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Fetal Acrania. Gray scale ultrasound of the fetal brain (3.5 MHz probe) in coronal plane. Gestational age 30 weeks. No skull is seen around the brain (arrows). Asterisk indicates inter-hemispheric fissure.
Source publication
We report a 35 year old female patient referred to our ultrasound department to rule out congenital anomalies. The fetus was found to have a completely formed brain, base of the skull and facial structures but lacking a cranium. The fetus was therapeutically aborted. We correlated our antenatal sonographic findings with gross pathological features...
Citations
... Specifically, the diagnosis of fetal acrania cannot be clearly formulated before 11 weeks of gestation and that is explained by the normal process of ossification of calvarial bones. In this respect, between 11 and 14 weeks of gestation, the majority of cranial ossification is located in the lateral aspects of the frontal bones and lower part of the parietal bones [21]. Thus, on a perfect midsagittal section used for the measurement of nuchal translucency, no vault ossification could be seen at this moment. ...
Acrania is a fetal malformation characterized by complete or partial absence of the calvaria above the orbits and supraciliary ridge. No exact mechanism is demonstrated for this anomaly but disturbances in mesenchymal migration during the fourth week of development are the most documented. The key sonographic features of acrania are absent calvaria and dorsally bulging brain (Mickey Mouse head). Due to the normal process of ossification of cranial bones, the diagnosis can be established only after 11 weeks of gestation. Early detection is extremely important. The prognosis is extremely poor so elective termination of pregnancy is the treatment of choice. In this paper, we discuss the things we know about pathogeny and ultrasonographic features of fetal cranial malformations based on a case diagnosed late during gestation.
... Spinal canal and cord were of normal morphology. In fetal autopsy, calvarium was missing, viscerocranium appeared normal while the brain was covered with a thick membrane [36]. ...
... Presented figures, however, do not give reason to diagnose acrania because of the lack of the "beret" sign, which would allow for differentiation of normal neurocranium from mentioned pathology. Images of the skull of a 16-week fetus in all presented planes show full ossification of the frontal and parietal bones (Fig. 4d-f), which is consistent with generally accepted knowledge [35][36][37][38]. ...
... In these cases, in which cranium is often deformed and difficult to differentiate from acrania, US may not be a reliable diagnostic tool. A family history of fractures helps differentiate [35,36]. ...
IntroductionNeural tube defects (NTDs) are a group of heterogeneous congenital anomalies of the central nervous system (CNS). Acrania is a non-NTD congenital disorder related to the CNS. It can transform into anencephaly through the acrania–exencephaly–anencephaly sequence (AEAS). In AEAS, the cerebral tissue is not protected and is gradually destroyed due to exposure to the harmful effect of amniotic fluid and mechanical injuries. These lead to exencephaly and then into anencephaly. In contrast to primary anencephaly (NTDs), this type of anencephaly authors suggests calling secondary anencephaly.Objective
Analysis of the known prenatal ultrasonography (US) signs associated with AEAS. Simultaneously, the authors propose a new sign in the differentiation of acrania from exencephaly and anencephaly, called the “beret” sign.Methods
It is a two-centre retrospective observational study. As part of the study, 4060 US scans were analyzed.ResultsIn 10 cases, the absence of calvarium was diagnosed, allowing recognition of either AEAS stages or primary anencephaly. In 5 cases, cerebral structures were enclosed by an inertial rippled thin membrane, with a smooth outer contour. Between the described membrane and the brain structures, a thin anechoic space corresponding to cerebrospinal fluid was observed. This sign was defined as the “beret” sign. In these cases, acrania was diagnosed. In three cases calvarium was missing. The brain structures had an irregular appearance, did not wave and remained motionless. The outer contour was unequal as if divided into lobes. Amniotic fluid was anechoic. Exencephaly was diagnosed in these cases. In two cases calvarium, brain structures, and meninges were missing. The “frog eyes” sign and slightly echogenic amniotic fluid were visible. In this case, anencephaly was diagnosed.Conclusions
The “beret” sign seems to be a promising tool in the diagnosis of acrania. Furthermore, echogenicity of amniotic fluid could be useful during differentiation between primary and secondary anencephaly.
... Acrania is a rare congenital anomaly with a reserved prognosis and still unclear etiology [1][2][3][4][5][6]. According to researchers, it is also known as exencephaly [7][8][9]. It is a cranial vault defect characterized by the partial or total absence of the cranial bones and the covering skin, with complete but abnormal development of the chondrocranium and the presence of brain tissue that is exposed [1 2,3,10]. ...
