Alobar holoprosencephaly

Amaç

Alobar holoprosensefali ön beyinin inkomplet bölünme ve morfogenezinden kaynaklanan yüzün orta hat malformasyonları ile karakterize bir anomalidir. 10 bin doğumda 0.6-1.9 oranında görülmektedir. Alobar holoprosensefalide görülen orta hat yüz anomalileri olan orbital hipotelorizm, silik burun veya probosis ile birlikte siklopia ve oral deformiteler gebeliğin erken dönemlerinde ultrasonografik olarak tespit edilebilmektedir.

Yöntem

Bu vaka takdiminde BPD ve FL ölçümlerine göre 24. gebelik haftasında bir alobar holoprosensefali olgusu sunuldu. Obstetrik ultrasonografik incelemede, spinal kanal, vertebralar ve kord normal olarak izlenirken, kranyumda interhemisferik fissür, falks serebri ve korpus kallosum izlenmedi. 3. ventrikül saptanmayıp monoventrikül hali mevcuttu. Yarımay şeklindeki holoventrikül büyük bir dorsal kist ile devam etmekte ve kalvaryumu doldurmakta idi.

Bulgular

İstenen pediatri konsültasyonu sonucu indüksiyon uygulanarak gebelik sonlandırıldı. Yapılan neonatal incelemede gövde ve ekstremitelerde belirgin bir deformite tespit edilmedi. Frontal bölgede 3x2 cm'lik yumuşak doku tespit edildi

Sonuç

Yarımay yapılar silik olup, yüzde orta hatta tek göz mevcuttu.

Anahtar Kelimeler

Alobar holoprosensefali, Prenatal tanı

Giriş

he incidence of alobar holoprosencephaly is 0.6-1.9/10.000 in deliveries. Alobar holoprosencephaly is composed of anomalies that result from interruption of the development of anterior brain at the early period of embryonic life. It is
characterised by unvisualized intracranial midline structures with only one central ventricle wide in size (2,3). Besides that, there is cyclopia and hypotelorism (1). The prognosis of these fetuses are poor and they die in intrauterin life or immeadiately after delivery (1,4). In this case report, we introduced a fetus with an alobar holoprosencephaly diagnosed at antenatal period and terminated by the willing of family.

Olgu

The pregnant woman was aged 28 years old with gravity 2 and parity 1. Her husbands age was 30 years old. There was no family history of significant medical problem in both parents. In mother’s obstetric history, there was a caesarean section 3 years ago because of cephalo pelvic disproportion, delivered 3000 g healthy infant without
any detected anomaly. In this pregnancy, she recieved no antenatal care until 28 weeks 2 days of gestational age according to her last normal menstrual period. Her first visit was to our out patient department and as a component of routine examination, on obstetric ultrasonography according to BPD and FL 24 weeks old pregnancy was
detected (fig. 1A- 1B). Spinal cord, vertebras and spinal canal were normal but inter-hemispheric fissure,
falx cerebri, corpus callosum and third ventricle could not be visualised and there was only one ventricle, semilunar shaped holoventricle, continued with a dorsal cyst that filled the calvarium (fig. 1A). These findings are relevant to alobar holoprosencephaly. After consultating with the pediatricians, decision for termination of the pregnancy
was made. Family was informed and they agreed with the decision. By labor induction, a male fetus with 3 apgar score at 1st minute weighing 1400 gr was delivered and in his neonatal examination, there was no gross deformity in the trunk and extremities (fig. 2). At the frontal region of the head, 3x2 cm sized, pedinculated soft tissue was
detected. Nasal structures were insignificant and only one eye was present at the middle of the face (fig. 3). Fetus died 5 minutes after the delivery.

