What is Spinal Cord Abscess?
An intramedullary spinal cord abscess (ISCA), which was first identified by Hart in 1830, is a very unusual type of spinal cord abscess in modern times. There are a few reasons why these abscesses are so rare:
1. The spinal cord has a relatively small size and surface area.
2. The specific spinal arteries that supply blood to the spinal cord come from a sharp angle.
3. The spinal cord is well-protected by the vertebral canal (the bony tunnel that contains the spinal cord) and the meningeal layers (protective coverings of the brain and spinal cord), especially the pia mater layer.
Even though these abscesses are rare, it’s extremely important to diagnose and treat them quickly. If not treated promptly, these abscesses can cause serious injury to the spinal cord, which can lead to loss of nerve function, and in some cases, can even be fatal.
What Causes Spinal Cord Abscess?
Almost 40% of Intramedullary Spinal Cord Abscesses (ISCA), a rare type of spinal cord infection, are cryptogenic. This complex term simply means that the cause of these cases is unknown. A review of cases from 1977 to 2009 found that only 9% of them were cryptogenic.
For children, a common cause of ISCA is something called Congenital Dermal Sinuses (CDS), accounting for 45% of cases. CDS are birth defects that appear as tiny dimples, dents or small skin openings, mostly located in the lower part of the spine (90% of cases). CDS can occur alongside other conditions such as dermoid and epidermoid tumors, which are benign (non-cancerous) but require medical attention. However, in adults, these spinal cord abscesses are often caused by the spread of an infection from another part of the body, such as from a urinary tract infection, heart infection (endocarditis), or pneumonia. This accounts for around 24% of adult ISCA cases.
The infections causing ISCA are often bacterial, the most common being staphylococcus, streptococcus, and coliform bacteria. Specifically, if the ISCA is related to congenital dermal sinuses, it is almost always associated with the bacteria Staphylococcus aureus.
It’s important to note that multiple abscesses, or collections of pus in the spinal cord, occur in about 26% of all ISCA cases.
Risk Factors and Frequency for Spinal Cord Abscess
ISCA, a condition first identified by Hart in 1830, is not very common. Up until now, only 137 cases have been reported in medical documents. It tends to occur at two specific times in people’s lives – their first or third decade. More men are diagnosed with this condition than women. We can’t say for certain if ISCA is more common in the United States, or if certain races are more affected by it.
- Hart first diagnosed ISCA in 1830.
- Since then, only about 137 cases have been reported in medical literature.
- This condition most commonly occurs in the first and third decades of a person’s life.
- More men are affected by ISCA than women.
- It’s unclear if the condition is more common in the United States.
- It’s also uncertain if certain races are more likely to have ISCA than others.
Signs and Symptoms of Spinal Cord Abscess
ISCA, or infectious spondylodiscitis, is a condition that can present in various stages: acute (lasting less than a week), subacute (lasting 1 to 6 weeks), or chronic (lasts more than six weeks).
It’s seen quite often in males, especially in their first and third decades of life. For females, slightly higher risks are seen within the first four decades, while for males, the risk remains constant throughout life.
Symptoms of ISCA can include fever, pain, and neurological deficits. However, not all patients have these symptoms; fever may or may not be present. In subacute or chronic cases, these symptoms may be altogether absent. In its acute stage, ISCA might look like acute transverse myelitis. If it’s chronic, it might resemble spinal cord tumors and chronic myelopathy.
Children with ISCA often have a rapid course of symptoms while adults tend to have a more gradual onset. The average age at which children show symptoms is three years. Only about one-third of children will have a fever in the early stages. Nearly 90% experience neurological issues. Other symptoms seen include stiffness of the neck in 20% of cases or checking of certain blood markers that show up in about 55% of cases.
The main signs and symptoms in children with ISCA are:
- Motor deficits (90% of cases)
- Infection signs (86% of cases)
- Sensory deficits (40% of cases)
- Urinary dysfunction (44% of cases)
- Bowel dysfunction (18% of cases)
A study of ISCA in adults and children showed the most common symptoms to be motor deficits, fever, pain, and bladder dysfunction. The tendency towards acute, subacute, and chronic phases varies amongst different patient groups. The most common symptoms include:
- Motor impairment (99% of cases)
- Sensory loss (87% of cases)
- Pain (56% of cases)
- Urinary involvement (50% of cases)
Testing for Spinal Cord Abscess
If you have symptoms that indicate an inflammatory spinal cord abscess (also known as ISCA), your doctor may order certain laboratory tests to check for inflammation. These could include tests that measure your white blood cell count, C-reactive protein (a substance in the blood that shows if inflammation is present), and erythrocyte sedimentation rate (tests how quickly red blood cells settle at the bottom of a test tube indicating inflammation). About 54% of patients with this condition have elevated levels of these markers.
