Epidural abscess

Introduction to epidural abscess Epidural abscess refers to the abscess between the skull and the dura mater, which is rarely seen clinically. basic knowledge The proportion of the disease: the probability of the population is 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: epilepsy

Cause of epidural abscess

(1) Causes of the disease

The pathogenic bacteria of the epidural abscess are similar to those of the subdural abscess. Staphylococcus and streptococcus are common, sometimes Gram-negative bacilli, and the route of infection:

1. Direct infection: such as skull osteomyelitis destroys the inner pole of the skull, frontal sinusitis destroys the posterior wall of the frontal sinus, otitis media and mastoiditis destroy the tympanic cap of the rock bone, bone of the rock bone or sigmoid sinus Causes an epidural abscess at each corresponding site.

2. Blood infection: If the head and face are infected, the bacteria can enter the skull through the cranial vein and the epidural abscess can occur. It can also be caused by infection or sepsis in the whole body, and the bacteria are spread by blood, but they are rare. .

(two) pathogenesis

The pathological changes of the epidural abscess depend on the virulence of the bacteria, the body's resistance and the duration of the infection, which immediately respond to the local involvement of mild dural and exudate in the dura mater, followed by fibrin deposition or abscess formation. If the virulence of the bacteria is small and the body's resistance is strong, the granulation tissue may be formed locally, or even into a dense fibrous tissue scar.

Epidural abscess prevention

Effectively treats suppurative lesions in adjacent areas, preventing infection of the head and face and all parts of the body through the blood.

Epidural abscess complications Complications

Epidural abscess can also be complicated by various other intracranial infections, but because the dura mater has a blocking effect on the spread of suppurative inflammation, most of the inflammation is limited to the extradural space. If the abscess is large, granulation tissue is formed and oppressed. Brain tissue can also be followed by epilepsy and other localized neurological symptoms.

Epidural abscess symptoms Common symptoms Overall discomfort High fever Cold warfare Bone destruction Focal symptoms Increased intracranial pressure Meningeal irritation Symptoms

1. Acute phase: Patients have chills, fever, general discomfort, localized headache (more corresponding to the location of the abscess), severe infection can present high fever, chills, convulsions and meningeal irritation, increased intracranial pressure Not obvious, cerebrospinal fluid examination generally does not change much.

2. Chronic phase: After the formation of general abscess, the symptoms are reduced, such as secondary to skull osteomyelitis. When the abscess or sinus is formed locally and pus is discharged, the symptoms may improve, but the local lesions will not heal. Occurred in frontal sinusitis, otitis media and mastoiditis, most of the skin has edema and sputum pain, otitis media caused by vertebral bone destruction can cause ipsilateral trigeminal nerve and nerve damage, occasionally due to abscess larger optic cortex Can cause focal symptoms, such as limited seizures, hemiplegia and so on.

Examination of epidural abscess

Cerebrospinal fluid examinations generally have little change and no special performance.

The CT scan is below the inner plate of the skull, and there is a fusiform low-density area outside the brain. The range is limited. The enhanced scan has obvious band-like enhancement on the inner edge, accompanied by adjacent cerebral edema and mass effect. In addition, the skull can be found. MRI examination of the primary infection lesions such as osteomyelitis, MRI examination showed a clear fusiform signal zone in the lower boundary of the skull, T1 image is between the brain tissue and cerebrospinal fluid, T2 image is higher than the brain tissue signal, if abscess When the protein content is high, the signal is strengthened. The inner edge of the fusiform region is a curved band with a high signal in the T1 and T2 images. It is an intradural dura mater. If the abscess contains gas, a liquid level appears above the gas. It is a black low signal area on both the T1 and T2 images.

Diagnosis and diagnosis of epidural abscess

The diagnosis of epidural abscess is mainly based on the medical history and the above clinical manifestations. For patients with skull osteomyelitis, frontal sinusitis, otitis media, mastoiditis or adjacent parts of the cranial cavity, if there is generalized infection symptoms, localized headache, local skin Swelling and tenderness, even when there are meningeal irritation or brain symptoms, the possibility of this disease should be considered. CT and MRI scans are helpful for diagnosis. If necessary, drilling and exploration can be confirmed.

In addition to the identification of other intracranial purulent infectious diseases, this disease should be differentiated from epidural hematoma and epidural effusion. The epidural hematoma can generally be traced to the history of trauma. CT shows acute hematoma. High-density lesions, CT values between 40 ~ 70Hu, higher than the CT value of pus, subacute hematoma can be high, low or mixed density, but no enhancement after encapsulation, hematoma in MRI T1, T2 There is a high signal on the upper, and the empyema shows a low or medium signal on the T1 image. The T2 image shows a slightly higher signal. The epidural effusion generally has no clinical symptoms. The water sample density is between -5 and +15Hu. The enhanced scan has no enhancement; the MRI T1 image shows a low signal, the T2 image shows a high signal, the surrounding brain tissue signal is normal, and the empyema CT value is high, and the MRI T1 image signal is significantly higher than the effusion signal.

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