eMedicine Specialties > Radiology > Pediatrics
Schizencephaly
Updated: Apr 16, 2009
Introduction
Background
Schizencephaly is an uncommon disorder of neuronal migrational characterized by a cerebrospinal fluid–filled cleft, which is lined by gray matter. The cleft extends across the entire cerebral hemisphere, from the ventricular surface (ependyma) to the periphery (pial surface) of the brain.
The clefts may be unilateral or bilateral and may be closed (fused lips), as in schizencephaly type I, or separated (open lips), as in schizencephaly type II.
Schizencephaly. Axial T2-weighted MRI in unilateral closed-lip (type I) schizencephaly. The cleft is lined by gray matter and extends from the pial surface to the lateral ventricle.
Schizencephaly. Axial T2-weighted MRI demonstrates a small open-lip schizencephaly. The septum pellucidum is absent.
Presentation and outcome are variable, but patients typically present with seizures, hemiparesis, and developmental deficits. Usually, the severity of symptoms is related to the amount of brain affected by the abnormality.1
Pathophysiology
Several theories have been proposed to explain the etiology of schizencephaly, although none is universally accepted. The leading theory indicates that schizencephaly results from an early, focal destruction of the germinal matrix and surrounding brain before the hemispheres are fully formed.2
Schizencephaly probably occurs as the end result of a variety of insults occurring at a critical time and in a critical location during brain development. No specific inciting or unusual prenatal events have been identified, and reported cases are sporadic.
The lesion is most likely related to multiple etiologies, including genetic, toxic, metabolic, vascular, or infectious causes. Familial cases of schizencephaly have been reported.3,4
Frequency
United States
Schizencephaly is uncommon; to our knowledge, there are no well-documented data on its specific incidence.
International
Schizencephaly is uncommon; to our knowledge, there are no documented geographical differences in its occurrence.
Mortality/Morbidity
Severity of the symptoms depends on the amount of brain involved. Affected patients typically have seizures, hemiparesis, variable developmental delay, and blindness. Patients also have variable degrees of mental retardation.
Patients with open-lip schizencephaly die at an earlier age than patients with the closed-lip form. Usually, death results from failure to thrive, chronic infections, and respiratory problems.
Patients with closed-lip schizencephaly may not present clinically until later in infancy or early childhood and may live to early adulthood.
Age
This condition is present at birth.
Anatomy
Schizencephaly is divided into 2 types, which have prognostic significance. In closed-lip or type I schizencephaly, the cleft walls are in apposition. In open-lip or type II schizencephaly, the cleft walls are separated. Schizencephaly type II occurs more commonly than type I.
The clefts in schizencephaly are lined either totally or in part by gray matter and extend from the pial surface to the ependyma of the lateral ventricle. The clefts can be located anywhere, but they commonly occur in the parasylvian regions. The clefts can be unilateral or bilateral, and can be either symmetric or asymmetric.
The cavity formed in the open-lip type varies in size from small to large and may communicate with the lateral ventricle. The ventricular system may be enlarged, particularly in patients with the open-lip form of schizencephaly.
Gray-matter heterotopia (collections of gray matter in abnormal locations), polymicrogyria, and arachnoid cysts can be associated with schizencephaly. Heterotopias and polymicrogyria typically line the clefts. Microcephaly has been noted in some patients. The septum pellucidum is absent in 80-90% of patients, and schizencephaly may coexist with septo-optic dysplasia.
Presentation
Clinical features of schizencephaly are highly variable. Patients with unilateral clefts with fused lips may have mild hemiparesis and seizures but otherwise have normal development. When the cleft is open, patients present with mild-to-moderate developmental delay and hemiparesis; severity is related to the extent of cortex involved in the defect.5,6
Patients with bilateral clefts present with severe mental deficits and severe motor anomalies including spastic quadriparesis. Frequently, these patients present with blindness, which is often associated with optic nerve hypoplasia. Language development is more likely to be normal in patients with unilateral schizencephaly compared to patients with bilateral clefts.
