Focal heterotopia of gray matter. Subependymal heterotopia of gray matter
See also:
- HETEROTROPHIC PLANTS(from the Greek heteros-other and trepho-nourish), plants that are unable to use CO2 as a source of C for the construction of organic matter and therefore require nutrition with organic compounds. They are opposed to autotrophic plants, which can build organic...
- HETEROPHORIA(from the Greek heteros - different and phero - strive), is a condition in which the eyes, solely under the influence of mechanical forces arising from differences in anatomical relationships, are established so that their visual lines cease to be parallel, ...
- HETEROCHROMIA(from the Greek heteros - different, different and chroma - color), different eye colors, depending on the different colors of the irises of both eyes. The color of the iris is closely related to the general pigmentation of a given individual...
- HETEROCHROMOSOMES(from the Greek heteros - different), a term that originally denoted chromosomes that differed in certain features during division (syn. allosomes); recently it is often used in a narrower sense: chromosomes present in somatic cells...
- HETEROCHRONY(from the Greek heteros-other and chronos-time), the untimeliness of any phenomenon. This term is often used in the doctrine of heredity to mean that one or another inherited trait is revealed in the offspring...
^ Heterotopy of brain matter diagnosed in 6 (6.3%) patients with CD. In some cases, heterotopias are “undetected” during neuroimaging, and single heterotopic cells are not noted during the analysis of autopsies or may be an accidental finding (Norman M. et al. 1995), which is confirmed by our data. The results of RCT of the brain turned out to be insufficiently informative in patients with heterotopia of the brain substance. During NSG, ventriculomegaly was detected in 4 patients with sheterotopia of the brain substance in the first year of life. At MRI of the brain Additionally, hypoplasia of the corpus callosum and/or ventriculomegaly was verified - 4, agenesis of the septum pellucidum - 1, cerebellar hypoplasia - 1 (Fig. 9).
Rice. 9. MRI of the brain of patient G., 8 years old, with right-sided temporal heterotopia. Axial sections (A - T2, B - Flair modes): dilatation and lengthening of the posterior horn of the left lateral ventricle.
^ When To clinical examination the only 6-month-old patient with heterotopia of the brain substance was diagnosed with West syndrome, 5 patients in older age groups were diagnosed with symptomatic focal epilepsy (temporal, frontotemporal-central, and undifferentiated). Motor impairment syndrome (spastic tetraparesis) was detected in one patient. Cerebral palsy (spastic diplegia) - in 2 patients of older age subgroups. Cognitive impairments of varying severity were found in 4 out of 6 children with heterotopia of the brain substance (severe - 1, moderate - 3). AtEEG in patients with heterotopia of the brain substance, a slowdown in the main activity of the background recording of varying length and localization, regional epileptiform activity in the fronto-central-temporal region with VBS, multifocal epileptiform activity with VBS without a clear focus of localization were determined.
^ in 2 patients a classic hypoplasia of the optic nerve, in 2 – excavation of the optic disc. When recording VEP in 6 patients with changes in the fundus, a decrease in the amplitude and an increase in the latency of the main positive component P100 were found.
Holoprosencephaly diagnosed in 5 (5.3%) patients with CD. in 4 patients the lobar form of holoprosencephaly was verified, in 1 – semilobar (Fig. 10). All cases of holoprosencephaly were combined with ventriculomegaly and diffuse atrophy of the cerebral cortex. During NSG, ventriculomegaly was discovered in 5 patients with sgoloprosencephaly in the first year of life.
Fig. 10. NSG patient A., 1 month old with holoprosencephaly, semilobar form.
A – the lateral ventricles are fused with each other in the anterior sections. Coronary scanning at the level of the foramen of Monroe and the third ventricle.
B - partial separation of the visual hillocks from each other. The brain substance is in the form of a mantle-like zone along the periphery of the lateral ventricles.
^ When To clinical examination 2 patients aged from 1 to 12 months. life, epileptic encephalopathy was identified (early myoclonic encephalopathy - 1, West syndrome - 1). 3 patients had symptomatic focal epilepsy: temporal, frontotemporal. Movement disorders syndrome (spastic tetraparesis) was identified in 2 patients in the first year of life. Cerebral palsy (double hemiplegia) - in 2 patients of older age subgroups. Severe cognitive impairment was noted in 100% of cases (severe – 4, moderate – 1). At EEG in patients with holoprosencephaly was determined : regional epileptiform activity in the central temporal and temporo-occipital regions with VBS, slowing down of the main activity of background recordings of varying length and localization.
^ During an ophthalmological examination at In 4 out of 5 patients, hypoplasia of the optic nerve and disturbances in the amplitude-time characteristics of P100 B-VEP were detected.
Porencephaly was diagnosed in 4 (4.2%) patients with KD. Data from radiological research methods, MRI of the brain Porencephaly was confirmed in all patients. In one patient, the porencephalic cyst was combined with FCD (Fig. 11), in 3 other cases - with polymicrogyria, ventriculomegaly and/or ventriculodilation. During NSG, ventriculomegaly was discovered in 4 patients with porencephaly in the first year of life.
A B 
Fig. 11 MRI of the brain of patient M., 7 years old with a porencephalic cyst. Axial sections (A - T2 mode, B - T1 mode): porencephalic cyst of the left parieto-occipital region, ventriculomegaly.
^ When To clinical examination The only patient in the first year of life with porencephaly was diagnosed with epileptic encephalopathy (West syndrome), in 3 patients - symptomatic forms of focal epilepsy (frontotemporo-occipital localization). Syndrome of motor disorders in the form of spastic hemiparesis - in one patient at the age of 3 months. Cerebral palsy (hemiparetic form, spastic tetraparesis) was diagnosed in 3 patients of older age subgroups. Moderate cognitive impairment was observed in all patients. With EEG in patients with porencephaly, regional epileptiform activity without VBS, continued slow-wave theta-delta activity with periodic inclusion of individual and group high-amplitude delta waves were recorded.
^ During an ophthalmological examination 4 patients had various forms of optic nerve hypoplasia. When recording B-VEP in 4 patients with porencephaly, a decrease in the amplitude and an increase in the latency of the main positive component P100 was found compared to the norm.
Hemimegalencephaly diagnosed in 4 (4.2%) patients with CD. Leducational research methods, brain MRI We verified hemimegalencephaly in combination with ventriculomegaly, hippocampal atrophy and/or hypoplasia of the corpus callosum and polymicrogyria (Fig. 12). During NSG, ventriculomegaly was detected in all patients with hemimegalencephaly in the first year of life.
R 
is. 12. Results of MRI of the brain (A-B) and registration of VEP (D) in patient X., 6 months old, with left-sided hemimegalencephaly.
