Year : 2005 | Volume
: 15 | Issue : 4 | Page : 507--510
Sincipital encephalocele with corpus callosum agenesis and intracranial lipoma : A case report
V Upadhyaya, DN Upadhyaya, S Sarkar
Sarkar Diagnostic Centre, Mahanagar, Lucknow - 226006, India
Sarkar Diagnostic Centre, C-1093, Sector A, mahanagar, Lucknow - 226006
|How to cite this article:|
Upadhyaya V, Upadhyaya D N, Sarkar S. Sincipital encephalocele with corpus callosum agenesis and intracranial lipoma : A case report.Indian J Radiol Imaging 2005;15:507-510
|How to cite this URL:|
Upadhyaya V, Upadhyaya D N, Sarkar S. Sincipital encephalocele with corpus callosum agenesis and intracranial lipoma : A case report. Indian J Radiol Imaging [serial online] 2005 [cited 2020 Dec 3 ];15:507-510
Available from: https://www.ijri.org/text.asp?2005/15/4/507/28784
Encephaloceles are extracranial herniations of intracranial structures through defects in the skull and dura. Meningoceles are herniations of meninges alone and meningoencephaloceles are herniations of brain tissue and meninges. If part of a ventricle is also included, it is called hydroencephalomeningocele. In most cases, these are detected prenatally by obstetric ultrasound or at birth by clinical presentation of a subcutaneous mass. Encephaloceles may be isolated anomalies, or they may be seen in conjunction with other anomalies, or may be a part of a syndrome. Agenesis or hypogenesis of the corpus callosum is a commonly associated finding.
We report one such case of sincipital encephalocele with agenesis of corpus callosum and intracranial lipoma.
A two year old boy presented with a large soft swelling on the forehead since birth. There was no history of delayed milestones. Local examination revealed a soft fluctuant swelling in the middle of forehead with a well defined defect in the subjacent cranium. The swelling was not transilluminant but had an expansile impulse on crying. The intercanthal distance was increased. The child had no apparent sensory motor deficit and was actively moving all limbs.
An MR study of the brain was done [Figure 1],[Figure 2],[Figure 3] which revealed a large sincipital encephalocele containing brain tissue and meninges. No dysplastic changes were seen in the herniated brain tissue. Corpus callosum was not seen on sagittal images and lateral ventricles were widely separated suggestive of callosal agenesis. There was an anterior interhemispheric mass of high signal intensity on T-1 weighted images and low signal intensity on T-2 weighted images suggestive of lipoma. Vessels were seen as signal void structures passing through the lipoma. There was distortion of brain stem and cerebellum. A large cisterna magna was also seen. CT was done [Figure 4],[Figure 5] for better delineation of the bony defect. There was a large frontal defect of about eight cms through which there was herniation of the brain and the meninges. Findings suggestive of callosal agenesis were also seen. On CT, the lipoma showed characteristic fat attenuation and peripheral small calcific foci were noted.
Surgical planning was done by a team of neurosurgeons and plastic surgeons and the priorities defined as below-
1. Both extracranial and intracranial approach was to be used.
2. Excision of the sac along with the abnormal dura and excision/invagination of the brain tissue followed by repair of the normal dura.
3. Skeletal reconstruction along with proper wound cover.
Pre-operative preparations were made but the surgery had to be shelved due to the refusal of the attendants to give high-risk consent.
Prognosis was explained and the patient discharged on request.
Encepahloceles occur due to failure of surface ectoderm to separate from the neuroectoderm which results in a bony defect in the skull table, which allows herniation of meninges or brain tissue. Ingraham and Matson divided encephaloceles into threee categories: occipital, sincipital and basal . Suwanwela and Suwanwela have subdivided the sincipital group further into frontoethmoidal encephaloceles, interfrontal encephaloceles and those encephaloceles associated with craniofacial clefts . The frontoethmoidal group is subdivided further into nasofrontal, nasoethmoidal and naso-orbital types.
Encephaloceles occur approximately 1 to 3 times in 10,000 live births. The incidence of sincipital encephalocele is substantially greater in the tropical latitudes, particularly in parts of Asia and Africa. Occipital encephaloceles are more common in Western Hemisphere.
With encephaloceles, there is a reasonably high incidence of associated facial anomalies in the form of midline clefts and associated brain malformations, such as agenesis of the corpus callosum, Arnold-Chiari malformation, Dandy-Walker malformation and brain migrational anomalies.
Most encephaloceles are diagnosed on routine antenatal US scanning. Postnatally, infants may present with CSF rhinorrhea and recurrent meningitis. Postnatal presentation also depends on the associated malformations and the size and contents of the defect. The prognosis and treatment depend on the site, size and the contents of the encephalocele.
The prognosis for the anterior encephalocele patient is generally good and is usually associated with normal intelligence and motor development. However, mental retardation, epilepsy and ocular problems have been described in this group . Poor prognostic indicators include a large or posterior encephalocele and systemic anomalies.
Postnatally, the aim of the radiologist is to precisely define the size of the encephalocele, delineate the contents and identify associated anomalies. MR is the modality of choice. CSF spaces and brain parenchyma are directly visualized. Although bony defects are poorly shown by MR, the MR studies in patients with encephaloceles are valuable because tissues within these defects produce a signal. On T-1 weighted images, brain tissue protrudes through the defect and contrasts with the surrounding low-intensity signal of CSF and the signal void of bone. On T-2 weighted images, CSF produces a signal that can be seen in contrast to the bony edges. The relationships of the encephalocele and its contents to the extracranial soft tissues are clearly shown. Large arteries and veins associated with the brain parenchyma are also well shown . MR also demonstrates associated intracranial anomalies. CT can provide excellent depiction of the bony defect but it cannot resolve the exact nature of the herniated contents. Like MR, it can identify associated intracranial anomalies.
The most commonly associated finding is agenesis or hypogenesis of the corpus callosum. Corpus callosum is the largest cerebral commissure connecting neocortical areas and develops between 12 to 20 weeks of gestation. The development results from neocortical commissural axon fasciculation and reflects the inter-hemispheric circuitry and successive steps of synaptogenesis . Development occurs from front to back with the exception of the rostrum, which develops after the splenium. Callosal agenesis can be partial or complete. Imaging by CT and MR in complete callosal agenesis reveals widely separated and nonconverging lateral ventricles, disproportionately enlarged occipital horns (colpocephaly) and an elevated third ventricle which is continuous superiorly with the interhemispheric fissure. In sagittal MR studies, corpus callosum, cingulate gyrus and sulcus are not seen. Gyri on the medial hemispheric surface radiate outward from the high-riding third ventricle. In partial agenesis of corpus callosum, the splenium and rostrum are absent.
Intracranial lipomas represent rare development malformations of the nervous system. They result from lipomatous differentiation of the persistent meninx primitiva, the mesenchymal derivative of the embryonic neural crest which envelops the developing embryo. Interhemispheric lipomas constitute 40% to 50% of intracranial lipomas and are frequently associated with a dysgenetic corpus callosum . Callosal lipomas are of two types: an anterior bulky tubulonodular variety which is associated with forebrain and rostral callosal anomalies and a more posterior ribbon-like curvilinear lipoma which is seen with a normal or nearly normal corpus callosum. CT scan shows findings of callosal agenesis with a fatty density mass that is variably calcified. On MR, the lipoma shows high signal on T-1 weighted studies and low signal on T-2 weighted studies. Prominent vessels often course directly through the more bulky anterior callosal lipomas .
Our patient had a sincipital encephalocele with corpus callosum agenesis and an anterior tubulonodular type of interhemispheric lipoma.
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