Comprehensive evaluation of left hemisphere type I schizencephaly

Neuroimaging of septo-optic dysplasia-plus with midbrain hypoplasia and ophthalmoplegia

Septo-optic dysplasia is a rare brain malformation that can be associated with anomalous cortical development, such as schizencephaly, which is referred to as septo-optic dysplasia plus. This report describes septo-optic dysplasia-plus associated with unilateral atrophy of the midbrain and oculomotor nerve deficiency, which was diagnosed on MRI in a teenage male who presented with ophthalmoplegia.

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Septo-optic dysplasia can be associated with schizencephaly.

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This article describes septo-optic dysplasia plus with midbrain involvement.

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These findings can be readily depicted on neuroimaging.

Neuropsychological functioning in a young adult case of schizencephaly

Schizencephaly is a rare neuromigrational/organizational disorder characterized by the development of cerebral clefts, which are typically associated with neurological sequelae including seizures, motor disturbances, and cognitive dysfunction. Although there are multiple case reports of schizencephaly and associated neurological sequelae, primarily in children, the literature regarding neuropsychological manifestations of schizencephaly is limited. This article reviews the case of a woman diagnosed with bilateral schizencephaly at age 29. Neuropsychological testing revealed intact intelligence and memory functioning. However, impairments were noted in attention, executive functioning, expressive language skills, visual-spatial abilities, and bilateral manual motor skills, all of which were adversely impacting her functional abilities (e.g., ability to be gainfully employed). Given the potential variability in deficits associated with schizencephaly, this case demonstrates the utility of neuropsychological evaluation for understanding cognitive and functional consequences of bilateral schizencephaly.

Malformations of cortical development and epilepsy

Malformations of cortical development (MCDs) are macroscopic or microscopic abnormalities of the cerebral cortex that arise as a consequence of an interruption to the normal steps of formation of the cortical plate. The human cortex develops its basic structure during the first two trimesters of pregnancy as a series of overlapping steps, beginning with proliferation and differentiation of neurons, which then migrate before finally organizing themselves in the developing cortex. Abnormalities at any of these stages, be they environmental or genetic in origin, may cause disruption of neuronal circuitry and predispose to a variety of clinical consequences, the most common of which is epileptic seizures, A large number of MCDs have now been described, each with characteristic pathological, clinical, and imaging features. The causes of many of these MCDs have been determined through the study of affected individuals, with many MCDs now established as being secondary to mutations in cortical development genes. This review will highlight the best-known of the human cortical malformations associated with epilepsy. The pathological, clinical, imaging, and etioiogic features of each MCD will be summarized, with representative magnetic resonance imaging (MRI) images shown for each MCD, The malformations tuberous sclerosis, focal cortical dysplasia, hemimegalencephaiy, classical iissencephaly, subcortical band heterotopia, periventricular nodular heterotopia, polymicrogyria, and schizencephaly will be presented.

Schizencephaly: clinical spectrum, epilepsy, and pathogenesis

After almost 60 years since the original description, we have reviewed the results of the more recent studies on schizencephaly in an attempt to delineate its imaging and clinical spectra of presentation and to point out the still unsettled controversies on its pathogenesis. The clinical picture is mainly based on the presence of motor deficits and mental retardation, but the severity of the clinical picture is extremely variable, mainly related to the size and location of the clefts and to the presence of associated cerebral malformations. By contrast, the outcome of epilepsy, which is present in about half of the cases and drug resistant in a third, is not strictly related to the severity of the malformation. Some clinical and functional magnetic resonance imaging studies have suggested that, beside the features of the anatomic damage, the functional reorganization of a malformed and unaffected cortex is most likely crucial in determining the clinical outcome. Review of the genetic studies and the more recent personal data suggests that the role of the EMX2 gene in schizencephaly, if any, is restricted to a minority of cases, leaving the etiopathogenesis of this brain malformation still a matter of study and debate.

Schizencephaly: clinical and imaging features in 30 infantile cases

Schizencephaly is an uncommon structural disorder of cerebral cortical development, characterized by congenital clefts spanning the cerebral hemispheres from the pial surface to the lateral ventricles and lined by cortical gray matter. Either an antenatal environmental incident or a genetic origin could be responsible for this lesion which occurs between the third and fourth month of gestation. We report the clinical and cranial imaging features of 30 children, of whom 15 had unilateral and 15 had bilateral lesions. Their ages at the time of the first presentation ranged from 1 month to 10 years. They were thoroughly studied from clinical, epileptical, imaging and electroencephalographic (EEG) viewpoints. Five patients were investigated by cranial computed tomography (CT), eight by cranial magnetic resonance (MR) imaging, and 17 by both methods. The clinical features consisted of mild hemiparesis in 17 cases (57%), 12/17 were related to a unilateral phenotype (80% of all unilateral forms) and 5/17 to a bilateral phenotype. A tetraparesis was present in nine cases, all of which were due to a bilateral cleft. Bilateral forms were significantly associated with tetraparesis, whereas unilateral forms were associated with hemiparesis. Mental retardation was observed in 17 cases (57%), and was observed significantly more often in bilateral clefts (80%). When both hemispheres are involved, an absence of reorganization of the brain function between the two hemispheres leads to severe mental deficits, in addition to the cerebral anomaly itself. Eleven patients had seizures (seven from unilateral and three from bilateral forms). The degree of malformation was not related to the severity of epilepsy. Migration disorders, such as dysplasia or heterotopia, were observed in 30% of cases and are also important etiopathogenetic factors. The septum pellucidum was absent in 13 cases (43%), with septo-optical dysplasia in two cases. Corpus callosum dysgenesis was noted in 30% of cases. Four cases of mega cisterna magna were noted. Although familial cases and environmental factors have been previously reported, schizencephaly appears to be, in the majority of cases, sporadic.

