Hemımegalencephaly assocıated wıth fetal cardıac faılure and hydrops

Introduction

Hemimegalencephaly (HME) is a rare congenital malformation of cortical development, characterised by enlargement and hypertrophy of all, or some, of one cerebral hemisphere (Alvarez et al. 2011). HME can be isolated or syndromic, and the syndromic form may be associated with cutaneous malformations (Sasaki et al. 2005). Imaging of the affected hemispheres may reveal signs of abnormal gyration, variable types of cortical malformation, dilated and/or constricted ipsilateral ventricles, displacement of the occipital lobe across the midline, thickened ipsilateral corpus callosum and, in rare cases, hypertrophy of the ipsilateral brain stem and cerebellum (Flores-Sarnat 2002). Here, we describe a case of HME accompanied by fetal high-output congestive heart failure due to decreased inter-cerebral vascular resistance and increased blood flow.

Case report

A 36-year-old woman, gravida 2, para 1, was referred to our department at 21 weeks’ gestation for detailed sonography due to a suspected cerebral malformation. A detailed evaluation revealed macrocrania, asymmetry of cerebral hemispheres, ventricular dilation, displacement of the occipital lobe across the midline, absence of the corpus callosum and colpocephaly (Figure 1a). Fetal echocardiography revealed no abnormalities, and fetal magnetic resonance imaging (MRI) was performed. The MR images revealed a significant increase in the volume of the right hemisphere. The cortical thickness of the right hemisphere was increased, and a subcortical band of heterotopic grey matter was also noted, in addition to sulcation and gyration anomalies in the right hemisphere. The absence of corpus callosum was also observed (Figure 1b–d). These radiological findings confirmed the diagnosis of HME and subcortical band heterotopia. The family was given detailed information about the expected impaired fetal neurological outcome, and the termination of the pregnancy was discussed. The family refused a termination and decided to carry on with the pregnancy. Sonographical evaluation at 24 weeks’ gestation revealed fetal hydrops and sinus tachycardia, with atrioventricular and ventriculoatrial concordance. Moderate cardiomegaly was observed, with right atrial, right ventricular and superior vena caval dilation (Figure 1e). The ascending aorta and brachiocephalic artery were dilated (Figure 1f). The bilateral internal jugular veins were dilated (Figure 1g). The aortic arch was 2.6 mm, and the velocity of the blood flow in the ascending aorta was 1.5 m/s. The aortic isthmus and transverse arch appeared hypoplastic, with turbulent flow across the area of narrowing (Figure 1f). The flow velocity in the aortic isthmus was 1.5 m/s, and this increased flow was considered a pseudocoarctation secondary to the increased low-resistance distal circulation, as no cardiac abnormality was observed in the preceding echocardiographical evaluation performed at 21 weeks’ gestation. Pulse and colour Doppler velocity waveforms of the middle cerebral artery also revealed increased velocity (Figure 1h). These findings were mostly consistent with fetal high-output congestive heart failure and impending fetal hydrops secondary to HMC.

Figure 1. (a) Transverse view of the fetal head, showing marked enlargement of the right cerebral hemisphere and its shift to the left across the middle line. (b–d). Sagittal, coronal and axial single-shot, fast spin-echo T2-weighted MR images, revealing a markedly enlarged right cerebral hemisphere, a dilated right lateral ventricle (V) and a thickened parieto-occipito-temporal cerebral cortex. (e) Fetal longitudinal right parasagittal view, showing marked dilation of the superior vena cava (SVC), which measures nearly three times the diameter of the inferior vena cava. (f) Fetal longitudinal left parasagittal view, showing marked dilation of the ascending aorta and brachiocephalic and left common carotid arteries. (g) Coronal view of the fetal neck, revealing marked dilation of the bilateral internal jugular vein. (h) Transverse view of the fetal head, showing the middle cerebral artery and the circle of Willis, with the Doppler gate positioned in the middle cerebral artery. High-velocity flow of approximately 90 cm/sec was recorded in the middle cerebral artery. RV, Right ventricle; RH, Right hemisphere; V, Ventricle; F, Falx cerebri; IVC, Internal vena cava; SVC, Superior vena cava; LBV, Left brachiocephalic vein; BCA, Brachiocephalic artery; LCA, Left common carotid artery; LSA, Left subclavian artery, IJV, Internal jugular vein; MCA, Middle cerebral artery.

Fetal demise was confirmed in the sonographical evaluation at 25 weeks’ gestation. A post-mortem was not performed after the delivery of the infant, as the parents did not give consent for the procedure.

Discussion

The pathogenesis of HME has been attributed to a variety of mechanisms, including disturbances in cellular lineages and proliferation (Barkovich et al. 2001, Salamon et al. 2006), differentiation (Flores-Sarnat 2002), migration (Barkovich and Chuang 1990, Battaglia et al. 2006), gene expression (Yu et al. 2005) and growth factors (Antonelli et al. 2004). The human fetal brain undergoes significant growth throughout intrauterine life. Major developmental events, such as neuronal proliferation and migration, occur during the first half of gestation (Barkovich et al. 2001). In general, the disturbances associated with HME are thought to occur between 12 and 20 weeks’ gestation (Barkovich and Chuang 1990; Battaglia et al. 2006).

The severity of HME is graded into three groups. Grade-1 HME is characterised by mild enlargement in the affected hemisphere and mild ventricular asymmetry, with straightening of the frontal horn. Patients with Grade-2 HME mostly present with moderate hemispheric enlargement, slight displacement of the midline, moderate ventriculomegaly and colpocephaly. In contrast, Grade-3 HME is characterised by significant hemispheric enlargement, marked distortion of the midline and severe ventriculomegaly and lissencephaly (Flores-Sarnat 2002). It is important to emphasise that both the isolated and syndromic forms share a common set of neuroimaging findings (Flores-Sarnat 2002).

Prenatal ultrasound features of HME, are macrocephaly, with marked ventricular asymmetry, a midline shift accompanied by displacement of the occipital lobe across the midline and large dilatation, which occurs mainly at the posterior horn of the affected lateral ventricle (Romero et al. 2011). MRI is helpful to confirm and define the brain abnormalities. MRI allows better differentiation of the type, extension and localisation of the cortical malformations (Romero et al. 2011).

Previous reports have provided insufficient information on the prenatal and neonatal echocardiographical findings that can accompany HME. As shown in the present case, HME can be associated with congestive heart failure, resulting from the decreased resistance and increased blood flow and may lead to in utero or neonatal death. We observed a dilated superior vena cava, with right atrial and right ventricular dilation due to the increased cardiac preload. In addition, the ascending aorta and the brachiocephalic vessels supplying the afferent flow to the HME are markedly dilated due to the diminished afterload afforded by the highly compliant cerebral circulation.

HME may be associated with congestive heart failure due to brain circulation. Cardiac failure and associated brain pathologies may be indicators of the survival of patients with this condition.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.