Encephalitis represents inflammation of the brain tissue. Very often encephalitis engages and spinal cord and then it is called encephalomyelitis. Sometimes the brain substance is involved by neighborhood in the inflammatory process in serous meningitis (inflammation of the meninges), and then the differentiation between these two diseases is very difficult.
Causes of encephalitis
Most causes of serous meningitis can cause and encephalitis. The most important role in this terms play viruses. Additionally, encephalitis may occur and in toxoplasmosis, trichinelosis, syphilis, typhus and others. Others causes include fracture of the skull (direct infection), penetration of microorganisms in adjacent, distantly (metastatic abscesses), toxins – alcohol, carbon monoxide, plumbum, arsenic, salts of heavy metals. Toxic damages do not lead to a real encephalitis, but rather to encephalophathies because the entire inflammatory process is not developed.
Symptoms of encephalitis
Convulsions, limited consciousness (all grades), difficult speaking (aphasia), paresis and paralysis, gait disturbance (ataxia), involuntary movements, spontaneous movements of the eyeballs (nystagmus), scattered involuntary limb movements (hyperkinesias), severe personality changes, stupidity (dementia) – when encephalitis dementia following the order of destruction of ganglial cells. Changes in cerebrospinal fluid in encephalitis – ksantohromal (buff), usually clear, increase of the cells, increase of the protein, normal glucose (mostly).
Types of encephalitis
- Polioencephalitis (poliomyelitis) – localization in the gray matter (gray nuclei) of the brain or spinal cord.
- Leucoencephalitis (leucoencephalomyelitis) – inflammation of the white matter of the brain.
- Panencephalomyelitis – inovlement of gray and white matter of the brain and spinal cord.
- Perivenous encephalomyelitis – this is a common morphological feature of encephalomyelitis that develops after acute viral infection after immunization.
General microscopic changes
- ganglion cells – severe degenerative changes and acute non-letal recycled cell damage in the early stages – necrobiosis, necrosis.
- blood vessels – perivascular infiltrates (mostly lymphocytes) perdiapedesis hemorrhage, perivascular edema.
- glia – proliferation of the microglia – rounding, loss of appendages, conversion to macrophages and accumulation around dead ganglion cells forming nodules. The process is called neuronophagia – in the center there are necrotic neurons with clustered around microglials cells.
- fibers – there is a demyelination of nerve fibers (myelinolysis) with clustering of lipophages.
Poliomyelitis (infantile paralysis) affects the gray matter of the front horn of the spinal cord. There is a destruction of the gray motor nuclei, with localization mainly in the neck intumescentia. Paresis and paralysis of apathetic type are developed. For damage caused by poliomyelitis is typical:
- mosaic of involved neurons – based on the faith of patients in a better prognosis.
- involvement can be unilateral – only in one horn of the spinal cord
- there is no severe gliosis
There is no cases of this zoonosis, in which the clinical picture to be fully deployed and then healing has occurred. Patients with developed clinical symptoms die. Localization – motornuclei in the medulla oblongata – vagus nerve, glossopharingeus nerve and other craniocerebral nerves (CHMN), also the cells in the Ammonium horn. In rabies neuronophagia is called nodules of Ernst-Babes. This disease is characterized by bodies of Negri, which are discovered electronomicroscopical as eosinophilic inclusions of the virus.
Lethargic encephalitis (disease of Economo)
It covers the upper floors – mesencephalon, diencephalon. Most severe damages subtance nigra, thalamus opticus, motor nucleus of the third CHMN, palidonigralic nuclei, hypothalamus. In disease of Economo the released melanin by substance nigra is phagocytosed or stays freely in the intercellular spaces. After time substance nigra (black) becomes the substance grisea (gray) or substance alba (white) because of the loss of melanin. This change should be searched in Parkinson’s disease!
Lethargic encephalitis symptoms
- The claim sleepiness (somnolence) of the patients because of engagement of reticular formation in the brain.
- Oily skin and body – caused to overactive sebaceous glands because of the involvement of the autonomic ganglia
- Scan (shredded, chopped) speech
- Parkinson’s syndrome (movement of the “miser” – as counting money)
- Closed eyes due to paralysis of muscles moving the eyeball
- Profuse salivation
- Multiple sclerosis
- Diseases of unknown etiology and pathogenesis
- Diffuse sclerosis of Schilden
- Concentric sclerosis of Ballo
- Acute primary disseminated encephalomyelitis
Affects gray and white brain matter. The brain is swollen , with smooth folds and restricted sulcuses. Microscopically are detected degenerative changes in neuroganglial cells, neuronophagia, perivascular infiltrates, demyelination, damage of neurofibriles, lipophages, microtrombosis in the vessel and consequently – ischemic necrosis (infarction). In the final stage occurs gliosclerosis.
Types of panencephalomielitis
- Mosquitoes – affect cortex, stem, cerebellum (cells of Purkinie), which leads to disturbance of the balance.
- Panencephalomielitis caused by mites– damages the spinal cord in the neck. Paresis and atrophy of muscles are developed, resulting in a patient’s head stands let down.
- Viral encephalitis
- Herpes simplex affects the basal ganglia and white brain tissue of the temporal lobes. In the brain are detected signs of swolling and point bleeding. Microscopical are seen perdiapedesis hemorrhages, perivascular inflammatory infiltrates, focal necrosis. By electron microscopy in the nuclei of neurons are found intranucleus inclusions representing nucleotides of the virus (type A).
- Influenza encephalitis is characterized by capillarophatia – confluent and small hemorrhages, degenerative and atrophic changes in ganglion cells, slight glial proliferation.
- Encephalitis in AIDS – the changes are like the type of myelitis or encephalopathy. 40 – 70% are affected by the patient with AIDS. The process engages the stem, spinal cord, peripheral nerves. Initially there are depressions due to damage of ganglion cell, which are with degenerative changes. There is cytomegalia- enormous cells in the brain substance. By electron microscopy are detected intracytoplasmic inclusions and no nevronophagia and perivascular infiltrates are found in the white brain matter. Later changes consist of diffuse sclerosis of the cerebral cortex.