Corpus callosum agenesis is a hereditary disorder and inhibitory malformation with partial or total malposition of the cerebral peduncle. Affected individuals often exhibit behavioral abnormalities and may suffer from symptoms such as visual and hearing loss. Agenesis is treated symptomatically because no causal therapy exists.
What is corpus callosum agenesia?
The corpus callosum is a bar between the left and right hemispheres of the brain, also known as the brain bar. A person’s brain bar is made up of more than 200 million nerve fibers and plays a supporting role in the exchange of information and coordination of the left and right hemispheres of the brain, which perform various information processing tasks. Corpus callosum agenesis is a hereditary disease belonging to the group of agenesias. It is defined as the complete absence of a certain organ due to a genetically absent predisposition. In corpus callosum agenesis, patients lack the brain bar between the two cerebral hemispheres. The malformation is one of the inhibitory malformations that predate any aplasias. The lack of the cerebral bar can result in severe disorders of the sensory systems and physical maldevelopment as well as spasticity. The cooperation of the two cerebral hemispheres is impeded by the absence of the corpus callosum. Agenesis of the cerebral balk may occur symptomatically in the context of various malformation syndromes. The incidence ranges from 3:1,000 to 7:1,000.
Causes
Agenesia usually results from a genetic failure to conceive. Although sporadic occurrence has been observed in association with corpus callosum agenesis, the occasional co-occurrence in sibling pairs at least points to the involvement of genetic factors. According to the observations, hereditary corpus callosum agenesis is based on either an X-linked or an autosomal recessive mode of inheritance. In these hereditary courses, medicine now assumes a trait carrier rate of up to ten percent. Four out of 50 children with agenesis show chromosomal peculiarities. In most cases, these are anomalies on chromosomes 8, 13 or 18. These anomalies have been observed mainly in patients with syndromes such as Pätau syndrome, Edwards syndrome or triploidy. Bar deficiency is not only present in people with the described anomalies. Reduced or non-applied bars have also been observed in people with chromosomal aberrations on chromosome three. All chromosomes mentioned are involved in the development of the corpus callosum. However, no single gene has yet been identified as a trigger of agenesis.
Symptoms, complaints, and signs
Some patients with CCA completely lack the cerebral bar from birth. In others, the separation of the two cerebral hemispheres is merely underdeveloped or incompletely absent. In addition to hearing loss, symptoms such as vision loss may occur as part of the malformation, which can extend to blindness. Some patients additionally suffer from hydrocephalus. In the case of hydrocephalus, intracranial pressure may be dangerously elevated. Sometimes micrencephaly is observed in patients with corpus callosum agenesis, which is equivalent to maldevelopment of the wider brain mass and is associated with mental retardation. In addition to epilepsy, spasticity, or decreased muscle tone, symptomatic short stature may be present in CCA. Agenesis can occur in the context of different malformation syndromes and is then associated with the specific symptoms of each syndrome. Aircade syndrome and oro-facio-digital syndromes are among the most common malformation syndromes associated with cerebral bar agenesia. In addition to chromosomal abnormalities, corpus callosum agenesis may occur, for example, in the context of metabolic diseases, viral embryopathy, or cranial fossa anomalies. Behavioral abnormalities or attention difficulties are almost always suffered by CCA patients.
Diagnosis and course
Corpus callosum agenesis is a congenital malformation that manifests at the latest in early childhood. In addition to diagnosis after manifestation, prenatal diagnosis is possible from the 20th week of gestation. Diagnostic imaging techniques such as transfontanelle ultrasonography, magnetic resonance imaging, and cranial computed tomography may be considered as diagnostic tools. The prognosis varies greatly from case to case.Prognostically, the most relevant factor is whether the malformation is isolated or is a symptom of a syndrome that causes further symptoms. The developmental prognosis for patients of beam agenesis may be for an almost symptomless future in cases of isolated agenesis. In other cases, the most severe physical and cognitive disabilities may occur, most notably in beam agenesias in the context of syndromes.
Complications
Various symptoms and complications may occur in corpus callosum agenesis. In most cases, however, there are behavioral disturbances and limitations in hearing and vision. Usually, the limitations do not appear suddenly, but lead to a constant reduction of these perceptions during the course of the disease. Complete blindness or complete hearing loss may also occur. Due to the increased brain pressure, in many cases there are headaches and maldevelopments in the brain. Due to these maldevelopments, behavioral disorders and other psychological complaints occur. Often, corpus callosum agenesis also occurs with short stature. Patients suffer from metabolic disorders and have a reduced quality of life. Concentration is also reduced, so there is usually decreased intelligence. Causal treatment is not possible because it is not possible to replicate the brain bar. For this reason, mainly behavioral therapies and learning therapies are used so that the patient’s intelligence is not reduced by the corpus callosum agenesis. Speech therapy must also be performed in many cases. If epileptic seizures occur, brain pressure must be reduced. In rare cases, corpus callosum agenesis does not cause any symptoms or complications.
When should you see a doctor?
Parents of affected children should always consult closely with a physician. The physician can determine the severity of corpus callosum agenesia and initiate treatment directly or consult a specialist if unusual symptoms are present. In any case, if the child shows behavioral problems or signs of other psychological problems, a therapist must be consulted. If signs of a metabolic disorder are noticed, an internal medicine specialist should be consulted. Physical and occupational therapy may be considered for ataxias and other movement limitations. Other symptoms should also be clarified quickly by the respective specialist and treated if necessary. Due to the multitude of complaints and symptoms that can occur in corpus callosum agenesis, parents should put together a team of doctors as early as possible. However, the first point of contact is the pediatrician, who can closely monitor the course of the disease. In the event of serious complications, it is best to contact the emergency medical services. Parents should also seek psychological support as soon as the child’s illness causes increasing physical but also psychological stress.
