Spinal Cord Abscess

Overview

A spinal cord abscess (SCA) is an uncommon illness that can result in persistent spinal cord injury and is linked with a high death rate and neurological morbidity. An abscess is a swelling region of your tissues that has a pus accumulation. It occurs when infected tissues get harmed. White blood cells are sent by your body's immune system to aid in the battle against illness. White blood cells start to fill the injured tissue, causing pus to form. Dead cells, immune cells, and bacteria make up pus.

Bacterial infection of the spinal cord is the most common cause of SCA. SCAs are most commonly caused by bacteria from the Staphylococcus and Streptococcus species. Once inside your body, these bacteria may find a home and flourish in your spinal cord.

An SCA may not cause any symptoms at first. However, if the infection or abscess spreads, it might put pressure on your spinal cord. The infection and pressure can produce potentially catastrophic symptoms such as quick onset of pain, rapid onset of weakness, loss of feeling below the abscess, paralysis below the abscess, loss of control of your bladder and intestines, and fever.

A prompt identification and treatment of this condition are critical for preventing long-term significant spinal cord injury or death. SCAs have become exceedingly infrequent with the widespread use of antibiotics. If you get one, your doctor would most likely treat it with surgery and antibiotics. They may also advise you to seek rehabilitative treatment to aid in your recovery from neurological issues.

Is Spinal Cord Abscess Common?

There have been at least 120 cases recorded in the medical literature since Hart first described the diagnosis in 1830. ISCA has a bimodal age distribution, with the majority of cases occurring in the first and third decades of life. Men are also more often affected than women. It is unknown whether this ailment is more frequent in the United States per capita than elsewhere in the globe, or whether particular races are more prone to be affected than others.

What Causes Spinal Cord Abscess?

Bacterial infection of the spinal cord is the most common cause of SCA. SCAs are most commonly caused by bacteria from the Staphylococcus and Streptococcus genera. Once inside your body, these bacteria may find a home and flourish in your spinal cord. Your body sends white blood cells to combat the bacterial infection, resulting in pus buildup and the formation of an abscess.

Other possible causes of an SCA include:

boils that develop on your skin, especially on the skin of your back or scalp.
septicemia, an infection of your blood that can spread to your central nervous system.
injury caused by a foreign object, such as a bullet or knife.
complications from back surgery or a lumbar puncture procedure.
dermal sinus, a channel that can form between your skin and spinal canal while you’re developing in utero.
tuberculosis.

How Does it Develop?

The spinal cord requires blood circulation of its tissues in order to function. When the pia mater is breached or a patient becomes infected in the bloodstream, the pathogen may pass across the blood-cord barrier.

As a component of the central nervous system, the blood-cord barrier is functionally equivalent to the blood-brain barrier, putting a subset of the population - particularly immunocompromised or intravenous drug users - at risk of developing a spinal cord infection due to mechanisms similar to those that can cause a brain abscess.

Risk Factors for SCA

Bacteria are the most common cause of a spinal abscess. The most prevalent organism is Staphylococcus aureus, followed by Escherichia coli. A fungal infection can induce an abscess in rare situations.

The risk for developing a spinal epidural abscess is increased in the following situations:

Recent back surgery or recent invasive procedure involving the spine.
An infection in the blood.
A boil (pus-filled bump under the skin caused by an infected hair follicle), especially on the back or scalp.
Bone infections of the spine (vertebral osteomyelitis).
Immunodeficiency [for example, acquired immunodeficiency syndrome (AIDS), chemotherapy, and immunosuppressive medications given to those who have undergone an organ transplant].
Spinal trauma.

Signs & Symptoms of SCA

Make a note of any infection, trauma, fever, or surgery on the thoracolumbar spine. The patient's history may show a condition that predisposes the patient to the acquisition of virulent blood-borne infections or immunosuppression, such as diabetes, HIV positive, or glucocorticoid usage.

Take note of any exposure to intravenous infection pathways, such as IV drug usage. The history may also indicate spinal cord trauma, leading in a breach of the pia mater and compromise of the blood-cord barrier. Spinal epidural abscess, vertebral osteomyelitis, or brain abscess are examples of local or systemic infections that can lead to ISCA.

Take note of any motor or sensory deficits, as well as the myotomes and dermatomes they display, during a physical examination. Consider vital indicators indicating fever or laboratory findings indicating leukocytosis, keeping in mind the limited sensitivity of these values.

Take note of lumbago that is localized to the midline of the back or that is referred along a dermatome. Pain on spinal palpation is unlikely with an ISCA, although it might indicate osteomyelitis, a compression fracture, or cancer. Regardless of whether or not there is an abscess of back discomfort, additional assessment is necessary in light of other positive findings on history or examination.

