ACC research report

Presented at the annual meeting of CORPAL (United Kingdom organization for the support of families of children with agenesis of the corpus callosum and Aicardi Syndrome) May 2001, Great Ormond Street Hospital, London, England.

Minding the Gap: A Large Scale Survey of
Agenesis of the Corpus Callosum
and Other Callosal Anamolies

Gary Schilmoeller & Kathy Schilmoeller


Existing information about agenesis of the corpus callosum (ACC) comes mostly from the medical field and the studies usually are based on very small numbers of participants (e.g., O’Brien, 1994; Wisniewski & Jeret, 1994). Noting that some professionals suggest that people who have only ACC may be asymptomatic – that is, they will develop normally and without delays, O’Brien argues that more comprehensive studies need to be conducted in order to test this hypothesis. He conducted a study of 47 children with ACC with the intent of beginning to describe the behavioral and developmental consequences of ACC (O’Brien, 1994). Our intent in this study was to expand upon O’Brien’s work with a more comprehensive survey of a much larger group of people with ACC.


In March, 2000, we mailed a comprehensive survey to 1,900 families who had a member with ACC. Six hundred and seventy eight (36%) of the surveys were returned. Most of the respondents were birth mothers (89.2%) with a small number of birth fathers (4.9%) and mothers of adopted children (3.0%). The mean age of the mothers of the person with ACC was 37 years old; the youngest mother was 19 and the oldest was 68. The mean age of the fathers was 40; the youngest father was 20 and the oldest was 75. Respondents had completed an mean of 14.9 years of school (ranging from completing ninth grade through more than 18 years of education). Their spouses had completed a mean of 14.7 years of school (ranging from completing sixth grade through more than 18 years of education).

The mean age of the persons with ACC was 7.6 years (ranging from 4 months to 45.5 years). Nearly fifty-eight percent (57.9%) were males and 42.1% were females. Most of the persons with ACC (91.3%) were white. A small number were Hispanic (3.9%) and Asian (2.0%). The rest were either Black, Native American, or listed their race or ethnicity as some other category.


The survey was constructed based on descriptive information published in earlier survey studies of people with ACC (e.g., O’Brien, 1994; Schilmoeller & Schilmoeller, 2000; Schilmoeller, Schilmoeller, & Baranowski, 1999) as well as from reports of parents who had shared information about their child with ACC through phone calls, emails, and regular mail correspondence with us at The ACC Network or through themes that appeared in discussions on the ACC-L listserv, an electronic discussion group focused on issues pertaining to ACC. Categories of questions focused on general diagnostic information as well as the physical, social, and communication skills of the persons with ACC. Types of learning style, settings where these children received education, and therapies received also were described.


Diagnostic History. The most frequent method of diagnosis was magnetic resonance imaging [MRI] (82.7%). Fifty percent of the parents reported that a CT scan was the method diagnosis. Ultrasound (26.9%) and EEG (21.0%) were also used to diagnose the ACC. The percentages add up to more than 100% because many children had more than one method used to determine and then corroborate the diagnosis.

Concurrent Conditions. The ten most frequently reported concurrent conditions were developmental delays (78.0%), learning disability (32.8%), seizures (29.9%), mental retardation (26.8%), cerebral palsy (16.1%), microcephaly (14.1%), hydrocephaly (12.8%), autism or autistic-like behaviors (9.9%), obsessive compulsive disorder (7.0%), and attention deficit hyperactivity disorder (6.7%).

Physical characteristics. Nearly half (46.7%) of the children were described as having a body size that was small or slightly smaller than average compared to others of the same age and gender. On the other hand, the number of children who were described as having smaller than average head size was nearly equal to the number described as having larger than average head size (31.6% v. 30.8%) with the remaining 37.6% described as being comparable in head size to others of the same age and gender. Asked about head and facial anomalies, 17.8% reported the person with ACC had eyes set wide apart, 19.6% had low-set ears, and 23.3% had unusual head shape. The incidence of cleft lip or cleft palate was very low (0.7% and 4.3% respectively). Over half of the respondents (53.9%) reported that their children were either slightly floppy or very floppy (hypotonic) in terms of muscle tone.

One physical characteristic often reported anecdotally by parents is that their children have a high tolerance for pain. For example, parents have reported a child putting a hand on a hot stove burner and not withdrawing the hand nor showing any sign of registering pain, a child getting a hand caught in a car door without protest, and a child with a broken collarbone that was not detected until several days after the injury. While this characteristic is not reported in the research literature about ACC, the anecdotal reports occur frequently enough that we included several questions about sensitivity to pain, touch, and cold. Respondents reported that over half (56.1%) of the children showed either little or no pain perception (19.8%) or less pain perception than average (36.3%). On the other hand, over 40% of the children were more sensitive to being touched by others (30.5%) or much more sensitive to being touched by others (10.0%). There was no discernible pattern of children being either more or less sensitive to cold than average.

Developmental milestones. Since 78% of the children experienced developmental delays, we asked whether or not children had met several milestones and at what age.

