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 »  Introduction
 »  Case reports
 »  Discussion
 »  References

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Year : 2000  |  Volume : 48  |  Issue : 2  |  Page : 155-7

Open and minimally open lips schizencephaly.


Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore, 560029, India.

Correspondence Address:
Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore, 560029, India.

  »  Abstract

Two patients with isolated schizencephaly, a very rare congenital anomaly of the brain, who presented with epilepsy are presented. According to imaging morphology, there are two types of schizencephaly, 'open lip' and 'minimally open lip'. These two cases emphasize that while MRI is superior to CT in the diagnosis of congenital brain anomalies, schizencephaly can be diagnosed by its characteristic CT features.

How to cite this article:
Srikanth S G, Jayakumar P N, Vasudev M K. Open and minimally open lips schizencephaly. Neurol India 2000;48:155


How to cite this URL:
Srikanth S G, Jayakumar P N, Vasudev M K. Open and minimally open lips schizencephaly. Neurol India [serial online] 2000 [cited 2020 Nov 28];48:155. Available from: https://www.neurologyindia.com/text.asp?2000/48/2/155/1556




   »   Introduction Top

Schizencephaly is a disorder of organogenesis of the brain with defect in sulcation.The resultant cleft in the cerebral parenchyma can cause intractable seizures and developmental delay. MRI has contributed to the improved understanding of brain malformations and associated anomalies have been described. Nevertheless, CT can demonstrate characteristic features in schizencephaly. We present and discuss two patients with intractable seizures and schizencephaly.


   »   Case reports Top

Case 1: An 18 year old lady presented to the casualty with a history suggestive of complex partial seizures of many years duration and intractable seizures for the preceeding two days.The patient was in altered sensorium but showed no gross motor deficits.CT scan demonstrated a well-defined hypodense linear lesion in the right parietal lobe extending from the cerebral cortex to the lateral ventricle, lined by welldefined gray matter.
Case 2: A 4 year old boy, born of nonconsanguineous parentage, presented to casualty in altered sensorium with history of seizures of 3 days duration. The history was suggestive of complex partial seizures with occasional generalisation. CT scan revealed linear hypodense well-defined lesion across the parietal parenchyma from the cortex to the ventricle.Both the patients had normal siblings.
CT scans of brain in both the patients showed well defined, linear, cleft-like hypodense lesions; the lips of the cleft in one patient were wide apart with CSF intervening [Figure. 1] and in the other, they were minimally opened [Figure. 2]. A key imaging feature of schizencephaly is the presence of a ventricular dimple, this is almost always seen in cases with closed or minimally open lips.[1] This was seen in both of our patients. Another feature of this anomaly with open lips is the pressure effects on the inner table of the skull vault by the CSF pulsations from the lateral ventricles. In one of our cases, thinning of the inner table was noted with minimally open lips [Figure.2] and thickening was noted in the other case [Figure. 1]. As the CT morphology was characteristic of schizencephaly, genetic counselling was advised.


   »   Discussion Top

Schizencephaly refers to full thickness clefts within the cerebral hemispheres [Figure.3]. Pathologically, these clefts are characterised by an infolding of gray matter along the cleft from the cortex into the ventricles and a fusion of the cortical pia and ventricular ependyma within the cleft. The understanding of schizencephaly has slowly evolved as advances in imaging techniques have resulted in a steady improvement in the in-vivo evaluation of this anomaly. These patients may exhibit a broad range of neurological disabilities, which are presumably related to the amount of brain tissue involved.[2] They may present with intractable seizures and variable developmental delay. In a series of 6 patients studied by Barkovich and Norman,[3] four patients were developmentally delayed while all patients had motor dysfunction and intractable seizures. While two of their patients with fused lips were of normal intelligence, the solitary patient with large unilateral cleft had moderate developmental delay and another patient with bilateral clefts had severe developmental delay. Our two patients had intractable seizures and motor dysfunction with normal intelligence inspite of a full thickness cleft.
Pathogenesis of schizencephaly has not been firmly established. However, an ischaemic episode occurring at the seventh week of gestation has been hypothesised as aetiological factor.[4] In the normal embryo, beginning seventh week of gestation, neuroblasts are generated in the the germinal matrix. During the 8th week these primitive cells begin to migrate along radially oriented glial cells to the cerebral cortical regions. During that period, any insult to the centripetal and centrifugal vessels in the region of germinal matrix may cause hypoxaemia and infarction with arrest of migration of these neuroblasts. Schizencephaly is usually associated with other congenital anomalies of the brain such as pachygyria, polymicrogyria and heterotopias.[3].
Septo-optic dysplasia is also noted in cases of schizencephaly. The septum pellucidum is absent or nearly absent in about 70-90% of affected patients and approximately 30-50% of these will have optic nerve hypoplasia on clinical examination.[1] The two cases in the present study showed an absent septum pellucidum but the optic nerves were clinically normal. CSF pulsations from the lateral ventricles with resultant pressure effects on the inner table of the skull vault is a well-described feature of open lip anomaly. This sometimes results plagiocephalic deformity which may need ventriculo peritoneal shunt. In the present study, thinning of the inner table of the vault was noted in the patient with minimally open lips and thickening was noted in the other case. In both our cases the right lateral ventricle was dilated suggesting probable subnormal development of the right cerebral hemisphere.
We intend to emphasise the importance of recognising this entity in patients presenting only with seizures because of the genetic implications of this anomaly. While MRI is superior to CT in the diagnosis of congenital brain anomalies, schizencephaly may be diagnosed by characteristic CT features. However, the associated anomalies like heterotopias, polymicrogyria, pachygyria, septo-optic dysplasia are better delineated by MR imaging.[3],[5]

 

  »   References Top

1.Truwit CL, Barkovich JA: Schizencephaly. Magnetic resonance imaging of brain and spine. Scott W. Atlas. Second Edition. Lipponcott-Raven. Philadelphia 1996; 250-257.   Back to cited text no. 1    
2.Miller GM, Stears JC, MaryAnne Guggenheim et al: Schizencephaly; a clinical and CT study. Neurology 1984; 34: 997-1002.   Back to cited text no. 2    
3.Barkovich JA, Norman D: MR imaging of schizencephaly. Am J Neuroradiology 1988; 9: 297-302.   Back to cited text no. 3    
4.Chuang SH, Fitz CR,Chilton SJ et al: Schizencephaly; Spectrum of CT findings in association with septo optic dysplasia. Presented at the 70th Scientific assembly and annual meeting of Radiological Society of North America Washington DC November (Summery of Scientific Program). Radiology l984; 153: 118.   Back to cited text no. 4    
5.Bird CR, Gilles FH: Type-1 schizencephaly; CT and neuropathologic findings . Am J Neuroradio l987; 8: 451-454.   Back to cited text no. 5    

 

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