Intractable seizures frequently are noted in schizencephaly. Several types of seizures have been reported including generalized tonic-clonic, partial motor, and sensory seizures. Infantile spasms have been seen in a few children. Reports have found no correlation between the subtype of schizencephaly and the occurrence or type of seizure disorder.
Preferred Examination
MRI is the imaging modality of choice because of its superior differentiation of gray matter and white matter and its ability to image in more than one plane.
Identification of gray matter lining the cleft is the pathognomonic finding in differentiating schizencephaly from porencephaly; this is best demonstrated on MRIs.
The more complete information obtained by MRI enables a more accurate prediction of neurologic outcome.
Limitations of Techniques
MRIs are degraded by patient motion, and sedation may be required for children. MRI is relatively expensive. The examination cannot be done portably in an ill neonate. The study is relatively lengthy.
Differential Diagnoses
Arachnoid Cyst
Other Problems to Be Considered
Porencephaly
Porencephalic cyst
Computed Tomography
Findings
Using CT, the diagnosis of schizencephaly is sometimes difficult, particularly type I, or closed lip schizencephaly.
CT scans of closed-lip schizencephaly may show only a slight outpouching at the ependymal surface of the cleft, and a full-thickness cleft may be difficult to identify on CT scan.
The cleft is partially or totally lined by gray matter and extends from the lateral ventricle to the pial surface of the cerebral hemisphere.
Secondary findings that can be identified on CT scan include hydrocephalus, heterotopia, polymicrogyria, subdural hygromas, and arachnoid cysts.
Degree of Confidence
The degree of confidence is high when the extent of the cleft and the gray matter lining its walls can be identified.
Magnetic Resonance Imaging
Schizencephaly. Axial T2-weighted MRI in unilateral closed-lip (type I) schizencephaly. The cleft is lined by gray matter and extends from the pial surface to the lateral ventricle.
Schizencephaly. Axial T2-weighted (left) and coronal T1-weighted (right) MRIs in bilateral closed-lip (type I) schizencephaly. A ventricular diverticulum defines the meeting of the closed-lip portion of the clefts with the margin of the ventricles. The septum pellucidum is absent, and the clefts are lined by gray matter and extend from the pial surface to the lateral ventricle.
Schizencephaly. Axial T2-weighted MRI demonstrates a small open-lip schizencephaly. The septum pellucidum is absent.
Schizencephaly. Axial T2-weighted MRI in unilateral open-lip (type II) schizencephaly. The septum pellucidum is absent, and a large cerebrospinal fluid–filled cleft extends from the lateral ventricle to the cortical surface. The cleft is lined by gray matter.
Schizencephaly. Coronal sonograms with a corresponding coronal T1-weighted MRI of open-lip bilateral schizencephaly. Extensive bilateral schizencephalic defects with large CSF-filled clefts extend from the lateral ventricles to the cortical surface. Image courtesy of Marta Hernanz-Schulman, MD, Professor Radiology and Pediatrics, Vanderbilt School of Medicine; Clinical Director, Department of Radiology, Division of Pediatric Radiology, Vanderbilt Children's Hospital.
Findings
MRI is the modality of choice for evaluating patients with schizencephaly. MRI better delineates the gray matter lining the cleft, which is the pathognomonic finding in schizencephaly. MRI also provides superb cortical anatomy detail and multiplanar capability. Primary findings related to the cleft and secondary findings associated with schizencephaly are identified using MRI.
The ability of MRI pulse sequences to differentiate gray matter and white matter permits demonstration of gray-matter heterotopias in the subcortical white matter beneath the cleft, abnormalities involving the cortex (eg, pachygyria or polymicrogyria), and other secondary findings also identified by using CT scans.
