Subacute sclerosing leukoencephalitis: causes, symptoms, diagnosis, treatment

The group of subacute sclerosing leukoencephalitis includes specific forms of chronic and subacute encephalitis with a progressive severe course (encephalitis with Dawson inclusions, subacute sclerosing leukoencephalitis of Van Bogaert, nodular panencephalitis of Pette-Doering). Since the differences in their clinical picture and morphology are relative and insignificant, they are currently treated as one disease, most often under the name "subacute sclerosing panencephalitis". This group of diseases also includes Schilder's periaxial encephalitis (diffuse periaxial sclerosis), which has some fairly clearly defined clinical and pathomorphological features.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ]

Causes of subacute sclerosing leukoencephalitis

In the etiology of subacute sclerosing encephalitis, a major role is played by persistent viral infection, apparently measles, enterovirus, tick-borne encephalitis virus. In patients with subacute sclerosing panencephalitis, very high titers of measles antibodies are found in the blood and cerebrospinal fluid (not observed even in patients with acute measles infection).

Autoimmune mechanisms, as well as acquired or congenital defects of the immune system, play a role in the pathogenesis of the disease.

Pathomorphology

Microscopically, pronounced diffuse demyelination and gliosis of the white matter of the cerebral hemispheres are detected. In some cases, multiple glial nodules are detected. In other cases, oxyphilic inclusions are detected in the nuclei of neurons of the cortex, subcortex, and brainstem against the background of their dystrophic changes. Axial cylinders initially remain relatively intact, then die. Moderately pronounced perivascular infiltration by lymphoid and plasma cells is noted. Schilder's leukoencephalitis is characterized by glial proliferation with foci of sclerosis.

Symptoms of subacute sclerosing leukoencephalitis

The disease mainly affects children and adolescents aged 2 to 15 years, but sometimes the disease occurs in adulthood. The onset of the disease is subacute. Symptoms that are considered neurasthenic appear: absent-mindedness, irritability, fatigue, tearfulness. Then signs of personality changes and behavioral deviations are detected. Patients become indifferent, lose the sense of distance, friendship, duty, correctness of relationships, discipline. Primitive drives begin to dominate: greed, selfishness, cruelty. At the same time, disorders of higher brain functions (agraphia, aphasia, alexia, apraxia), spatial orientation, and body scheme disorders appear and slowly increase. 2-3 months after the onset of the disease, hyperkinesis in the form of myoclonus, torsion spasm, hemiballismus are detected in the neurological status. At the same time, convulsive epileptic seizures, minor epileptic seizures, and constant partial seizures of the Kozhevnikovsky epilepsy type occur. Later, as the disease progresses, hyperkinesis weakens, but parkinsonism and dystonic disorders begin to increase, up to decerebrate rigidity. Extrapyramidal disorders are usually combined with pronounced vegetative disorders: greasiness of the face, salivation, hyperhidrosis, vasomotor lability, tachycardia, tachypnea. Involuntary laughter and crying, sudden screams ("seagull cry") often occur. A common symptom is static and locomotor ataxia of frontal origin (the patient does not hold the body in an upright position).

In the late stage of the disease, mono-, hemi- and tetraparesis of a spastic nature occur, superimposed on extrapyramidal and frontocerebellar motor disorders. Sensory and motor aphasia, auditory and visual agnosia are revealed. Cachexia progresses.

Course and prognosis

During the course of subacute sclerosing encephalitis, 3 stages are distinguished.

• In stage I, the predominant symptoms are personality changes, behavioral deviations, increasing defects in higher brain functions, various hyperkinesis, convulsive and non-convulsive seizures.
• In stage II, extrapyramidal tone disturbances and disorders of the autonomic central regulation increase.
• Stage III is characterized by cachexia and complete decortication.

The course of sclerosing encephalitis is steadily progressive and always ends fatally. The duration of the disease is usually from 6 months to 2-3 years. There are forms that are chronic with periodic remissions. Death occurs in a state of complete immobility, cachexia, marasmus, most often in epileptic status or due to pneumonia.

[ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ]

Diagnosis of subacute sclerosing leukoencephalitis

Some difficulties are encountered at an early stage, when neurasthenia, hysteria, and schizophrenia are often mistakenly diagnosed. Later, differential diagnostics are performed with a brain tumor. Diagnostics should rely on the diffuseness (not single-focality) of the lesion, the absence of intracranial hypertension, the displacement of the midline structures of the brain during EchoES, MRI, and the pathognomonic picture of EEG results. The diagnosis is confirmed by the results of molecular genetic, immunological studies, and neuroimaging methods.

Symptoms of Schilder's leukoencephalitis have some peculiarities: pyramidal symptoms are more pronounced, dominating over extrapyramidal ones, grand mal seizures are more often observed. In the initial stages, mental disorders prevail. The course of the disease may be in the form of a pseudo-tumorous form with signs of increasing unifocal hemispheric symptoms, accompanied by intracranial hypertension. Damage to the cranial nerves is characteristic, especially the II and VIII pairs. Amblyopia up to amaurosis is possible. Atrophy of the optic discs is detected on the fundus. In some cases, pupillary reactions to light remain intact with amaurosis, which is due to the central nature (due to damage to the occipital lobe) of amaurosis.

Moderate pleocytosis, increased protein and γ-globulin content are detected in the cerebrospinal fluid. Lange's colloid reaction gives a paralytic curve in subacute sclerosing encephalitis, inflammatory and mixed - in Schilder's leukoencephalitis. Pathological changes in the Lange reaction and hypergammaglobulinorachia are early signs of leuko- and panencephalitis. EEG records periodic stereotypical regular bilaterally synchronous high-amplitude discharges of electrical activity (Rademaker complexes). EchoES, carried out in cases with pseudotumorous leukoencephalitis, does not reveal displacements of the midline structures. Axial CT is the most informative.

[ 13 ], [ 14 ], [ 15 ]