Otogenic brain abscesses: causes, symptoms, diagnosis, treatment

Abscess - a cavity filled with pus and delimited from surrounding tissues and organs by a pyogenic membrane.

Classification of otogenic brain abscesses

By the time of occurrence, the abscesses are divided into early and late ones. To late carry abscesses, formed later 3 months.

Early abscesses in their development pass through a series of successive stages:

• purulent-necrotic encephalitis:
• the formation of a pyogenic capsule;
• manifestations of abscess;
• terminal stage.

Late abscesses in the clinical course are subdivided into rapidly developing, slowly developing and asymptomatic.

Pathogenesis of otogenic brain abscesses

Otogennye abscesses of the brain arise in the immediate vicinity of the focus of the infection and are most often localized in the temporal lobe and the cerebellum.

In the early stage of encephalitis (the first 1 3 days), a local inflammatory reaction arises around the blood vessels. The development of encephalitis is associated with edema of the brain tissue and the formation of the necrosis region. In the late stage of encephalitis (4-9th day), such important histological changes as maximal edema of brain tissue, an increase in the size of necrosis and the formation of pus are observed. Fibroblasts form around the inflammation zone the reticular network, which serves as the precursor of the collagen capsule.

In the early stage (the 10th-13th day) of the capsule formation, the collagen network thickens and the necrotic center is isolated from the surrounding brain substance. Obviously, this process is decisive in protecting the surrounding tissue from damage. In the late stage of capsule formation (the 14th day and later), the abscess has five different layers:

• necrotic center;
• peripheral zone of inflammatory cells and fibroblasts;
• collagen capsule:
• area of newly formed vessels;
• area of reactive gliosis with edema.

To develop a well-formed capsule 2 weeks is required.

Factors influencing the formation of the capsule include the type of pathogen, the source of infection, the state of the body's immune system, the use of antibiotics and glucocorticoids.

Symptoms of otogenic brain abscesses

The clinical manifestations of the abscess depend on its location and volume, the virulence of the pathogen, the immune status of the patient, the presence of cerebral edema and the severity of intracranial hypertension. Abscess is an acute inflammatory process, usually rapidly developing, which is the main difference from other intracranial volumetric formations. The symptomatology of the abscess develops not more than two weeks, and often less than one week.

A characteristic feature of a late abscess is the presence of a well-expressed capsule. The clinical manifestations of late abscesses are very diverse and are determined by the localization of the pathological focus, its size. Leading symptoms of late abscesses can be considered a manifestation of intracranial hypertension with the appearance of ophthalmological and radiographic signs of pathological volumetric education in the cranial cavity.

The most formidable complication of brain abscess is the breakthrough of the purulent cavity in the path of cerebrospinal fluid flow and especially in the ventricles of the brain.

Isolate the initial, latent and apparent stages of development of the abscess.

In the initial stage, the main symptom is a headache. It can have the nature of hemicrania, but most often it is diffuse, permanently resistant to treatment. If there is a significant increase in intracranial pressure, then the headache is accompanied by nausea and vomiting. Increased intracranial pressure, together with the mass effect caused by an abscess, can lead to a violation of the level of consciousness: from moderate stunning to the development of coma. The state of consciousness is the single most important predictor. The duration of this stage is 1-2 weeks.

Further within 2-6 weeks of development of the latent stage of obvious symptoms of brain damage is not observed, but the patient's state of health is more often changed. The mood worsens, apathy develops, general weakness, increased fatigue.

The apparent stage lasts an average of 2 weeks. Inattentive observation of the patient, the initial stage goes unnoticed, and the apparent stage is recognized with delay.

Diagnosis of otogenic brain abscesses

Physical examination

When the patient is physically examined in the obvious stage of the disease, four groups of symptoms can be distinguished: general infectious, general cerebral, conductive and focal.

The first group includes general weakness, lack of appetite, stool retardation, weight loss. Body temperature is usually normal or subferinal, ESR is increased, leukocytosis is moderate with no significant change in the leukocyte blood count. Half of patients may experience occasional irregular body temperature increase up to 39 ° C or higher.

Cerebral symptoms are caused by increased intracranial pressure. These include headache, vomiting without previous nausea, stiff neck, Kernig symptom. Unlike meningitis, there is bradycardia due to pressure on the medulla oblongata. More often than with meningitis, when examining the fundus, stagnant discs of optic nerves are revealed. Meningitis is present in 20% of patients. Edema of the nipples of the optic nerves is associated with intracranial hypertension and is detected in 23-50% of patients

The collapse of the conductor systems and subcortical nuclei results from the dislocation of brain tissue. Contralateral hemiparesis and paralysis are noted. Cerebral nerves may suffer. Paresis of the oculomotor and facial nerve develops according to the central type. The central innervation of the upper troupe of mimic muscles is two-sided, so when the lower group of muscles is paresis, the facial muscle function of the forehead is preserved. Pyramidal symptoms are noted.

The greatest diagnostic value is focal neurological symptoms. Focal neurological deficit was noted in 50-80% of patients, its manifestations are associated with the localization of the abscess.

