Spinal subdural and epidural abscess

Spinal subdural and epidural abscess is an accumulation of pus in the subdural or epidural space that causes mechanical compression of the spinal cord.

Spinal subural and epidural abscesses usually occur in the thoracic and lumbar regions. Usually it is possible to identify the focus of infection. It can be at a distance (for example, endocarditis, furuncle, dental abscess) or nearby (for example, spine osteomyelitis, pressure ulcers, retroperitoneal abscess). It can occur spontaneously, spreads hematogenically, is often a consequence of an infection of the urinary tract, which spreads to the epidural space through the intertwining of Butson. Most often, epidural abscess occurs after instrumental action on the spinal cord, including surgical operations and epidural neural blockades. The literature indicates that the introduction of steroids into the epidural space leads to immunosuppression and an increase in the incidence of epidural abscesses. Despite the theoretical likelihood, statistics (given that thousands of epidural injections are conducted in the US daily) leave this opinion in doubt. In about 1/3 of the cases, the reason can not be established. The most common spinal subdural and epidural abscess is caused by Staphylococcus aureus, followed by E. Coli and mixed anaerobic flora. Rarely, the cause may be a tuberculous abscess of the thoracic region (Pott's disease). Can occur in any part of the spine and skull.

Symptoms begin with local or radicular pain in the back, tenderness with percussion, which are gradually more pronounced. Usually there is a fever. Compression of the spinal cord, the cauda equina roots, causing paresis of the lower extremities (horse tail syndrome) can develop. Neurological deficits can progress for hours and days. Subfebrile temperature and general symptoms, including malaise and lack of appetite, progress to severe sepsis with high fever, stiffness and chills. At this point, the patient has a motor, sensory deficit, symptoms of the bladder and bowel as a result of compression of the nerves. As the abscess spreads, the blood supply to the affected area of the spinal cord is impaired, which leads to ischemia and, in the absence of treatment, to a heart attack and an irreversible neurological deficit.

Diagnosis is clinically confirmed by pain in the back, worse in the supine position, paresis of the legs, dysfunction of the rectum and bladder, especially when combined with fever and infection. It is diagnosed by means of MRI. It is necessary to study the bacterial culture from blood and inflammatory foci. Lumbar puncture is contraindicated, since it can cause an abscess with an increase in compression of the spinal cord. Routine radiography is indicated, but it reveals osteomyelitis in only 1/3 of the patients.

All patients with suspected epidural abscess should undergo laboratory tests, including a general blood test, ESR, blood biochemistry. Also, in all patients with a pre-epidural abscess, a blood and urine culture should be taken to immediately initiate antibiotic therapy until the examination is completed. It is necessary to stain Gram and get a culture, but do not delay treatment with antibiotics until these results are obtained.

A quick start of treatment is essential to prevent such consequences as irreversible neurological deficits or death. Treatment of the epidural abscess has two purposes: treating the infection with antibiotics and draining the abscess to reduce the compression of the neural structures. Since most cases of epidural abscess are caused by Staphylococcus aureus, treatment with antibiotics, such as vancomycin, which affects staphylococcal infection, should begin immediately after a blood and urine culture is taken. Antibiotic therapy can be corrected taking into account the results of culture and sensitivity. As mentioned, do not delay the onset of antibiotic therapy until a final diagnosis is made if the epidural abscess is treated as a differential diagnosis.

The administration of antibiotics is rarely effective, even if the diagnosis was made at the onset of the disease; for an effective recovery requires the drainage of the abscess. Drainage of the epidural abscess is usually performed by decompression laminectomy and evacuation of the contents. Recently, surgeons-radiologists have succeeded in draining the epidural abscess percutaneously, using drainage catheters under the control of CT and MRI. Series CT and MRI are useful in the future when solving the process; The scan must be repeated immediately at the first sign of impairment of the patient's neurological status.

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Differential diagnosis

The diagnosis of an epidural abscess should be suspected and excluded in all patients with back pain and fever, especially if the patient underwent spinal surgery or an epidural blockade for surgical anesthesia or pain control. Other pathological conditions that need to be considered as a differential diagnosis include spinal cord diseases proper (demyelinating diseases, syringomyelia), and other processes that can lead to compression of the spinal cord and nerve root exit sites (metastatic tumor, Paget's disease and neurofibromatosis). The general rule is that, without concomitant infection, none of these diseases is usually accompanied by fever, only pain in the back.

Failure to diagnose and quickly and thoroughly treat an epidural abscess can lead to a catastrophe for both the doctor and the patient.

The asymptomatic onset of a neurological deficit associated with an epidural abscess can inspire a doctor with a sense of security, which in turn can cause irreversible harm to the patient. If you suspect an abscess or other cause of spinal cord compression, you should follow the following algorithm:

• Immediate collection of blood and urine for culture
• Immediate initiation of treatment with high doses of antibiotics, whose spectrum of action is covered by Staphylococcus aureus
• Immediate assignment of available imaging techniques (MRI, CT, myelography) that can confirm the presence of spinal cord compression (tumor, abscess)
• In the absence of one of the above measures, the patient must be immediately transported to a highly specialized center
• Repetition of the study and surgical consultation with any deterioration in the neurological status of the patient

The delay in making the diagnosis puts the patient and the doctor at great risk of an unfavorable outcome. The doctor should presume in all patients with back pain and fever to diagnose an epidural abscess until another diagnosis is confirmed and treat accordingly. Excess confidence in a single negative or questionable result of the visualization method is an error. The CT and MRI series are shown with any deterioration in the neurological status of the patient.

[8], [9], [10], [11], [12], [13], [14], [15]