Epidural abscess

Introduction to epidural abscess Epidural abscess is a rare disease that often causes damage to patients due to misdiagnosis. Factors that are prone to epidural abscess include diabetes, chronic kidney disease, immunodeficiency, alcohol abuse, malignancy, intravenous drug abuse, spinal surgery, and trauma. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: thrombosis

Causes of epidural abscess

(1) Causes of the disease

The vast majority are secondary, the primary infection can be adjacent or distant parts of the sore, edema or cellulitis and other purulent lesions, or for various organ infections, such as lung abscess, ovarian abscess, peritonitis, etc. It can also be a complication of systemic sepsis. The location of the disease is closely related to the anatomical features. The dura mater is formed by a two-layer structure of the periosteum and dura mater. The epidural space is filled with loose connective tissue and venous plexus rich in fat. The two layers in front of the dura mater are closely connected and are in contact with the posterior longitudinal ligament of the spine. In fact, there is no cavity. The epidural tissue is mainly on the dorsal side and the lateral side, and gradually increases from the space below the neck. The cavity between ~8 is 0.5-0.7cm, and the cavity between chest 9 and waist 2 is gradually narrowed. Therefore, the lesion is the dorsal side of the spinal cord, and the thoracolumbar segment is the most common, rarely occurring in the upper thoracic segment and the cervical segment.

The main routes of infection are:

1. Blood-borne infection: The pathogenic bacteria pass from the nearby or distant infection to the epidural space through the blood.

2. Direct spread of infection: direct spread from suppurative infections around the spine, such as spinal suppurative osteomyelitis, fistula infection of the appendix.

3. Direct entry: Open trauma such as lumbar puncture or epidural blockage, such as open trauma to the spine.

4. The path of cryptogenic infection is unknown.

Common pathogens are Staphylococcus aureus, Staphylococcus aureus, Streptococcus, Pseudomonas, Salmonella typhi, etc., and occasionally fungi, such as actinomycetes, buds and the like.

(two) pathogenesis

After the pathogen invades the epidural space, cellulitis is formed in the interstitial space rich in fat and venous plexus, with tissue congestion, exudation and massive leukocyte infiltration, further developing adipose tissue necrosis, dural congestion, edema, The pus gradually increases and spreads, forming an abscess. The abscess is mainly located on the dorsal and bilateral sides of the dural sac, rarely invading the ventral side, and the upper and lower spread can reach several segments. In some cases, the spinal canal can be involved. The full length, even to the intracranial spread, the abscess is mostly single, in a few cases there are multiple scattered in the small abscess and a major abscess, the form and dynamic changes of the abscess and pathogenic bacteria, body and local tissue immune response The anatomical features of the epidural space, the vascular and lymphatic system structures, etc., respiratory movements and vascular pulsations can increase the negative pressure difference in the spinal canal, which spreads inflammation through the blood vessels or lymphatic system to the epidural space. It has the function of "attraction", and the mobility of the spinal cord and dura mater caused by the flexion of the head and torso creates favorable conditions for the upper and lower spread of the abscess. The tissue is proliferated and eventually forms granulation tissue. In addition to direct mechanical compression of the spinal cord, the abscess can also cause inflammatory thrombosis of the blood vessels, causing blood supply to the spinal cord, and finally causing spinal cord softening and irreversible damage. According to the pathology of inflammation. Morphology, epidural abscess can be divided into:

1. Acute type: all are pus.

2. Subacute type: pus and granulation tissue coexist.

3. Chronic type: Mainly inflammatory granulation tissue.

Clinically, subacute and chronic types are more common, and acute types are rare.

Epidural abscess prevention

Control the primary infection of each part to prevent it from developing into a dural abscess.

Epidural abscess complications Complications thrombosis

After the formation of the abscess, compression of the spinal cord can also cause inflammatory thrombosis of the blood vessels, causing blood supply to the spinal cord, which may cause paralysis.

Epidural abscess symptoms Common symptoms Frail hypothermia chills back pain high fever sensory disorder abscess spinal cord sphincter edema edema

Most cases present an acute course, and a small number of inflammatory granulation tissues become the main pathological features, which can be manifested as subacute or chronic processes.

Acute epidural abscess

Onset, there are high fever, chills, general fatigue, lack of energy, headache, white blood cell count and neutrophil count increased systemic infection signs, some cases have meningeal irritation, early patients with obvious pain in the back of the lesion, lesions or nearby Spinous processes have tenderness and pain, local skin may have mild edema, tenderness and pain in the paraspinal tissue, nerve root pain due to inflammation of the nerve roots in the lesion, chest to the chest due to different lesions, abdominal radiation In the lumbosacral abscess, lower extremity pain may occur, and urinary retention may occur in the early stage. As the disease progresses, the lower limbs may be weak, numb, pyramidal tract sign, and the transverse symptoms often appear within one to several days after the occurrence of spinal cord symptoms. , manifested as limb flaccid paralysis, sensory disturbance combined with obvious sphincter dysfunction.

