Porencephalic cyst is the formation of pathological cavities in the brain of different shapes and sizes filled with fluid. The disease occurs primarily in the prenatal period under the influence of genetic, teratogenic or hypoxic influences, as well as secondarily — against the background of encephalitis, cerebral hemorrhages. Porencephaly is manifested by epileptic seizures, decreased motor functions, lag in intellectual development. Diagnosis of the disease requires MRI, CT, neurosonography and EEG. Treatment is carried out conservatively (anticonvulsants, dehydrators, nootropics) or surgically.
ICD 10
Q04.6 Congenital cerebral cysts
General information
For the first time the term “porencephaly” was used in 1859 when describing a defect of the cerebral hemispheres in newborns. True congenital porencephaly is more commonly known as schizencephaly. A severe degree of pathology is called polycystic brain disease. The frequency of occurrence is about 2-3 cases per 100,000 population, there are no sex differences in the incidence. Porencephalic cystic formations do not lose their relevance in pediatric neurology, which is due to the lack of effective therapies, the risk of irreversible neurological deficit.
Causes
Primary (true) porencephalic cyst is formed during the intrauterine development of a child under the influence of genetic mutations (COL4A1, EMX2), fetal hypoxia, teratogenic factors (chemical toxins, neuroinfections, some medications) and usually manifests in newborns. The exact causes of the birth defect have not yet been established. The etiological structure of secondary porencephaly is more studied and includes the following factors:
- Inflammatory processes. The formation of porencephaly is possible in patients with meningitis, encephalitis, ventriculitis, which have a prolonged or chronic course. Pathological changes are caused by the proliferation of connective tissue, filling the formed cavity with liquor.
- Intracerebral hemorrhages. The occurrence of porencephalic cysts is possible with the resorption and organization of large foci that appeared after TBI, hemorrhagic stroke. This is often found in newborns who have suffered hypoxia or birth trauma to the head.
- Surgical interventions. Iatrogenic factors of the development of the cystic cavity include complications after puncture of the cerebral ventricles, including with poor functioning of the shunt, ongoing hypertension-hydrocephalus syndrome.
Pathogenesis
Porencephaly occurs during intrauterine development as a result of violations of the morphogenesis of cerebral nerve tissues or with various disorders of cerebral circulation. Genetically determined disorders of the vascular structure (in the presence of pathological collagen chains), teratogenic effects play a role in the pathogenesis. Hypoxic-ischemic encephalopathy is an important link in the mechanism of formation of cystic formations in newborns.
The sizes of pathological cavities vary widely, in severe cases they occupy the entire cerebral hemisphere. From the inside, the neoplasms have a smooth surface covered with an ependym-like shell. Sections of the heterotopic cerebral cortex are microscopically determined. Porencephalic cyst can be filled with cerebrospinal fluid or cystic fluid, which has a yellow color, contains many protein inclusions.
Regarding the morphological features of the communication of porencephalic cysts with the ventricular system of the brain, there are still disputes among specialists. Some consider the presence of such a message an optional condition for making a diagnosis, others diagnose porencephaly if there is at least one outflow pathway (into the ventricles or into the subarachnoid space), third authors are convinced of the need for both types of communication.
Symptoms
The clinical symptoms are very diverse, which depends on the size, quantity, localization of volumetric formations. Large cystic cavities manifest during the newborn period or in the first year of a child’s life. The first signs are usually various types of convulsive seizures: generalized tonic-clonic, simple and complex focal seizures, focal paroxysms with secondary generalization.
Already in the first months of life, pathological muscle spasticity is determined, which is why a newborn or infant has stiffness of movements with a reduced amplitude, the formation of motor skills lags behind age norms. Gradually, motor disorders progress: paresis and paralysis of the musculature develop, the bulbar group muscles are involved in the process, which is manifested by disorders of swallowing, gulping, pronunciation of the first words.
Neurological signs are largely determined by the location of the porencephalic cyst. The visual analyzer is often affected: visual acuity decreases, visual fields narrow, photopsies appear. Damage to the temporal lobe of the brain is fraught with a feeling of noise in the head, vestibular disorders, difficulties in speech development. With damage to the cerebellum, complaints are supplemented by tremor of the hands, instability of posture and gait.