Homolateral absence of the sylvian vasculature, small medullary pyramids, a low position of the fornix, and thinning of the corpus callosum are findings related to absent cerebral cortex and are better demonstrated by MRI than with other studies.
Degree of Confidence
The degree of confidence is high.
False Positives/Negatives
MRI can demonstrate that the cleft is lined with gray matter, which distinguishes a schizencephaly from areas of encephalomalacia, which are usually lined by white matter.
A closed-lipped schizencephaly may be difficult to visualize on MRI; however, a dimple at the junction of the cleft and ventricle should alert one to a possible schizencephaly.
Ultrasonography
Schizencephaly. Coronal sonograms with a corresponding coronal T1-weighted MRI of open-lip bilateral schizencephaly. Extensive bilateral schizencephalic defects with large CSF-filled clefts extend from the lateral ventricles to the cortical surface. Image courtesy of Marta Hernanz-Schulman, MD, Professor Radiology and Pediatrics, Vanderbilt School of Medicine; Clinical Director, Department of Radiology, Division of Pediatric Radiology, Vanderbilt Children's Hospital.
Findings
Ultrasonography can be in the neonatal period in patients in whom this anomaly is suspected.
In schizencephaly type I, a hyperechoic line extends from the parasylvian region to the anterior portion of the lateral ventricle. The hyperechoic line represents the cortex lining the fused cleft. This type of anomaly is difficult to detect with ultrasound, and requires a high index of suspicion and highly skilled operator.
In schizencephaly type II, an anechoic band or cavity, representing the fluid-filled cleft, extends from the cortical surface to the lateral ventricle. The meeting of the closed-lip portion, or apex of the cleft, with the margin of the ventricle, may be identified as a ventricular diverticulum or dimple.
The size of the thalamus, caudate, and lenticular nuclei (subcortical gray matter structures) is decreased. Other associated anomalies, such as ventricular enlargement, may also be identified.
Intervention
Seizure medications and physical therapy are used to treat patients with schizencephaly.
Select patients with schizencephaly and medically intractable epilepsy can be treated operatively by resection of tissue in the cleft or temporal lobe.7
In patients with hydrocephalus surgical placement of a ventricular shunt may be required.
Medicolegal Pitfalls
- Failure to make the diagnosis based on imaging studies
- Failure to differentiate schizencephaly from porencephaly or other brain disorders
Multimedia
Media file 1: Schizencephaly. Axial T2-weighted MRI in unilateral closed-lip (type I) schizencephaly. The cleft is lined by gray matter and extends from the pial surface to the lateral ventricle.
Media file 2: Schizencephaly. Axial T2-weighted (left) and coronal T1-weighted (right) MRIs in bilateral closed-lip (type I) schizencephaly. A ventricular diverticulum defines the meeting of the closed-lip portion of the clefts with the margin of the ventricles. The septum pellucidum is absent, and the clefts are lined by gray matter and extend from the pial surface to the lateral ventricle.
Media file 3: Schizencephaly. Axial T2-weighted MRI demonstrates a small open-lip schizencephaly. The septum pellucidum is absent.
Media file 4: Schizencephaly. Axial T2-weighted MRI in unilateral open-lip (type II) schizencephaly. The septum pellucidum is absent, and a large cerebrospinal fluid–filled cleft extends from the lateral ventricle to the cortical surface. The cleft is lined by gray matter.
Media file 5: Schizencephaly. Coronal sonograms with a corresponding coronal T1-weighted MRI of open-lip bilateral schizencephaly. Extensive bilateral schizencephalic defects with large CSF-filled clefts extend from the lateral ventricles to the cortical surface. Image courtesy of Marta Hernanz-Schulman, MD, Professor Radiology and Pediatrics, Vanderbilt School of Medicine; Clinical Director, Department of Radiology, Division of Pediatric Radiology, Vanderbilt Children's Hospital.
References
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Goez H, Zelnik N. Schizencephaly in Infants With Thrombophilia. J Child Neurol. Jan 23 2009;[Medline].
