Updated: Jul 31, 2021
42 year old male with headache and history of cerebral palsy. What is the diagnosis? • Xray of the Week
Figure 1. Head CT. What are the significant findings?
Figure 2. Head CT. Red arrows indicate focal encephalomalacia of the left parietal lobe with replacement by a cystic mass that communicates with the left lateral ventricle. Green arrows indicate white matter lining the porencephalic cyst. Note that there is no mass effect.
Porencephaly is a rare congenital neurological disorder of the central nervous system that is characterized by encephalomalacia that communicates with the ventricular system . Derived from Greek meaning 'holes in the brain', the term porencephaly was coined by Richard L. Heschl in 1859 . The lesions can have varying etiologies including destructive (encephaloclastic), abnormal development (malformities), direct damage, inflammation, or hemorrhage . Depending on the patient and severity, this disorder may cause only minor neurological problems, without any disruption of intelligence, while others may be severely disabled or face death before the second decade of their lives .
Recent studies have suggested a genetic etiology to the development of porencephaly [3-6]. Mutated COL4A1 leads to weakened blood vessels within the brain which increases the chance of intracranial hemorrhage and eventually porencephaly during neurodevelopment of infantile stage [3,5]. In utero exposure to cocaine and other street drugs have also been shown to increase the risk of porencephaly .
Seizures and spasticity are often the most common initial signs. Other common symptoms include language impairment, intellectual disability, and motor deficits. In severe cases, the cyst can exert mass-effect on the surrounding skull resulting in expansion and cranial deformities. Other possible symptoms include delayed growth and development, hypotonia, macrocephaly, and microcephaly [8,9].
Porencephaly is readily diagnosed via imaging. Antenatal ultrasound may show one or more intracranial cysts that communicate with the ventricular system and/or subarachnoid space. There may also be asymmetrical ventricles with displacement of the midline ventricular echo. On CT and MR imaging, porencephalic cysts appear as an intracranial cyst that has a well-defined border and central attenuation the same as CSF (Fig. 2). Typically, there is no mass effect on the adjacent parenchyma, however enlarging cysts can result in local mass effect. There is no enhancement with contrast and no solid component. The cyst will appear well defined and often corresponds to a vascular territory. The cyst is lined by white matter and communicates with the ventricles and/or the subarachnoid space with possible gliosis depending on the age at which the cyst developed. The earlier the insult occurred in development, the more likely a glial reaction will be present. It is important to distinguish that the cyst is not lined by grey matter. This allows for delineation from arachnoid cysts and schizencephaly, which are typically either lined with heterotopic grey matter or not lined at all . On MRI, the cystic components will appear as low signal intensity on T1 weighted images, high signal intensity on T2 weighted images, low signal intensity on FLAIR images, and will have no restricted diffusion on DWI [10-12].
Since there is no cure for porencephaly, treatment is targeted towards symptomatic relief. This may include physical therapy, rehabilitation, medication for seizures, shunt, or rarely neurosurgical removal of the cyst. Adequate seizure control has been shown in porencephaly patients with appropriate drug therapy such as valproate, carbamazepine, and clobazam [3,5].
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Hirowatari C, Kodama R, Sasaki Y, et al. Porencephaly in a cynomolgus monkey (macaca fascicularis). J Toxicol Pathol. 2012;25(1):45-49. doi:10.1293/tox.25.45.
Debus O., Kosch A., Strater R., Rossi R., Nowak-Gottl U. (2004). "The Factor V G1691A Mutation is a Risk for Porencephaly: A Case-control Study". Annals of Neurology. 56 (2): 287–290. doi:10.1002/ana.20184. PMID 15293282.
Meuwissen ME, Halley DJ, Smit LS, et al. The expanding phenotype of COL4A1 and COL4A2 mutations: clinical data on 13 newly identified families and a review of the literature. Genet Med. 2015;17(11):843-853. doi:10.1038/gim.2014.210
Thomas L. Genetic mutation predisposes to porencephaly. Lancet Neurol. 2005;4(7):400. doi:10.1016/s1474-4422(05)70114-9
Dominguez R, Aguirre Vila-Coro A, Slopis JM, Bohan TP. Brain and ocular abnormalities in infants with in utero exposure to cocaine and other street drugs. Am J Dis Child. 1991;145(6):688-695. doi:10.1001/archpedi.1991.02160060106030
Cephalic disorders fact sheet. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Cephalic-Disorders-Fact-Sheet
Huang SB, Doherty D. “Congenital Malformations of the Central Nervous System.” Avery’s Diseases of the Newborn, Elsevier, 2018, pp. 857-878.e5. doi:10.1016/B978-0-323-40139-5.00059-0.
Mikic, Aleksandra Novakov, et al. “Ultrasound and Magnetic Resonance in Prenatal Diagnosis of Congenital Anomalies.” Reproductive and Developmental Toxicology, Elsevier, 2011, pp. 971–82. doi:10.1016/B978-0-12-382032-7.10074-8.
Contro, Elena, et al. “Intracranial Hemorrhage, Cysts, Tumors, and Destructive Lesions.” Obstetric Imaging: Fetal Diagnosis and Care, Elsevier, 2018, pp. 204 212.e1. doi:10.1016/B978-0-323-44548-1.00040-1.
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“Encephalomalacia, Porencephaly.” Diagnostic Imaging: Obstetrics, Elsevier, 2016, pp. 158–61. doi:10.1016/B978-0-323-39256-3.50045-5.
Jay Vora is a medical student at Edward Via College of Osteopathic Medicine (VCOM) – Virginia and plans to pursue a residency in diagnostic radiology. He graduated from UMBC in 2015 with a major in Biochemistry and Molecular Biology. He worked as a research assistant at Brimrose Engineering Corporation of America for 5 years where he completed projects in nanodot detection using imaging and helped develop cancer detection methods in cells using polarized near-infrared autofluorescence and near-infrared reflectance imaging with laser diodes and continuous-wave imaging. He graduated from Eastern Virginia Medical School with a masters in Biomedical science where he was completed research in the study of the barriers that the homeless population faces when seeking healthcare as well as genetic analysis of brain tissue from patients diagnosed with Alzheimer’s. He discovered his passion for radiology during the first radiology lecture at VCOM. Seeing the radiographic images made medical education come to life for him. While shadowing and on rotations, Jay saw how integral the field of radiology is to every other specialty in medicine and its key role in patient care. In his free time, Jay enjoys playing golf and basketball, playing guitar, and technology.
Follow Jay Vora on Twitter @JS_Vora
Kevin M. Rice, MD is the president of Global Radiology CME
Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.
Follow Dr. Rice on Twitter @KevinRiceMD