A-B - axial sections (A - T2 mode, B - T1 mode, C - Flair mode): polymicrogyria, asymmetric ventriculomegaly, hypoplasia of the corpus callosum, expansion of the subarachnoid space.
G - cross-sectional asymmetry of VEP per flash.
^ When To clinical examination the only infant patient with hemimegalencephaly was diagnosed with epileptic encephalopathy (West syndrome), 3 patients in older age groups were diagnosed with symptomatic forms of focal epilepsy (frontal and temporocentral localization). Movement disorders syndrome (spastic hemiparesis) was detected in one patient in the first year of life. Cerebral palsy (hemiparetic form) was identified in 3 patients of older age subgroups. All patients had moderate cognitive impairment. At EEG in patients with hemimegalencephaly the following were determined: modified hypsarrhythmia, regional epileptiform activity with/without VBS.
^ During an ophthalmological examination at 4 In patients with hemimegalencephaly, hemianoptic hypoplasia of the optic nerve was revealed, characterized by a decrease in the diameter of the ipsilateral optic disc to 0.8 RD, expansion of the excavation or segmental blanching of the contralateral optic disc. In all patients, cross-VEP VEP asymmetry was detected when they were recorded from three active electrodes (Fig. 12 D), as well as a significant decrease in the P100 amplitude without lengthening its latency during standard VEP recording with the location of the 1st active electrode at the point inion.
Lissencephaly was diagnosed in 2 (2.1%) children with CD. Lissencephaly is a diffuse lesion of the cerebral cortex, radiologically manifested by the absence of sulci and gyri. In our study, lissencephaly was combined with hypoplasia of the corpus callosum in 1 patient, and ventriculomegaly in 1 observation. During NSG, ventriculomegaly was discovered in 2 patients with lissencephaly in the first year of life.
^ At kclinical examination 2 patients with lissencephaly aged 1 to 12 months were diagnosed with epileptic encephalopathy - West syndrome. The syndrome of motor disorders (spastic tetraparesis) was identified in 2 children of the first year of life. All patients with lissencephaly showed severe cognitive impairment. AtEEG in patients with lissencephaly, modified hypsarrhythmia was determined.
^ During an ophthalmological examination One patient with lissencephaly had optic nerve hypoplasia, and another had extended excavation syndrome. When recording VEP in 2 patients, the amplitude of the main positive component P100 was reduced to 6-14 μV, the latency was normal.
Thus, the analysis of the results of paroxysmal neurological events in the study showed that in the subgroup of children with CD from 1 to 12 months of life, infantile spasms (23.2%) and myoclonic seizures (10.5%), secondary generalized seizures prevailed ( 10.5%), being the main clinical manifestation of KD in infants and forming the basis of the following epileptic syndromes: West syndrome in 23.2% of patients; early myoclonic encephalopathy - 4.2%, Ohtahara syndrome - 3.2% (diagram 2.3).
Diagram 2
Semiotics of seizures in patients with cortical dysgenesis
With age, all surviving children developed symptomatic focal epilepsy with a predominance of simple and/or complex focal seizures with motor phenomena with/without secondary generalization in 69.5% of patients, predominantly frontotemporal (24.1%), frontal (21.1 %) and temporal localization (17.9%).
Diagram 3
Epilepsy with cortical dysgenesis
As shown in Diagram 3, in total, in 47.3% of cases in children of the first year of life, West syndrome and symptomatic frontotemporal epilepsy dominated in older age subgroups for all types of CD. The severity of epilepsy was determined by the age of onset of epileptic seizures (Diagram 4).
Diagram 4
In patients with cortical dysgenesis
The results of comparing the age of onset of epileptic seizures did not show significant differences between groups I and III (p>0.05).
Table 2
Structure of epileptic seizures in patients
With cortical dysgenesis
| Group | Seizure frequency | Frequency | % of group size |
| single | 39 | 41,0 |
|
| serial | 49 | 31,6 |
|
| I | status | 7 | 7,4 |
| single | 56 | 61,5 |
|
| serial | 25 | 27,5 |
|
| III** | status | 10 | 10,9 |
| Note: ** the results of comparing the age of onset of epileptic seizures did not show significant differences between groups I and III (p>0.05) |
|||
Movement disorders occurred in 69.5% of children with CD. Among them, 37.9% of children older than the first year of life had cerebral palsy, mainly in the form of hemiparetic form or spastic tetraparesis. The group “at risk for cerebral palsy” consisted of all patients in the first year of life with a prevalence of motor disorders in the form of spastic tetraparesis in combination with the persistence of unconditioned reflexes (Table 3).
Table 3
| Group | | Frequency | % of group size |
| 0 | 29 | 30,5 |
|
| 1 | 0 | 0 |
|
| I | 2 | 8 | 8,4 |
| 3 | 15 | 15,8 |
|
| 4 | 9 | 9,5 |
|
| 5 | 34 | 35,8 |
|
| 0 | 33 | 36,3 |
|
| 1 | 3 | 3,3 |
|
| 2 | 6 | 6,6 |
|
| III** | 3 | 13 | 14,3 |
| 4 | 13 | 14,3 |
|
| 5 | 23 | 25,3 |
|
| Note: ** the results of comparing the severity of motor disorders did not show significant differences between groups I and III (p>0.05) |
|||
Cognitive impairments of varying severity (severe - 42.1%, moderate - 39%, mild - 13%) in children with CD were identified in total in 94.7% of cases.
The study of ante-, intra- and postnatal risk factors for the development of KD showed that the threat of miscarriage and early gestosis prevailed among them (p
The prognosis of CD may vary. The most unfavorable forms of CD include holoprosencephaly, lissencephaly, schizencephaly, megalencephaly, with a status-serial course of epileptic seizures, which are part of the structure of drug-resistant epileptic syndromes and symptomatic epilepsy. A relatively favorable course was observed in patients with focal pachygyria.
Morphology of cortical dysgenesis
The structure of the CD, based on the results of a histological examination of the brains of deceased children, is presented in Diagram 5.
Diagram 5.
Structure of cortical dysgenesis according to the results
morphological examination (n=50)
Microcephaly was confirmed in 40 cases (total 80%, n=50). In 62.5% of cases, a combination of microcephaly with various cerebral malformations was identified; most often these were ventriculomegaly, microgyria, hypoplasia of individual parts of the hemispheres and subcortical structures, focal gliosis, and less often - porencephaly.
