Case Report: An infant with agenesis of the corpus callosum (AgCC) with normal developmental milestones

Introduction

Agenesis of the corpus callosum (AgCC) is a rare brain disorder presented as total absence or isolated agenesis. The worldwide incidence rate is 0.5 per 10000 live births, while the prevalence has been estimated to be as high as 230 in 10,000 for children with developmental issues.¹ Corpus callosum is a collection of nerve fibers that helps connect two cerebral hemispheres, which is important for communication. It controls movements, cognitive skills, and power of sight. It develops around 70-74 days of gestation and completes about 100 to 115 days.² The exact cause is not known, but there are links to ingestion of alcohol during pregnancy, phenylketonuria, Chiari 2 malformation, genetic factors like Apert syndrome, Joubert syndrome, X-linked like Aicardi syndrome.³

It's true that despite the connection between agenesis and associated issues with AgCC, the range of neurological assessment can vary significantly from normal to severe.⁴ This demonstrates that developmental problems can present in various ways, and it's crucial to have a comprehensive understanding of each case.

Patients who have isolated AgCC with no cognitive dysfunction initially can develop neurological disorders later in life as cognitive demands increase with age. Regular neuropsychological screening is highly recommended for individuals with AgCC. This can help identify any underlying problems associated with AgCC and ensure they are addressed promptly. With a comprehensive understanding of each case, it's possible to address developmental issues in various ways and ensure that the appropriate interventions are put in place as needed.

While there is no cure for AgCC, early diagnosis and symptomatic treatment can help prevent complications.⁵ This includes physiotherapy, occupational therapy, and speech therapy. It is crucial that individuals with AgCC receive empathetic care and adequate counseling toward the family to ensure future care.

Case report

A full-term male newborn delivered vaginally was brought to the present center. Their birth weight was 2.5 kg. The mother was primigravida, with no history of consanguineous marriage, no history of abortion, or congenital anomalies in the family. The antenatal and postnatal history was not significant. Fetal Ultrasonography (USG) was done at 24 weeks of gestation, which showed signs of AgCC (Figure 1).

Figure 1. Ultrasonography scan shows Agenesis of the corpus callosum in a fetus at 24 weeks gestation.

The risk factor was explained to the parents, but they wanted to continue the pregnancy. A postnatal cranial ultrasonography scan showed complete AgCC. MRI (magnetic resonance images) show complete callosal agenesis (Figure 2). The occipitofrontal circumference was at the 95th percentile, and general and systemic examination was normal.

Figure 2. Magnetic resonance image of the brain shows the absence of corpus callosum.

After a 10-day stay in the hospital, the baby was advised to return after a month for a routine checkup and immunization. The mother was explicitly advised to keep a notebook for recording the date of noticing new developmental milestones, which were checked during each follow-up visit. Hearing screening and eye examination were done at two months, which was normal. Genetic and metabolic screening were not performed as the parents were not willing. On follow-up, the infant's head circumference and domains of development were noted: neck holding at three months, sitting without support at seven months, standing with support at 9month, and walking alone at 15 months. Fine motor development, reaching objects with both hands at four months, pincer grasp at 12 months of age. Personal and social understanding included a social smile for two months, recognizing their mother at three months, Language had a syllabus at nine months,1-2 meaningful words at 12 months, and vision and hearing were normal for his age.

His brain's magnetic resonance imaging (MRI) was repeated at 24 months of age and showed total AgCC. His pattern of postnatal growth and neurocognitive development was normal. During the medical examination, he was alert, aware, oriented, and asymptomatic. His Language was normal for his age, and gross and fine milestones were according to age. Intelligent quotient (I.Q.) done, found to be 1 which is within the normal IQ range at this age (1 to 10). Blood tests were taken for liver function, kidney function test, serum electrolytes, vitamin B12, and folic acid, which showed a normal range. We planned a similar blood test every six months of his visit. Neurologist appointments will be taken every two months during his visits to the hospital.

Discussion

Agenesis of the corpus callosum (AgCC) is a congenital disability in the brain where the corpus callosum is missing or partially missing. It can occur alone or with other brain and extracranial malformations. AgCC is associated with many factors, such as intrauterine injury or infection, ingestion of alcohol during pregnancy, or genetic syndromes like Dandy-Walker syndrome, Andermann syndrome, and autosomal dominant, recessive, and X-linked. AgCC can develop neurological and cognitive disorders later in life, so it is crucial that individuals with AgCC undergo regular neuropsychological screening to ensure timely identification and address of potential issues. Physicians and medical professionals should receive education and training on this condition to provide individuals with AgCC the care and support they need to thrive. While there is no specific treatment for AgCC, early diagnosis and symptomatic treatment can help prevent complications. It is essential that individuals with AgCC receive empathetic care and adequate counseling for their families to ensure future care.⁶

In a recently published case report, Pierre-Kahn et al. evaluated the guideline that agenesis of the corpus callosum (AgCC) is considered isolated when antenatal MRI or genetic tests do not indicate additional anomalies. This guideline was assessed in the case study context, highlighting the importance of regular neuropsychological screening and empathetic care for individuals with AgCC.⁷

It's interesting to note that AgCC can be associated with various congenital syndromes related to different exposures and genetic disorders, as Tomasch J et al. discussed in their findings, which were not seen in the present study.⁸ Fetal alcohol syndrome (FAS) was found by Mattson SN et al. to be a significant non-genetic congenital cause of AgCC in their study, which was not seen in the present case report.⁹

The study by Santo S, D'antonio F et al. revealed that Ultrasonography (USG) performed during the 18-22 weeks of gestation could detect features indicative of AgCC. It's fascinating to see how technology has advanced to the point where such diagnoses can be made early on in a pregnancy. It's crucial to detect such anomalies as early as possible to ensure the best possible outcome for the child. USG was done in the present case report, similar to the above study.¹⁰

It has been shown in a study conducted by Yakovlev PI et al. that patients with isolated AgCC and normal intelligence could significantly benefit from early detection of neurocognitive anomalies. They may improve their independence and compensate for deficits by receiving timely rehabilitative strategies. This information was considered and followed in the present case report, which suggests that Ultrasonography performed between 18 and 22 weeks of gestation could potentially diagnose features indicative of AgCC and have significant implications for diagnosing and managing this condition.¹¹

It's worth noting that individuals with AgCC may encounter challenges when integrating or interpreting social and emotional information, as demonstrated in a study conducted by Brown WS, Paul LK, et al. However, the present case report did not show any such difficulties. Instead, it highlighted the vital role of early detection and timely rehabilitative measures in enhancing independence and compensating for deficits in patients with isolated AgCC and normal intelligence.¹²

Individuals with isolated primary AgCC typically have a favorable functional outcome, with minimal impact on their overall cognitive capacity, as Fischer M et al. demonstrated in their study, similar to a present case report. However, there are still disabilities consistently observed in isolated cases, such as difficulties with abstract reasoning, problem-solving, and category fluency, which require follow-up. This was an essential consideration in our case report when advising patients' relatives during follow-up.¹³

Conclusion

It's crucial for medical professionals to be aware of AgCC, a disorder that can cause various disabilities. Although rare, it's essential to recognize the clinical presentation of AgCC to ensure early diagnosis and proper intervention to prevent complications.

Consent

Written informed consent was taken from the father of the patient.