SPINAL INFECTIONS

Spinal Infections

An infection in the area between the bones of the spine or on the outer covering of the spinal cord is known as a spinal epidural abscess. Although uncommon, if left untreated, a spinal epidural abscess can kill a person. Early diagnosis and treatment are associated with the best prognosis and the lowest risk of complications. Also, spinal epidural abscesses are most commonly found in the thoracic or lumbar regions. Furthermore, an underlying infection accompanies the abscess.  Now, the underlying infection may be distant (e.g., endocarditis, furuncle, dental abscess) or contiguous (e.g., endocarditis, furuncle, dental abscess, vertebral osteomyelitis, pressure ulcer, or retroperitoneal abscess).

In roughly one-third of cases, the cause remains unknown. On the other hand, staphylococcus aureus occurs more than any other, followed by Escherichia coli and mixed anaerobes. A tuberculous abscess of the thoracic spine can occasionally occur, while bacteremia can occur as a result of medical instrumentation, a dental procedure, or IV drug use. A similar abscess can occur in the subdural space on rare occasions.

Epidural Abscess Defined

An epidural abscess is an infection that develops in the space between your skull bones and the lining of your brain. It frequently forms in the space between your spine’s bones and the lining membrane of your spinal cord. Also, an epidural abscess causes a pocket of pus to form and cause swelling.

It can put pressure on your bones as well as the membranes that protect your spinal cord and brain. For instance, this swelling, as well as the underlying infection, can interfere with sensations and physical movement, as well as cause other issues. Doctors should treat an epidural abscess as soon as possible. An epidural abscess is typically caused by a Staphylococcus aureus bacterial infection. Additionally, it could also originate via a fungus or another germ circulating the body. Often, healthcare providers cannot determine the cause of an infection.

What can Cause a Spinal Epidural Abscess?

Some of the most common causes of an epidural abscess are as follows:

• Previous back surgery or an invasive spine procedure.
• Infections of the circulatory system
• Cervical osteomyelitis (bone infection of the spine).
• Use of intravenous drugs
• Consistent sinusitis
• Ear infections that are chronic.
• Recent brain surgery
• A brain injury

Symptoms and Signs of a Spinal Epidural Abscess

The signs and symptoms of an epidural abscess vary according to the location of the abscess and may include:

• Disruption of consciousness.
• Problems with coordination and movement.
• Unusual sensations all over the body.
• Difficulty walking.
• Increased muscle weakness in both the legs and the arms.
• Inability to regulate bladder or bowel motions.
• Nausea or the sensation of vomiting.

Diagnosis of Spinal Infections

Because prompt treatment will avoid or minimize neurologic deficits, clinicians should consider spinal epidural abscess if patients have significant atraumatic back pain, especially if a tenderness exists over the spine, or if they have a fever or have recently had an infection or dental procedure. Characteristic neurologic deficits are more specific but may appear later, so delaying imaging until these neurologic deficits are present may increase the likelihood of a poor outcome. If a person has symptoms of an epidural abscess, the doctor may order magnetic resonance imaging (MRI). Therefore, an MRI provides detailed images of organs and structures within the body using a combination of large magnets, radio frequencies, and a computer.

The doctor will draw blood to perform a complete blood count (CBC) to determine if infection exists. The amount of white blood cells increases during an infection. This occurs because white blood cells attack and destroy the organisms that cause the infection. In this case, blood cultures can identify the organism (bacteria or fungus) that produces the infection.

Imaging Tools

Imaging studies will determine the exact location and extent of a lesion. The specific imaging techniques used vary slightly depending on the location of the infection.

Spinal Infections Risk Factors

Bacteria typically cause spinal epidural abscesses. In his case, Staphylococcus aureus appears as the most prevalent organism, followed by Escherichia coli. Additionally, a fungal infection can cause an abscess in some cases. The following circumstances increase the likelihood of developing a spinal epidural abscess:

• Recent back surgery or invasive spine procedure.
• A bacterial infection in the blood.
• A boil (a pus-filled bump beneath the skin caused by an infected hair follicle), most commonly on the back or scalp.
• Spine-related bone infections (vertebral osteomyelitis).
• Immunodeficiency [for example, an acquired immunodeficiency syndrome (AIDS), chemotherapy, and immunosuppressive medications administered to organ transplant recipients].
• Spinal cord injury.

