Iniencephaly: Case Report.

The iniencephaly involves a variable defect in the occipital bone, resulting in a large foramen magnum, partial or total absence of the cervical and thoracic vertebrae, accompanied by incomplete closure of arcs and/or vertebral bodies, significant shortening of the spinal column and hyperextension of the malformed cervicothoracic spine; the individual's face is deviated upward, the mandibular skin is directly continuous with anterior thorax due to the absence of neck. Its incidence is about 1:1000-1:2000 births, so this is a pretty rare neural tube defect. We present a case of iniencephaly in association with cardiovascular, spinal cord, and intracranial malformations that ended demonstrating the low survival of patients affected with this condition.

Introduction

The neural tube closure occurs around day 28 after conception; its closure failure may result in a defect that can range from anencephaly, incompatible with life, to small meningoceles.[1] The definition of neural tube defects (NTD) include anencephaly, craniorachischisis, iniencephaly, meningocele, meningomyelocele, and encephalocele, but not isolated findings of hydrocephalus or spina bifida oculta.[1] Iniencephaly, from the ancient Greek “inion” meaning “nape of the neck”, had its first report by Saint-Hilaire in 1836,[2] is characterized by a variable defect of the occipital bone, resulting in a large foramen magnum; partial or total absence of the cervical and thoracic vertebrae with irregular melting of those present, accompanied by incomplete closure of arcs and/or vertebral bodies, marked lordosis, hyperextension of the cervicothoracic spine; and a face deflected up.[3] The incidence is about 1:1000–1:2000 births,[4] then is a pretty rare NTD. We present iniencephaly associated with cardiovascular, spinal cord, and intracranial malformations.

Case Report

Male newborn, product of uncontrolled 37 weeks pregnancy, weighing 2580 g at birth, who had a deformed trunk and neck, with deviation of the spinal column, in whom, given the phenotypic characteristics and ventilatory compromise, was decided to provide neonatal resuscitation measures and immediate Neonatal Intensive Care Unit transfer. Head circumference: 34.5 cm, macrocephaly, with forced extension of the neck, which was extremely short. The occiput kept close contact with the skin of the back. The anterior fontanelle is large and normotensive, low-set ears [Figure 1a] moist oral mucosa, hard palate without clefts. Patient had asymmetrical barrel chest; restrictive, irregular breathing pattern with tachypnea and chest retractions; presence of crackles and mobilization of secretions on auscultation. Heart sounds were rhythmic without audible murmurs, marked on the right side of the chest, so it was suspected dextrocardia. The abdomen was soft and depressible, not distended, peristalsis present, mummified umbilical cord. At thoracolumbar level was a spinal medial defect, 5 cm × 5 cm, suggestive of spina bifida with myelomeningocele [Figure 1b]. External genitalia are macroscopically normal for his age.

Figure 1

Patient phenotypic characteristics support iniencephaly. (a) Significant shortening of the spinal column by marked lordosis and hyperextension of the malformed cervicothoracic column is evident; deflected up face, or neck hyperextended, the mandibular skin is directly continuous with the anterior thorax, which is asymmetric and barreled. Absence of neck, low-set ears, and flat convex feet. (b) medial, thoracolumbar defect, 5 cm × 5 cm, suggestive of spina bifida with myelomeningocele

On neurological assessment patient was active, reactive to tactile stimulation, without paroxysmal movements. Limbs were mobile, symmetrical, both feet flat and convex; distal and central pulses present, capillary refill of 2 s; skin with mild pallor.

Portable X-ray evidenced the physical deformity of the costal arch and spine, with severe scoliosis, lung volume of eight intercostal spaces; few reticulonodular infiltrates with pulmonary acceptable transparency. Cardio-thymic silhouette is visible with dextrocardia. The abdomen shows gas in the gastric camera and intestinal loops without edema or pneumatosis [Figure 2].

Figure 2

Portable X-ray image showing: Cervical vertebras in block, thoracic vertebras with irregular fusion resulting in severe scoliosis with hyperextension of the malformed cervicothoracic spine. Cardiothymic silhouette is visible with dextrocardia

The echocardiogram showed the presence of complex congenital heart disease, aortic end of 2.4 cm, and 1.8 cm in the pulmonary end, atrial septal defect with dextrocardia. Transfontanelar ultrasonography showed hydrocephalus. The intra-abdominal organs were assessed as normal by total abdominal ultrasound.

After neurosurgical assessment, was considered given those findings, a case of iniencephaly associated with a dorsal myelomeningocele through which neural elements were observed, with no cerebrospinal fluid leaks. It was decided to perform surgery to correct it. During the surgery a thoracic intramedullary tumor was evident, which was resected; with macroscopic appearance of lipoma versus neuroma, however, the histopathology analysis reported astrocytoma. The patient persisted with irregular breathing pattern, needing for supplemental oxygen at high flow, tendency to bradycardia and hypotension, hyporesponsiveness. Posteriorly the patient develops generalized edema and jaundice, with mucocutaneous pallor; no lower limb movements. The patient evolves disastrously with respiratory complications, developed respiratory failure and died despite resuscitation on the 3rd day of life.

