Teaching Case

38-year-old male with Right hand and foot dystonia.

A porencephalic cavity is occupying the left parietal corona radiata/centrum semiovale, communicating with the atrium/posterior body of the left lateral ventricle (Figure 1 ). The mild mass effect upon the overlying cortex of the left parietal lobe with narrowing of the adjacent gyri. Minimal mass effect upon the posterior margin of the left precentral gyrus (Figure 2). No diffusion restriction or associated susceptibility. No significant T2/FLAIR hyperintense. Minimal asymmetric enlargement of the occipital horn of the left lateral ventricle is also noted (Figure 3).

The destructive brain lesions included porencephaly, schizencephaly, and hydranencephaly and are usually related to prenatal vascular events.

Porencephaly is fluid-filled cavitation in the brain that may communicate ("porous·) with the intracerebral CSF spaces with gliotic white matter lining the cleft. It occurs after neuronal migration.
Schizencephaly is a neuronal migration disorder, where the clefts are lined by abnormal gray matter, sometimes described as polymicrogyria.
Hydranencephaly has been considered the most severe form of porencephaly is due to bilateral occlusion of carotid arteries[1].

The porencephaly can be caused by, vascular thrombosis, hemorrhage, infections, brain contusions, and genetic causes.

Collagen IV (COL4A1, COL4A2, ) mutations can cause porencephaly and schizencephaly and have been associated with cerebral small-vessel disease, perinatal intracerebral hemorrhage., microbleeds, and lacunar strokes [2].
Some cases of porencephaly are associated with tubulopathy caused by a TUBA1A mutation [3].

Clinical manifestation in a patient with porencephaly depend on size and location cyst and may be asymptomatic or have delayed growth and development, spastic hemiplegia and epilepsy partial or generalized. Treatment includes physical therapy, anti-epileptic drugs, a shunt in case of hydrocephalus and surgery (hemispherectomy and hemispherotomy) in cases with antiepileptic drug-resistant epilepsy[4].

On CT and MRI (Figure 4) the cyst has to be lined by white matter, which can demonstrate evidence of gliosis depends on the gestational age at which the insult occurred, with well-defined border communicate with the CSF spaces (ventricles and the subarachnoid space) with no mass effect on the adjacent parenchyma. There is no enhancement with contrast. The cyst has not bylined by grey matter, where you would think of arachnoid cyst or schizencephaly [5].

Written informed patient consent for publication has been obtained.