Treatment of Spinal Infections

Surgery and antibiotics or antifungals are commonly used to treat spinal epidural abscesses. In some cases, treatment may consist solely of antibiotics. Thus, antibiotics are typically administered for 4-6 weeks. If the abscess puts pressure on the spinal cord, the surgeon will perform surgical spinal cord decompression to reduce/remove the pressure. Moreover, the surgeon may perform a laminectomy to remove the lamina, a bone that covers the spinal canal, to decompress the spinal cord. Also, the removal of the lamina makes room for the spinal cord and allows it to function properly. In most cases, Doctors recommend  a laminectomy for complicated infections.

If the abscess causes neurological symptoms like bladder/bowel dysfunction, via the cauda equina syndrome, the surgeon will immediately drain the abscess. After draining the abscess, the surgeon will order a culture to ensure that the medications prescribed are effective against the specific organism causing the infection. In cases where neural structures are compressed, immediate surgical decompression and drainage are required. As such, doctors will collect the abscess fluid for culture and diagnostic purposes. If left untreated, serious complications such as the following can occur:

• Infection within the skull or spine bones.
• Meningococcal meningitis (infection of the meninges).
• A spinal cord abscess
• Chronic back pain.
• Permanent nervous system or brain damage, including paralysis
• Untreated spinal epidural abscesses

Antimicrobial Therapy

Doctors recommend bed rest and parenteral antimicrobials to treat spinal epidural abscesses that do not compromise neurological function. However, due to the risk of progressive neurological dysfunction despite antimicrobial therapy, as well as the link between improved outcome and preoperative neurologic function, doctors will closely monitor the patient.  In addition, surgical intervention should occur at the first sign of deterioration. Medical management will occur in patients who possess neurological symptoms; patients who may experience complications during surgery; patients who possess complete paresis for more than 48-72 hours, or in patients who experience extensive infections involving many vertebral levels of the neural axis.

When a significant surgery gets delayed and significant neurologic dysfunction occurs, or the patient is septic or critically ill, antimicrobials should be started. Also, empiric antimicrobial therapy should begin as soon as cultures are obtained and should cover both Gram-positive cocci (including methicillin-resistant S. aureus (MRSA), such as vancomycin) and Gram-negative bacilli (third- or fourth-generation cephalosporins, such as ceftriaxone, ceftazidime, or cefepime), especially in patients with distant Gram-negative infection or bacteremia.

There are no evidence-based recommendations for the duration of parenteral antimicrobials for spinal epidural abscesses that do not compress epidural regions. However, clinical efficacy usually suggests a course of 6 to 8 weeks of parenteral antimicrobials. Although, some specialists will prescribe oral antimicrobials for an additional 1 to 2 months, close monitoring will occur.

Nonsurgical Treatment

Long-term intravenous antibiotic or antifungal therapy becomes necessary for spinal epidural abscesses, which can result in the patient being hospitalized for an extended period of time. In addition, immobilization may occur when there significant pain or the possibility of spine instability exists. Once the organism causing the infection has been identified, antibiotic treatment should begin if the patient is neurologically and structurally stable. As such, doctors will prescribe antimicrobial therapy to patients for at least six to eight weeks. In the end, doctors will prescribe Individual medication based on the patient’s unique circumstances, including age.

Surgical Treatment of Spinal Infections

Finally, doctors should implement nonsurgical treatments when patients display low or no neurological abnormalities and surgical intervention has a high morbidity and death rate. However, if any of the following conditions exist, doctors will suggest surgery:

• Significant bone destruction, which causes spinal instability.
• Deficits in neurology.
• Sepsis with clinical toxicity caused by an antibiotic-resistant abscess.
• The needle biopsy was unable to obtain the required cultures.
• Intravenous antibiotics cannot eradicate the infection.

The primary goals of surgery:

• Remove infected tissue (clean and remove it).
• Allow sufficient blood flow to infected tissue to aid in healing.
• Restore spinal stability by instrumenting the unstable spine.
• Restore function or lessen neurological impairment.

When surgery becomes necessary, imaging tools such as plain x-rays, CT scans, or MRI can help further pinpoint the the area where surgery will benefit the patient.