From Big Medical Encyclopedia

PORENCEPHALIA (porencephalia; grech, poros pass, an opening, is time + for enkephalos a brain) — the pathological cystous cavities of a different form and size which are located in tissue of a brain. The term «porencephalia» is entered in 1859 by R. L. Heschl who described inborn defect of big hemispheres brain (see), stretching from a cerebral cortex to a wall of a side ventricle. In 1969 Mr. D. D. Matson suggested to use this term only in relation to cystous cavities of a brain of an inborn origin. In neurosurgical practice by this term sometimes designate artificially created message between subarachnoid space (cavitas subarachnoidalis) and a side ventricle of a brain.

Cystous cavities as malformations of a brain in some cases are formed in the pre-natal period as a result of disturbances of process of a morphogenesis or owing to change of blood circulation or a hematencephalon. Sometimes such cavities arise at early children's age or in the subsequent age periods owing to disturbance of cerebral circulation, an injury, an infection, inflammatory, tumoral and others patol, the processes causing damage of gray and white matter of a brain.

Fig. 1. Macrodrug of a brain at a true porencephalia (a frontal section): the intracerebral cystous cavity (is specified by shooters) which is reported with a side ventricle and a surface of a cerebral hemisphere.

Distinguish true and false the Item. At true P. cysts can be reported with cerebral cavities, being as if their diverticulums sometimes extending to an outer surface of a cerebral hemisphere (fig. 1). Less often cystous cavities with cerebral cavities are not reported. The size of cysts is very variable; some of them can sometimes occupy a half and more than a half of a cerebral hemisphere. The inner surface of a cyst most often smooth, is covered by an ependimopodobny cover. If the cyst is reported with cerebral cavities, it contains cerebrospinal liquid and if it is not reported — cystous yellowish liquid with a large amount of protein. Microscopically in a wall of a cyst sites, educated geterotopirovanno, the cerebral cortex having the wrong structure come to light. In walls of cysts sometimes find gemoglobinogenny pigmentation (signs of focal hemorrhages) and small anoxic necroses. Side ventricles often have irregular shape and are expanded, especially in the field of a prileganiye of a porencephalic cyst. Crinkles of cerebral hemispheres are radially submersed in the direction of a cyst, and sometimes in this area absolutely are absent and on their place there is only a lamina from marrow and a soft cover of a brain which is crateriform sinking down during the opening of a cavity. Gistol, changes in the crinkles of a brain, next to a cyst, are characterized by the expressed depression of ganglionic cells and the wrong orientation of cellular layers. In a soft cover of a brain focal necroses are noted. These changes indicate early emergence true the Item.

Fig. 2. Macrodrug of a brain at a false polycystic porencephalia (a horizontal section): shooters specified the multiple intracerebral cystous cavities which are located in white matter of a brain.

False porencephalia call the cavities which are located in tissue of a brain, but not reaching the surface of a brain and not reported with cerebral cavities (fig. 2).

These cavities can be located in one or both cerebral hemispheres, hl. obr. in its white matter, happen single and multiple, reported among themselves. Outward of crinkles of a cerebral cortex is, as a rule, not changed. In walls of adventitious cysts cicatricial fabric comes to light.

The most sharply expressed P.'s degree — a so-called vesical brain, at Krom in patol, process the trunk, basal kernels and cerebral hemispheres are involved. The vesical brain has an appearance of two big bubbles filled with liquid. Cystous defects of a cerebellum of type P. meet seldom.

The item at newborns and at early children's age is shown by a delay of mental development, spastic paralyzes or paresis of extremities (see. Paralyses, paresis ), sometimes epileptic seizures (see. Epilepsy ). Quite often note symptoms of defeat extrapyramidal system (see) and cranial nerves (see). Along with P. in some cases find an underdevelopment of a corpus collosum, to the tsefalotsella (loss of a part of substance of a brain), asymmetry of a skull with protrusion of a scaly part of a temporal bone on the party of defeat, nanocephalia (see), Cryptorchism (see) and other malformations of bodies.

It is clinically very difficult to distinguish false P. from true. Sometimes cysts of a brain, even multiple, at false P. are shown focal nevrol, symptomatology without signs of mental disturbances.

Fig. 3. A pneumoencephalogram at a true porencephalia (a side projection): the intracerebral cyst (1) having the wide message with a side ventricle (2).

Items establish on the basis of signs of organic lesion of a brain and data of a pnevmoen-tsefalografichesky research (see. Pnevmoentsefalografiya ). At true P, by means of a pneumoencephalography reveal the cystous cavities which are reported with cerebral cavities, at the same time ventricles are usually tightened to area of defect of tissue of brain (fig. 3). The anastomosis between a cyst and a cerebral cavity is defined on a pneumoencephalogram if diameter makes it not less than 2 mm. The small cavities located in the depth of a brain which are reported with a cerebral cavity very narrow course are presented on roentgenograms as otshnurovanny cystous cavities.

At false P. on a pneumoencephalogram note the shift of cerebral cavities; character of shift allows to establish localization of the closed cystous cavity and its volume.

By means of an angiography reveal the typical shift of vessels of a brain according to localization and volume of a cyst, it is frequent with an extensive avascular zone in the field of defect (see. Carotid angiography , Cerebral angiography ).

Fig. 4. The computer tomogram of the head at a true porencephalia: the intracerebral cystous cavity (1) which is reported with ventricular system of a brain (2).

Form and localization of cysts, especially multiple, most precisely establish by means of a computer tomography (see. Tomography computer ). At true P. on tomograms find in a brain the centers of the lowered density, the corresponding density of cerebrospinal liquid, with accurate contours, without the phenomena of hypostasis of surrounding fabric. At the message of a cystous cavity with a cerebral cavity of shift it to the opposite side is not noted (fig. 4). At false P. in a brain reveal the outlined cystous cavities; in case of their localization in one hemisphere cerebral cavities are quite often displaced to the opposite side.

Treatment at true P. in most cases conservative using pharmaceuticals, physical therapy and holding orthopedic actions. During the progressing of the process which is followed by increase of epileptic seizures and development of secondary hydrocephaly (see), operational treatment is shown. During operation make opening of a cyst and delete the vascular texture seen in its depth. In the absence of positive effect from this operation make drainage of cerebral cavities by imposing of the ventrikuloatrialny or ventri-kuloperitonealny shunt.

Forecast depends on the size of a cystous cavity, plurality of cysts and extent of damage of a brain. At extensive bilateral defeats an outcome, as a rule, adverse.

Bibliography: Gilyarovsky V. A. To a question of pathological anatomy and a pathogeny of a porencephalia, a yew., M., 1909; The Multivolume guide to pathological anatomy, under the editorship of A. I. Strukov, t. 2, page 570, M., 1962; H e sc hl R. Ge-hirndefect und Hydrocephalus, Vrtljschr. f. d. Prakt. Heilk., Bd 61, S. 59, 1859; Lorber J. Emery J. L. Intracerebral cysts complicating ventricular needling in hydrocephalic infants, Develop. Med. Child Neurol., v. 6, p. 125, 1964; Matson D. D. Neurosurgery of infancy and childhood, p. 188, Springfield, 1969; Pediatrische Neurochirurgie, hrsg. v. J. Gerlach u. a., S. 241, Stuttgart, 1967.

I. M. Irger.