Apparently, microcephaly is not an isolated malformation of the cerebral cortex. In this regard, the concept of stimulating neuronal apoptosis during normal neuroblastic migration seems more convincing. Activated apoptosis occurs in two phases: during the early phase of programmed death, neuroblasts with incomplete differentiation do not undergo (I and II trimester of pregnancy); in the second phase, already differentiated neurons of the fetal brain (III trimester and postnatal period) undergo additional apoptosis (Harvey B. Sarnat L. Flores - Sarnat 2005). This concept explains the presence of isolated microcephaly in children (in our material – 37.5%) with autosomal recessive inheritance, i.e. defects in those genes that regulate apoptosis or inhibit the expression of apoptotic genes (Stevenson R.E., Hall J.G. 2006). However, in most cases, microcephaly is accompanied by disturbances in neuroblastic migration, which leads to concomitant brain abnormalities or microcephaly with multiple malformations. A statistically significant correlation was revealed between head circumference (HC) indicators and brain mass deficit (correlation coefficient r = - 0.67). A decrease in the total brain mass from 19 to 70% of the deficit relative to the age norm is the dominant sign of microcephaly (Fig. 13).
Rice. 13. Macroscopic specimen of the brain of a 1 year 7 month old boy - a combination of microcephaly and pachygyria, brain mass deficiency - 71.7%.
Rice. 13 illustrates the insignificant information content of the widely used clinically used OH measurement for diagnosing microcephaly, especially in the presence of external hydrocephalus. Corresponding disproportions in brain volume and cranium diameter were noted during X-ray examination, as well as when analyzing the results of prenatal NSG. In Fig. Figure 14 shows a microslide of the brain demonstrating a violation of cytoarchitecture in a patient with microcephaly.
Rice. 14. Microscopic specimen of the brain of a 1 year 2 month old girl with microcephaly. Lack of differentiation of the cortical layers into the marginal, outer granular, layer of small pyramidal cells and inner granular layer. Hematoxylin-eosin staining, x 100.
Histological examination of 6 deceased patients (a total of 12%, n=50) confirmed the presence of polymicrogyria in combination with ventriculomegaly - 83.3%, atrophy of the subcortical nuclei and cerebellar hemispheres - 33.3%, pachygyria - 16%, however, statistical significance It is too early to talk about the results obtained. In Fig. Figure 15 shows a gross specimen of the brain demonstrating polymicrogyria.
R 
is. 15. Macroscopic specimen of the brain of a girl K., 6 months old, with polymicrogyria, pachygyria, microcephaly.
An X-ray scan of the brain revealed “malformation of the sulci, underdevelopment of the frontal lobes.” The maximum information content was obtained solely through analysis of the histological picture with the identification of pachygyria in the frontal regions and polymicrogyria in the occipital regions of the cerebral cortex.
Thus, in this case, there is a discrepancy between the final clinical and pathoanatomical diagnoses, which confirms the maximum information content of histological examination in comparison with radiological diagnostic methods.
When analyzing autopsies with polymicrogyria, disorganization of the layers of the cortex was discovered, mainly in the zone of shallow gyri (Fig. 16) with a barely contoured marginal layer (I) without a clear boundary of the transition to the outer granular layer (II). At the same time, with polymicrogyria, brain weight generally corresponds to age standards.
Rice. 16. Microscopic specimen of the brain of a sick girl K., 6 months old, with polymicrogyria. Shallow and wide gyrus without distinguishing the marginal and granular layers. Hematoxylin-eosin staining x 100.
Holoprosencephaly was confirmed by morphological examination of 4 deceased patients (total 12%, n=50). Two types of holoprosencephaly have been morphologically verified: alobar form (n=2); semilobar form (n=2). Holoprosencephaly was combined with microcephaly - 50%, ventriculomegaly - 25%. In Fig. Figure 17 shows the patient’s phenotype, intravital results of CT scan of the brain, fundus and post-mortem macro- and microscopic specimens of the brain of a 2-month-old sick girl with holoprosencephaly.
Fig. 17. Patient Ch., 2 months old, with holoprosencephaly, semilobar form.
A – appearance of the patient.
B – RCT of the brain. Holoprosencephaly, semilobar form. The temporal horns, part of the posterior horns of the lateral ventricles of the brain, are visualized. The interhemispheric fissure divides the brain into two hemispheres.
C, D - fundus of the right and left eyes of the same patient (explanations in the text).
^ When ophthalmological examination in patient Ch., 2 months. Hypoplasia of the optic nerve (Fig. 17 C, D) was detected in both eyes, absence of foveal and macular reflexes, and corkscrew-shaped tortuosity of the retinal vessels.
R 
is. 18. Macroscopic specimen of the brain of patient Ch., 2 months. with holoprosencephaly (semilobar form). The hemispheres are separated by a shallow groove; When one lobe was separated, a common large ventricle without lateral branches was revealed.
In Fig. Figure 19 shows a microslide of the brain of the same patient with holoprosencephaly, demonstrating a picture of a violation of the cytoarchitectonics of the layers of the neocortex.
R 
is. 19. Microscopic specimen of the brain of the same patient with holoprosencephaly. Large dysmorphic neurons in the V layer of the cortex, their vacuolar degeneration.
Thus, histological examination has established that CDs are usually combined and have common cytological signs: a reduction in the number and density of neurons, mainly pyramidal cells, disturbances in the cytoarchitecture of the layers of the neocortex, and the presence of large dysmorphic neurons. The obtained neurohistological data indicate an unfavorable prognosis for the above-listed CDs. MRI diagnostics of the fetus in some cases makes it possible to prevent the birth of a non-viable child with CD.
Associated anomalies of internal organs
(according to autopsies)
It turned out that most cases of microcephaly, all cases with polymicrogyria and holoprosencephaly were combined with other anomalies of internal organs. Malformations of the heart and great vessels were more common (in 32 cases - 64%), of which congenital defects of the heart and great vessels - in 18.7%, minor anomalies of the heart (MADC) - 43.7%, cardiac dysplasia, including fibromatosis atrioventricular valve leaflets (28.5%). Among them, the most severe forms were patent ductus arteriosus, microcardia, coartation of the abdominal aorta, and aortic stenosis.
Diagram 7
Structure of concomitant anomalies of internal organs
(according to autopsies) 
The presence of concomitant malformations of the heart and great vessels in children with CD indicates two important features. Firstly, it allows us to clarify the termination period of their common occurrence; since it is known that the above cardiac malformations form at 4-8 weeks of pregnancy, they violate the optimal conditions for further brain development, including neuroblast migration (G.I. Lazyuk, 1991). Other defects of internal organs are presented in Diagram 7. Secondly, such combinations should be taken into account in the prognostic assessment of the child’s condition, and his cardiovascular system, abdominal organs and retroperitoneal space should be additionally examined.
Thus, it is reasonable to conclude that CD is combined with other cerebral anomalies, and the diagnosis of isolated forms is based on dominant macroscopic signs, which was confirmed in the analysis of 50 autopsies.
So, in Fig. Figure 20 shows a macro picture of two different in volume and structure of the convolutions of the hemispheres; in the left hemisphere large fused convolutions predominate (pachygyria); the right hemisphere is hypoplastic and lacks clear convolutions (smooth cortex), which corresponds to the classic type of lissencephaly.
