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At a glance

Heterogenous group of extremely rare familial malformative disorders characterized by intracerebral cerebrospinal fluid (CSF)-filled cavitations associated with various malformations and neurologic impairments. The presence of raised intracranial pressure must be taken into considerations.

Synonym

Infantile Hemiplegia Porencephaly Syndrome.

Classification

There are two types that consists of:

  • Type I: Encephaloclastic porencephaly

  • Type II: Schizencephalic porencephaly

History

A developmental defect of the brain, porencephaly is defined as any cavitation or CSF-filled cyst in the brain that communicates directly with the ventricular system. It may occur prenatally or postnatally. Berg et al provided the first description of familial porencephaly in 1983.

Incidence

An autopsy review showed an incidence of 22:1,000 infants with intracerebral injuries.

Genetic inheritance

Infantile hemiplegia with porencephaly is transmitted as an autosomal dominant trait.

Pathophysiology

Type I, or encephaloclastic porencephaly, is an acquired and usually unilateral condition thought to occur in the third trimester. It can result from fetal vascular occlusion, birth trauma, ventricular puncture, inflammatory processes, coxsackie virus infection, hemorrhage, or embolism. Type II, or schizencephalic porencephaly, usually is symmetrical, is thought to occur during the second trimester, and represents a primary defect in morphogenesis of the neuroectoderm. Later findings indicate that deficiencies in the protein C anticoagulant pathway have an important role in the etiology of congenital porencephaly.

Diagnosis

Prenatal and postnatal ultrasonography and MRI can demonstrate characteristic images of porencephaly. Cranial transillumination may be positive. Types I and II are distinguishable both anatomically and histopathologically. Type I usually presents as a unilateral cyst, whereas Type II usually is bilateral, located around the sylvian fissure, and often communicating with the lateral ventricles. Angiographically, Type I porencephaly shows preexisting vessels, which cross the cavitation, whereas Type II is noted for the continuity between the cortical vessels and the subependymal vessels. Histologic findings associated with Type I reveal a cavity that is lined by cicatricial glial membrane. Type II presents a cavity that is lined by ependymal tissue.

Clinical aspects

Patients with infantile hemiplegia and porencephaly usually present with permanent neurologic disabilities. Prognosis generally depends on the extent of the lesion. In most patients, symptoms begin in the first decade of life. A few patients develop only minor neurologic signs and have normal intelligence. The character and etiology of porencephaly, congenital or acquired, is diversiform and often difficult to recognize. Classically, those with Type I lesions have severe impairment, ranging from mental retardation and seizures to spastic hemiparesis or tetraplegia and blindness. Infants with Type I cysts have a more variable course. The use of cocaine during pregnancy is associated with a higher risk (four times normal) ...

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