Spinal epidural abscess is a limited purulent inflammation of the epidural spinal space. It is manifested by acute back pain, transforming into radicular syndrome, the appearance and progression of paresis, pelvic disorders and sensitive disorders in accordance with the topic of the abscess. During the diagnosis, it is optimal to conduct an MRI of the spinal cord, in the absence of such a possibility — spinal puncture and myelography. Treatment consists in the earliest possible surgical decompression of the spinal cord with drainage of the abscess, carried out against the background of massive antibiotic therapy.
General information
Spinal epidural abscess is a local purulent-inflammatory process that occurs in the epidural space. The latter is a gap located between the dura (dural) spinal meninges and the walls of the spinal canal. The epidural space is filled with loose fiber and venous plexuses. Through it, purulent inflammation can spread in the cerebral or caudal direction, occupying a space corresponding to several vertebral segments.
In the literature on neurology, spinal epidural abscess can be found under the synonymous name “limited purulent epiduritis”. The frequency of occurrence of epidural abscess of the spinal cord on average is 1 case per 10 thousand hospitalizations. Most often, about half of the cases, there is an abscess of the mid-thoracic spine. About 35% are due to epidural abscesses of the lumbar region, 15% – to the cervical region. Mostly people aged 40 to 75 years with reduced resistance of the immune system get sick. The current trend towards an increase in morbidity is likely due to an increase in the elderly population and the number of people with reduced immunity.
Causes
Spinal epidural abscess is a consequence of infection entering the subdural space. Staphylococci (50-60% of cases), streptococcal infection, anaerobic microorganisms, specific pathogens (for example, tuberculosis bacillus), fungi can act as infectious agents. Infection can be introduced into the epidural space by hemato- and lymphogenic methods from remote infectious foci existing in the body, such as furunculosis, pharyngeal abscess, suppurated mediastinal cyst, infectious endocarditis, pyelonephritis, purulent cystitis, periodontitis, purulent otitis, pneumonia, etc.
Spinal epidural abscess can occur as a result of the spread of purulent inflammation from nearby structures in osteomyelitis or tuberculosis of the spine, abscess of the lumbar muscle, bedsores, retroperitoneal abscess. Approximately up to 30% of cases of epidural abscess are associated with the penetration of infection due to spinal injury, for example, a fracture of a vertebra with its parts or fragments wedged into the tissue of the epidural space. The formation of a post-traumatic hematoma with its subsequent suppuration is possible. In rare cases, spinal epidural abscess is formed as a complication of epidural anesthesia, lumbar punctures or spinal surgery.
Of no small importance in the development of abscessing is the immunocompromised state of the patient’s body, in which microorganisms penetrating into the subdural space do not receive a worthy rebuff from the immune system. The reasons for the decrease in the immune response may be old age, chronic alcoholism, drug addiction, HIV infection, diabetes, etc.
The formation of an abscess in the spinal epidural space is accompanied by the development of a cerebrospinal fluid block and increasing compression of the spinal cord. In the absence of rapid elimination of an abscess in the spinal cord, irreversible degenerative processes occur against the background of compression, resulting in the formation of a persistent neurological deficit.
Symptoms
A spinal epidural abscess manifests itself with a diffuse back pain corresponding to its localization, a rise in body temperature to high numbers, chills. There is a local rigidity of the vertebral muscles, painfulness of percussion of the spinous processes, positive symptoms of tension. Then comes the 2nd stage of the disease — the pain is transformed into a radiculopathy, which is accompanied by a decrease in tendon reflexes in accordance with the level of lesion. At the 3rd stage, paresis and pelvic disorders occur, indicating compression of the conductive spinal pathways, paresthesia is often observed. The transition to the 4th stage is accompanied by a rapid increase in paresis up to complete paralysis, conductive sensitivity disorders.
The neurological picture is nonspecific. Peripheral flaccid paralysis is noted at the level of localization of a subdural abscess, and below this level, conduction disorders are determined: central paralysis and sensory disorders. In the projection of the abscess on the surface of the back, hyperemia of the skin and swelling of the underlying tissues may be observed.
The rate of development of the clinic in accordance with the above stages is variable. Acute subdural abscess is characterized by the formation of paralysis a few days after the onset of the disease, chronic — after 2-3 weeks. With a chronic abscess, high fever is often absent, subfebrility is more often observed. The transformation of an acute abscess into a chronic one is accompanied by a decrease in body temperature and some stabilization of the clinic, sometimes a decrease in the severity of spinal compression symptoms. The course of a chronic abscess is a change of exacerbations and attenuation of clinical symptoms.
Diagnostics
The non-specificity of symptoms and neurological status data do not allow a neurologist and a neurosurgeon to reliably diagnose a spinal subdural abscess. It can be suspected if there is an infectious process in the spinal column or a remote focus of purulent infection. In the acute process, there are corresponding changes in the clinical blood test (acceleration of ESR, leukocytosis), a chronic abscess is characterized by a weak severity of inflammatory changes in the blood. Data on the nature of the causative agent can be given by blood back-sowing.
Spine x-ray helps to identify or exclude osteomyelitis and tuberculous spondylitis. Lumbar puncture is possible only if the abscess is located above the lower thoracic segments. A lesion below the thoracic level is a contraindication for its implementation, since there is a danger of introducing a puncture needle infection into the arachnoid space with the development of purulent meningitis. In such cases, a suboccipital puncture is possible.
Lumbar or suboccipital puncture is combined with ascending or descending myelography, respectively. The latter reveals extradural (partial or complete) compression of the spinal cord, however, it is not informative enough regarding the differentiation of the volume formation that caused compression, i.e. it cannot distinguish between an abscess, a hematoma and a spinal cord tumor. The most reliable and safe way to diagnose a spinal subdural abscess is to conduct a CT scan, optimally — an MRI of the spine.
Treatment and prognosis
Spinal epidural abscess is an indication for urgent surgical intervention. Spinal cord decompression is performed by laminectomy and drainage of the subdural space. In the presence of osteomyelitis, non-viable bone tissues are removed during the operation, followed by fixation of the spine. A timely operation prevents the development of paresis or reduces their degree.
Antibiotic therapy begins empirically (before receiving the results of bakposev) even at the stage of preoperative preparation with parenteral administration of broad-spectrum drugs (amoxicillin, rifampicin, vancomycin, cefotaxime), their combination or combined antibacterial drugs (for example, amoxicillin + clavulanic acid). Then they switch to oral antibiotics. The duration of antibiotic treatment is from 1 to 2 months. When diagnosing tuberculosis, a phthisiatrician is consulted and anti-tuberculosis therapy is prescribed.
From 18% to 23% of cases of subdural abscess of the spinal cord end in death as a result of sepsis, PE, etc. complications. The most unfavorable prognosis in elderly patients during surgical intervention after the development of paralysis. With early diagnosis and surgical treatment before the onset of paresis, the prognosis is favorable. After surgery, there is a stop in the progression of neurological disorders. However, with the pronounced nature of the neurological deficit, its regression does not occur even in cases when surgical treatment was carried out in the first 6-12 hours of its appearance.