Diagnosis of SCA

Fever, leukocytosis, back discomfort, and localized neurological impairments should necessitate an urgent radiographic assessment of the spine utilizing MRI with gadolinium. Take note of any loss of bladder or bowel continence. Progressive lower-extremity paraparesis or saddle anesthesia might be symptoms of focal neurological abnormalities.

This constellation of symptoms is considerably more likely to be caused by a spinal epidural abscess than by ISCA. This workup, however, may reveal that the patient does, in fact, have an ISCA. This ISCA can be single or numerous, although it is more often solitary. It is most commonly seen in the thoracic distribution, however it may be found anywhere throughout the spinal cord.

Laboratory Studies:

Preoperative lab investigations include a CBC count, blood cultures, and blood cultures. Leukocytosis affects around two-thirds of individuals.
ESR (erythrocyte sedimentation rate) elevation: According to one study, the average ESR was 51 mm/h. The ESR may be quite high.
Leukocytosis and ESR elevation are nonspecific laboratory results that do not always occur. The existence of these symptoms, as well as the degree of laboratory abnormalities, are not specific for spinal epidural abscess.

Imaging Studies:

When the diagnosis is clinically suspected, immediate imaging of the spine and spinal cord is required.

Gadolinium-enhanced magnetic resonance imaging is the preferred method for detecting a suspected intramedullary spinal cord abscess. If there is a high possibility of a spinal anomaly, an MRI of the region will reveal the mass. Magnetic resonance imaging can also be used to show any related disease process (eg, epidural or subdural infection, bone involvement, dermal sinus).

Magnetic resonance imaging does not distinguish between different types of masses (for example, tumor vs abscess), while an abscess usually has ring enhancement and a metastatic lesion usually has a nodular pattern of enhancement.

On T1-weighted images, spinal cord abscesses cause uniform spinal cord expansion but high signal intensity on T2-weighted images. Gadolinium is used to brighten the abscess edge.

Diffusion-weighted imaging (DWI) with a b-value of 1000 and apparent diffusion coefficient (ADC) maps identify abscess and pus accumulation early and accurately. Diffusion-weighted MRI can help patients with pyogenic and nonpyogenic spinal infections not only diagnose but also plan therapy.

The majority of conventional diagnostic techniques are ineffective in detecting an abscess. Plain radiographs simply reveal bone changes (if present). Myelography often demonstrates spinal cord expansion.

Other Tests:

If a spinal epidural abscess is suspected, lumbar puncture (LP) is often contraindicated. However, LP may be required to rule out meningitis in the differential diagnosis. Lumbar puncture exposes the patient to the possibility of introducing pathogenic material into the subarachnoid space. If a spinal epidural abscess is suspected, some recommend cautiously extending the needle with gentle syringe aspiration; if purulent material is encountered, it should be aspirated gently to acquire laboratory specimens, and the needle should not be advanced further.

Cerebrospinal fluid (CSF) may contain inflammatory cells, which are often a mix of polymorphonuclear and mononuclear cells. Cell counts are typically elevated, ranging from 10-1000 leukocytes/L. CSF protein is normally raised at 100 mg/dL, although it can be higher, especially if there is a spinal block. CSF glucose levels are normally normal; depression may suggest the presence of concomitant meningitis.

Possible Complications

The abscess can injure the spinal cord from direct pressure. Or, it can cut off the blood supply to the spinal cord.

Complications may include:
Infection returns.
Back pain.
Loss of bladder/bowel control.
Loss of sensation.
Male impotence.
Weakness, paralysis.

Treatment / Management

Medical Therapy:

Treatment consists of three components: surgical draining of the abscess chamber, identification of the infectious organism, and administration of suitable antibiotics for an appropriate period of time.

Steroids are given throughout the therapy to minimize spinal cord swelling and edema caused by the abscess.

Cultures of the abscess cavity should include testing for aerobic and anaerobic bacteria, fungi, and TB, as indicated under Lab Studies. Slides to search for parasites are also advised.

Before identifying the organism, a broad-spectrum penicillin should be given.

Antibiotics can be provided once the organisms have been identified and their sensitivities have been determined.

ISCA complications include bowel and bladder incontinence, paraplegia, dysesthesia, and weakness.

Consultations with neurologists, neurosurgeons, infectious disease experts, and physical medicine and rehabilitation specialists are also possible.

Surgical Therapy:

Once the abscess has been located via MRI, a laminectomy is performed to expose the lesion and the surrounding cord. For total abscess visibility, a laminectomy is frequently performed 1 level above and below the abscess borders. The dura is opened, and the location of spinal cord involvement is diagnosed by edema, bleeding, and dilated veins.

