Magnetic resonance imaging findings of two cases with West syndrome and hypomelanosis of Ito with hemimegalencephaly: a report of two cases

Abstract

Abstract Background Hemimegalencephaly is an unusual congenital non-familial malformation of the brain which is characterized by enlargement of the whole or part of one hemisphere due to neural proliferation and dysfunction in the cell migration. The brain stem and cerebellum may also be involved. There are also the common cortical malformation, unusual white matter proliferation, gliosis, and abnormal myelination in hemimegalencephaly. In addition, structural brain abnormalities like atrophy/hypertrophy, demyelination, gliosis, increased thickness of the cortical grey matter, increase signal intensity in the subcortical white matter, abnormal gyral patterns, blurring of the grey-white matter transition, and hamartomatous aspect can be observed on magnetic resonance imaging. Case presentation Two patients who underwent brain magnetic resonance imaging because of West syndrome and hypomelanosis of Ito were diagnosed as hemimegalencephaly. The first case was a 9-day-old male patient initially diagnosed with West syndrome. On the brain magnetic resonance imaging performed for epilepsy, right total hemimegalencephaly, diffuse polymicrogyria, and heterotopic grey matter foci on the right hemisphere were observed. In addition, right cerebellar dysgenesis, upward angulation in the lateral ventricle's anterior horn, and colpocephalic dilatation in the posterior horn were evident. The second case was a 2-year-old female patient with hypomelanosis of Ito disease. The main reason for her parents' hospital visit was the shortness of the right leg. Initial examination showed the hypopigmented lesions on the right side and hemihypertrophy in the left leg. Brain magnetic resonance imaging revealed mild hemimegalencephaly in the right cerebral hemisphere, T1-weighted isointense, T2-weighted hyperintense white matter lesions extending from the basal ganglia to the ventricular body and the periventricular fronto-parieto-occipital white matter, and dilatation of the lateral ventricle. Conclusions Hemimegalencephaly is a rare condition which may accompany syndromic cases with epilepsy or neurocutaneous disease. Brain magnetic resonance imaging should be performed in patients with a suspicious medical history in order to make the correct diagnosis of hemimegalencephaly and to determine the severity of brain involvement, if any.