Infant amaurosis
Introduction
Introduction to infantile black dementia Infant black senile dementia is Bielschowsky syndrome, also known as Bielschowsky-Jansky syndrome, Döllinger-Bielschowsky syndrome, Bernheimer-Seitelberger syndrome, late infantile melanotype dementia, infantile waxy lipofuscin Disease, GM2 ganglionosis type III (GM2gangliosidosis), juvenile gangliosideosis (juvenile GM2gangliosidosis) and the like. This symptom is an autosomal recessive inheritance. Due to the lack of aminohexosidase or sphingolipidactivator protein, GM2 gangliosides and associated glycosphingolipids are deposited, causing degeneration of the brain. basic knowledge Sickness ratio: 0.0001% Susceptible people: children Mode of infection: non-infectious Complications: ataxia, macular degeneration, optic atrophy,
Cause
Causes of infantile black dementia
Tay-Sachs disease (30%):
This disease is the earliest discovered ganglioside accumulation disease, which is known to be due to the complete or partial lack of activity of the hexaminidase (HEX) hydrolyzing ganglioside GM2 type, so that GM2 cannot be degraded in vivo. Accumulated in (brain, eye, liver, spleen, and bone marrow). According to the classification in recent years, the classic Tay-Sachs disease can occur in the absence of HEX-A type, and the Sandoff disease is another if both types of A and B in HEX are lacking.
Pathogenesis The central nervous system contains a variety of complex lipids, including dozens of gangliosides (complex glycolipids). Their chemical structures are mainly ceramides, which are conjugated to several molecules of hexose (galactose, glucose) and sialic acid (N-acetylneuraminic acid, NANA). . Since the number of NANA contained therein is different, they are named GM (single NANA), GD (two molecules), GT (three molecules), GQ (four molecules), and the like. The substance accumulated in the brain cells of patients with this disease is GM2 containing a single molecule of NANA and three hexose residues, which is degraded from tetrahexosides GM1 by -galactosidase and further degraded to GM3 by HEX. .
The disease is more common in Eastern European Jews, but non-Jewish and non-white children cannot be excluded from the diagnosis.
Diagnosis relies on the determination of aminohexosasease isoenzyme A. There is no special treatment for this disease, usually 3 to 4 years old.
Sandhoff's disease (30%):
The patient lacks hexosaminidase A and B, which not only causes GM2 gangliosides to deposit in the brain, but other -aminohexose final products such as glycolipids, glycoproteins and oligosaccharides are also in the brain. Deposition in the internal organs. The clinical manifestations are similar to Tay-Sachs disease, but there is visceral involvement. The content of GM2 gangliosides in the brain is increased by 100 to 200 times, and the liver, kidney, spleen and erythrocyte glycosides are greatly increased, and in the red blood cells, mainly glycosphingolipids.
Juvenile GM2 gangliosidosis (30%):
(Type III) is caused by a partial deficiency of aminohexosaminidase A, which is later than Tay-Sachs disease and Sandhoff disease. Ataxia and progressive mental retardation development begin at 2 to 6 years of age. Language loss, progressive rigidity, hand and limbs in a Xu-like posture, and the occurrence of small sputum, no organ enlargement, skeletal deformities and vacuolar cells, can be blind in the late stage. Most children die between 5 and 15 years of age.
Prevention
Infant black Mongolian dementia prevention
Check the activity of hexosamine isoenzyme A in the blood, and check the patient and the carrier; the biochemical analysis of the cultured amniotic fluid cells can make prenatal diagnosis. The above methods are conducive to preventive work and terminate the pregnancy if necessary.
Complication
Infant black Mongolian dementia complications Complications, ataxia, macular degeneration, optic atrophy
Severe convulsions, exercise and mental retardation, vision loss, ataxia, retinal atrophy, macular degeneration, optic atrophy and progressive blindness, small brain deformity, now hands and feet Xu, sputum.
Symptom
Symptoms of infantile black dementia common symptoms convulsions, tension muscle myoclonus, ataxia, dementia, reflexes, hyperthyroidism, muscle tension
1. Clinical manifestations of both sexes can occur, starting from 1 to 4 years old, sudden severe convulsions, often myoclonic or no action, sports and mental development, vision loss, muscle tension, ataxia, Retinal atrophy, macular degeneration, optic atrophy and gradual blindness, the anti-convulsant drugs of the children's myoclonic dysfunction are often ineffective, often with small brain deformities, hand and foot movements, convulsions, grip reflexes and cervical reflexes are late .
2. Clinical stage Morell and Torrss (1960) The disease was divided into 4 stages according to the clinical process, and the clinical manifestations and EEG findings of each stage were discussed.