Surgery for malformations of cortical development causing epilepsy

Malformations of cortical development (MCD) are responsible for many cases of refractory epilepsy in adults and children. The results of surgical treatment are difficult to assess from the published literature. Judging from the limited number of adequately reported cases, approximately 40% of all cases of MCD treated surgically may be rendered seizure-free over a minimum 2-year follow-up period. This figure is the same for focal cortical dysplasia (FCD), the most common variety of MCD in surgical reports. In comparison with outcome for epilepsy associated with hippocampal sclerosis, this figure is low. Part of the difference may be artificial and related to limited reporting. Much of the difference is likely to relate to the complex underlying biology of MCD. Analysis of epileptogenesis in MCD has been undertaken. Different types of MCD have different sequelae. Some varieties are intrinsically epileptogenic; these include FCD and heterotopia. Although in most cases, the visualized MCD lies within the region of brain responsible for generating seizures (the epileptogenic zone), it may not constitute the entire epileptogenic zone in all cases. For polymicrogyria and schizencephaly in particular, the visualized abnormalities are probably not the most important component of the epileptogenic zone. There is evidence that the epileptogenic zone is spatially distributed and also, in some cases, temporally distributed. These findings may explain poor surgical outcome and the inadequacy of current presurgical evaluative methods. New preoperative techniques offer the opportunity of improved presurgical planning and selection of cases more likely to be rendered seizure-free by current surgical techniques. Of paramount importance is improved reporting. The establishment of a central registry may facilitate this aim. Specific recommendations are made for surgical strategies based on current experience and understanding.

Bilateral inferior insertion of lateral rectus muscles associated with schizencephaly

A 5-year-old boy with a large V-pattern exotropia is described. He has a background of congenital left hemiparesis associated with schizencephaly. At the time of surgery the lateral recti were found to be abnormally inferiorly positioned. Accordingly, both lateral rectus muscles were recessed 6.5 mm and supraplaced. A V-pattern exotropia persisted postoperatively with clinical overaction of the inferior obliques. To our knowledge this is the first known case of extraocular muscle abnormalities associated with schizencephaly.

Function and organization in dysgenic cortex. Case report

Cerebral dysgenesis is a subject of interest because of its relationship to cerebral development and dysfunction and to epilepsy. The authors present a detailed study of a 16-year-old boy who underwent surgery for a severe seizure disorder. This patient had dysgenesis of the right hemisphere, which was composed of a giant central frontoparietal nodular gray matter heterotopia with overlying large islands of cortical dysplasia around a displaced central fissure. Exceptional insight into the function, biochemistry, electrophysiology, and histological structure of this lesion was obtained from neurological studies that revealed complementary information: magnetic resonance (MR) imaging, [18]fluoro-2-deoxy-D-glucose positron emission tomography (PET), functional PET scanning, proton MR spectroscopic (1H-MRS) imaging, intraoperative cortical mapping and electrocorticography, in vitro electrophysiology, and immunocytochemistry. These studies demonstrated compensatory cortical reorganization and showed that large areas of heterotopia and cortical dysplasia in the central area may retain normal motor and sensory function despite strikingly altered cytoarchitectonic organization and neuronal metabolism. Such lesions necessitate appropriate functional imaging studies prior to surgery and cortical mapping to avoid creating neurological deficits. Integrated studies, such as PET, 1H-MRS imaging, cortical mapping, immunocytochemistry, and electrophysiology may provide information on the function of developmental disorders of cerebral organization.

Schizencephaly: neuroradiologic and epileptologic findings

PURPOSE

Nine patients affected by schizencephaly were analyzed, and the epileptologic findings prospectively studied, to define the relations between the anatomic brain malformations and clinical outcome.

METHODS

The schizencephaly was diagnosed by means of magnetic resonance imaging (eight cases) or computed tomography (one case). The clinical histories of all the patients were analyzed, and a psychometric evaluation was made. The electroclinical features and course of epilepsy in the six patients with epilepsy were prospectively followed up for a period ranging from 3 to 14 years.

RESULTS

The patients were divided into those who were unilaterally (six) and those bilaterally (three) affected. The former were characterized by mild neurologic deficits and late-onset epilepsy; their epileptologic features were consistent in terms of age of onset, seizure semiology, the absence of secondary generalization, and resistance to antiepileptic treatment. The patients with bilateral schizencephaly associated with other brain malformations were characterized by severe neurologic deficits but were only rarely affected by epilepsy, which was always completely controlled by antiepileptic treatment.

CONCLUSIONS

Our data show that the extent of anatomic malformation is strictly related to the severity of motor and mental impairment but not to the presence or severity of epilepsy. The absence of prenatal risk factors for brain damage in our series, previously described familial cases of schizencephaly, and the recent report of mutations in homeobox gene EMX2 associated with cases of schizencephaly all indicate that genetic factors may play a key role in the pathogenesis of this brain malformation.