BACKGROUND: The term “Iniencephaly” derives its nomenclature from two greek words ‘Inion’ meaning back of the head and ‘encephalos’ meaning brain. Isolated Iniencephaly is a rare neural tube defect(~0.1-10:10,000 ) whereas Anencephaly represents the most common neural tube defect (~1:1000). CASE: We describe a rare case of Iniencephaly with Anencephaly and Gastrointestinal atresia diagnosed at 18 weeks of gestation. Pregnancy was terminated due to its fatal prognosis.
CONCLUSIONS: These parents should be given adequate emotional support and counselled about recurrence risk,need for periconceptional folic acid supplementation and an early ultrasound scanning at 11 weeks during next pregnancy, to prevent any delay in diagnosis of such lethal anomalies.
Iniencephaly is an uncommon and fatal neural tube defect(NTD) involving the occiput and inion combined with rachischisis of the cervical and thoracic spine with retroflexion of the head . The incidence of iniencephaly varies from 0.1-10:10,000. . Whereas Isolated Anencephaly represents the most common NTD. Its incidence is approximately 1:1000 with female predominance (4:1) and geographical variability.
A 28 years old primigravida of noncansanguinous marriage, of Indian origin, presented to Antenatal Outpatient Department at 18 weeks. There was no past or present medical or surgical illness. Her family history was not contributory. There was no history of radiation exposure or drug intake during this pregnancy. She had a previous dating scan of 7 weeks which was corresponding to her menstrual age. She was referred for an ultrasound scan at 18 weeks to rule out any congenital anomalies. The Ultrasound scan revealed a grossly anomalous fetus with frog -like eyes, absent calvaria and freely suspended brain matter in the surrounding liquor (Fig1a,b; Fig 2a,b), star-gazing fetus(extended head), absence of stomach bubble suggestive of esophageal atresia (Fig 3a,b ; Fig 4a,b ), spinal curvature abnormality on saggital scan (Fig 1b), spinal defect in cervical and thoracic region on coronal scan(Fig 5). The limb bones appeared normal and there was no evidence of polydactyly or club foot.The patient was sympathetically counselled and informed about the diagnosis. Termination of pregnancy was advised in view of the lethal nature of the abnormality.
Medical second trimester abortion was carried out using oral Mifepristone and Misoprostol. The female abortus weighed 376 gms and showed features corresponding to the Ultrasound findings. Frog like protruding eyes on the fixed retroflexed face with absence of cranial vault and extensive hanging out brain matter could be seen.(fig6a). Face was upturned and mandibular skin was directly continuous with that of the chest due to the lack of neck(fig 6b). Significant shortening of the spinal column due to marked thoracic lordosis and hyperextension of the malformed cervical-thoracic spine The arms appeared longer than the legs due to apparent shortening of spine caused by deformed spinal curvature. (Fig 6c).The rachischisis extended from the cervical through thoracic spine.
There was anal atresia (only a dimple present at the site of anal opening). (fig 6d). The extremities and digits were normal.(fig 7a,b,c) Karyotyping revealed 46, XX. The patient was given adequate emotional support and was well counselled about recurrence risk, need for periconceptional folic acid supplementation, and need for an early ultrasound scanning at 11-12 weeks during next pregnancy, to prevent any delay in diagnosis of such lethal anomalies.
Anencephaly was the first fetal malformation diagnosed prenatally by Campbellet al  using transabdominal ultrasound. Étienne Geoffroy Saint-Hilaire  first described Iniencephaly as being caused by arrest of the embryo in physiological retroflexion during the third week of gestation or by failure of normal forward bending during the fourth week. Other probable etiological factors implicated in causing Iniencephaly are, environmental factors like maternal syphilis, drugs such as clomiphene citrate and sedatives . Eberhard Merz et al  proposed that due to absence of cervical vertebra and a large foramen magnum, the head assumes an extreme dorsiflexion..Lewis classified iniencephaly into two main groups which are iniencephaly apertus which has an encephalocele and iniencephaly clausus which has a spinal defect but no cephalocele. Much discrepancy exists between various reports regarding the incidence of iniencephaly, varying from 0.1-10:10,000 . Jayant K et al have reported an Indian incidence of 1 per 65,000 deliveries with female preponderance in 90% of cases . Morocz I et al also have described male to female occurrence ratio of Iniencephaly as 1:9 , as was seen in our case.
