PP-13 Partial corpus callosum agenesis a case report

Objective

The corpus callosum is the commissural fiber bundle that carries motor, sensory and cognitive information between the two hemispheres of the brain. Anomalies affecting the corpus callosum are complete or partial agenesis, dysgenesis or hypoplasia.[1] Partial or complete agenesis of the corpus callosum indicates the absence of these commissural fiber bundles.[1] The development of the corpus callosum begins at the 8th gestational week and is completed at the prenatal 18th-19th week, although its postnatal maturation and development continues.[2] The prevalence of corpus callosum agenesis at birth has been reported between 1:2000 and 1:5000 in various studies.[3,4] This rate has been reported as 2-3% in fetuses with developmental delay.[4] This malformation can be seen in isolation or may occur due to chromosomal anomalies, syndromes, infections, teratogenic agents or ischemic causes.[1,5] Whether the corpus callosum agenesis is complete or partial has various clinical consequences. Although epilepsy, motor impairment and mental retardation can be observed, asymptomatic cases are more common, but neurodevelopmental outcomes are worse in the presence of accompanying anomalies.[1,5] Ultrasound and MRI images are characteristic in corpus callosum agenesis. In partial agenesis, the posterior segment of the corpus callosum is usually absent. In complete agenesis, the absence of the cavum septum pellucidum in the second trimester ultrasound raises suspicion.[5] Another finding that raises suspicion is the shape and size of the lateral ventricles, typically called “teardrops”, which is the enlargement of the occipital horn compared to the frontal horn.[1] Since the etiology of corpus callosum agenesis is heterogeneous, genetic tests, family history, accompanying minor and major anomalies may be helpful in the differential diagnosis. Fetal MRI can be very useful, especially in the presence of accompanying additional brain anomalies.[1] In this case, the findings of the detection of partial corpus callosum agenesis by ultrasound findings and follow-up throughout pregnancy are presented.

Methods

Computer-based, laboratory and ultrasonography records of a case of corpus callosum agenesis who applied to the Perinatology outpatient clinic of Prof. Dr. Cemil Taşçıoğlu City Hospital for the first time at the 23rd week of pregnancy were scanned retrospectively from the hospital software and the history of the ultrasonography device. Fetal ultrasonography examination was performed using Mindray Resona 7 device and its 1.2-6 MHz convex abdominal probe. Ultrasonography, laboratory, amniocentesis findings and patient history were noted.

Case

36-year-old primigravid pregnant woman without follow-up was admitted to our hospital for second-trimester ultrasound at the age of 23 weeks and 4 days. In the first ultrasound examination, the transcerebellar diameter was 23.7mm, the cisterna magna was 4.9mm, the nuchal fold thickness was 5.6mm, and the nasal bone was 8.5mm. Ultrasonography revealed a trilaminar appearance and the transverse diameter of the cavum septum pellicidum was larger than the anteroposterior diameter (Figure 1-3). In the sagittal section, a structure thought to be the anterior part of the corpus callosum with a length of 10.5 mm and a width of 1.7 mm was observed, Doppler evaluation was also suitable for the anterior part (Figure 1,2). The structure thought to be the genus of the corpus callosum was observed in the coronal section. It was evaluated as partial agenesis of the corpus callosum. No additional anomaly was observed in the ultrasonographic examination. The patient was informed about amniocentesis. Amniocentesis was performed at 23 weeks and 5 days of age. Amniocentesis culture result was reported as 46 chromosomes, array result arr(--,1-22)x2 pathogenic or possibly pathogenic copy number variant was not detected. The patient was referred to the Department of Medical Genetics and received genetic counseling. The chromosomal analysis results of the mother and father were normal. Postnatal Pediatric Neurology control was recommended. The patient was admitted to our hospital due to premature rupture of membranes at 37 weeks and 3 days of gestation, and a 2995 g male baby was delivered live by cesarean section for the patient who developed fetal distress during labor follow-up. In the postnatal examinations, the baby was observed to be hypotonic and was intubated. It was observed that he had problems in spontaneous breathing when he left the intubation. Prenatal diagnosis was confirmed by cranial USG.

Results

Corpus callosum agenesis is a rare congenital anomaly. Corpus callosum agenesis may be complete or partial, or may accompany chromosomal abnormalities or other syndromes. Since such patients require a multidisciplinary approach, they should be followed in tertiary centers. In addition to the second-trimester ultrasound examination, invasive tests should be performed, karyotyping and array should be checked, and the TORCH panel should be seen to investigate fetal infections. Fetal MRI may be particularly useful in detecting additional anomalies. The family should be informed as best as possible, as there is a wide variation in prognosis from asymptomatic to syndromes with poor prognosis. The location of detailed fetal cranial ultrasonography is very important in the diagnosis. In the case we presented, the diagnosis of partial corpus callosum agenesis was made in the late period of detailed fetal ultrasonography.

Conclusion

These patients should be followed up in centers with adequate technical facilities, experienced maternal and fetal medicine and perinatology specialists and a multidisciplinary approach, and the family should be informed in detail.

Keywords

Partial agenesis of corpus callosum, amniocentesis, ultrasound, prenatal diagnosis

1. Rotmensch S, Monteagudo A. Agenesis of the Corpus Callosum. American Journal of Obstetrics and Gynecology. 2020 Dec;223(6):B17–22.
2. Craven I, Bradburn MJ, Griffiths PD. Antenatal diagnosis of agenesis of the corpus callosum. Clinical Radiology. 2015 Mar;70(3):248–53. 
3. des Portes V, Rolland A, Velazquez-Dominguez J, Peyric E, Cordier MP, Gaucherand P, et al. Outcome of isolated agenesis of the corpus callosum: A population-based prospective study. European Journal of Paediatric Neurology. 2018 Jan;22(1):82–92. 
4. Bayram AK, Kütük MS, Doganay S, Özgün MT, Gümüş H, Başbuğ M, et al. An analysis of 109 fetuses with prenatal diagnosis of complete agenesis of corpus callosum. Neurological Sciences. 2020 Jan 22;41(6):1521–9. 
5. Hofman J, Hutny M, Sztuba K, Paprocka J. Corpus Callosum Agenesis: An Insight into the Etiology and Spectrum of Symptoms. Brain Sciences. 2020 Sep 1;10(9):625

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	Fig.1 Doppler ultrasound evaluation of partial corpus callosum agenesis
	Fig.2 Second-trimester ultrasound evaluation of partial corpus callosum agenesis
	Fig.3 Atypical cavum septum pellicidum appearance