanent paralysis), and higher mortality. The antibiotics used in medical therapy may also find it harder to penetrate the necrotic center of the abscess. In some cases, Computed Tomography (CT) guided aspiration, a procedure to drain the abscess, can be used as an option for patients who are neurologically intact and frail.
The primary determinant of the outcome of the disease is typically the neurological status of the patient when they first present themselves for treatment.
The risk variables that predict unsuccessful treatment include the presence of neurological deficits, age over 65, and concurrent diabetes.
What else can Spinal Epidural Abscess be?
When dealing with medical conditions related to the spinal area, there are many potential issues or diseases to consider:
- Disc prolapse (slipping of a spinal disc)
- Degenerative spinal canal stenosis (narrowing of the spinal canal)
- Vertebral discitis and osteomyelitis (inflammation and infection of the vertebrae and discs)
- Transverse myelitis (inflammation of the spinal cord)
- Spinal cord hematoma (blood clot in the spinal cord)
- Psoas abscess (infection in the psoas muscle in the lower back)
- Meningitis (inflammation of the protective membranes covering the brain and spinal cord)
- Urinary tract infection
- Pyelonephritis/ perirenal abscess (kidney infection/ abscess around the kidney)
- Endocarditis (heart valve infection)
What to expect with Spinal Epidural Abscess
The disease presents a puzzling situation. The time between when symptoms appear and when a person arrives at the hospital varies greatly and is completely unpredictable. Early diagnosis is extremely important in managing and treating this condition.
If the diagnosis of the disease is delayed, meaning multiple visits before a clear diagnosis and treatment begins, this can lead to lingering weakness or even lasting nerve damage.
Sadly, despite modern medical advances, irreversible paralysis still impacts 4 to 22% of patients, mainly due to delays in diagnosis and less than ideal management. Many patients, between 11 to 75%, are originally misdiagnosed.
About 5% of the patients succumb to the condition due to sepsis or other related complications. Furthermore, between 4 to 22% suffer from irreversible paralysis.
There are limited information available on how well patients recover neurologically after surgery. However, recovery varies and is largely influenced by several factors like age, overall health, existing health conditions, and how quickly the condition was diagnosed. Starting treatment promptly is incredibly important.
Why timely surgical interventions are essential for patients with this disease:
* Surgeries conducted in the early stages (1 or 2) can greatly lessen pain and lead to improvements in over 90% of cases.
* Surgeries conducted during stage 3 could reverse or at least minimize nerve deficits.
* Surgeries conducted within 36 hours of reaching stage 4 may restore some nerve functions.
In patients who have persistent or repeat infections, doctors need to rule out situations like tears in the esophagus and irregular connections between the intestine and spine.
Some patients face higher risks of recurrence including those who have:
* A history of intravenous drug use
* Bowel issues when they were first diagnosed
* A local wound infection at the same time
* Compromised immune systems or who are taking drugs that suppress the immune system.
Patients who have lost motor function upon diagnosis have a higher risk of dying within 90 days. This makes it all the more crucial for timely diagnosis and management of the disease.
Possible Complications When Diagnosed with Spinal Epidural Abscess
The complications that can arise from SEA include:
- Pressure sores
- Urinary tract infections
- Deep-vein thrombosis or blood clots in the leg
- Sepsis, a severe reaction to an infection
- Meningitis, an infection of the membrane surrounding the brain and spinal cord
- Death
Most deaths result from sepsis or meningitis, and the death rate varies broadly between 1.3% and 31%. Thankfully, the death rate has improved over the years, dropping from 34% in the 1960s down to 15% in the 1990s. Although the reported number of SEA cases has doubled over the past twenty years, the associated death rate has dropped by almost half to around 14%. Patients who died or were left paralyzed from SEA generally experienced a significantly longer delay between their medical imaging and final results.
Preventing Spinal Epidural Abscess
Patients should maintain regular contact with their surgical team. This is to ensure that any complications from the surgery, or new symptoms like feeling weak or having a fever, get promptly noticed and addressed.
Undergoing rehabilitation with physical or occupational therapists is crucial for patients showing signs of weakness or other changes in their ability to move or think. Their expertise can help patients regain control over affected parts of their body.
Patients should also remember to take their medicines as prescribed. Getting assistance from home healthcare providers can make this process easier and more efficient.
Finally, if patients ever feel unmotivated, depressed, or have thoughts about suicide, it’s important that they reach out to their healthcare professionals. Knowing about these feelings allow doctors to provide the necessary help and appropriate referrals.