R 
is.20. Macroscopic specimen of the brain of a 1 year 4 month old boy - a combination of diffuse pachygyria in the left hemisphere and classic lissencephaly in the right hemisphere.
Spectrum of neurological disorders in deceased patients
with cortical dysgenesis
Analysis of the results of paroxysmal neurological disorders in the study showed that the main clinical manifestations of CD in the subgroup of deceased children with CD from 1 to 12 months of life were secondary generalized seizures (20%), complex focal seizures with motor phenomena (20%), generalized convulsive seizures (15%), infantile spasms (10%), less often - attacks of apnea with cyanosis (6%) and myoclonic seizures (5%) (Diagram 8).
Diagram 8
Semiotics of epileptic seizures
In deceased patients with cortical dysgenesis
In deceased children of older age subgroups, complex focal seizures with motor phenomena and secondary generalization dominated (19%), generalized convulsive seizures (10%), complex focal seizures without secondary generalization (8%), myoclonic seizures (5%), included in the structure symptomatic focal or multifocal epilepsy predominantly of frontotemporal (24%), temporal (20%) and frontal (16%) localization (Diagram 9).
Diagram 9
Spectrum of epileptic syndromes and symptomatic
Epilepsy with cortical dysgenesis in deceased patients
So, in 32% of cases, West syndrome and symptomatic focal epilepsy in total dominated in deceased children of the first year of life, less often - severe myoclonic epilepsy of infancy - 4%, Ohtahara syndrome - 4%. Among deceased patients of older age subgroups, various forms of symptomatic epilepsy were identified (frontotemporal - 24%, temporal - 20%, frontal - 16%). The severity of epilepsy was determined by the age of onset and the structure of epileptic seizures (Diagram 10, Table 2).
Diagram 10
Age periods of manifestation of epileptic seizures
In deceased children with cortical dysgenesis
It should be noted that in 94% of observations the manifestation of epileptic seizures in the group of deceased children with CD
was in the first year of life. In all study groups, there was a statistically significant difference in the frequency of onset of attacks (p
Table 2
Structure of epileptic seizures in deceased children
With cortical dysgenesis
| Group | Seizure frequency | Frequency | % of group size |
| single | 9 | 18,0 |
|
| II | serial | 29 | 58,0* |
| status | 12 | 24,0 |
|
| Note: *the structure of epileptic seizures had statistically significant differences (p 0.05) - table. 2 |
|||
A history of movement disorders was noted in all deceased patients with CD (Table 3).
Table 3
Distribution of severity of movement disorders
(GMFCS scale, R. Palisano et al., 1997)
| Group | Severity of movement disorders (scores) | Frequency | % of group size |
| 0 | 0 | 0 |
|
| II | 1 | 0 | 0 |
| 2 | 0 | 0 |
|
| 3 | 1 | 2,0 |
|
| 4 | 18 | 36,0* |
|
| 5 | 31 | 62,0* |
|
| Note: *results of comparison of motor disorders in groups I, II and III of patients revealed a statistically significant difference (p 0.05) |
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Severe cognitive impairment was identified in the anamnesis of all deceased patients with CD.
Causes of death in patients with cortical dysgenesis
An important clinical and morphological aspect in the problem of brain CD in children with epileptic syndromes and symptomatic epilepsy is their life expectancy and the distribution of deaths by age (Diagram 11).
Diagram 11
Distribution of deceased patients with cortical dysgenesis
The mortality rate of children with CD occurred in 3 periods: maximum - the first three years, average 6-7 years and high 12-14 years of life; its direct causes were bronchopneumonia (64.0%), acute viral respiratory diseases, sepsis and multiple organ failure (10.0%), other causes (6.0%).
The minimum life expectancy was found in children with the most severe forms of CD (holoprosencephaly) and concomitant somatic pathology, which emphasizes the importance of early diagnosis and attempts at early correction.
Unfortunately, even modern intravital neuroimaging studies cannot always verify the true prevalence of a structural defect in brain tissue.
In 40% of deceased patients with CD, a discrepancy was found between the final clinical and pathoanatomical diagnoses.
Antiepileptic therapy for cortical dysgenesis
In all patients with KD valproate(VPA) were the first drugs in the treatment of epilepsy. VPA in the treatment of 90 patients with KD, aged from 1 month to 17 years, were prescribed monotherapy: 29 (32.3%) patients; in polytherapy: (VPA+TPM) - 27 (30.0%) patients, (VPA+LTG) – 3 (3.4%), (VPA+TPM+LTG) – 11 (12.3%), (VPA +LTG+LEV) – 10 (11.2%), (VPA+CZP+PB) – 10 (11.2%). Doses of VPA in mono- and polytherapy varied from 20 to 70 mg/kg/day, with an average of 30 - 50 mg/kg/day. In our study, valproic acid salts were used more often. Topiramate (TPM) was used in the treatment of 29 patients with KD aged from 4 to 17 years in polytherapy in 38 (42.3%) patients, in monotherapy - 2. TPM doses were prescribed from 2.8 to 17 mg/kg/day, an average of 6, 6 mg/kg/day. Lamotrigine (LTG) was used in the treatment of 27 patients with KD aged from 6 to 17 years in polytherapy in 24 (26.7%) patients, in monotherapy - 3. Doses of LTG in monotherapy - from 4.5 to 8.5 mg/kg/day, on average 7 mg/kg/day, in polytherapy - from 0.5 to 6 mg/kg/day, on average 4.5 - 5.5 mg/kg/day. Phenobarbital (P.B.) in polytherapy with valproate and p benzodiazepine derivatives (CZP) were prescribed to 10 patients aged from 1 month to 17 years at a dose of 1.5 to 10 mg/kg/day, average 5.4 mg/kg/day, CZP - 0.5 - 1.0 mg/kg/ day. Levetiracetam (LEV) in polytherapy (VPA+LTG+LEV) was prescribed to 10 patients aged 4 to 17 years at a rate of 30 - 50 mg/kg/day per kilogram of patient weight.
An important clinical criterion for the effectiveness of antiepileptic therapy is the cessation of attacks or a reduction in their frequency during treatment.
Analysis of treatment results in the valproate monotherapy group (n=29) and in the group of patients receiving valproate as part of polytherapy (n=61) was assessed using the χ2 test, which did not reveal statistical differences in the frequency of seizure reduction (p
Infants treated with VPA had a minimal duration of illness from the onset of seizures to the start of the drug - on average, about 1 month 14 days. Noteworthy is the aggravation of myoclonic seizures by valproate in 2 patients in the first year of life, which is apparently associated with disorders of the neuronal receptor apparatus or metabolism.