The defeat of the dominant temporal lobe of the brain (left-right and right-handed in left-handers) is characterized by sensory and amnestic aphasia. With sensory aphasia and well-preserved hearing, the patient does not understand what he is told. His speech becomes a meaningless set of elephant. This is due to the defeat of the Wernicke Center in the posterior part of the upper temporal gyrus of the cortex of the dominant hemisphere of the brain. The patient can not also read (aleksii) and write (agra). Amnestic aphasia is manifested by the fact that the patient, instead of the name of the object, describes their purpose, which is associated with visual-auditory dissociation as a result of the lesion of the lower and posterior parts of the temporal and parietal lobes.

An abscess in an "invisible" temporal lobe may be manifested by mental disorders: euphoria or depression, a reduction in criticism that often goes unnoticed. Therefore, such a share is called "dumb".

The pathology of any of the temporal lobes of the brain is accompanied by the loss of the same-named fields of vision of both eyes (homonymous Hemannopia). Involvement of cortical vestibular representation is accompanied by dizziness and ataxia with deviation of the body to the opposite lesion side.

Abscess of the cerebellum is characterized by a violation of the tone of the extremities, ataxia, spontaneous nystagmus and cerebellar symptoms. There is a deviation and lowering of the hand on the side of the lesion in the finger-finger sample. With index and finger-nasal tests, there is a miss in the affected side. The patient's knee-sharp knee test is unsteadily performed by the foot on the side of the lesion, bringing it further than required. Cerebellar ataxia manifests itself as a deviation of the body in Romberg's posture to the affected Side and the "drunken" gait with a deviation in the same direction. Deviations of the body and limbs coincide with the direction of the rapid component of the nystagmus, in contrast to the vestibular ataxia, in which the deviations of the body and limbs coincide with the direction of the slow component of the nystagmus. Spontaneous nystagmus is large-scale, with extensive damage to the cerebellum can be multiple. Vertical nystagmus is an unfavorable prognostic sign. Cerebellar symptoms include the inability to perform a flank gait in the direction of the affected hemisphere of the cerebellum, adiadochokinesis, intentional jitter during the palcenosal test.

With an abscess of the brain, a sudden deterioration in the patient's condition is possible. The latter is due either to the dislocation of the brain, or to the breakthrough of the contents of the abscess into the subarachnoid space or into the ventricles of the brain. In the unfavorable course of the disease in the terminal stage, due to the pronounced dislocation syndrome, anisocoria, narrowing of the gaze upwards, loss of consciousness and violation of the rhythm of respiration are observed. Death occurs either against the backdrop of an increasing swelling of the brain from stopping breathing and cardiac activity, or against purulent ventriculitis when a pus breaks through the ventricles of the brain.

Laboratory research

With abscesses of the brain, a moderate neutrophilic leukocytosis with a shift of the leukocyte formula to the left, an increase in ESR up to 20 mm / h and above is noted.

Spinal puncture with cerebral abscess is dangerous and quickly leads to clinical deterioration. Changes in cerebrospinal fluid are nonspecific. The cerebrospinal fluid is clear, flows out under pressure, the protein content is slightly increased and the pleocytosis is poorly expressed (up to 100-200 cells / μl). When pus breakthrough into the subarachnoid space, secondary meningitis develops, characterized by corresponding changes in the cerebrospinal fluid.

Instrumental research

Radiation diagnosis is of great importance in the diagnosis of cerebral abscesses. Absolute radiologic signs of an abscess are the contouring of calcified walls of an abscess with the presence of a liquid or gas level in it.

In carrying out echoencephalography and carotid angiography, signs of an intracranial volumetric process that shifts the median structures of the brain can be established.

Wide use of CT and MRI is necessary for accurate diagnosis of the location of cerebral abscesses. When CT is detected smooth, thin, having the correct contours and accumulating the contrasting wall of the abscess, as well as the central region of the abscess of reduced density. With MRI on T1-weighted images, central necrosis is represented by a zone of hypo-intensity, the capsule surrounds the necrosis zone and looks like a thin iso- or hyperintense layer. Outside the abscess is a zone of hypo-intensity. Which is an edema. On T2-weighted images, the same data is reproduced as a hyperintense center, a well-differentiated hypointense capsule and the surrounding hyperintensive edema. Based on CT and MRT data, optimal access to the pathological focus can be determined.

In the temporal lobe of the brain, the abscess is more often round in shape, and in the cerebellum is slit. Most smoothly flow smooth-walled abscesses with a well-expressed capsule. However, often the capsule is absent, and the abscess is surrounded by the inflamed and softened substance of the brain.

In the absence of the possibility of CT and MRI for diagnosis, pneumoencephalography, as well as radioisotope scintigraphy, can be performed.

Differential diagnostics

Otogenous brain abscess should be distinguished from abscessed encephalitis. The formation of a delicate purulent cavity in the brain substance is most often a consequence of encephalitis, representing one of the variants of its outcome. Differential diagnosis of late abscess should also be carried out with a brain tumor.

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