ABSTRACT: Tethered spinal cord is mostly caused by myelomeningocele and lipomyelomeningocele, while dermal sinus tract, diastematomyelia, lipoma, tumor,.
Case Report
Prenatal Diagnosis of Tethered Spinal Cord Associated with Sacrococcygeal Teratoma Tugba Sarac Sivrikoz, MD,1 Recep Has, MD,1 Aytul Corbacioglu Esmer, MD,2 Ibrahim Kalelioglu, MD,1 Atil Yuksel, MD,1 Orhun Cig Taskin, MD3 1
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey 2 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Kanuni Sultan Suleyman Research and Teaching Hospital, Istanbul, Turkey 3 Department of Pathology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey Received 22 December 2015; accepted 20 January 2016
ABSTRACT: Tethered spinal cord is mostly caused by myelomeningocele and lipomyelomeningocele, while dermal sinus tract, diastematomyelia, lipoma, tumor, thickened/tight filum terminale, spinal trauma, and spinal surgery are among the other causes. Prenatal diagnosis of tethered cord has been reported, and it is usually associated with neural tube defects. We present an atypical presentation of a tethered spinal cord, which was associated with a sacrococcygeal teratoma and was diagnosed in the 23rd week of pregnancy by C 2016 Wiley Periodicals, Inc. J Clin ultrasonography. V Ultrasound 44:506–509, 2016; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jcu.22344 Keywords: tethered spinal cord; sacrococcygeal teratoma; fetal spine; fetal spinal cord; conus medullaris; ultrasonography; obstetrics
INTRODUCTION
T
ethered spinal cord (TSC) is defined as the fixation of the caudal portion of the spinal cord, which results in a tight pull or stretching on the lower portion of the spinal cord and can lead to neurologic compromise. It is mostly caused by myelomeningocele and lipomyelomeningocele, while dermal sinus tract, diastematomyelia, lipoma, tumor, thickened/tight filum
Additional Supporting Information may be found in the online version of this article. Correspondence to: A. Corbacioglu Esmer C 2016 Wiley Periodicals, Inc. V
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terminale, spinal trauma, and spinal surgery are other causes of TSC. The true incidence of primary TSC is not known, and it is usually diagnosed with the onset of symptoms. Prenatal diagnosis of TSC is possible, and it is typically associated with neural tube defects (NTDs).1 We report an atypical presentation of TSC, which was associated with a sacrococcygeal teratoma and diagnosed in the 23rd week of pregnancy by ultrasonography.
CASE REPORT
A 30-year-old woman, gravida 1, para 0, was referred to our clinic in the 23rd week of gestation after a sonographic examination of the fetus revealed a mass in the sacral region. Detailed sonographic examination was performed using a 2–5-MHz curved-array transabdominal transducer and a 5–13 MHz endovaginal transducer connected to a Voluson E8 scanner (GE Healthcare, Milwaukee, WI). Sagittal scans showed a 4.5-mm vertebral defect in the sacrum and a small cystic mass. This cystic mass was associated with the conus medullaris, which was stretched out through the vertebral defect, suggesting the diagnosis of TSC (Figure 1). In the axial plane, another solid mass measuring 36 3 28 3 27 mm was observed. This mass was connected by a 10-mm pedicle to the sacral portion of the spinal canal, passing through the aforementioned cystic mass (Figure 2, Video). On Doppler examination, there was a low-velocity flow signal within the proximal part of the JOURNAL OF CLINICAL ULTRASOUND
TETHERED CORD AND SACROCOCCYGEAL TERATOMA
FIGURE 1. Longitudinal sonogram demonstrates the cystic mass connected with the conus medullaris, which is stretched out through the vertebral defect (arrow).
FIGURE 2. Transverse sonogram shows the solid mass with a torsioned pedicle (arrow) connected to the sacral portion of the spinal canal.
pedicle, but there was no blood flow signal inside the mass itself (Figure 3). The pedicle was torsioned and the mass was dangling. The appearance of the mass was homogenous suggesting edematous tissue. The tumor was considered to be a sacrococcygeal teratoma, of which vascular supply was obliterated after torsion of the pedicle. There was also a separate dimple on the sacrum just 1 cm below the pedicle attachment site. The appearance of the fetal perineum was normal. There were no associated central nervous system and extra-central nervous system anomalies such as Chiari II malformation or pes equinovarus. Maternal serum alpha-fetoprotein (AFP) level was 1.18 MoM. The parents were counseled by a pediatric neurologist regarding the risks of TSC, and they opted for termination of the pregnancy. The postmortem macroscopic and microscopic examinations confirmed the diagnoses of sacroVOL. 44, NO. 8, OCTOBER 2016
FIGURE 3. Longitudinal color Doppler sonogram shows the lowvelocity flow within the proximal part of the pedicle (arrow), whereas there is no blood flow signal inside the mass itself.