Treatment and therapy
A causal therapy does not yet exist for bar agenesis. The missing brain bar cannot be reconstructed. For this reason, treatment for patients with corpus callosum agenesis is purely symptomatic and is strongly directed toward the symptoms in the individual case. For example, if behavioral abnormalities are present, psychotherapy or behavioral therapy is indicated. In the case of ataxias or other physical movement restrictions, physical and occupational therapy measures may be considered as countermeasures. Lack of muscular toni can also be increased by strengthening the muscles through physical therapy. Speech and learning impairments can also be symptoms of the disease. Due to the missing connection between the two hemispheres of the brain, the patients’ attention, for example, is often affected by restrictions. Such abnormalities can, if necessary, be regulated by attention training. In addition to the therapeutic approaches mentioned above, speech therapy can be used to combat speech problems. Anticonvulsive treatment is also conceivable as symptomatic therapy in some cases. If additional symptoms such as hydrocephalus or epilepsy are present, these symptoms may be given preference in treatment. Reducing intracranial pressure, for example, is vital in cases of hydrocephalus with increased intracranial pressure. Equally important in the case of epilepsy may be treatment to that effect.In some cases of isolated corpus callosum agenesis, no therapeutic measures are required because patients remain asymptomatic and unremarkable throughout their lives.
Outlook and prognosis
The prognosis of corpus callosum agenesis is often unfavorable. Due to legal as well as medical possibilities, the hereditary disease is not considered curable or treatable. Nevertheless, the occurrence of the disease in the offspring of affected individuals is sporadic. Not all children of affected parents suffer an outbreak of corpus callosum agenesis. In addition, the individual symptoms in affected patients are individual in their nature as well as their expression. Therefore, they need not be the same as those of other family members.
| A concerned mother wrote to us thus:
“Our child was diagnosed with a neck fold that was too large. Further examinations revealed an isolated partial bar deficiency and we were advised to terminate the pregnancy. I can only say, thank God we decided against the abortion. Our son is now 4 years old and very healthy. There is nothing negative about our child at all. On the contrary, he speaks much more clearly and thoughtfully than most other children his age and he has a super happy and contented disposition. I can’t believe that, at least according to one doctor, he shouldn’t even exist. The way we experienced all this, we come to the impression that medicine itself does not know enough about it yet. In a normal ultrasound examination at the gynecologist, the bar deficiency cannot be detected at all. Nobody knows how many people live with such a condition. Only very few are examined so thoroughly. My recommendation: don’t let it drive you crazy.” |
Depending on the severity of the symptoms, individual therapy is given to alleviate each complaint. Nevertheless, despite great efforts and immediate treatment after the birth of the child, freedom from symptoms is not achieved in corpus callosum agenesis. In the case of a mild malformation, the quality of life as well as the well-being of the patient can be considerably improved with great effort and regular participation in various offered therapeutic measures. If the patient’s intracranial pressure increases in the course of life, the probability of a life-threatening condition increases. In addition, further brain damage may occur, significantly worsening the state of health. Most patients suffer irreparable impairment from the tissue damage. In addition, many affected individuals suffer from other conditions that contribute to worsening health. Because of the dysfunction of individual sensory systems, the patient requires lifelong care and medical attention.
Prevention
The responsible gene and the exact circumstances for corpus callosum agenesis have not yet been identified. For this reason, the malformation cannot be prevented to date.
Follow-up
There are usually no or very few aftercare measures available to the affected person with corpus callosum agenesis, as this disease is hereditary. If the patient wishes to have children, genetic testing and counseling should be performed to prevent the disease from recurring in the children. Corpus callosum agenesis cannot be completely treated, so the affected person is entitled to purely symptomatic treatment. In most cases, the symptoms of this disease are limited by measures of physiotherapy. Many of the exercises from such a therapy can also be performed in the patient’s own home. The affected children are dependent on the support and intensive care of their parents and relatives in their lives. Intensive and loving conversations also prove to be very positive and can prevent psychological upsets or depression. Speech therapy is also often necessary in this disease, and here, too, the parents must clearly support the child. With corpus callosum agenesis, regular checkups with a doctor are necessary. In this case, it cannot be universally predicted whether the disease will result in a decreased life expectancy for the patient.
Here’s what you can do yourself
Because corpus callosum agenesis is a congenital damage in the brain, it is not possible for the affected child to perform self-help activities to support his or her well-being.If the disease presents itself in adulthood, the options are also severely limited. Due to the existing symptoms, such as behavioral abnormalities as well as disturbances of the sensory systems, the child is already medically cared for in the first months of life and often cared for by people in the close environment. In everyday life, the mental and emotional support of the relatives should therefore not be disregarded in the case of this disease. They are exposed to special challenges and can make use of self-help measures. It is important not to lose the courage to face life and optimism despite the fateful illness of one’s own child or partner. One’s own social life should continue and be adapted to the new conditions. A social withdrawal leads to a lowered mood among the relatives. Since they spend a lot of time looking after and caring for the ill person, they need periods of rest and recuperation to maintain their own reserves of strength. Comprehensive information about the disease is important in order to be informed about the course of development, treatment options and symptoms. At the same time, one’s own psychological limits should be respected and one should treat oneself considerately.