An abnormal CSF (CerebroSpinal Fluid) study can also be seen in 78% of patients, showing that something isn’t quite right with the fluid in the brain and spinal cord.
If these tests suggest an abscess, the next step is usually an MRI (Magnetic Resonance Imaging) scan with contrast. This special type of imaging can highlight areas where tissues differ, making it easier to see any abnormalities. On an MRI, the spinal cord abscess typically appears bright on T2 images, a specific type of MRI imaging, and shows a typical ring enhancement when a contrast agent is used.
However, in the early stages of an abscess, this enhancement may look more patchy and ill-defined, whereas in later stages, it usually shows a characteristic peripheral ring enhancement. When treated with antibiotics, the abscess typically gets smaller, and its appearance on the MRI changes with it becoming less bright on T2 images.
Another advantage of MRI is that it can also show other abnormalities, such as swelling (edema) of the spinal cord, spinal dysraphism (a congenital deformity of the spine), and secondary syrinx (a fluid-filled cavity in the spinal cord).
A special type of MRI known as diffusion-weighted MRI can be especially helpful in distinguishing a spinal cord abscess from a tumor and other conditions that could cause similar symptoms.
Sometimes an MRI might show a drop sign or precipitation – this is especially common in intramedullary tubercular abscess (an abscess linked to tuberculosis).
For patients who have a fever of unknown origin, a nuclear medicine imaging test using Indium-111 labeled white blood cells can be very helpful. This test involves giving a small amount of radioactive material that will then accumulate in areas of inflammation.
Treatment Options for Spinal Cord Abscess
Surgical treatment and appropriate antibiotic therapy is the primary way to manage intramedullary spinal abscess (ISCA), an infection inside the spinal cord. This process usually involves an operation where the abscess is either drained by making an incision in the spine or by aspiration (sucking the fluid out) using a needle guided by a navigation system. Sometimes there is a risk of cord injury, so the procedure is done carefully without using drills.
The surgical procedure often includes the use of a fluorescent dye to identify and plan the operation. Devices such as an intra-operative ultrasound are used to accurately determine the site and depth of the incisions, particularly in situations where there are multiple abscesses. Neuromonitoring technology aids in ensuring the safest removal of the infectious material, and an incision is typically made where the spinal cord is most swollen. To break up the abscess, a special tube is inserted, and the area is washed with an antibiotic solution.
In some cases, instead of a typical abscess, solid inflamed tissue and other problematic tissue are present and need to be safely removed after biopsy. If the infection spans the entire spinal cord, drainage and aspiration is usually done with the help of a catheter or feeding tube. Specific devices are sometimes used for post-operative care to frequently drain the area.
To prevent any future spinal deformities, particularly in children, techniques referred to as expansile duraplasty and osteopathic laminoplasty are performed. This involves using artificial or harvested materials to replace and support the structure of the spinal cord and to alleviate the pressure caused by swelling.
In order to prevent potential complications, a full removal of the dermal sinus tract (a tube-like structure that connects the skin to deeper tissues or cavities) has been suggested. Steroids might be used very cautiously to reduce the swelling and inflammation on the spinal cord.
Interestingly, between 25-40% of ISCA are sterile, meaning there are no live bacteria or micro-organisms in the abscess. However, in the cases that involve micro-organisms, the most common culprits include staphylococcus, streptococcus, escherichia coli, proteus, listeria, and others.
In treating ISCA, early broad-spectrum antibiotics are usually initiated promptly. These are aimed at fighting off a wide variety of bacteria including, but not limited to staphylococcus, streptococcus, and various types of gram-negative bacilli and anaerobes (bacteria that can live without oxygen). The antibiotics are typically given through an intravenous line for 4 to 6 weeks, followed by oral antibiotics for at least 2 to 3 months. The preferred combination of antibiotics usually includes vancomycin, metronidazole, and cefotaxime.