Tartışma

Craniospinal anomalies are the most commonly seen congenital anomalies and can be diagnosed easily by ultrasonographic imaging. Ultrasonographic visualisation of fetus during pregnancy can detect large group of pathologies at the early period of embriyonal life. The perfect time for that is at the 16th to 18th weeks of pregnancy. The major congenital anomalies can be easily diagnosed by performing ultrasonography at that time interval.
More detailed ultrasonographic imaging is necessary for lethal diagnosis. In this way, pregnancy can be terminated at an early period of gestational age in cases of lethal malformations.
Holoprosencephaly can be divided into labor, semi-lobar and alobar subgroups according to cleavage defect of prosencephalon during developmental period. Among them, the most easily diagnosed anomaly is the alobar holoprosencephaly which is characterised by unvisualised midline intracranial structures, fusion of thalamus and presence of only one ventricle wide in size (2,3). Brain is small in size. Instead of ventricular system, only lateral
and third ventricles are present and there is no connection between them, the monoventricle system in relation with dorsal sac is present. Thalamus and corpus striatum are in connection. Corpus callosum, fornices, falx cerebri, optic tractus and olfactory prominence are not present midbrain, brain stem and cerebellum are normal in structures.
There is cyclopia and hypotelorism (1,6). In semilobar holoprosencephaly, falx cerebri and temporal lobe are developed partially in posterior part but there is thalamic and ventricular fusion in anterior part. In lobar holoprosencephaly, only lateral ventricules are present and continue with the other anterior portion (2,3).
Facial anomalies are present together with holoprosencephaly and its progression is severe. The severe forms of facial dimorphism are generally seen in alobar holoprosencephaly. Cyclopia and ethmocephaly are always present with alobar holoprosencephaly (1,7). In our case, there was a 3x4 cm sized pedinculated soft tissue located at the frontal region with insignificant nasal structures. And one eye was present in the middle of the face. 
Fetal karyotyping must be regarded in the presence of all CNS anomalies. The specific craniofacial findings for trisomy 13 are cleft palate and lip, hypotelorism, depressed rudimentary nose and cyclopia. Karyotyping is absolutely indicated in alobar holoprosencephaly cases because high incidence of chromosome anomalies have been detected. Trisomy 13 is frequently seen but other anomalies can also be detected (1,7). Unfortunately
we could not perform karyotyping because of technical difficulties.
In intrauterine life, all the variations of holoprosencephaly
can be diagnosed by ultrasonographic imaging. Detection of severe forms are more common but also lobar holoprosencephaly can be detected (4,5,8). Obstetric approach for holoprosencephaly cases is dependent upon the gestational age and severity of anomaly at the time of diagnosis (9). If diagnosis of holoprosencephaly can
be made before 24th weeks of gestation, parents can prefer termination of pregnancy. Development
of macrocephaly because of ventricular dilatation can prevent vaginal delivery, so that in hopeless patients, cephalosynthesis can be performed to avoid cesarean section. 

Sonuç

Recently some cases are presented from our country remarking bad fetal prognosis and need to terminate pregnancy (10,11).


 

Kaynaklar

1. Cohen MM Jirasek JE, Guzman RT, et al: Holoprosencephaly and facial dysmorphia: Nosology, etiology and pathogenesis. Birth Defects 1971;7:125
2. Donnenfeld AE, Mennuti MT: Sonographic Findings in fetuses with common choromosome abnormalites. Clin Obstet Gynecol 1998;31:80-96
3. McGahan JP, Nyberg DA, Mack LA: Sonography of facial features of alobar and semilobar holoprosencephaly. AJR 1990;154:143-8
4. Filly RA, Chinn DH, Callen PW: Alobar holoprosencephaly: Ultrasonographic prenatal diagnosis. Radiology 1984; 151 455
5. Hoffman-Tretin JC,Horoupian DS, Koengisberg M, et al: Lobar holoprosencephaly with hydrocephalus: Antenatal demonstration and differantial diagnosis. J Ultrasound Med 1986 5:691
6. Cohen MM: An update on the holoprosencephalic disorders. J Pediatr 1982;101:865
7. Warkany J, Lemire R, Cohen M: Holoprosencephaly: Cyclopia series. In Warkany J: Mental Retardation and Congenital Malformations of the Central Nervous System, Chicago, Year Book Medical Publishers, 1981; pp:176-190 8. Cayea PD, Balcar I, Alberti O, Jones TB: Prenatal diagnosis of semilobar holoprosencephaly. Am J Radiol 1984;142:401
9. Chernavak FA, Isaacson G, Mahoney MJ, et al: The obstetric significance of holoprosencephaly. Obstet Gynecol 1984;163:115
10. Yüksel A, Başaran S, Ermiş H, Kovancı E, Kayserili H, et al: Prenatal diagnosis of holoprosencephaly: Obstet Gynecol 1994;8:174-9
11. Bayhan G, Yayla M, Alp N, Yalınkaya A, Erden AC: Cerebral monoventricule in prenatal diagnosis: Report of five cases. J Ultrasonography 1998; 2: 181-4

	Dosya / Açıklama
	Figure 1 1A- 1B. A 24 weeks old pregnancy according to BPD and FL. Inter-hemispheric fissure, falx cerebri, corpus callosum and third ventricle are not visible and there is only one ventricle, semilunar shaped holoventricle, continuing with a dorsal cyst that fills the calvarium.
	Figure 2 There is no gross deformity in the trunk and extremities
	Figure 3 3x2 cm sized, pedinculated soft tissue with insignificant nasal structures and only one eye is present in the middle of the face.