Stage I: 6 to 10 months after birth, the whole body muscle tension is reduced, the light reflection exists and there is a phenomenon of chasing, which is sensitive to sound, and the EEG shows irregular waveforms with irregular wave rates and high-wavelength slow-wave bursts, sometimes Visible spikes can be seen.
Phase II: 1 to 1.5 years old, muscle tension begins to increase, tendon reflexes, tension neck reflex, sometimes with tonic convulsions, EEG is mainly 1 to 2 Hz high amplitude slow wave, sometimes frequent two The lateral spine slow wave synthesis is similar to the height loss law.
Phase III: 1 year, 4 months to 2 years old, often have myoclonic seizures, indifferent to the surrounding things, vision loss or even blindness, EEG graphic amplitude is reduced, focal epileptic waves are erupted, no arousal response.
Stage IV: After 2 years of age, completely blind, often with systemic convulsions, EEG shows low amplitude activity, but epileptic waves gradually disappear.
3. Clinical classification
(1) Tay-Sachs disease (type I GM2 gangliosidosis): The typical clinical manifestation is that after 4 to 6 months of normal development, the child develops mental retardation and degeneration, and has a shock response to the sound. Low muscle tone, reduced excitement to the surrounding environment, head can not be controlled, apathy occurs early, cherry erythema may be late, convulsion occurs later, in the advanced stage of the disease, the patient responds poorly to external stimuli, the head is big, in the final stage Significantly increased, no visceral enlargement found.
The disease is more common in Eastern European Jews, but non-Jewish and non-white children cannot be excluded from the diagnosis.
Diagnosis depends on the determination of hexosaminidase isoenzyme A. There is no special treatment for this disease, and it usually dies at 3 to 4 years old.
(2) Sandhoff disease (type II GM2 gangliosidosis): clinical manifestations similar to Tay-Sachs disease, but with visceral involvement.
(3) juvenile GM2 gangliosidosis (type III): the onset is later than Tay-Sachs disease and Sandhoff disease, ataxia and progressive psychomotor developmental delay begin at 2 to 6 years old, language loss, progressive In the state of tonicity, the hands and limbs are in a swaying posture, and small sputum occurs. No organ enlargement, skeletal malformation and vacuolar cells are found. In the advanced stage, the patient may be blind, and the children are mostly 5 to 15 years old.
Examine
Examination of infantile black dementia
The peripheral blood lymphocytes of this disease have vacuoles, polynuclear leukocytes have increased azurophilic granules, cerebrospinal fluid protein has a slight increase, no more than 80mg / L, skin, muscle, rectal mucosa biopsy can be deposited by histochemical methods and electron microscopy It is also easier to collect urine sediment for electron microscopy to diagnose the disease.
1. EEG changes
Paroxysmal 2, 5 ~ 4c / s slow wave and atypical spine slow wave.
2. Retinal current map
Abnormal electroretinogram can be used as a diagnostic reference.
3. Laboratory inspection
The peripheral blood lymphocytes of infantile infants with melanotype dementia have vacuoles. Polynuclear leukocytes have increased anthraquinone blue particles. Cerebrospinal fluid protein is slightly increased. Skin, muscle, and rectal mucosal biopsies can be examined by histochemical methods and electron microscopy. Urine sediments can also be collected for electron microscopy to diagnose the disease.
4. EEG examination
Tay-Sachs disease (type I GM2 gangliosidosis) In the infants, EEG examinations are mostly in the normal range before clinical symptoms appear. After the onset of symptoms, there may be a burst of paroxysmal high-frequency slow waves, or a multi-phase spike and a high-amplitude disorder. Most of the low amplitude slow wave activity is seen in the late stage.
5. ECG examination
One third of the children with an electrocardiogram have abnormalities such as arrhythmia.
Diagnosis
Diagnosis and diagnosis of infantile black blind dementia
diagnosis
According to clinical manifestations and laboratory tests confirmed.
Differential diagnosis
Identification with GML gangliosideosis.
The disease develops from infancy and is a disease characterized by progressive brain degeneration and mucopolysaccharidosis.
GML gangliosides are monosialogangliosides present in the normal cerebral cortex and white matter, and also in small amounts in the viscera, which can also form in the normal catabolism of polysialogangliosides.
Due to the lack of -galactosidase activity, GML gangliosides are catabolized, resulting in deposition of GML gangliosides, which can cause severe neuronal damage in the brain, accompanied by demyelination and Glial hyperplasia, the affected nerves show cytoplasmic membranous bodies, as seen in Tay-Sachs disease, this disease is autosomal recessive.
