Journal of Genetic Disorders & Genetic Reports ISSN: 2327-5790

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Case Report, J Genet Disor Genet Rep Vol: 2 Issue: 2

Congenital Cerebral Ischemic Lesions in Monochorionic Twins

Olajide Dolapo* and Ravi Kudumula
University of Tennessee Health Science Center, Memphis, TN, USA
Corresponding author : Dr. Olajide Dolapo
University of Tennessee Health Science Center, Memphis, TN, USA
E-mail: [email protected]
Received: August 30, 2013 Accepted: November 11, 2013 Published: November 18, 2013
Citation: Dolapo O, Kudumula R (2013) Congenital Cerebral Ischemic Lesions in Monochorionic Twins. J Genet Disor Genet Rep 2:2. doi:10.4172/2327-5790.1000107

Abstract

Congenital Cerebral Ischemic Lesions in Monochorionic Twins

Congenital cerebral anomalies arising from in-utero ischemic events are rare. Schizencephaly and hydranencephaly occurring together in both surviving monochorionic twins is even rarer. We report a case of monochorionic female twins of 31 weeks gestation. The twins were diagnosed at 25 weeks, one with hydranencephaly and the other with schizencephaly. These defects are commonly presumed to be the result of in utero disruption of previously normally formed structures through a secondary vascular exchange from a dead to a living monozygotic twin through placental vascular anastomoses.

Keywords: Monochorionic; Hydranencephaly; Schizencephaly

Keywords

Monochorionic; Hydranencephaly; Schizencephaly

Introduction

Congenital cerebral anomalies arising from in-utero ischemic events are rare, but well described. These lesions are usually regarded as secondary to forebrain arterial prenatal strokes, and are a part of a spectrum namely, porencephaly, schizencephaly and hydranencephaly. Schizencephaly and hydranencephaly occurring together in both surviving monochorionic twins is very rare. Co-twin survival with hydranencephaly does not support “the deceased twin vascular disruption” hypothesis.

Case

We report a case of monochorionic female twins of 31 weeks gestation, born to a 16year old G1P1 African American mother, by Caesarean section for severe pre-eclampsia and HELLP syndrome. Birth weights were 1390 grams (Twin A) and 1180 grams (Twin B). There was no known history of antenatal exposure to teratogens or illicit drugs. Maternal serologic tests were negative for HIV and syphilis. Rubella immunity was confirmed and there was a negative history for herpes simplex. Amniocentesis for TORCH screen and karyotype was declined; however Toxoplasma Ig G and Ig M were negative in both infants. Neonatal urine CMV cultures yielded no growth in both cases. Cerebral anomalies were prenatally diagnosed in both twins at 25 weeks. There was no evidence of twin-to-twin transfusion and cord insertions were centrally and marginally attached to a single placenta by fetus A and B respectively.
Both fetuses were concordant and appropriate for gestational age, for growth and amniotic fluid volumes.
In twin A, antenatal ultrasound scanning (US) was suggestive of holoprosencephalic features, showing bilateral ventriculomegaly with dangling choroid plexus, absent cavum septum pellucidum and nonvisualization of the corpus callosum. Post natal head US and MRI brain in twin A (Figure 1a, 1b and 2), however demonstrated a leftsided open lip schizencephaly with a 4cm open gap, extending to the body of corpus callosum and the left hippocampus. Area involved was the distribution of the middle cerebral artery. No seizures were observed. Primitive reflexes were present; patient had spontaneous movements and achieved full par oral feeding by 3rd week of life.
Figure 1a: Coronal section of the brain in a postnatal US of Twin A, showing the left-sided open lip schizencephaly with a 4cm open gap.
Figure 1b: Sagittal section of a post natal US in Twin A, showing ventriculomegaly and non-visualization of the corpus callosum.
Figure 2: Post natal MRI of Twin A showing the schizencephalic defect.
Twin B had antenatal findings suggestive of hydranencephaly versus porencephaly, and this was confirmed on postnatal US and MRI as hydranencephaly, with absence of majority of cortex and thalami, but present cerebellum, brainstem and cortical remnants of parenchyma, as shown in Figures 3a, 3b and 4. Twin B had neurogenic diabetes insipidus on day of life 4 and temperature instability. Patient had minimal spontaneous movements and inability to swallow, requiring feeds through orogastric tube route. Outlook remained poor. No other congenital anomalies were identified in either twin.
Figure 3: A coronal and sagittal section of a postnatal US for Twin B, demonstrating the absence of majority of cortex and thalami, but present cerebellum, brainstem and cortical remnants of parenchyma
Figure 4: Postnatal MRI Brain of Twin B demonstrating absence of majority of cortex and thalami, but present cerebellum, brainstem and cortical remnants of parenchyma in hydranencephaly.

Discussion

Schizencephaly or abnormal clefts in the cerebral hemisphere is extremely rare (incidence 1.5/100,000 births) [1] and similarly hydranencephaly, the complete or near complete absence of the cerebral cortex and thalami, replaced by a membranous sac of cerebrospinal fluid, is a rare anomaly (incidence 1-2.5/10,000 births) [2].
Schizencephaly is a term introduced by Yakovlev and Waldworth in 1946 to describe a “brain lesion that results from an abnormal development” [3]. It is characterized by an early focal destruction of the germinal matrix and surrounding brain, before the hemispheres are fully formed [3-5]. In addition, for unknown reasons, schizencephaly occurs more frequently in fetuses of young mothers [1], and is commonly found with anomalies associated with vascular disruption sequences such as septo-optic dysplasia, absent cavum septum pellucidum and gastroschisis [1,3]. The question persists whether schizencephaly results from a lack of development of brain tissue or from a destruction of the final formed brain. There is no known report of its co-existence with hydranencephaly in monochorionic twins.
Hydranencephaly was first described by Cruveilher (1892) as “Anencephalie hydrocephalique” or “Hydroanencephalie” to describe a condition characterized by the absence and replacement of the cerebral hemispheres with cerebrospinal fluid [6]. Crome and Sylvester then reviewed the disease and defined it as a congenital condition [7].
The most common diagnostic problem is differentiation among hydranencephaly, extreme hydrocephalus, alobar holoprosencephaly and porencephaly. Some spared cortical mantle should still be seen with porencephaly and alobar holoprosencephaly. Serial sonograms may be necessary to evaluate an evolving intracranial process. Extreme hydrocephalus may be difficult to differentiate form hydranencephaly if a falx remnant is present [8].
This case illustrates a rare occurrence of these two cerebral anomalies presenting in monochorionic twins. This report further illustrates the possibility of having a surviving monochorionic twin in a case of hydranencephaly, unlike previous reports where the prevailing theory of vascular disruption and thromboplastin release is based on a deceased co-twin [9-11]. It also suggests an alternative explanation for hypercoagulability other than polycythemia or clot transfer from twin-to-twin transfusion [12,14], such as a possible thromboembolic phenomenon in the mother that may include hereditary coagulopathies or maternal cocaine [13,14]. No history of cocaine use or family history of coagulopathies was identified in this report. Primary mechanism in this case remains unclear. Several implicated mechanism of disease in hydranencephaly and schizencephaly include fetal hypotensive vasculopathy, intrauterine infections or genetics. Our findings however, revealed that an unknown vascular disruption process occurring together in the two fetuses of the case described, may be a more likely mechanism for these cerebral anomalies than the previously reported “deceased twin” hypothesis.

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