Schizencephaly is a congenital defect of the central nervous system in the form of a cleft in the brain that occurs as a result of late neuronal migration. The main risk factors for the disease are genetic defects, teratogenic effects in the antenatal period, intrauterine hypoxia and neuroinfections. The condition is manifested by polymorphic convulsive seizures, delayed psychomotor development, focal neurological symptoms. Prenatal diagnosis is performed on planned ultrasound screening of pregnancy, postnatal – with the help of cerebral MR scanning, neurosonography, EEG. Supportive treatment: anticonvulsants, nootropics, complex rehabilitation. In the presence of complications, neurosurgical interventions are performed.
ICD 10
Q04.6 Congenital cerebral cysts
General information
The first descriptions of pathology were made by Wilmart in 1887, after which in 1946 scientists Yakovlev and Vadsdorf identified two morphological subtypes of the disease. The first description of the ultrasonic pattern of the defect belongs to W. Klingensmith, D. Koiffi-Ragan. Schizencephaly occurs with a frequency of 1.5:100,000 live births. Pathology is much more often registered among patients with epileptic seizures — 1 case per 1,650 patients. Racial and sexual differences among the patients were not revealed.
Causes
The etiological factors of the anomaly have not been sufficiently studied. In modern neurology, there are different opinions about the defect: some experts associate its development with cerebral ischemia in the embryonic period, others with corruption (a destructive process in an initially correctly formed organ) that arose under the influence of unknown causes. There are the following risk factors for the formation of a brain cleft:
- Gene mutations. A number of newborns have a mutant gene EMX2 (homeobox gene), which is involved in the growth and differentiation of neuroblasts. Occasionally, schizencephaly is detected with the COL4A1 mutation. Since not all patients have a gene defect, other factors also play a role in etiopathogenesis.
- Intrauterine hypoxia. This condition occurs when the mother has extragenital diseases (anemia, heart failure, lung disease), pregnancy pathologies (Rh conflict), various genetic syndromes in the fetus.
- Toxic effects. Disorders of embryonic development are often provoked by the negative influence of tobacco smoke (including passive smoking), alcohol, household and industrial chemical toxins. Some medications (anticoagulants, antibiotics, cytostatics) can also disrupt the formation of the central nervous system in the fetus.
- Intrauterine infections. The occurrence of schizencephaly is possible with primary infection or activation of latent infection in the first trimester of pregnancy. Herpes simplex viruses, cytomegalovirus, and toxoplasma have the greatest tropicity to the nervous tissue.
Pathogenesis
A number of researchers call intrauterine stroke in the basin of the middle cerebral artery the main link of pathogenesis, which leads to the formation of an area of ischemic tissue in which the processes of structural organization of cells are disrupted. Cerebral hypoxia in the formation of schizencephaly is usually accompanied by a chronic inflammatory process caused by neuroinfection.
There are two types of disease, taking into account pathomorphological features. Type 1 is characterized by a closed cleft, the edges of which are separated by a narrow groove covered with an ependyma and a spider sheath on top. With type 2 pathology, an open cleft is formed with edges far apart from each other. In this case, the ventricles communicate with the subarachnoid space, the circulation of the cerebrospinal fluid occurs.
Macroscopically, pathology in newborns is a gap in the brain with a predominant localization in the area of the lateral sulcus. Microscopically, with such a defect of the central nervous system, dysplasia of the gray matter covering the cleft is observed, a violation of the structure of the layers of the cerebral cortex in the affected area. Often, in addition to schizencephaly, other defects are detected in newborns and children of other ages: congenital anomalies of the transparent septum, corpus callosum, and visual intersection.
Symptoms
The clinical picture of the disease varies depending on the location and size of the cleft. The average age of manifestation of symptoms is 4 years, although in severe cases some signs are already detected in newborns. For schizencephaly, as for other cystic cavities of the brain, there is a typical delay in clinical manifestations, which makes it difficult to diagnose if it was not performed during prenatal screening.
The main sign of the disease is a variety of epileptic paroxysms: complex focal seizures (disturbances of consciousness in combination with twitching of one of the limbs), simple focal seizures, focal paroxysms with secondary generalization. The intensity of paroxysmal phenomena ranges from single attacks to 10-30 paroxysms per day. In newborns and children of the first year of life, single tonic or myoclonic seizures are noted.
Non-paroxysmal symptoms of the disease include violations of the innervation of facial muscles, which is manifested by facial asymmetry, impoverishment of facial expressions. Also, paresis of muscles innervated by the bulbar group of nerves develops, which manifests as disorders of swallowing, pronunciation of sounds. In newborns, as well as infants, the persistence of unconditioned reflexes is possible, in older children — a hemiparetic form of cerebral palsy.