FIGURE 4. Postmortem examination shows the vertebral defect (arrowhead) and the torsioned pedicle of the tumor connected to the spinal canal (arrow).
coccygeal teratoma and TSC (Figure 4). The stem of the teratoma was connected to the spinal canal. The pedicle of the tumor was torsioned. The defect created by the mass was observed, and tethered cord was confirmed anatomically. Also, histopathologic examination showed that the mass did not contain any neural tissue, thereby excluding a meningomyelocele.
DISCUSSION
Prenatal sonographic evaluation of the spinal cord using high-frequency linear transducers can depict exquisite anatomic details of the spinal cord, such as the conus medullaris, the filum terminale, and the nerve root bundles.2 During routine sonographic examination, an attempt may be made to visualize the spinal cord, the conus medullaris, and also the vertebral bodies up to the end of the spine on a 507
SARAC SIVRIKOZ ET AL
midsagittal view, and determination of the terminal part of the conus medullaris has been proposed as a screening method for diagnosis of TSC.3 In 71% of fetuses, the conus medullaris level can be determined at the 20–24 week’ gestation on an anomaly scan, usually at the L2-L3 level.2,4 During this period, a conus medullaris positioned at or below L4 or displaced dorsally is highly suggestive of closed spinal dysraphism. Sohaey et al5 showed examples of tethered cord in a variety of fetuses with spine anomalies. The prognosis of prenatally diagnosed TSC is still unclear, as only a few cases have been reported. Neurologic sequelae might have already developed in affected fetuses at the time of diagnosis. Sacrococcygeal teratoma is the most common congenital tumor. The prevalence is 1/35,000– 40,000 in live births, and it is three times more frequent in the female population.6 Most sacrococcygeal teratomas appear sonographically as masses of cystic, solid, or mixed echogenicity originating from the sacral area and protruding through the perineum or buttocks. Mortality associated with a prenatally diagnosed sacrococcygeal teratoma ranges between 30% and 50% and is attributed to tumor morphology and vascularity.7 Although some fetuses are born without complications, others can develop highoutput cardiac failure, nonimmune hydrops fetalis, and ultimately, fetal demise. Sacrococcygeal teratomas are classified into four types according to the extent of the tumor.8 In our case, type 1, which is predominantly external, was found, and the expected prognosis was good. However, the presence of tethered cord increased the risk for neurologic insult and made the parents opt for termination. The differential diagnosis of a fetal sacrococcygeal mass includes meningocele, myelomeningocele, myelocystocele, teratoma, lipoma, hamartoma, hemangioma, lymphangima, chorDifferentiation doma, and ependymoma.9 between sacrococcygeal teratoma and NTD may be difficult, and there are several case reports in the literature in which the prenatal findings were interpreted as a cystic sacrococcygeal teratoma but the mass proved to be a NTD postnatally, or vice versa.9–11 Terminal myelocystocele, which is a skin-covered NTD, is a localized dilation of the spinal cord central canal herniating through a dorsal spinal defect.9 It is associated with a spinal dysraphism, and typically the cord is tethered to the mass.9 Also, levels of AFP in maternal blood and amniotic fluid are typically normal, because, in contrast to menin508
gomyelocele, a myelocystocele is a closed NTD.9 By contrast, in sacrococcygeal teratomas, there is no spinal dysraphism, and occasionally there may be sacral dysgenesis or hemivertebra.9 In addition, AFP level may be high. Moreover, Sugitani et al6 suggested that the presence of a feeding artery within the wall of the lesion is characteristic of a sacrococcygeal teratoma and emphasized the role of color Doppler in the differential diagnosis of sacral masses. In the case we presented, even though the normal maternal AFP level, the presence of tethered cord, and a vertebral defect with a small cystic mass depicted in Figure 1 were characteristics of a closed NTD, the predominantly solid component of the mass attached to the sacral part of spinal canal by a pedicle with a blood supply up to the torsioned level led us to consider the diagnosis of sacrococcygeal teratoma. The association of anococcygeal malformations with TSC has been reported in the literature, but sacrococcygeal teratoma associated with TSC is extremely rare, and to the best of our knowledge, there is no prenatally diagnosed case in the literature.12 TSC is mostly associated with NTDs. However, when a TSC associated with a mass in the sacral region is diagnosed prenatally, sacrococcygeal teratoma should be considered in differential diagnosis.
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10. Ben-Sira L, Garel C, Malinger G, et al. Prenatal diagnosis of spinal dysraphism. Childs Nerv Syst 2013;29:1541. 11. Evans MJ, Danielian PJ, Gray ES. Sacrococcygeal teratoma: a case of mistaken identity. Pediatr Radiol 1994;24:52. 12. Levitt MA, Patel M, Rodriguez G, et al. The tethered spinal cord in patients with anorectal malformations. J Pediatr Surg 1997;32:462.
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