The most effective duotherapy was a combination of valproate in combination with topiramate, which completely stopped epileptic seizures in 10.4% of patients with microcephaly, FCD. In 9.2% of patients, a decrease in the frequency of attacks by more than 50% was noted.
In the group of patients taking TPM, the average duration of disease before inclusion of the drug in the treatment protocol was about 3 years 8 months, and almost all patients had already received previous therapy with other AEDs.
Patients taking LTG before starting the drug had already had previous therapy with other AEDs. In our observation, LTG in monotherapy stopped epileptic seizures by 50-100% in 2 patients with focal pachygyria.
When new generation anticonvulsants (topiramate, lamictal) are used in polytherapy, it is possible to reduce the frequency of attacks, although remission is achieved in a small percentage of cases. It can be assumed that the combination of two AEDs with different mechanisms of action is potentially more promising in terms of achieving remission; however, the effectiveness of different treatment regimens in children with KD requires further study.
Thus, pharmacoresistant epilepsy was identified in 82.1% of patients, regardless of the type of CD. Epileptic seizures were stopped in 17.9% of patients, a reduction of 50% or more was achieved in 21.1% of patients, treatment was ineffective in 61.1% of patients. The drug of choice in the treatment of patients with various types of CD is valproate as part of polytherapy. The optimal regimen is a combination of valproic acid derivatives and topiramate.
Nodular gray matter heterotopias are present in many patients with other migration disorders such as polymicrogyria or schizencephaly. Single or multifocal large heterotopic nodes can be the focus of partial seizures. However, even giant heterotopias affecting one hemisphere may remain asymptomatic. A detailed neuropsychological study of one such case demonstrated subtle hemispheric dysfunction despite normal intelligence (Calabrese et al., 1994).
Spectrum of classical lissencephaly and subcortical linear heterotopia. These migration abnormalities can be considered to assess different degrees of severity of the underlying neuronal migration pathology, although they differ genetically (Palmini et al., 1993).
Lissencephaly refers to smooth brain. The term agyria-pachygyria is better because the surface of the brain is not always smooth (Aicardi, 1991). In the most severe cases, the gyri are not formed (agyria). In most cases, several convolutions are present (pachygyria). Dobyns and Leventer (2003) distinguish 6 degrees of lissencephaly (1 to 6), depending on the number of gyri visible on MRI. Only grade I deserves the name lissencephaly; grades 2-4 are cases with pachygyria, and grades 5 and 6 refer to subcortical linear heterotopia. This section brings together the various types as having a similar spectrum and, obviously, partly similar mechanisms. Although there are several forms of lissencephaly, this section will only discuss the LIS1 gene mutation on chromosome 17.
Classical (type 1, Bielschowsky) lissencephaly. In classical lissencephaly, the brain is small and has only primary and sometimes several secondary gyri. In the absence of convolutions, the vessels become tortuous. The cortex is pathologically thickened (10-20 mm), while the white matter appears as a narrow strip along the ventricles. Typically there are four layers of bark:
1) superficial, sparse cellular layer, similar to the molecular layer of the normal brain;
2) a narrow, densely cellular layer, where large pyramidal neurons are located, which normally should be located in deeper sections;
3) a thin layer of white matter, below which is
4) a wide band of small ectopic neurons, extending almost to the wall of the ventricles (Dobyns and Leventer, 2003).
Many neurons in cell layers are irregularly oriented, with the apical dendrite pointing downward or sideways (Takashima et al., 1987). The deeper cellular layer is formed from ectopic neurons that have stopped migrating from the germinative layer to the cortex at approximately 12 weeks of gestation, so the cortex appears like that of a 13-week fetus. The neurons of this layer have an excessive columnar organization. In the medulla oblongata, ectopia of the olivary nucleus is characteristic. The dentate nuclei are abnormally entangled and the pyramids are hypoplastic or absent (Friede, 1989).
Agenesis of the corpus callosum is unusual in this type. Type I lissencephaly in 65% of cases results from a mutation in the LIS1 gene, which encodes the 46D protein, the non-catalytic part of platelet activating factor acetyl hydrolase (Bix and Clark, 1998, Gleeson et al., 1999). Most cases are sporadic. Cases have been reported due to congenital cytomegalovirus infection, but with variable pathological changes (Hayward et al., 1991). Some cases occur due to chromosomal pathology, deletion of the distal part of the short arm of chromosome 17 (17p13.3).
Some of these cases are part of a specific dysmorphic related gene syndrome, Miller-Dieker syndrome, which is characterized by a narrow forehead, wide nasal bridge, lack of an upper lip notch, upturned nostrils, retrognathism, digital abnormalities, and retinal hypervascularization (Dobyns and Leventer, 2003). In such cases, Dobyns and Truwit (1995) identified an overt deletion of 17p13.3 in 14 of 25 patients and submicroscopic deletions in 25 of 38 cases using cytogenetic methods and in 35 of 38 cases with fluorescence in situ hybridization. Siblings with Miller-Dieker syndrome were born to couples in which one of the parents had a proportional translocation of the terminal fragment of chromosome 17p to chromosome 13-15 of the pair, which manifested itself in unbalanced forms in the affected children (Greenberg et al., 1986, Dobyns and Leventer, 2003).
(left) Type I (classical) lissencephaly. Four-layer bark. From surface (top) down: (1) molecular layer;
(2) a superficial cell layer containing several cell types, including large pyramids, normally located deeper in the fifth layer;
(3) a broad, acellular layer;
(4) a wide band of heterotopic cells arrested in migration - note the columnar arrangement.
(right) Normal position.
Most cases with type I lissencephaly are not part of Miller-Dieker syndrome and are defined as an "isolated" consequence of lissencephaly.
Clinical manifestations in all cases are characterized by severe mental retardation and diplegia, often of the atonic type (de Rijk-van Andel et al., 1990). As a rule, there are partial seizures and, as a rule, infantile spasms. Most patients have some degree of microcephaly, usually mild. In non-chromosomal pathology, dysmorphism is not expressed, although the forehead is narrow and retrognathism is often present. The prognosis is poor, with limited survival.
Some cases of LIS1 mutation may be more associated with subcortical group heterotopias than with lissencephaly (Gleeson et al., 2000).
The diagnosis of type I lissencephaly has become possible with the help of modern neuroimaging techniques. CT and MRI demonstrate the characteristic appearance of a broad cortical plate, with several gyri present or absent, separated from the hypodense white matter by a slightly wavy or almost linear border. Cortical lamination can be detected with high-resolution CT or MRI. Pathological changes usually dominate the posterior part of the cortex, while a few bends can be found anteriorly. With ultrasonography, the smoothness of the fetal or newborn cortex is determined already from 18.5-25 weeks (Toi et al., 2004). MRI provides more accurate results (Ghai et al., 2006).
