Disorders of the Corpus Callosum and the Validity of a SOD Diagnosis

A couple of days ago a virtual friend of mine (I call her son Sweet Pea's Australian twin, as we experienced an almost identical pregnancy, NICU stay and diagnosis) posted on Facebook that the ONH Research Lab at Children's Hospital LA was taking questions online and would try to answer as many as possible. Although we were headed out the door I took a few minutes to ask the one question that has bothered me since Sweet Pea's diagnosis with SOD:  

My 10 mo. old was born with SOD - no vision problems though and optic nerve looks perfect. How common is it to have SOD without the vision issues? Could she develop problems later? She also has DI, hypothyroid and has emergency cortisol... may need GH later as she is still only 12 pounds but blood sugar is fine. Is anyone researching just SOD?

I was so happy to get their response yesterday:

The defining feature of SOD is ONH (small optic nerves and vision impairment) plus other features. As a side note, we just use the term ONH as it encompasses all of these features. Have you had a second opinion by a pediatric neuro-ophthalmologist? If the optic nerves are normal, there can be no ONH and thus, no SOD. Children can have hormone deficiencys due to some other cause.

Of course, this brought up another question:

 Thanks for the response! We've had both a pedi neurologist and a pedi ophthalmologist care for her over the past 10 months from Boston Children's Hospital. They explained there were 3 areas (hormones, brain structures, or vision) involved in ONH/SOD and that you only had to have problems in two areas to be considered SOD. In my daughter's case she is missing hormones, has no septum pellucidum, thinning of the corpus callosum posteriorly, and a small pituitary - but normal optic nerves (checked three times now). We've thought of seeking a second opinion though - can you point us in the direction of someone in the New England/east coast area? THANK YOU for your response! It is great to have the opportunity to ask questions!

And their response:

There are 3 areas involved in ONHl; however, the definition they are using is incorrect. The defining feature is small optic nerves (ONH) and over the years, many physicians began using the term SOD when there is ONH (small optic nerve) plus hormone dysfunction and/or brain malformations. Without small optic nerves, neither the diagnosis ONH or SOD can be accurate. For a better explanation of this diagnosis, email our study coordinator Joyce Sutedja (jsutedja@chla.usc.edu) and ask for a copy of the JNO article titled "Reappraisal of the Optic Nerve Hypoplasia Syndrome". For recommended ophthalmologists, take a look at our searchable database on the ONH webportal: www.chla.org/onh

I requested the JNO article and received it within the hour. Basically, it states that "'Septo-optic dysplasia' and 'de Morsier syndrome' are historically inaccurate and clinically misleading terms that should be abandoned." It says that Caroline cannot have ONH/SOD without the hypoplastic optic nerve. Dr. Borchert's office recommended that we get a second opinion from a pediatric neuro-opthamologist to confirm that her optic nerves are normal. I've requested an appointment with the neuro-optha office at Children's and have emailed our neurologist with both the article and questions about Sweet Pea's diagnosis.

One of the common associations of ONH is something called corpus callosum hypoplasia. Last week, in a totally unrelated series of events, a high school friend posted a link (again on Facebook) to her friend's blog. When reading her friend's blog post I noticed on the sidebar a link to the National Organization for Disorders of the Corpus Callosum (something my friend's friend's daughter has - isn't it a small world?) and had briefly scanned the website and decided I should look at it later. Yesterday, when I read the association between ONH and what I am going to call CCH (corpus callosum hypoplasia) I decided to pull out Sweet Pea's medical discharge paperwork from Boston.

When I read the discharge paperwork on our way home from the hospital there was something mentioned about Sweet Pea having a "thinning of the corpus callosum" which was discovered when neurology did her MRI. This was new information to me and I didn't know what it meant. All that neuro said to me in our meeting re: Sweet Pea's diagnosis was that she was missing the septum pellucidum which was an indicator of SOD and that it meant nothing else (it's like the brain equivalent of your appendix). I assumed upon reading this new information in her discharge papers that this too must be something not very important... and I never thought of it again until last week. (Even at our last neuro appointment when the resident showed us Sweet Pea's MRI and pointed out the thinning of the CC, I didn't think to ask what that meant because of my prior assumption.)

Yesterday, after reading Dr. Borchert's article, I decided it was time to also read the NODCC website that I had found by accident. I was - and am - pretty shocked and upset by what I found for two reasons. First, the information itself took my breath away like a sucker punch. Second, I couldn't believe that this was never brought up by neurology at Boston as it seems to be even more important than Sweet Pea's endocrine issues! Along with the SOD diagnosis I emailed about, I wrote in detail to our neurologist for an explanation regarding this new information.

If Sweet Pea does have this "thinning of the corpus callosum" it is medically referred to as hypoplasia of the corpus callosum:

Hypoplasia refers to a thin corpus callosum. On a mid-line view of the brain, the structure may extend through the entire area front-to-back as would a typical corpus callosum, but it looks notably thinner. It is unclear in this case if the callosal nerve fibers are fully functional and just limited in number, or if they are both less plentiful and more dysfunctional.

What does this mean?

Likewise, in partial ACC and hypoplasia, once the infant’s brain is developed, no new callosal fibers will emerge. 

In that sense, disorders of the corpus callosum are conditions one must “learn to live with” rather than “hope to recover from.” Long-term challenges are associated with malformation of the corpus callosum, but this in no way suggests that individuals with DCC cannot lead productive and meaningful lives.

The 200 million fibers of the corpus callosum are the most important structures in the brain for sending messages from the right to left hemispheres. If they are not fully developed (or absent) then the brain can not "communicate movement or... think about complex information." They are formed between 12-16 weeks gestation and are fully functioning by 12 years old. Thus around the age of 12, children with CC issues begin to fall behind developmentally and behaviorally. You can find a list of common issues here. Can you see why I would be a little upset?!?!


It also made me think about the small delay's that Sweet Pea has faced so far. Our doctors and our Early Intervention therapist have blamed these delays on two things: 
1. She was a preemie (side note: I did find a study that shows preemies or more likely to have disorders of the corpus callosum when compared to full term babies)
2. She wasn't fed for so many days in the NICU and as a result did not grow appropriately making it physically impossible for Sweet Pea to do certain things on time.


Now I ask myself if these two reasons explain anything at all? Granted, Sweet Pea is pretty much on target for her adjusted age but it looks like we could be in for more significant delays as she gets older. Or maybe she will be perfectly fine? Who knows! In the meantime I will probably question everything and worry way too much. 


I have requested a hard copy of Sweet Pea's MRI and the neurologist's report and am anxiously awaiting a reply from her neurologist to see what she says about all of the above. It will be a real kick-in-the-ass if she confirms what I have learned. Then I'll be curious to know why this wasn't brought to our attention sooner (couldn't we been given a handout of some sort while in the NICU?).