Milestone Percentage
Mean Age
in Months When Met
Lifted head 62% 5.6
Rolled over 67% 9.9
Sit alone 66% 12.3
Crawled 56% 19.2
Stood alone 47% 21.7
Walked alone 55% 25.3
Talked single words 42% 23.4
Toilet trained 34% 49.9
Rode a bicycle 13% 84.9

Eating and Elimination problems. Parents reported their children had multiple problems with eating. For example, 55% had an inadequate sucking reflex at birth, and 16% had or have a gastric feeding tube. Parents also reported that their children either “occasionally,” “often,” or “in the past” had difficulty swallowing (41.3%), experienced reflux (43.9%), did not know when the child had enough food or fluid (36.9%), tried to eat things other than food (24.9%), or had chewing difficulty (51.9%). Many children had trouble with bladder control (57.2%), constipation (61.4%), or diarrhea (38.8%).

Social Behavior. Parents rated their children’s social behavior on a five point scale – much less, slightly less, about the same, slightly more, much more than others. These children with ACC were slightly or much more likely to enjoy social interaction (44.0%) and be friendly with strangers (42.5%). They also were less likely to be reserved or shy (47.5%) than others. On the other hand, only 21.8% were more likely to enjoy interacting with a peer group. This corroborates parental reports that their children often get along well with adults and younger children, but not as well with age peers. Forty percent of the children also had difficulty using appropriate physical space. This corresponds to the 40% who were more sensitive to touch by others, raising the question of whether sensitivity to touch migh play a role in the less frequent social interaction with peers.

Parents rated disruptive behavior on a three point scale – rare/not true, occasional, or very frequent. Some parents reported their children occasionally or frequently physically attacked other people (21.5%), suddenly lashed out for no apparent reason (25.4%), or deliberately destroyed things (16.6%).

Children were rated as often or almost always happy and cheerful (91.0%), content (87.0%), and relaxed (72.5%). By contrast, only 6.4% were sad or unhappy and only 10.6% were angry. Some children showed fearfulness or anxiousness (17.4%), experienced quick mood shifts (22.0%), or showed moods out of place (11.7%).

In summary, children with ACC tended to be rated as very happy, socially-engaging children though they tended to be less social with age peers and to occasionally have problems with anger control.

Communication Skills. Parents reported that the vast majority of children with ACC (81.6%) showed at least some ability to understand from communication, ranging from understanding single words to understanding most messages that are at the person’s age level. Indeed, 60.3% were able to understand either most long sentences or understand most age-level messages. In terms of expressive communication, though, 33.9% were not able to communicate verbally at all. And, in contrast to the 60.3% who could understand long sentences or age-level messages, only 40.9% could express such verbally.

Communications by these children were sometimes challenging. For example, children occasionally or frequently engaged in meaningless conversation (38.1%), shouted or screamed unexpectedly (39.9%), engaged in out-of-place conversations (45.2%), or repeated words or phrases apparently without understanding them (30.5%).

Learning Variables. According to their parents, children with ACC “often” or “almost always” learn by repetition (84.1%) and by imitation (66.3%). They also have good memories (58.2%). And many enjoy learning and working on computers (57.5%).

On the other hand, these children have difficulty with abstract reasoning (67.6%), have difficulty staying on task when learning (54.0%), and perseverate on some details when learning something (42.0%).

Parents report a variety of settings in which learning can occur for their children with ACC including play groups (40.1%), preschools (56.3%), self-contained special education classrooms (46.1%), regular education classrooms (32.4%), resource room (sometimes called “pull-out” programs) (19.4%), and other types of special education programs (20.0%). A small percentage of children attend Headstart programs (8.0%) or are home-schooled (7.9%). Often a single child experiences a variety of these programs, sometimes at the same time and at other times sequentially as the child gets older. Nearly one-fifth (18.3%) of the children were too young to begin any form of schooling.

Therapies and Intervention Services. More than half of the children with ACC received three therapies – speech therapy (65.1%), occupational therapy (64.1%), and physical therapy (60.5%). Other therapies commonly reported were early intervention (36.9%), sensori-integration (36.3%), academic counseling (23.9%), and vision therapy (18.0%). Early intervention also was reported to have been received “only in the past” by 45.1% of the families. Thus, speech therapy, occupational therapy, physical therapy, and early intervention are the therapies most frequently provided for these children.

Summary Comments

These data represent only a very preliminary analysis. In subsequent analyses, we will look at these variables for different age groups of the children with ACC. We will compare those with complete ACC and those with partial ACC to see whether there will be differences between groups on some of the categories we reported here. We also will try to distinguish between children who have ACC and many other concurrent conditions with those who have only ACC and no other or only a few other concurrent conditions. Results of these and other subsequent analyses will be published in later newsletters.


O’Brien, G. (1994) The behavioral and developmental consequences of corpus callosal agenesis and Aicardi syndrome. In M. Lassonde & M.A. Jeeves. (Eds.), Callosal Agenesis: A Natural Split Brain? (Pp. 235 – 246). New York: Plenum Press.

Schilmoeller, G.L. & Schilmoeller, K. (2000). Filling a void: Facilitating family support through networking for children with a rare disorder. Family Science Review, 13, 224 – 233.

Schilmoeller, G.L., Schilmoeller, K.J., & Baranowski, M.D. (1999, November). Creating community for families with a rare disorder: The case of agenesis of the corpus callosum. Presented at the annual meeting of the National Council on Family Relations, Irvine, CA.

Wisniewski, K.E. & Jeret, J.S. (1994). Callosal Agenesis: Review of clinical, pathological and cytogenetic features. In M. Lassonde & M.A. Jeeves. (Eds.), Callosal Agenesis: A Natural Split Brain? (Pp. 1 – 6). New York: Plenum Press.