2. Subacute epidural abscess

The clinical course is similar to acute, except that the back pain is more obvious and the time is longer. The nerve root pain occurs 1 to 2 weeks after the onset of the disease. The pain is increased due to activity or abdominal pressure such as defecation, coughing, sneezing, and further development of spinal cord dysfunction. .

3. Chronic epidural abscess

The course of the disease is longer, ranging from 1.5 to 18 months. The onset is slow, sometimes there is hypothermia, the symptoms are ups and downs, and the symptoms of spinal cord compression appear, which are manifested as spastic paraplegia, sensation and sphincter dysfunction, and often with intraspinal tumors. Hard to identify.

Examination of epidural abscess

Lumbar puncture in patients with epidural abscess has the risk of bringing the infection into the subarachnoid space. Therefore, this test should not be performed at random. If it is necessary to perform the procedure, the needle should be carefully inserted during the operation. See if there is pus, when there is pus extraction, it is not appropriate to enter the needle to avoid the needle entering the subarachnoid space.

X-ray film

33% to 65% of patients showed abnormal changes in cones and their attachments on X-ray films, 70% of which were found in chronic epidural abscesses and 10% in acute epidural abscesses because of cones and The attachment infection causes bone destruction and hyperplasia, and it takes time for the vertebral body collapse and paravertebral infection.

2. Radionuclide scanning The positive rate is 67% to 100%.

3. Spinal cord iodine angiography

It was the main method for diagnosing epidural abscess, which can identify the segment and extent of the lesion for surgery.

4. CT and CT angiography

The positive rate of enhanced CT examination can reach 100%, and CT canal angiography can reach 90%, but it is still difficult to clearly show the extent of the lesion.

5.MRI

It is currently the most reliable and accurate method for diagnosing epidural abscesses. It can show pyramidal osteomyelitis (T1 low signal, high T2 signal), intervertebral space and soft tissue infection (increased T2 signal) and spinal cord compression and abscess (T1 is a low or equal signal) range, such as MRI and CT still can not be clearly diagnosed, spinal neoformin should be used.

Diagnosis and diagnosis of epidural abscess

Diagnostic criteria

For patients with a history of suppurative infection, especially onset, fever, chills, increased white blood cells, and even symptoms of sepsis, after a certain period of time, severe localized chest and back pain, cramps and local skin edema, if progressive Spinal cord compression, should be highly suspected of the possibility of epidural abscess, epidural puncture if the pus can be extracted, when the diagnosis can be confirmed, spinal X-ray film, spinal iodine angiography, MRI performance helps For diagnosis.

History

Ask the body whether there is an infected lesion, whether there is surgery, lumbar puncture history, emergency onset, whether there is acute fever, chills and other acute systemic infection symptoms, whether there is pain in the lower back or lower limbs, numbness in both lower extremities, weakness and dysfunction .

2. Physical examination

Check the back and back for swelling and tenderness; check the level of the sensory disappearance, the level of muscle strength of both lower extremities, and whether there is hyperreflexia and pathological reflex. Check the area of the infected area and measure body temperature and pulse.

3. Laboratory examination of white blood cell counts and classification counts.

4. Puncture examination

Clinical symptoms and signs can be roughly determined by the segment of the lesion. The epidural puncture and secretion can be taken at the corresponding site or the secretions can be taken for smear after washing. See the pus cells for a clear diagnosis.

5.CT, MRI scan

The lesions and lesions of the spinal cord, epidural space and vertebrae can be confirmed.

Differential diagnosis

1. Acute myelitis: There is often no history of primary purulent infection, physical examination without localized spinous process, pain or tenderness, low back pain is not obvious, generally within 3 days after the onset of disease, the limb is completely paralyzed, spinal arachnoid The lower cavity is not blocked.

2. Spinal metastases: Primary cancers can often be found, such as lung, breast, prostate or digestive tract. X-ray films can be seen as "accordion"-like vertebral compression and rupture.

3. Arachnoiditis: Generally, the onset is slow, the symptoms are light and heavy, the distribution of sensory disturbances is often irregular, and all symptoms can not be explained by single-segment damage; the lipiodol flow slows, disperses, and does not Regular drip, strip or flaky shadows, the edges of the blocked end of the iodized oil are not neat.

4. Intraspinal tumor: often no history of infection, if necessary, can be used for spinal canal iodine angiography or spinal MRI examination, surgical exploration can also distinguish.

5. Spinal tuberculosis: There is a history of tuberculosis or tuberculosis in other parts of the body. The symptoms of low back pain and hypothermia last longer. The spine may have a posterior deformity. X-ray films show bone destruction and parasitic cold abscess shadows. CT and MRI also have Help with differential diagnosis.

6. Acute abdomen and other diseases (such as intercostal neuralgia): Careful examination of medical history and examination is not difficult to identify.

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