At this time, the lesion is aspirated for aerobic and anaerobic organism culture, as well as fungal infection and TB testing. A thorough Gram stain and India ink preparation should also be examined. Following that, a myelotomy is done down the length of the abscess, with full draining of the abscess cavity. Finally, the incision and abscess cavity are treated with an antibiotic solution, and anatomic layers of closure are accomplished. A drain is not required.

Dexamethasone is used to minimize cord swelling during the preoperative period. The standard dose is 4-10 mg every 6 hours.

Following surgery, intravenous antibiotic treatment is administered for a minimum of 6 weeks. Dexamethasone, like in the preoperative period, can be given to minimize cord swelling during the postoperative period. The standard dose is 4-10 mg every 6 hours. Steroids are reduced gradually over time (eg, after 2 weeks of treatment).

Follow-up MRI will be used to identify the return of the abscess. However, the cavity will most likely be enhanced for several weeks.

Outcome

The patient's neurologic state shortly before surgery is the single most important predictor of the eventual neurologic outcome. Unless perioperative difficulties arise, the final neurologic status in patients with an appropriately decompressed spinal epidural abscess is as good as or better than the preoperative condition.

Patients undergoing surgery in stages 1 or 2 are predicted to stay neurologically intact and may have a lower chance of back and radicular discomfort, but those in stage 3 may have no or less weakness after surgery than before surgery. Patients in stage 4 who have been paralyzed for 24 to 36 hours are likely to regain some neurologic function following surgery.

Unsurprisingly, there is no published data comparing the postoperative prognosis in individuals who were paralyzed for varying lengths of time throughout the surgical window of opportunity of 24 to 36 hours. In certain patients with virulent illness and fast worsening of their neurologic status, earlier surgery may be associated with a better prognosis. Similarly, neurologic worsening between admission and correct diagnosis may result in a worse prognosis.

Although MRI findings (related to the length of the abscess and the extent of spinal-canal stenosis), degree of leukocytosis, and level of elevation of the erythrocyte sedimentation rate or C-reactive protein were reported to correlate with outcome, these potential relationships were identified by univariate analyses that did not take pretreatment neurologic status into account and, thus, need to be investigated further.

Approximately 5% of patients with spinal epidural abscess die, mainly as a result of uncontrolled sepsis, the progression of meningitis, or other underlying disorders. Patients' final neurologic result and functional ability should be evaluated at least one year following therapy, because patients may continue to regain some neurologic function and benefit from rehabilitation until then. Pressure sores, urinary tract infection, deep-vein thrombosis, and pneumonia in individuals with cervical abscess are the most prevalent consequences of spinal cord damage.

A well-coordinated multidisciplinary approach involving emergency medicine specialists, hospitalists, internists, infectious-disease physicians, neurologists, neurosurgeons, orthopedic surgeons, nurses, and physical and occupational therapists is required for the best possible outcome.

Conclusion

Spinal cord abscess is an uncommon condition, especially in children. Extradural, subdural, and intradural (intramedullary or extramedullary) spinal cord abscesses are all possible, with intramedullary being exceedingly rare.

Spinal cord abscesses form in the parenchyma of the spinal cord and can be single or numerous, contiguous or isolated, chronic or acute, depending on the organism and the particular patient. Solitary lesions, as predicted, are more prevalent and are most likely to arise in the thoracic cord.

ISCA's cause is mostly infectious. An infection of the spinal cord parenchyma can be acquired in two ways: by hematologic transfer or through contact with contaminated tissue or cerebrospinal fluid. Although ISCA is mainly caused by SEA, various etiologies have been identified. Aortic valve endocarditis is one case. In another case, ISCA was linked with a spinal dural arteriovenous fistula, which facilitated hematogenous spinal cord infection.

Signs and symptoms vary depending on the location and length of the abscess, as with other CNS disorders. Symptoms of infection (e.g., fever, chills, back pain, malaise) are typical in an acute presentation. Weakness, paresthesia, dysesthesia, bladder and bowel incontinence, and acute paraplegia are examples of neurologic symptoms and signs. The location of the abscess in the spinal cord determines the neurologic signs and symptoms; the thoracic spinal cord is the most common site for an intramedullary abscess. Clinical signs are comparable to those seen in individuals with epidural abscesses, although there is no percussion discomfort.

In more chronic instances, the signs and symptoms are similar to those of an intramedullary tumor, and neurologic symptoms outnumber those of a systemic infection. Neurologic progression is slow. A high level of awareness is required to diagnosis chronic spinal cord abscess; acute abscesses, on the other hand, are typically observed in critically sick individuals who report with sudden onset of back pain.