Alobar holoprosencephaly: a case report

Alobar holoprosencephaly is a rare and severe congenital brain anomaly which is caused by developmental defect in the fore brain associated with non-disjunction of both hemispheres and ventricles during embryonic period. Depending on the severity of non-disjunction, holoprosencephaly can be classified as alobar, semilobar or lobar. Alobar holoprosencephaly is the most severe form and results with monoventricular cavity formation, fusion of thalami and non-development of corpus callosum, falx cerebri, optical paths and olfactory structures. Its ethiology is multifactorial, and chromosomal anomalies or monogenic defects are the major reasons with the rate of 40-50%. The patient with gravida 1 and parity 0 was referred to our clinic at 30 weeks of gestation due to lateral ventriculomegaly. There was no risk factor in the medical history of the patient. The result of combined screening test was normal. In her ultrasonography, composite lateral ventricular and monoventricular appearances were observed. Bilateral thalamic fusion was detected. Vermian agenesis was found.  Inter-orbital length was measured as 10.6 mm and hypotelorism was observed. Median cleft was seen on the midline of upper lip. The results of the evaluation of other systems and fetal cardiac screening were normal. Fetal karyotyping was carried out by cordocentesis and karyotyping was resulted as normal. The patient was discussed at our council and the patient was informed about the progress of the pregnancy. The termination of pregnancy was offered as an option to the patient and she accepted the termination option. After the fetocide, the pregnancy was terminated vaginally. Postpartum median cleft lip and hypothelorism were confirmed. Since the family did not approved, fetal autopsy could not be performed. The diagnosis of HPE is established primarily when monoventricular structure, fusioned thalami and cavum septum pellucidum cannot be observed. Various brain anomalies and facial anomalies are frequently concomitant. In our case, we have presented an alobar holoprosencephaly case diagnosed by the presence of monoventricular structure, fusioned thalami, vermian agenesis and cleft lip.

Keywords

Alobar holoprosencephaly, cleft lipt, vermian agenesis.