As the child grows older, cognitive deficits become more noticeable. Patients with large porencephalic cysts lag significantly behind in speech development, often do not speak at all or express themselves in separate words. Children suffer from varying degrees of mental retardation, cannot study in regular classes. There are also frequent cases of mental disorders, primarily autism spectrum disorders.
Complications
With large cerebral cavities in newborns of the first days of life, severe violations of vital functions occur, which end in death in the neonatal period. If the child can be saved, he reveals a deep neurological deficit, there is no psychomotor development, medical care is required in the intensive care unit. Such patients die at an early age.
During the formation of synechiae, an excessive amount of cerebrospinal fluid accumulates in the cystic cavity, which is a predictor of the development of hydrocephalus. In such cases, newborns have an increase in the size and deformation of the head, an increase in convulsive seizures, disorders of consciousness. When porencephaly is combined with agenesis of the corpus callosum, motor disorders worsen, and the risk of pharmacoresistant epilepsy increases.
Diagnostics
During a clinical examination of a newborn by a neonatologist, children of other ages by a pediatrician, and then by a pediatric neurologist, various focal signs are determined: unilateral hemiparesis, bulbar syndrome, hyporeflexia, symptoms of cognitive deficit. A pediatric ophthalmologist is involved in the examination to assess the condition of the fundus. To confirm the presence of porencephalic cysts, the following diagnostic tests are performed:
- Neurosonography. Ultrasound of the brain is an informative method of examining newborns, with the help of which the cerebral cavities filled with fluid are visualized, their size and localization are determined. According to the indications, the study is supplemented by cerebral vascular ultrasound.
- MRI of the brain. The most accurate method of verifying the diagnosis, which shows all structural changes in the nervous tissue, is used for the differential diagnosis of true cystic cavities (lined with dysplastic gray matter of the cortex) and secondary porencephaly (formations from the inside are covered with white matter of the brain). It is allowed for examination of newborns and infants.
- CT scan of the brain. Computed tomography is performed in older children, in adults. Newborn and younger children are produced in exceptional cases by doctor’s prescription. According to the images, it is possible to detect a volumetric hollow neoplasm that does not have a solid component, does not absorb X-ray contrast agent. A characteristic feature is the absence of a mass effect even with a large porencephalic cyst.
- EEG. Electroencephalography is recommended for all patients with convulsive syndrome, including newborns, to study the electrical activity of the brain. According to its results, areas of spontaneous epileptiform activity are detected, usually accompanied by secondary bilateral synchronization.
In modern neurology, true porencephaly in most cases is diagnosed antenatally during routine ultrasound screening of pregnancy. Information about the presence of an anomaly is necessary for obstetricians and gynecologists to make a rational choice of delivery tactics, planning emergency care for newborns during the first hours of life.
Treatment
Specific care for patients with porencephalic cyst has not been developed, so treatment is reduced to maintenance therapy. Patients are under the dispensary supervision of a pediatric neurologist, the examination program includes regular neuroimaging to control the size of the cyst. The individual treatment plan for porencephaly, compiled in accordance with the clinical manifestations of the disease in the patient, may include:
- Anticonvulsant therapy. For the relief of epileptic seizures, individual combinations of anticonvulsants of different types of action are selected. Constant monitoring of their effectiveness is required, given the frequent cases of pharmacoresistant seizures in porencephalic cysts.
- Symptomatic therapy. To activate blood supply and trophism of cerebral tissues, neurometabolic drugs, nootropics, and means that improve microcirculation are indicated. With an increase in intracranial pressure, osmodiuretics, saluretics are used.
- Neurosurgical treatment. If operative access to the cystic cavity is possible, its opening, aspiration of liquid contents, excision of the vascular plexus is carried out. With a complicated course of the disease, ventriculoperitoneal or ventriculoatrial bypass surgery is necessary.
- Rehabilitation. Kinesiotherapy, mechanotherapy, and massage are prescribed to improve coordination of movements and muscle strength. Children need classes with a speech therapist, speech pathologist, neuropsychologist.
Prognosis and prevention
With small porencephalic cyst, the prognosis is favorable if there is no gross neurological deficit. Large formations occupying a significant part of the brain are incompatible with life: intrauterine fetal death or the death of a newborn is observed. Prevention of true porencephaly involves proper management of pregnancy and preparation for childbirth, secondary — timely treatment of inflammatory and vascular pathologies of the central nervous system.