Cimmino CV et al  and Bose S et al have described the presently being used diagnostic criteria for iniencephaly,which are a)A variable deficit of the occipital bones resulting in an enlarged foramen magnum, b)Partial or total absence of cervical and thoracic vertebrae with an irregular fusion of those present, accompanied by incomplete closure of the vertebral arches and/or bodies (rachischisis), c) Significant shortening of the spinal column due to marked lordosis and hyperextension of the malformed cervical-thoracic spine, d)Upward turned face and mandibular skin directly continuous with that of the chest due to the lack of neck. Our case showed the last 3 features. The occipital bones were highly underdeveloped as in anencephaly.The time of onset of Iniencephaly is probably only a few days later than anencephaly.Pathogenesis of isolated Iniencephaly is different from anencephaly in that the anterior neuropore has closed in isolated iniencephaly.
The cervical vertebrae are normal in isolated anencephaly, while they are very abnormal in iniencephaly. In our case since there was both an absence of calvarium with abnormal cervical vertebrae, it was a case of Iniencephaly with anencephaly. As Trenouth had demonstrated that brain growth in normal fetuses influences the development of cranial base and position of the face in general and the nasomaxillary segment in particular. In anencephaly, as the influence of the expanding brain is removed, it causes secondary adaptive alterations in the cranial base. The squamous occipital bones are under-developed compared with the normal standard.. Iniencephalic fetus can have any of the following associated anomalies, like Anencephaly (as in our case), cephalocele, holoprosencephaly, agnathia-microstomia-synotia, palatal anteversion, spina bifida, omphalocele, gastroschisis, diaphragmatic hernia or agenesis, pulmonary hypoplasia or hyperplasia, cardiac malformations, renal anomalies, overgrowth of the arms compared to the legs, genu recurvatum, arthrogryposis, club-foot, gastrointestinal atresia (presence of esophageal atresia and imperforate anus /anal atresia in our case) [1,8-10,12-14].
The differential diagnosis includes Klippel-Feil syndrome (shortness of the neck associated with fusion of cervical vertebrae), anencephaly, and a cervical myelomeningocele. The differentiation between iniencephaly clausus and Klippel-Feil syndrome is difficult and controversial. Some authors feel that Klippel-Feil syndrome may be the mildest form of iniencephaly. The recurrence risk for Iniencephaly and anencephaly is like any other NTD – 1-4%. Hence adequate counselling about recurrence risk, folic acid supplementation and early fetal surveillance are advisable.
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Fig 1a– Transvaginal scan showing bulging frog-like orbits.
Fig 1b– Transvaginal scan with Absent calvarium & brain matter freely suspended in liquor amnii.The hyperechoic spine is seen in medial sagittal view and shows abnormal curvature ( thoracic lordosis ).
Fig 2a– Transabdominal scan showing coronal view of face with orbits, absent cranial vault and freely suspended brain matter.
Fig 2b-Bulging frog -like eyes.
Fig 3a– Transabdominal scan with Abdominal cross-section showing umbilical vein and absence of stomach bubble suggesting esophageal atresia.
Fig 3b– Colour Doppler image of 4-chamber heart with apex to left. (normally stomach bubble present on left side in abdominal cross section, confirms normal SITUS).
Fig 4a– Transabdominal scan with Abdominal cross-section (higher level oblique section)showing rachischisis of thoracic vertebra (transverse section of vertebra shows a defect -absence of posterior skin with exposed neural tissue).
Fig 4b-Normal foot
Fig 5-Transvaginal scan showing abnormal spinal curvature and cervical and thoracic rachischisis .
Fig6a – Abortus with frog like protruding eyes on the fixed retroflexed face with absence of cranial vault and extensive hanging out brain matter . Fig 6b -Upturned face and mandibular skin is directly continuous with that of the chest due to the lack of neck. Fig 6c – Significant shortening of the spinal column due to marked thoracic lordosis and hyperextension of the malformed cervical-thoracic spine The arms appear longer than the legs due to apparent shortening of spine caused by deformed spinal curvature. Fig 6d -The rachischisis extended from the cervical through thoracic spine. There was anal atresia(only a dimple present at the site of anus instead of an opening).
Fig 7a,b,c – The extremities, hands, feet and digits were normal.
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