... Thus, folic acid supplementation may be a possible protective factor to the acrania, and its effect only occurs if the supplementation is initiated before gestation. The environmental factors involved in the pathology include hyperthermia, uncontrolled pre-gestational diabetes, antiepileptic drugs, lead exposure, maternal obesity and folate deficiency [5].Studies have shown that prenatal sonographic diagnosis of acrania is established by the following criteria: the fetus should have a normal facial bone and a normal cervical column but without fetal skull and a volume of brain tissue equivalent to a third of the expected size of the brain [7,16]. ...
We described a cranial vault defect associated with amniotic band syndrome of a post-bariatric pregnancy. Obstetric ultrasonography with gestational age of 14 weeks and six days showed fetal acrania and at 21 weeks, revealed also a tortuosity of right radius and ulna. Case report: newborn, vaginal delivery, preterm (35 weeks and three days of gestation), Apgar 6/6, presented at birth a diagnosis of acrania and amniotic
constriction band in the left upper limb without radial pulse in this limb. Transferred after birth to a Neonatal ICU, she died after 9 days. This rare lethal anomaly has important implications for obstetric management and counseling. Although there is no consensus in the literature regarding the risks of gestations after malabsorption procedures, gestations after bariatric surgery should be accompanied with extreme care aiming at an adequate nutritional intervention at risk of affecting the intrauterine environment and the developing fetus.
... The differential diagnosis included ectopic pregnancy, spontaneous abortion, threatened abortion, inevitable abortion, septic abortion, gestational trophoblastic disease, and mechanical trauma. 5 A POCUS was performed to confirm intra-uterine pregnancy and evaluate fetal viability. Initial transabdominal ultrasound revealed a single intrauterine pregnancy at approximately 10 weeks gestation. ...
Background:
Early pregnancy complaints in emergency medicine are common. Emergency physicians (EP) increasingly employ ultrasound (US) in the evaluation of these complaints. As a result, it is likely that rare and important diagnoses will be encountered. We report a case of fetal anencephaly diagnosed by bedside emergency US in a patient presenting with first-trimester vaginal bleeding.
Case report:
A 33-year-old patient at 10 weeks gestation presented with vaginal bleeding. After initial history and physical examination, a bedside US was performed. The EP noted the abnormal appearance of the fetal cranium and anencephaly was suspected. This finding was confirmed by a consultative high-resolution fetal US. Making the diagnosis at the point of care allowed earlier detection and more comprehensive maternal counseling about pregnancy options. This particular patient underwent elective abortion which was able to be performed at an earlier gestation, thus decreasing maternal risk. If this diagnosis would not have been recognized by the EP at the point of care, it may not have been diagnosed until the second trimester, and lower-risk maternal options would not have been available.
... The brain may be fully developed but amorphous and surrounded by amniotic fluid. [18][19][20][21] Polyhydramnios Not all complications of gestational diabetes are quite as destructive as fetal acrania. In case 2, the levels of amniotic fluid were measured to be larger than expected. ...
Gestational diabetes mellitus (GDM) is defined as glucose intolerance that begins or is first recognized during pregnancy. Numerous clinical factors are associated with an increased likelihood of GDM, such as increasing age, obesity, ethnicity, family history of diabetes and past obstetric history. There is a well-documented relationship between maternal hyperglycemia and increased rate of macrosomia, cesarean section, stillbirth, fetal congenital malformations, shoulder dystocia, hypoglycemia, hyperbilirubinemia, pre-eclampsia, preterm delivery, childhood obesity, and increased risk of maternal development of type 2 DM later on in her life. This case-based review is designed to provide health care workers a framework on using various ultrasound imaging modalities in early detection of the effects of gestational diabetes, and the specific conditions and/or anomalies seen in diabetic pregnancies.
How to cite this article
Appleton K, Barnard J, Jantz AK, Pooh R, Comas-Gabriel C, Kupesic-Plavsic S. The Role of Ultrasound in the Diagnosis of Complications Associated with Maternal Diabetes. Donald School J Ultrasound Obstet Gynecol 2013;7(4):506-515.
Acrania is a rare, life-threatening congenital anomaly in which the flat bones in the cranial vault are either completely or partially absent, with complete but abnormal development of the cerebral hemispheres. In severe cases, surgical intervention is required for improved outcome. We present a 31-week gestational age, 1.6 kg female preterm neonate with acrania and no other associated congenital anomaly. On the eighth day of life, a scalp transpositional flap based on the superficial temporal and posterior auricular arteries was raised to cover the primary defect, and a split thickness skin graft was used to resurface the secondary defect. The patient did well postoperatively and was discharged to be monitored in the clinic. Early detection and multimodal specialist care is imperative for necessary intervention to prevent untoward complications.