Discussion

In general, for all NTD, genetic (70%) and non-genetic factors (30%) are involved.[5] Several observational studies find a reduction in NTD risk in women who consume folic acid supplements or have a high dietary intake during pregnancy early stages.[67] Other etiologic factors associated with increased risk of NTD include maternal diabetes and obesity, antifolate medication, and certain anticonvulsant medications, including sodium valproate and carbamazepine.[89] In this case, because it was an uncontrolled pregnancy, there was little adherence to supplemental vitamin treatments, which is rigueur in all pregnant women throughout our country, Colombia; plus the fact that in these same controls, regular fetal ultrasound examinations are performed, in order to determine these changes radiologically. The patient did not have them.

Some authors consider that NTD as encephaloceles, meningoceles and iniencephaly most likely not arise directly from a failure in neural tube formation, but more probably from a postneurulation disorder; which is a consistent fact with findings from other causes, for example, encephalocele when these are part of Meckel syndrome.[5] Iniencephaly is not considered to be an open defect because usually the sac containing CSF contains neural tissue and is covered by an intact dermis.[10] Lewis[11] classifies iniencephaly in “iniencephalus apertus” when associated with encephalocele, and “anencephalus clausus”, which is not associated encephalocele. Subsequently, Howkins and Lawrie[12] classified into simple, in which the variants “apertus” and “clausus” are included, and iniencephaly with anencephaly (anencephaly with spinal retroflexion).

In most reported cases of iniencephaly with or without craniorraquisquisis, which to date do not add more than 100, 75% have associated abnormalities, which in frequencies involves:[13] Anencephaly (42.9%); omphalocele (20%); clubfoot (19%); encephalocele (14%); lung defects (14%); single umbilical artery (14%); congenital diaphragmatic hernia (12.7%); facial clefts (9.5%); duodenal atresia (6.4%); renal agenesis or dysgenesis (6.4%); myelomeningocele (6.4%); ventriculomegaly or hydrocephalus (6.4%), genital abnormalities (3.2%), cystic hygroma (3.2%); heart defects (3.2%); holoprosencephaly (1.6%); imperforate anus (1.6%); lissencephaly (1.6%) and syringomyelia (1.6%). Other associated anomalies include Dandy-Walker malformation, caudal regression sequence, and arthrogryposis. Our patient had as associations, a severe congenital heart defect (dextrocardia and atrial septal defect), secondary ventriculomegaly, clubfoot, myelomeningocele and an intramedullary tumor, which correspond to astrocytoma.

Phenotypic characteristics comprising iniencephaly are clinically apparent, absent or very short neck, head in forced extension, associated with additional defects, in this case, the defect in the thoracolumbar spine. This patient had asymmetrical barrel chest, which compromised, in addition to the arrangement of the spine, all the breathing mechanism, evolving from a restrictive ventilatory pattern to respiratory failure and consequently death. To make the diagnosis of iniencephaly, differential diagnosis must be made with cervical hyperextension, nuchal or cervical tumors such as teratomas, goiter, lymphangiomas, cervical myelomeningocele, encephalocele, Klippel-Feil syndrome and Jarcho-Levin syndrome.

Klippel-Feil syndrome is caused by the unsuccessful segmentation of cervical vertebrae during early fetal development; is characterized by a short neck, low hairline implantation, and limited cervical movements. It can be associated with deafness, congenital heart defects, neurocognitive disorders, cleft palate, rib defects, Sprengel anomaly, dermoid cysts, scoliosis and kidney abnormalities. The involved gene (s) in this syndrome have not yet been determined, possibly located at 5q11.2, 5q35.1, 8p21.1, and 17q23. The other important differential diagnosis is the spondylocostal dysostosis or Jarcho-Levin syndrome, which is an autosomal recessive disorder syndrome, is characterized by a short trunk, head in opisthotonus, short neck, a barrel chest, vertebrae minted or block, spina bifida and rib abnormalities.

Prenatal diagnosis can be performed by ultrasonography. However, in uterus-magnetic resonance image (MRI) provides a reliable tool to evaluate the fetus and outline the characteristics of fetal disorders allowing proper classification, affecting management planning and counseling to parents.[10] Fetal MRI is an interactive assessment, allowed by the use of rapid sequences. A standard sequence is the mono-shot spin-echo-T2 images. The advantage of MRI is that fetal visualization is not limited by maternal obesity, fetal position or oligohydramnios. Furthermore, brain display is not restricted by the ossified skull.[14] In general, serum biochemical markers for NTD such as alpha-fetoprotein are abnormal. However, despite all the advantages of the use of fetal MRI, its high cost and non-availability of these devices in health centers, makes ultrasound or ultrasonography the pillar of antenatal diagnosis. Since the distortion of the fetal body can endanger the life of the mother during labor, cesarean section is indicated in some cases. With regard to treatment, has been reported in a few survivors, neurosurgical intervention may improve cervical deformity, especially those with associated minor malformations.[15]

Conclusions

Neural tube defects are relatively common congenital malformations in association with other cardiac or genitourinary anomalies. Although multifactorial in origin, there are few truly important etiological factors, such as poor folate substitution in pregnant women. It is important to consider, that failure to recognize iniencephaly when part of more complex defects may explain the low incidence of their reports. We present a case of iniencephaly in association with cardiovascular, spinal cord, and intracranial malformations that ended demonstrating the low survival of patients affected with this condition. Although reported specific genetic association does not exist, it is assumed that genetic factors play an important role in the development of this disorder.