|Year : 2019 | Volume
| Issue : 2 | Page : 97-101
Agenesis of corpus callosum
Narayana Hrudayalaya College of Nursing, Bengaluru, Karnataka, India
|Date of Submission||19-Jul-2018|
|Date of Acceptance||17-Aug-2019|
|Date of Web Publication||01-Jun-2020|
Mrs. Jeyasutha Chokkian
Narayana Hrudayalaya College of Nursing, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Having a child born with a congenital defect is traumatic for the parents and family. Some congenital anomalies can be corrected resulting in good quality of life, and few others may grossly affect the life of children because of the long-term effects. One such anomaly is agenesis of the corpus callosum which is a brain anomaly where the nerve fibres connecting the left and right hemispheres of the brain are completely or partially absent. Many factors are associated with the presence of the anomaly. The clinical manifestations and the extent of neurological dysfunctions are related to the magnitude of defect. Symptom-specific supportive management, enhancement of growth and development and parental support interventions are key to managing children with agenesis corpus callosum.
Keywords: Agenesis of corpus callosum, children, nursing care
|How to cite this article:|
Chokkian J. Agenesis of corpus callosum. Indian J Cont Nsg Edn 2019;20:97-101
| Introduction|| |
Corpus callosum is one of the largest midline white matter structures of the brain, which begins to develop around 10th–11th week of intrauterine life. The corpus callosum consists of over 300 million nerve fibres that connect the left and right hemispheres of the brain, which transfer and integrate motor, sensory and cognitive information between the cerebral hemispheres. The maturation of the corpus callosum continues throughout the foetal period and after birth into childhood and adolescence.
| Definition and Incidence|| |
Agenesis (absence) or dysgenesis (malformation) of the corpus callosum is a brain abnormality involving the large bundle of nerve fibres that connect the two hemispheres of the brain. These fibres may be completely absent, partially absent, thin (or) malformed. It occurs when the normal brain cell migration is disrupted in the early foetal life. The defect can occur in isolation or with other congenital malformations, especially the malformations of the face. It is estimated that at least one in 4000 has the disorder of the corpus callosum.
| Causes|| |
It is difficult to determine a specific cause for agenesis of the corpus callosum (ACC). Some factors are considered to be associated with ACC and are thought to be possible causes. They are:
- Genetic causes – Gene mutations and inherited genetic factors
- Chromosomal abnormalities – Abnormalities of chromosome 8, 11, 13–15 and 18
- Prenatal infections or injuries
- Maternal alcohol ingestion during pregnancy
- Exposure to toxins or medications in early pregnancy
- Structural blockages such as cyst in the brain
- Metabolic disorders
- Other unknown factors.
| Pathophysiology|| |
The defective genesis of the corpus callosum starts very early in the intrauterine life. The corpus callosum develops from the alar plate of the upper segment of the prosencephalon during the foetal development. The changes that take place in the prosencephalon lead to the formation of the corpus callosum. These changes happen in four stages:
- Prosencephalic cleavage (28–35 days)
- Commissural plate formation (36–73 days)
- Corpus callosum formation (74–115 days)
- Corpus callosum growth (after 115 days).
Stage I – Prosencephalic cleavage
Prosencephalic cleavage takes place from 28 to 35 days of gestational age. During the cleavage, prosencephalon splits into telencephalon and diencephalon. This process starts by disproportionate growth of the upper and lower segments of the prosencephalon in relation to mid segments, which leads to appearance of two vesicles, upper vesicles (telencephalon) and lower vesicles (diencephalon) separated by a sulcus.
Stage II – Commissural plate formation
Commissural plate formation takes place from 36 to 73 days of gestational age. The lamina terminalis goes through changes that are conducive to the passage of axons. The ventral area of the lamina terminalis thickens by 39 days of gestational age. The thickened area is known as lamina reuniens (or) the commissural plate. The commissural plate continues to thicken, and by 73 days, the following four structures are formed within it: (1) The site of future corpus callosum, (2) the area of future anterior commissure, (3) the hippocampal commissure and (4) the septum cavum pellucidum. Axons destined to cross at the level of the corpus callosum are progressing towards the direction of the future corpus callosum. During the period of commissural formation, along with the lamina terminalis, changes also occur in the hemisphere and in the overall brain anatomy.
Stage III – Corpus callosum formation
Corpus callosum formation takes place from 74 to 115 days of gestational age when the cortical axons from the right and left hemispheres start to cross through the area of the commissural plate destined to become the corpus callosum. The axons from different regions of the brain cross at different times. All the areas of the corpus callosum are present at 115 days of gestational age.
Stage IV – Corpus callosum growth (after 115 days)
Adult morphology of the corpus callosum is achieved by 115 days. Three months after birth, the corpus callosum size decreases, as a large proportion of the huge population of callosal axons is eliminated. This weeding out confines contacts between the hemispheres to certain cortical zones and makes the connection between the two hemispheres of the brain precise. The differences in the size and form of the corpus callosum represent the cognitive abilities of the individual.