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Maeda T, Akaishi M, Shimizu M, Sekiguchi K, Anan A, Takano T, et al. The subclassification of schizencephaly and its clinical characterization. Brain Dev. Nov 25 2008;[Medline].
Steinbok P, Gan PY, Connolly MB, Carmant L, Barry Sinclair D, Rutka J, et al. Epilepsy surgery in the first 3 years of life: A Canadian survey. Epilepsia. Jan 19 2009;[Medline].
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DiPietro MA, Brody BA, Kuban K, Cole FS. Schizencephaly: rare cerebral malformation demonstrated by sonography. AJNR Am J Neuroradiol. Mar-Apr 1984;5(2):196-8. [Medline].
Komarniski CA, Cyr DR, Mack LA, Weinberger E. Prenatal diagnosis of schizencephaly. J Ultrasound Med. May 1990;9(5):305-7. [Medline].
Lee SH, Rao K, Zimmerman RA. Schizencephaly. In: Cranial MRI and CT. 4th ed. New York: McGraw-Hill;. 1999: 163-5.
Miller GM, Stears JC, Guggenheim MA, Wilkening GN. Schizencephaly: a clinical and CT study. Neurology. Aug 1984;34(8):997-1001. [Medline].
Osborne AG. Schizencephaly. In: Diagnostic Neuroradiology. St Louis: Mosby-Year Book;. 1994:52-6.
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Keywords
schizencephaly, cerebrospinal fluid–filled cleft in the brain, abnormal cleft of the brain, type I schizencephaly, type II schizencephaly, open-lip schizencephaly, closed-lip schizencephaly
Contributor Information and Disclosures
Author
Ken R Close, MD, Staff Physician, Department of Radiology, Texas A&M University College of Medicine, Scott and White Memorial Hospital and Clinic
Disclosure: Nothing to disclose.
Coauthor(s)
L Gill Naul, MD, Professor and Head, Department of Radiology, Texas A&M University College of Medicine; Chair, Department of Radiology, Chief, Section of Magnetic Resonance Imaging, Scott and White Memorial Hospital and Clinic
L Gill Naul, MD is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, Radiological Society of North America, and Texas Medical Association
Disclosure: Nothing to disclose.
Medical Editor
Charles M Glasier, MD, Professor, Departments of Radiology and Pediatrics, University of Arkansas for Medical Sciences; Chief, Magnetic Resonance Imaging, Vice-Chief, Pediatric Radiology, Arkansas Children's Hospital
Charles M Glasier, MD is a member of the following medical societies: American College of Radiology, American Society of Neuroradiology, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.
Pharmacy Editor
Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.
Managing Editor
Marta Hernanz-Schulman, MD, FAAP, Professor, Radiology, Radiological Sciences, and Pediatrics, Director, Department of Pediatric Radiology, Radiologist-in-Chief, Director, Department of Diagnostic Imaging, Vanderbilt University Medical Center, Vanderbilt Children's Hospital
Marta Hernanz-Schulman, MD, FAAP is a member of the following medical societies: American Institute of Ultrasound in Medicine and American Roentgen Ray Society
Disclosure: Nothing to disclose.
CME Editor
Robert M Krasny, MD, Consulting Staff, Department of Radiology, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.
Chief Editor
James G Smirniotopoulos, MD, Professor of Radiology, Neurology, and Biomedical Informatics, Chairman, Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences
James G Smirniotopoulos, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Head and Neck Radiology, American Society of Neuroradiology, American Society of Pediatric Neuroradiology, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.
Clinical guidelines
Guidelines on routine cerebrospinal fluid analysis. Report from an EFNS task force.
European Federation of Neurological Societies - Medical Specialty Society. 2006 Sep. 10 pages. NGC:005489
Clinical trials
Human Epilepsy Genetics--Neuronal Migration Disorders Study
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