What else can Spinal Cord Abscess be?
Here are some medical conditions that can appear similar to Intramedullary Spinal Cord Abscesses (ISCA) and need to be ruled out during diagnosis:
- Acute transverse myelitis
- Tuberculomas
- Hypervascular neoplasm (conditions like ependymoma, hemangioblastoma, astrocytoma)
- Metastatic lesions (like renal cell carcinoma)
- Demyelinating lesions
- Resolving hematoma
- Cord infarction
- Neurocysticercosis
- Schistosomiasis
- Type I dural fistula
- Cavernous malformations
To accurately identify ISCA, medical professionals look out for certain signs including decreased diffusion within the cavity of ISCA on a Diffusion-Weighted Imaging (DWI) scan, and the rapidly worsening nature of the condition. This helps differentiate ISCA from conditions that may appear similar.
What to expect with Spinal Cord Abscess
Recovering from a brain condition known as ISCA depends mainly on how quickly it’s diagnosed, how soon surgical treatment is given, and the use of the right antibiotics. Studies of ISCA in children have found varying rates of recovery and lasting effects.
In a study of 38 cases from 1875 to 2001, 18% of children made a full recovery, while 39% had mild lasting effects. 11% suffered severe, lasting effects, and unfortunately, 21% passed away.
More recent data from 137 cases shows an improvement: 20% recover fully, but 17.1% have some lasting effects while 40% suffer long term issues. The death rate in this group was 14.2%.
Why is this varying? Well, certain factors can affect recovery. For instance, children whose ISCA is due to infected cysts in the skin (dermoid cysts) have less than a 20% chance of neurological improvement. Also, children who have fever and weakness in a limb were seen with higher chances of a less positive outcome.
But there’s some good news. With advances in areas like antibiotics, imaging tests (radiology), and surgery, the death rate for ISCA has dropped dramatically – from 90% between 1840 and 1944, to between 4 and 8% from 1998 to 2007. Interestingly, though, as many as 40 to 70% of patients still experience some lasting neurological issues, despite these advances. These individuals can benefit from physiotherapy and other rehabilitation methods to help manage their symptoms.
Possible Complications When Diagnosed with Spinal Cord Abscess
Neurological effects in patients may occur from:
- Mechanical compression.
- Septic thrombosis leading to spinal cord damage.
- Formation of fluid-filled cavities in the spinal cord known as syrinx.[44]
If the abscess accidentally ruptures and spreads, it could result in:
- Meningitis, an infection of the protective layers around the brain and spinal cord.
- Abscess in the brain.
- Meningoencephalitis, a serious condition causing inflammation of the brain.
- Sepsis, a serious blood infection.
- Possibility of death.[7]
Recovery from Spinal Cord Abscess
The biggest factor affecting the condition of children with ISCA is whether or not they are paralyzed, which happens about 60% of the time. Specialists in Physical Medicine and Rehabilitation can help those who are having trouble moving around or doing daily activities.
Doctors recommend checking in regularly and getting an MRI within the first year after surgery to make sure the ISCA has not come back, as this happens in about 25% of cases. They also suggest ongoing follow-up appointments as the ISCA can come back even a long time after the surgery.
Preventing Spinal Cord Abscess
It’s important for patients to grasp the seriousness of their own health issues. This is especially so when dealing with an abscess, which is a pocket of pus that has collected in one spot. The ideal treatment method can differ quite a bit, depending on the specific position and condition of the abscess.
For instance, if the abscess is pressing on the spinal cord, surgery will be needed to remove it. Patients will also need to be briefed about what to do after this operation, commonly known as a laminectomy. In cases where the abscess is causing neurological symptoms or a condition known as cauda equina syndrome, which affects the nerves in the lower back, emergency treatment is required due to the severe nature of the condition.
Following surgery, patients have to adhere strictly to all therapeutic activities in order to recover properly. If surgery isn’t needed, patients will receive guidance on how to properly follow their antibiotic prescription to fight the infection.
Spinal dermal sinus tracts, which are rare congenital deformities that involve the skin on the back and the spine, should be treated through surgery as soon as possible. If the sinus is completely removed before the child is six months old, it can prevent the formation of an intraspinal abscess collection (IASC), a potential complication.