During the embryological period when the corpus callosum develops from the alar plate of the upper segment of the foetus (prosencephalon), many abnormal changes may lead to the absence of the corpus callosum. These include:
- Prosencephalic cleavage failure (holoprosencephaly)
- Abnormal commissural plate formation (agenesis of the anterior commissures)
- Abnormality in the area of the commissural plate destined to form the corpus callosum (agenesis of the corpus callosum)
- Failure of cortical axons to reach the corpus callosum analogue (agenesis of the corpus callosum)
- Destructive lesions of the corpus callosum.
Other factors that are earlier mentioned can also cause disruption in the development of the corpus callosum at any stage of the development, leading to agenesis or dysgenesis.
| Types of Agenesis of Corpus Callosum|| |
Sarnat  has elaborated on the types of agenesis of the corpus callosum as follows:
- ACC: All (or) a portion of the corpus callosum is absent. It includes partial or complete ACC (c-ACC)
- c-ACC: The corpus callosum is completely absent
- Partial ACC: A portion of the corpus callosum is absent. Generally, the posterior portion is absent. It is otherwise called hypogenesis of the corpus callosum
- Hypoplasia of the corpus callosum: The corpus callosum is present but is abnormally thin
- Dysgenesis of the corpus callosum: The corpus callosum is present but malformed in different form.
| Signs and Symptoms|| |
According to the National Institute of Neurological Disorders and Stroke, the effects of the defect depend on the extent of the disorder and can range from mild neurological dysfunction to severe deficits involving multiple organs.
Children born with severe malformations may manifest with seizures, intellectual impairment, spasticity, global developmental delay and hydrocephalus. Congenital malformations and hearing and speech deficits may be associated with partial absence or thinner fibres of the corpus callosum. Inability to communicate appropriately and poor social skills are other manifestations that may mimic or overlap other development disorders such as autism and may make early diagnosis of milder forms of the corpus callosum abnormalities difficult.
Variants of ACC can further complicate life with the presence of other manifestations. Children with ACC may have feeding and swallowing difficulties. Poor muscle tone and lack of coordination in movement also are manifested in many children with one or other type of ACC. Insomnia and sleep problems, attention deficit and obsessive behaviour may be present. In general, the manifestations can be summarised as follows:
- Pleasant disposition and happy personality
- Developmental delays – delayed mile stones
- Speech and language issues – inability to understand some words and phrases
- Poor muscle tone resulting in poor coordination and clumsiness and spasticity
- Sensory impairments – vision and hearing deficits, high sensitivity to touch and high tolerance to pain
- Sleep problems – sleep walking and insomnia
- Inappropriate social behaviour – hyperactivity, restlessness, lack of self-awareness, difficulty in maintaining relationships and inability to understand social clues.Z
| Diagnostic Evaluation|| |
Ultrasonography and magnetic resonance imaging (MRI) in the foetal or postnatal period help in the diagnosis of ACC.,,
- Foetal ultrasonography – A high-resolution ultrasonography will help diagnose the condition in the prenatal period as the corpus callosum may not be visualised
- Foetal MRI
- Foetal MRI is advised to confirm findings of ultrasonography and to identify additional cerebral anomalies
- Foetal MRI shows the absence of interhemispheric commissure.
Karyotyping is done to identify genetic disorders that may be associated with ACC.
If the diagnosis of ACC is missed during the prenatal period, the diagnosis depends on manifestations of symptoms in the postnatal period. The first manifestation may be seizures. Children may go undiagnosed for some years if signs and symptoms are not appropriately connected to ACC.
In the postnatal period, the diagnosis depends on
- History of child's behaviour
- Growth and development – May reveal delayed milestones, poor coordination and other sensory deficits
- Associated manifestations such as hydrocephalus or seizures
- Sagittal view: Superior displacement of the third ventricles
- Parasagittal view: Medical cortical sulci radiate superiorly instead of horizontally and the absence of normal echogenic pericallosal sulcus
- Coronal view: Absence of callosum and probst longitudinal bundles indenting the dorsomedial aspect of lateral ventricles.
- Sagittal image
- Four components of the corpus callosum are viewed
- MRI reveals the absence of the corpus callosum, and the cortical gyri have radiating disposition [Figure 1].
Diffusion tensor imaging and tractography – It is used to study the interhemispheres connectivity.
| Management|| |
There is no specific treatment to restore the corpus callosum to normal. Early diagnosis and initiation of supportive interventions are the key principles of management for children born with ACC. Seizure control and prevention of complications in addition to supportive therapy are the focus of treatment for children with severe form of corpus callosum abnormalities.
