Imaging of open spinal dysraphisms in the era of prenatal surgery
- PDF / 1,822,075 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 61 Downloads / 185 Views
FETAL IMAGING
Imaging of open spinal dysraphisms in the era of prenatal surgery Usha D. Nagaraj 1,2
&
Beth M. Kline-Fath 1,2
Received: 20 September 2019 / Revised: 15 April 2020 / Accepted: 20 May 2020 / Published online: 19 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Over the last decade fetal surgery to repair open spinal dysraphisms has become an acceptable and in some cases desirable alternative to the traditional method of postnatal closure. Fetal MRI is an essential part of the workup in these patients, not only to select the appropriate candidates for fetal surgery but also to guide prenatal counseling and perinatal management. In this article we review current surgical techniques for prenatal repair, relevant imaging findings in the era of fetal surgery, and expected imaging findings of the brain and spine in the fetal and postnatal periods. Keywords Chiari II . Dysraphism . Fetus . Magnetic resonance imaging . Myelomeningocele . Spine
Introduction The term spinal dysraphism refers to a wide spectrum of neural tube defects involving the spine and spinal cord [1]. There are two main categories of spinal dysraphisms: open and closed. The differentiating factor between the two is absence (open) or presence (closed) of a skin covering at birth [2]. While this distinction is apparent clinically at birth, it is not always easy to distinguish prenatally by imaging [3]. From a fetal surgery perspective, the difference is crucial because only patients with open spinal dysraphisms are candidates for prenatal repair of the spinal dysraphic defect [4]. The two main categories of open spinal dysraphism are myelomeningoceles and myeloceles. Myelomeningoceles are associated with a sac containing the neural placode outside the spinal canal. Myeloceles, also known as myeloschisis, have a neural placode that is either flush with the skin surface or within the spinal canal without a measurable extraspinal sac [1, 2]. The constellation of intracranial findings in the presence of an open spinal dysraphism, including but not limited to hindbrain herniation, is referred to as Chiari II malformation [5].
Open spinal dysraphisms are one of the most common congenital abnormalities of the central nervous system and are almost always detected prenatally [6]. Maternal serum screening by measuring alpha-fetoprotein (AFP) has been described to detect up to 90% of open spinal dysraphisms prenatally [7]. However, second-trimester US examination is more specific and has been shown to detect more open spinal dysraphisms than maternal serum AFP alone [8]. Elevated AFP and a substance called acetylcholinesterase can be evaluated in the patient’s amniotic fluid to help confirm the presence of an open spinal dysraphism, and patients who are interested in pursuing fetal surgery require an amniocentesis to confirm a normal fetal karyotype [9]. In addition to amniocentesis, fetal MRI is an essential tool in the workup and selection of candidates for fetal surgery. Candidates for fetal surgery are require
Data Loading...