On the EEG, in most cases one can see high-amplitude fast activity of alpha and beta frequencies, alternating even in the same recording with high-amplitude delta or theta slow rhythms, which can simulate slow spike-wave complexes or hypsarrhythmia (de Rijk-van Andel et al., 1992 , Quirk et al., 1993, Mori et al., 1994).
Differential diagnosis is carried out with other conditions in which there is thickening of the cortex and a violation of the layered structure. Pachygyria due to LIS1 mutation is considered only a mild form of lissencephaly and is not relevant to the differential diagnosis. Certain fetal developmental disorders, especially cytomegalovirus infection, appear to cause the development of pachygyria, which is histologically associated with polymicrogyria. Periventricular calcification may be accompanied by pathology in the formation of brain convolutions. In such cases, the microfolds may merge and resemble pachygyria.
Prenatal diagnosis is not possible in late pregnancy using ultrasonography because the tertiary sulci are just emerging at this time (Toi et al., 2004). DNA tests may reveal a mutated or missing LIS1 gene. To determine the risk of relapse when looking for laminar heteropias, chromosomal analysis and MRI of the parents (especially mothers) are necessary.
Classic (type I) lissencephaly. T1-weighted axial MRI: (LIS I mutation) thick cortical band with a smooth surface and a straight, non-wavy border between gray and white matter.
Note the presence of several small grooves in the frontal region and the complete absence of grooves posteriorly,
lack of operculation with a wide open Sylvian fissure and layered cortex with a weak boundary between heterotopated and fully migrated neurons.
Subcortical laminar heterotopia and lissencephaly as a result of a mutation in the DCX gene. Ribbon heterotopias (Barkovich et al., 1994, Franzoni et al., 1995) or “double cortex” (Livingston and Aicardi, 1990, Palmini et al., 1991) are the result of disturbed migration, in which the superficial cortex, apparently normal or with abnormalities in the gyri, separated by a thin layer of white matter from a strip of gray matter. The border between the gray matter and the underlying white matter is smooth, as in agyria-pachygyria. Patients with this anomaly often suffer from seizures, which may be focal or generalized, sometimes in the form of Lenox-Gastaut syndrome and abnormal EEG (Hashimoto et al., 1993, Parmeggiani et al., 1994).
Intellectual development disorders vary widely, with some patients developing normally (Livingston and Aicardi, 1990, Ianetti et al., 1993). Barkovich et al. (1994), in a detailed study of 27 cases, found a significant correlation between intellectual level and the thickness of the heterotopic stripe; an apparently normal cortex has been associated with better development, but this is likely to vary. On EEG, the band was found to be capable of producing paroxysmal activity and increased blood flow, as demonstrated by SPECT, indicating cortical activation.
This condition is in most cases caused by a sex-linked mutation in the DCX gene encoding doublecortin (des Portes et al, 1998, Gleeson et al., 1999). However, a similar mutation in boys can lead to classic lissencephaly (Pilz et al., 1998). The mutation is expressed very differently in women and even in some men (Cardoso et al. 2000, Gleeson 2000) and is therefore difficult to recognize. Therefore, genetic counseling for a family of a boy with lissencephaly should include a careful search for laminar heterotopia on MRI and, if necessary, DCX mutations in the mother and sisters. Families are known where the affected mother gave birth to boys with lissencephaly and girls with laminar heterotopia (Pinard et al., 1994). Rare cases of laminar heterotopia are associated with a LIS1 missense mutation and a more mild phenotype (Leventer et al., 2001).
On imaging, the severity of expression in girls varies from broad subcortical bands, sometimes covered by abnormal cortex, to subtle, difficult-to-detect bands that are visible only under limited areas of cortex. Unilateral and partial linear heterotopias are sometimes difficult to recognize and may require special sections and modification of the MPT format to identify them (Gallucci et al., 1991). In boys, the picture of classical lissencephaly is the same as in LIS1. However, the anterior portions of the cortex have a smoother surface compared to the posterior portions, in contrast to what occurs with the LIS1 mutation.
Epilepsy associated with laminar heterotopias may be amenable to drug treatment, but can also be resistant. Surgical treatment turned out to be ineffective.
Baraitser-Winter syndrome includes dysmorphic features and brain malformations in the form of classical lissencephaly or subcortical laminar heterotopias (Rossi et al., 2003).
Pachygyria. This type represents a less severe form of the lissencephaly spectrum and likely results from the same mechanisms. However, this form is heterogeneous and can be part of different syndromes. Clinically, pachygyria presents with various similar symptoms, but with less severity. MRI reveals cortical thickening and linear separation between the cortex and white matter.
(a) Lissencephaly-pachygyria in a 2-year-old girl: EEG shows typical fast rhythms with alpha and higher frequencies. (b| Miller-Dieker syndrome in a 14-week-old girl: rhythmic activity of various frequencies, but mainly in the theta range.
(c) Miller-Dieker syndrome in a 2-year-old boy: although there is some excess theta-alpha activity, the recording is dominated by repetitive bursts of sharp waves reaching 500-600 μW.
Other forms and syndromes of lissencephaly. Recognizing some of the less common variants of lissencephaly is equally important due to the differences in genetic and prognostic implications (Hennekam and Barth, 2003, Raoul et al., 2003).
Microlissencephaly consists of extremely pronounced congenital and agyria or pachygyria with a wide cortex. At least five or six recessive types have been described, with varying degrees of cortical thickening, the location of the sulci present, and the presence of associated defects such as cerebellar hypoplasia, brainstem atrophy, and ventricular enlargement (Ross et al., 2002, Dobyns and Leventer, 2003, Sztriha et al., 2004). Some authors (Dobyns and Barkovich, 1999) have distinguished these cases from “oligyric microcephaly” (Hanefeld, 1999), which they regard as a form of primary microcephaly rather than a form of migration disorder. One of these syndromes may be associated with a mutation in the Reelin gene (Hong et al., 2000, Crino, 2001).
Lissencephaly with cerebellar hypoplasia is a distant manifestation of microcephaly with a rudimentary bilayer cortex and severe cerebellar hypoplasia (Ross et al., 2001, Sztriah et al., 2005). Probably with recessive inheritance.
Lissencephaly with hypoplasia of the corpus callosum is genetically heterogeneous. Some cases may be part of the LIS1 mutation or microlissencephaly group.
X-linked lissencephaly with genital anomaly (XLAG) is a congenital disorder with microcephaly, severe developmental delay, a tendency to hypothermia, absence of the corpus callosum, and multiple brain abnormalities (Berry-Kravis and Israel, 1994, Dobyns et al., 1999). Genital hypoplasia is more likely than agenesis. XLAG results from a mutation in the homeobox gene ARX on chromosome X33.2 (Uyanik et al. 2003), on which other mutations may also cause some neurological syndromes (Kato et al. 2004, Suri 2005), including X-linked mental retardation development (MRX54), agenesis of the corpus callosum with genital pathology and Partington syndrome with mental retardation, ataxia and dystonia, depending on the type of mutation.