Rehabilitation is a best option for patients with ACC and is based on the premise of the central nervous system (CNS) plasticity. CNS plasticity denotes the ability of the brain to change continuously throughout a person's life. Life events can change the way a brain functions and grows, and therefore, it is believed that appropriate rehabilitative activities planned and implemented early and consistently can moderate the abnormal behaviours that are manifested in patients with ACC. Rehabilitation measures should be tailored to the individual needs unique to each patient. The aspects of rehabilitation include physiotherapy, speech and language training, psychomotor therapy, occupational therapy, parent training and counselling of teachers.
The aim of physiotherapy is to reduce motor problems and is given to improve muscle strength and co-ordination, mobilise the joints and release the contracted muscle, tendon and fascia in case of spasticity.
Speech and language therapy
The purpose of speech therapy is to help with speech and language development as they have problems with the interpretation of non-verbal communication of others and understanding slangs, jokes and sarcasm. They also cannot understand abstract language and concepts. Therefore, different techniques are used to improve child's language and reading and writing skills.
Psychomotor therapy is offered to improve global development by combining motor, cognitive and relational activities. By the way of play-based activities, children are empowered to know oneself and others in their world in order to establish meaningful and acceptable relationships.
The purpose of occupational therapy is to help build self-care and mobility skills such as eating, dressing and walking. Fine motor skills and sensory processing skills and coordination of activities are planned and implemented.
Parent training and support
The purpose of parent training is to improve parental attitude towards their child, helping them to accept his/her limitations and favour the child's global development. Parents also need support from a multidisciplinary team to enhance optimal growth for their children with ACC.
Counselling for teachers
Teachers have to be counselled to provide better adapted learning opportunities to the children by
- Encouraging the children to focus on their strength rather than weaknesses
- Understanding that children will be slow in learning
- Being supportive to the children.
| Case Report|| |
Baby X was born preterm with low birth weight (2.1 kg) and presented with poor sucking reflex and feeding problems. On examination, the baby appeared normal. After many investigations, an MRI was done, which showed partial corpus callosum agenesis (posterior). The newborn was admitted in the neonatal intensive care unit for observation and weight gain and was fed with expressed breast milk through nasogastric tube. The baby started to gain weight gradually. As the baby continued to have poor sucking reflex, he was discharged with the nasogastric tube feed. The parents were explained about the defect and the possible problems associated with ACC. The need for growth and development monitoring, multimodality interventions and early initiation of rehabilitation were emphasised to the parents in a supportive environment. The parents were counselled on care of the newborn and the follow-up.
The general nursing care of a child with ACC is discussed here.
| Nursing Management|| |
1. Nursing diagnosis
Impaired growth and development related to agenesis (or) dysgenesis of the corpus callosum as evidenced by impaired co-ordination and the presence of contracted muscle and joints.
Normal movement within the functional capacity may be established.
- Teach about assessing milestones of infant as he grows
- Assist the patient with joint mobilisation (gentle gliding techniques) along with the physiotherapist
- Provide muscle-stretching exercises
- Provide massage to the soft tissues
- Teach the parents how to do the range of motion exercises, co-ordination and balances exercises, ambulation exercises and muscle-strengthening exercises to the children
- Practice transfer training to the child
- Provide opportunities for motor planning and organisational skills (the ability to plan and execute an activity with desired output) to the child
- Provide simulated environment to develop sensory processing skills (the ability to process different kinds of sensory input include tactile, vestibular balance and smell) to the child
- Provide assistance with developing feeding skills.
2. Nursing diagnosis
Impaired verbal communication related to the absence of communication between two hemispheres as evidenced by decreased language ability.
Language skill will expand, and child will be able to communicate appropriately.
- Teach speech and signing skills to the child
- Use multiple modalities, repeated presentations, planned movements and episodic organisation of discourse.
3. Nursing diagnosis
Self-care deficit (bathing, dressing, feeding and toileting) related to impaired coordination of extremities.
Child will improve in independence in self-care.
- Maintain postural stability (the ability to sit upright in a chair) to the child
- Teach the self-care skills such as bathing, dressing, feeding and toileting to the child
- Provide continuous training to develop visual motor skills (the ability to coordinate pencil/paper tasks) and bilateral hand coordination (using both hands together, e.g., cutting) to the child.
4. Nursing diagnosis
Ineffective coping related to the diagnosis and associated developmental issues in the child.
Parents will be able to demonstrate effective coping.
- Relay a diagnosis with compassion and hope to the parents
- Ask the parents how much and what types of communication they find helpful and build rapport with honesty and caring
- Encourage parents to ask questions and express their emotions
- Know the resources available to assist the child and parents
- Reinforce the practice of parent participation in helping their child learn and develop
- Implement parent training skills which help them to support their children in
- Skills of daily living
- Speech and language skills
- Skills in stimulation of sensory and motor function
- Skills in play activities
- Encourage parents and appreciate their efforts in every stage
- Assist in coordinating the multidisciplinary activities for the child.
| Conclusion|| |
ACC is a congenital condition with complex issues that requires sensitive and child-specific approaches to care. It is a condition that calls for empathetic care and adequate counselling to the family so that the child receives the support and assistance required from the healthcare professionals and others.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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