More rare signs of brain cleft are sleep disturbances, sensations of noise or pulsation in the head, visual disturbances (bright flashes of light in front of the eyes, deterioration of visual acuity, narrowing of visual fields). Such complaints are mainly made by school-age children. There may be violations of coordination of movements, instability of gait, fine-pitched tremor.
Complications
A cleft in the brain is fraught with the formation of hydrocephalus, which is manifested by an increase and deformation of the child’s head, a violation of the outflow of cerebrospinal fluid. Without timely medical care, there is a risk of hypertension-hydrocephalus syndrome. A newborn, an infant, has generalized convulsions, swelling of the fontanel, cerebral vomiting. If the brain stem is affected against the background of hydrocephalus, a fatal outcome is possible.
Severe neurological deficit is observed with a combination of schizencephaly and septo-optic dysplasia, gray matter heterotopia. Children with a cleft brain suffer from mental retardation, delayed speech function, and various mental abnormalities. The danger is represented by pharmacoresistant convulsive seizures, which are fraught with the development of an epileptic status.
Diagnostics
At the present stage of development of ultrasound diagnostics, in most cases schizencephaly is diagnosed antenatally during planned pregnancy screening. A closed-type cleft is much better visualized, whereas open schizencephaly can go unnoticed. For postnatal confirmation of the diagnosis, a pediatric neurologist requires the following research methods:
- MRI of the brain. Magnetic resonance imaging is a safe method even for newborns. With type 1 of the anomaly, a bulging ventricular wall with a narrow channel is detected. Type 2 is characterized by an open cleft that is filled with cerebrospinal fluid. If necessary, an MRI of the cerebral vessels is performed.
- Neurosonography. Ultrasound of the brain is used as an alternative to MRI in newborns, infants before the closure of the large fontanel. Sonography is quite informative for type I schizencephaly. The method is also used to identify concomitant anomalies of the structure of cerebral structures. To clarify the diagnosis, neurosonography is supplemented with cerebral vascular ultrasound.
- EEG. According to the results of electroencephalography in patients of different age groups, including newborns, a slowdown in the main background activity, regional epileptiform patterns in the frontal-central temporal zone are determined. Less often there is secondary bilateral synchronization, multifocal epileptiform activity.
- Ophthalmoscopy. Examination of the fundus reveals an important ophthalmological symptom of hydrocephalus — swelling of the optic nerve discs. The method is applicable for patients of different ages, including newborns. Visometry, perimetry, and biomicroscopy of the eye are recommended to evaluate the work of the visual analyzer.
- Genetic testing. Since the anomaly is combined with mutations of EMX2, COL4A1, automatic sequencing of the exon is shown. However, the informativeness of this method remains low due to the polyetiological nature of the disease.
Treatment
Conservative therapy
Medical care for children with schizencephaly is limited to supportive symptomatic treatment. Patients are shown dynamic observation by a pediatric neurologist, regular CT or MRI monitoring of the cleft condition, determination of the presence or absence of secondary structural changes in brain tissue. The main groups of drugs that are included by a specialist in an individual treatment regimen for schizencephaly:
- Anticonvulsants. Various combinations of anticonvulsants are prescribed for the relief of epileptic seizures, prevention of relapses.
- Neurometabolites. Drugs that improve the trophism of the brain are used to stimulate psycho-speech and motor development, reduce neurological deficit.
- Dehydrators. Osmotic diuretics, saluretics, oncodehydrants can be recommended to normalize fluid dynamics. Treatment is carried out under the control of diuresis and the volume of injected infusion solutions.
Surgical treatment
Surgical treatment is used in the complicated course of the disease. Usually, operations are performed on newborns, infants to eliminate the growing hydrocephalus. Most often, endoscopic ventriculostomy of the III ventricle and cerebrospinal fluid bypass interventions are performed. With an increase in epileptic paroxysms, the appearance and increase of gross focal neurological symptoms in a newborn or a patient of another age, aspiration of the contents of large cysts is performed.
Rehabilitation
Comprehensive rehabilitation of patients, including newborns and infants, plays an important role. Massage, reflexology, mechanotherapy and physical therapy are used to increase muscle strength, the volume of voluntary movements. For the development of speech, the child needs the help of a speech pathologist. In order to increase the learning ability and socialization of patients, they resort to the services of a neuropsychologist, a correctional teacher.
Prognosis and prevention
A favorable course is characteristic of newborns with closed unilateral schizencephaly, which is not accompanied by a gross neurological deficit. The open bilateral form of the defect, which causes early disability and death of patients, inspires fears. Preventive measures include rational management of pregnancy, exclusion of teratogenic effects on the body of the expectant mother, improvement of prenatal ultrasound screening techniques.