Interestingly, lissencephaly with neonatal seizures and severe neurodevelopmental abnormalities has been found to be associated with glutamine deficiency.
Subcortical group heterotopia (“double cortex”): (a) Axial MRI slice: wide, continuous groups with the same signal as from the cortex.
(b) Coronal section: in the same case there is dilatation of the ventricles predominantly anteriorly.
(c, d) MPT, T1-weighted sequence - (c) axial section, (d) sagittal section - a thin layer of white matter lying between the true cortex and a thin linear heterotopia of gray matter (arrows).
The connections of the human brain structure include two fundamental components - white and gray matter. White matter fills the entire spatial region between the gray on the cortex and the underlying ganglia. The surface is covered with a layer of gray component with multi-billion neurons, the thickness of the layer is approximately 4-5 mm.
There are quite a lot of different sources about what gray is and what it is responsible for, however, many people still do not have a complete understanding of this important component of the human brain.
Let's start with the key component - gray matter, which is a fundamental component of our central nervous system. The gray matter of the brain is formed from nerve cells, processes of these cells, as well as from thin vessels. This component differs mainly from the white one in that the latter does not contain neural bodies, but consists of a group of nerve fibers.
Gray matter is distinguished by a brownish color, this color is given by the vessels and neuronal bodies that are part of the substance itself. This component occurs in the cortex of the main hemispheres - the cerebellum and also in the internal structures of the cerebrum.
Mainly responsible for muscle activity and holistic reflection of objects (hearing, vision), as well as cognitive functions and emotional perception. Significant changes in the volume of the gray component occur in elderly people and with short-term memory impairment.
Some indicative gray matter abnormalities can be found in people with mental pathologies. With heterotopia of the gray matter of the brain, the development of epileptic syndrome is observed, especially in pediatric patients.
There were no changes in the total volume of the gray component in patients with bipolar disorder, as well as in completely healthy patients.
Role of white matter
The gray matter and white matter of the brain of the human central nervous system have different color intensities, which are determined by the white color of myelin, and its formation occurs from neuronal processes. It is located inside the brain and is surrounded by gray matter, and in the spinal cord it is located outside this component. Neural processes of white matter include:
- Sensory nerves consisting of dendrites that carry impulses from receptors directly to the central nervous system
- Motor nerves consisting of axons. Conducts the necessary impulse from the central nervous system to the motor organs, mainly to the muscles
- Mixed nerves consisting of both dendrites and axons. The impulse is carried out in both directions
White matter appears as a group of myelinated fibers. The ascending fibers carry out the conduction path from the nerve cells of the spinal cord and further into the cerebrum, and the descending fibers carry out the transmission of information.
The white matter of the two halves of the spinal cord is connected by connecting tissue (commissures):
- External, which is located under the ascending paths
- Internal, located nearby, responsible for the movement of the columns of the gray component
Nerve fibers
These fibers are multibillion-dollar processes of neurons that conduct nerve impulses in the brain and spinal cord.
The main part of the nerve fiber is the neuron process itself, which subsequently forms the fiber axis. To a large extent it is an axon. The thickness of a human neuron fiber is on average 25 micrometers.
Neuron fibers are divided into:
- myelin
- Unmyelinated
The peripheral and central nervous system is determined by the predominance of myelin fibers. Neuron fibers lacking myelin are usually located in the sympathetic part of the autonomic nervous system.
The main function of neural fibers is the transmission of nerve impulses. To date, scientists have studied only two types of its transmission:
- Pulse (provided by electrolytes and neurotransmitters)
- Pulseless
Medulla oblongata
In the cavity of the cranium, the spinal cord smoothly flows into the medulla oblongata. The upper border of the inner surface flows along the inferior edge of the bridge, and on the outer surface it is located near the medullary stripes of the 4th ventricle.
The upper sections are somewhat thicker than its lower sections. And the length of this section in an adult is on average 2.5 cm.
The medulla oblongata began its development along with the auditory organs, as well as an apparatus that has a direct effect on the respiratory system and blood circulation. It also contained the nuclei of the gray component, which is responsible for balance, motor coordination, and is also responsible for the performance of metabolic functions and controls the activity of our respiratory and circulatory systems.
The functions of this department perform the following tasks:
- Defense reactions (cough, vomiting)
- Maintaining normal breathing
- Functioning of vascular tone and regulation of cardiac activity
- Functioning of the respiratory system
- Regulating the activity of the digestive tract
- Maintaining muscle tone
hindbrain
This section includes the cerebellum and the pons. On the front side, the bridge appears in the form of a cushion with cerebral peduncles, and on the other side, the upper half of the rhomboid fossa.
Gray matter is part of the cerebellar cortex. The white matter of the brain in this part is located under the cerebellar cortex. It occurs in all gyri and various fibers that perform the connecting function of the lobules and gyri, or are directed to the nuclei.
The cerebellum coordinates our movements and orientation in space. The pons performs connecting functions with the middle brain, which in turn acts as a conductor.
Midbrain
This section begins its development from the median cerebral bladder. The cavity of this section appears to be a kind of cerebral aqueduct. On the outer surface it is limited by the roof of the midbrain, and on the inner surface by the cover of the cerebral peduncles. Functions of the midbrain:
- Stereoscopic vision
- Pupil response to stimulus
- Synchronization of head and eye movements
- Processing of primary data (hearing, smell, vision)
Most often, the middle brain region performs functions with the medulla oblongata, which in turn control every reflex action of the human body. The functioning of these departments allows you to navigate in space, instantly respond to external stimuli, and also control the rotation of the body in the direction of gaze.
Diencephalon
This section is laid under the corpus callosum and fornix, fused on the two sides of the hemispheres of the telencephalon. The gray matter of the intermediate section directly constitutes the nuclei, which directly relate to the subcortical centers.
This brain region is divided into:
- Thalamus
- Hypothalamus
- Third ventricle
The main activity of the medulla oblongata is aimed at:
- Regulating body reflexes
- Coordinating the activities of internal organs
- Metabolism
- Maintaining body temperature
Naturally, this department cannot work on its own, perform various functions, etc. Therefore, its activity consists of interconnected work with the brain, which allows for complete regulation of the system, as well as coordination of internal processes in the body.
Finite brain
It seems to be the most developed department, which covers all other parts of the brain.
