Unilateral megalencephaly associated with neonatal high output cardiac failure

Dysplastic megalencephaly phenotype presenting with prenatal high-output cardiac failure

Dysplastic megalencephaly, also known as bilateral hemimegalencephaly, is a rare cerebral malformation characterized by bilateral cerebral hemisphere overgrowth and extensive malformation of cortical development. Affected patients present clinically with intractable seizures, severe neurological impairment and global developmental delay. There is a small body of literature reporting megalencephaly's association with neonatal high-output cardiac failure and a lack of literature describing prenatal findings. We report a case of dysplastic megalencephaly presenting with progressive high-output cardiac failure during fetal life. Prenatal and postnatal imaging findings as well as neonatal course are described. A companion case with similar imaging findings will help illustrate the prenatal imaging characteristics of this association. Knowledge of this potential complication related to dysplastic megalencephaly may help guide parental counseling and obstetric management.

Hemimegalencephaly associated with somatic hemihypertrophy and a malformation of the feet: case report

Hemimegalencephaly (HME) is a rare neuronal migration anomaly, rarely associated with hemihypertrophy or some other somatic malformation; it can coexist with intracranial arteriovenous shunts which cause cardiac failure. We report a rare case associated with hemihypertrophy of the face, trunk and limbs and malformation of the feet. The neuroradiological findings are underlined and the differential diagnoses discussed.

The role of hemispherectomy in the treatment of holohemispheric hemimegaloencephaly

The role of hemispherectomy in treating holohemispheric hemimegaloencephaly, a unilateral brain malformation, is still not well defined. The authors describe the cases of five infants presenting with intractable seizures, progressive neurological deficits, and severe developmental delay. Electroencephalography (EEG) showed generalized polyspikes from the megaloencephalic hemisphere and progressive slowing on the opposite side in all children; contralateral seizure spikes occurred in three children. Three of the five children underwent hemispherectomy for intractable seizures before 2 years of age, after which the seizures subsided completely in two children and improved remarkably in the third. Preoperative Wada testing proved useful in evaluating pharmacologically the effect of hemispherectomy on contralateral polyspikes. Postoperative EEG revealed the absence of polyspikes in the operated hemisphere and decreased slowing on the contralateral side. Psychomotor development in the surgically treated infants exceeded that of the children not undergoing hemispherectomy. Of the two children treated medically, one died at 4 years of age in status epilepticus and the other (now 5 years old) has frequent seizures and severe developmental delay. Based on these results, hemispherectomy appears to be a useful procedure for controlling seizures and improving psychomotor development in children with hemimegaloencephaly involving the entire hemisphere. Surgery in infancy can prevent or minimize seizure foci and encephalopathic changes that may develop in the contralateral hemisphere. Staging the procedure and exercising meticulous hemostasis make surgery relatively safe in infants who otherwise may have significant blood loss associated with increased blood flow to the megaloencephalic hemisphere.

Surgical implications of cerebral dysgenesis

Cerebral dysgenesis encompasses varied disorders of brain development. Based on the understanding of these conditions provided by histopathologists, embryologists, radiologists and developmental pediatricians, surgeons are able to appropriately assist in the care of these patients. The surgeon can offer assessment of the ventriculomegaly that commonly accompanies cerebral dysgenesis in addition to providing methods to control hydrocephalus, to reconstruct cranial and facial malformations and to remove dysfunctional tissue. For most patients, surgical intervention is only one of the many factors that determine developmental prognosis. Based on the foundation built by other specialists, this review discusses cerebral dysgenesis from the perspective of historical and current surgical interventions.