Fluid-filled cavity within the cerebral hemispheres, can be unilateral or bilateral and may or may not communicate with cerebrospinal fluid spaces (CSF spaces)
Porencephaly is a term used for any cavitation or cerebrospinal fluid-filled cyst in the brain. One form, called encephaloclastic, or type 1, porencephaly, is usually unilateral and results from focal destructive lesions such as fetal vascular occlusion or ... Porencephaly is a term used for any cavitation or cerebrospinal fluid-filled cyst in the brain. One form, called encephaloclastic, or type 1, porencephaly, is usually unilateral and results from focal destructive lesions such as fetal vascular occlusion or birth trauma. Another form, called schizencephalic, or type 2, porencephaly, is usually symmetric and represents a primary defect or arrest in the development of the cerebral ventricles. Encephaloclastic porencephaly is more common (Airaksinen, 1984; Sensi et al., 1990). Genetic Heterogeneity of Porencephaly See also POREN2 (614483), caused by mutation in the COL4A2 gene (120090).
Berg et al. (1983) provided the first description of familial porencephaly. In 1 family, a grandmother was hemiparetic; of her 9 children, 1 had seizures, 1 had hemiparesis and 1 had both, and all 3 children of her ... Berg et al. (1983) provided the first description of familial porencephaly. In 1 family, a grandmother was hemiparetic; of her 9 children, 1 had seizures, 1 had hemiparesis and 1 had both, and all 3 children of her oldest son had porencephaly. In a second family, 2 sibs had porencephaly. The same disorder appears to have been reported by Smit et al. (1984). Airaksinen (1984) reported 2 affected sibs who were born after normal full-term pregnancies. One child was diagnosed with cerebral palsy at age 4 months after developing restlessness, abnormal movements, increased muscle tone, and seizures. Brain imaging showed a right-sided dilatation of lateral ventricles and a parietal porencephalic cyst. Her younger brother showed abnormal primitive reflexes and opisthotonos at 6 weeks of age. Brain imaging showed a right-sided cyst and dilated ventricles. Both children were severely handicapped. Zonana et al. (1986) evaluated 2 families in which 6 persons were affected with infantile hemiplegia and 5 of these were shown to have congenital porencephaly. In the first family, a brother and sister were affected; a 42-year-old uncle had right-sided hemiplegia since infancy and a left-sided porencephalic cyst. In the second family, the proband was seen at 8.5 months of age for left-sided hemiplegia, and the father was said to have mild left-sided hemiplegia since infancy. A paternal uncle's son was said to have mild right-sided hemiplegia since infancy, but examination was impossible. Computerized tomography in patients with familial porencephaly usually shows unilateral enlargement of the lateral ventricle, although a few have had bilateral involvement. The frontal horn usually shows the most enlargement. Vilain et al. (2002) performed cerebral imaging in 3 of 6 members of a family who had congenital hemiplegia and found porencephaly in all. Cerebral imaging in 3 asymptomatic obligate carriers in this family, including MRI in 1, was normal, indicating that cerebral imaging is unreliable as a means of detecting obligate carriers of familial porencephaly. Aguglia et al. (2004) reported a 3-generation Italian family in which 9 individuals had type 1 porencephaly inherited in an autosomal dominant pattern. A high rate of miscarriages was reported. Four patients had a severe phenotype with unilateral porencephalic cyst, pyramidal signs, tetraparesis, limb dystonia, seizures, exotropia, visual field defects, and low IQ. The other affected members manifested some of these features. Three patients had perinatal asphyxia, and 4 patients had mitral valve prolapse. The pattern of brain abnormalities were consistent with in utero insults occurring late in the second trimester. Van der Knaap et al. (2006) provided follow-up of the family reported by Smit et al. (1984). Reexamination of the 3 affected individuals, a mother and her son and daughter, showed leukoencephalopathy in all 3 and lacunar infarcts, microbleeds, and macrobleeds in the mother. She had divergent squint at age 4 years, and CT scan at age 24 years, following the diagnosis of her children, showed porencephaly and mild diffuse hypodensity of the white matter. She had several stroke-like episodes in her forties. Examination at age 54 years showed mild expressive dysphasia, central facial paresis, and hemiparesis. Her son presented with developmental delay and hemiparesis at age 8 months. CT scan showed porencephaly, and he also had seizures, no active speech, and cognitive defects. Examination at age 33 years showed mild convergent squint, mild central facial paresis, and pseudobulbar dysfunction with masseter reflex and drooling. He had a severe spastic hemiparesis, extensor plantar responses, and polar cataracts. Her daughter developed progressive hydrocephalus at age 6 weeks. Pneumoencephalography showed dilated right lateral ventricle with midline shift. CT scan showed destruction of large parts of the right hemisphere with calcium deposits. She had seizures and delayed psychomotor development but learned to speak. Examination at age 30 years showed mild divergent squint, mild facial paresis, and pseudobulbar dysarthria. She also had hemiparesis and nuclear cataract. Electron microscopy of skin biopsies in the 2 offspring showed striking abnormalities, with about 20% of capillaries having a thickened and fragmented basement membrane. Van der Knaap et al. (2006) concluded that mutations in the COL4A1 gene are a major risk factor for microangiopathy and ischemic infarct. De Vries et al. (2009) reported 2 Dutch sibs with antenatal intracerebral hemorrhage and porencephaly. The sibs were born at 34 and 31 weeks' gestation, respectively. The first infant had a possible antenatal trauma at 23 weeks' gestation. Routine brain imaging in both infants at birth showed resolving intracranial hemorrhages in the left lateral ventricles with an ipsilateral porencephalic cyst and small cystic lesions in the periventricular white matter of the contralateral hemisphere. At age 18 months, the older child had right-sided hemiplegia, strabismus associated with a quadrant hemianopia, but no cataract or tortuosity of the retinal arteries. His developmental quotient was 68. At age 9 months, the second child had increased tone of the lower limbs and strabismus. Brain MRI of the mother showed mild ventricular dilatation and multiple hyperintense lesions in the periventricular white matter of both hemispheres, but no dilated perivascular spaces or evidence of microbleed. Her father had a history of transient ischemic attacks and died at age 52 years after a severe intracranial hemorrhage. MRI of the father showed porencephalic dilatation of the left lateral ventricle and hyperintense lesions in the periventricular white matter of both hemispheres. Genetic analysis identified a heterozygous mutation in the COL4A1 gene (G1580R; 120130.0011) in both sibs and the mother. De Vries et al. (2009) suggested that COL4A1 mutation carriers are at risk for intracranial hemorrhage from fetal life into adulthood and that antenatal intracerebral hemorrhage can lead to porencephaly in the newborn infant.
Gould et al. (2005) assessed families previously described by Smit et al. (1984) and Aguglia et al. (2004) for mutations in the COL4A1 gene. The first family had a gly-to-arg substitution at codon 1236 (120130.0001); the second family ... Gould et al. (2005) assessed families previously described by Smit et al. (1984) and Aguglia et al. (2004) for mutations in the COL4A1 gene. The first family had a gly-to-arg substitution at codon 1236 (120130.0001); the second family had a gly-to-ser substitution at codon 749 (120130.0002). Both mutations changed conserved glycine residues within the Gly-X-Y repeats in the triple helical domain.