As we noted, the cerebrum is represented by two hemispheres. Each hemisphere is represented by a kind of cloak, a department of smell and ganglia. The lateral ventricles located in the hemispheres are represented as cavities. The separation of the hemispheres from each other is accomplished by the longitudinal fissure, and their connection by the corpus callosum.
The overlying cortex appears to be a small plate of gray matter, approximately 2-4 mm thick. White matter is represented by systems of neuronal fibers, namely:
- Commissural, arise at the same time as the formation of the hemispheres
- Projection (ascending and descending), take part in the formation of complex reflex arcs
- Associative (intercalary) providing a functional relationship between individual neural layers of the cortex
The following centers are located in the terminal medulla:
- Motor regulation
- Control of conditioned reflexes and higher mental functions that perform the following functions:
- Speech production (frontal lobe)
- Muscle and skin sensitivity (parietal lobe)
- Visual functionality (occipital lobe)
- Smell, hearing and taste (temporal lobe)
Brain lesions
Today, in the era of innovative discoveries and new scientific achievements, it has become possible to conduct highly accurate and technologically advanced brain diagnostics. Therefore, if there is a pathological abnormality of the white matter, then there is the possibility of its early detection, which allows therapy to be started at an early stage of the disease.
Among the pathologies that are associated with damage to the white matter, there are some pathological abnormalities in various parts of the brain. For example, if the posterior leg is affected, the patient may be paralyzed on one side.
This problem may also be associated with impaired vision functionality. Impaired functioning of the corpus callosum can contribute to the development of mental disorders. In this case, often the person does not recognize the surrounding objects and phenomena and there is a pronounced dysfunction of purposeful actions. With bilateral pathology, it may become difficult for a person to speak and swallow.
A gradual loss of the gray component and cognitive functions is observed in people with a long history of smoking and occurs noticeably faster than in patients without this bad habit. Long-term smokers who were not smoking at the time of the study lost fewer cells and retained better mental performance than those who started smoking.
Also very interesting is that adolescents who were subjected to violent punishment or suffered from attention deficit disorder had significantly lower gray content in the prefrontal cortex.
Rice. 3.18. Lissencephaly. MRI.
a - T1-weighted image, sagittal plane. Agyria of the occipital lobe. The convolutions of the parietal lobe are thickened and wide.
b - IR IP, axial plane. The thickness of the cortex is increased, the ventricles of the brain are expanded.
Rice. 3.19. Periventricular heterotopia. MRI. a - IR IP, axial plane; b - IR IP, coronal plane.
Multiple nodes of heterotopia are located along the walls of the lateral ventricles.
The following forms of heterotopia are distinguished: periventricular nodular, periventricular and subcortical, both with and without changes in the structure of the cortex, giant, combined with cortical dysplasia, and ribbon-like.
Periventricular nodular heterotopia is characterized by clearly defined nodes located along the wall of the brain ventricle. The nodes can be either single or multiple and usually protrude into the ventricular cavity (Fig. 3.19).
Periventricular and subcortical heterotopia, both with and without changes in the structure of the cortex, is manifested by nodular periventricular heterotopia and accumulation of gray matter in the subcortical regions. The lesion is in most cases unilateral. Subcortical accumulation of gray matter can lead to local deformation of the sulci and thickening of the cortex (Fig. 3.20).
A giant form of heterotopia with a change in the structure of the cortex is a large accumulation of gray matter, occupying most of the hemisphere, from the wall of the ventricle to the surface of the cortex, leading to deformation of the cortical surface of the brain. With this form of heterotopia, accumulation of gray matter in the form of individual nodes is not observed. The giant form of heterotopia, due to the large size of the affected area, must be differentiated from pathological formations. With heterotopia, unlike tumors, perifocal edema, displacement of midline structures are not detected, and there is no signal enhancement after the administration of a contrast agent.
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Rice. 3.20. Periventricular-subcortical heterotopia. MRI.
a - IR IP, axial plane. Heterotopia nodes are located along the wall of the left lateral ventricle and in the subcortical sections of the white matter. Between the subcortical nodes, layers of white matter are preserved. The surface of the cortex is deformed.
b - T2-weighted image, coronal plane. The subependymal nodes protrude into the cavity of the left lateral ventricle, which makes its contours wavy.
Ribbon heterotopia, or double cortex syndrome, manifests itself as a well-defined ribbon-like layer of neurons separated from the cortex by a strip of white matter. This pathology can only be diagnosed using MRI data. In this case, the images reveal a smooth, clearly defined strip of gray matter located parallel to the lateral ventricle and separated from the cortex and wall of the ventricle by a layer of gray matter. The cerebral cortex may be unchanged or may change from moderate pachygyria to complete agyria (Fig. 3.21). Foci of hyperintense signal may be detected in the white matter on T2-weighted images. Ribbon heterotopia is difficult to differentiate from lissencephaly: they probably represent different degrees of the same general process of impaired neuronal migration. Unlike lissencephaly, with ribbon-like heterotopia, changes in the cortex are less pronounced.
Rice. 3.21. Ribbon heterotopia. MRI.
a - IR IP, axial plane; b - T2-weighted image, axial plane.
A band of heterotopic gray matter is separated
layer of white matter from the cortex and ventricles of the brain.
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Rice. 3.22. Bilateral open schizencephaly. MRI.
a - T2-weighted image, axial plane; b - T1-weighted image, coronal plane.
In both hemispheres of the brain, clefts are identified, extending from the subarachnoid space to the lateral ventricle. In the right hemisphere there is a wide connection between the subarachnoid space and the lateral ventricle. There is a narrow cleft in the left hemisphere of the brain. The ventricles of the brain are dilated and deformed.
Rice. 3.23. Open schizencephaly of the right frontal lobe. MRI.
a - IR IP, axial plane.
The edges of the cleft, located in the right frontal lobe, are represented by dysplastic gray matter. The cleft cavity is filled with cerebrospinal fluid. In the left hemisphere, a change in the course of the furrows and thickening of the cortex are determined.
b - T1-weighted image, coronal plane.
A cleft of complex shape with the formation of several small blind-ending branches was identified in the frontal lobe. The adjacent subarachnoid space and the anterior horn of the lateral ventricle are dilated.
Schizencephaly is a variant of cortical dysplasia, when a cleft is identified that runs through the entire cerebral hemisphere - from the lateral ventricle to the cortical surface. Clinical symptoms depend on the severity of the changes and are manifested by seizures, hemiparesis, and developmental delay. Most often, the cleft is localized in the pre- and postcentral gyrus and can be either unilateral or bilateral (Fig. 3.22). In most cases, with unilateral schizencephaly, other types of cortical dysplasias (pachygyria, polymicrogyria) are detected in the contralateral hemisphere (Fig. 3.23). Large vessels can be traced in the area of the cleft. The gray matter covering the cleft is dysplastic, thickened, and has an uneven internal and external surface.
