Sunday, 30 August 2015

Treatable Chiari 1 “brain hernia” present in 7% of Autism

Today’s post is again prompted by a reader’s comment.

Regular readers will be accustomed to learning here about “rare”, often treatable, disorders that may cause, or just aggravate autism; add Chiari 1 to that list.
The Chiari 1 brain hernia occurs when part of the brain is forced downwards into the spinal column.  It is supposedly very rare, occurring in only one person per thousand.  It is generally not life-threatening and can be surgically repaired.  The symptoms of Chiari 1 do rather overlap with those of autism.

You can diagnose Chiari 1 using an MRI scan.  Very few people with autism ever receive any diagnostic follow up, be it genetic testing, metabolic testing or a scan of their brain.

There have been anecdotal reports associating Chiari with autism, and indeed of the corrective surgery greatly improving autism symptoms.  This goes back to the day of Bernie Rimland (Autism Research Institute and DAN).

Finally we have some genuine data:-

Patients with symptomatic Chiari malformation Type I (CM-I) frequently present with headaches, neck pain, difficulty swallowing, and balance disturbances. In children with autism spectrum disorder (ASD), diagnosing CM-I can be a challenging task. Moreover, even if symptomatic, some patients do not undergo further evaluation or management, as their presentations are attributed to autism and its myriad symptoms. Therefore, cranial MRI findings were reviewed after evaluating and treating patients with coexisting ASD and CM-I. In this paper, the authors report on 5 children with ASD and symptomatic CM-I, including their clinical presentation, imaging studies, management, and outcomes, and discuss the likely under recognized coexistence of these conditions.
All pediatric patients with ASD and cranial MRI conducted for any reason in the period from 1999 to 2013 were considered for analysis. All cases with concomitant symptomatic CM-I were eligible for this retrospective analysis.
One hundred twenty-five pediatric patients diagnosed with ASD had undergone MRI, and 9 of them had evidence of cerebellar tonsillar herniation. Five patients were symptomatic and underwent suboccipital craniectomy, a C-1 or a C-1 and C-2 laminectomy, and duraplasty with bovine pericardium or Type I collagen allograft. There were no intraoperative complications. All patients showed symptom improvement and/or resolution of presenting symptoms, which included headache, dysphasia, speech, and irritability.
There is no identified cause of autism. Children with ASD can be difficult to assess specifically in a neurological examination. Thus, cranial MRI considered when completing a comprehensive diagnostic evaluation. While cranial MRI is not a routine part of ASD evaluation, this study demonstrates that CM-I and ASD may coexist and be underrecognized. The study reinforces the importance of a comprehensive medical evaluation designed to elucidate neurological findings in children with impaired communication abilities and suggests the judicious use of neuroimaging.
ASD = autism spectrum disorder; CM-I = Chiari malformation Type I; Chiari malformation I; autism; autism spectrum disorder; suboccipital craniectomy


We know that in many cases of classic autism there is accelerated brain growth until the age of five (Courchesne, UC San Diego) and frequently this is associated with large heads (Macrocephaly).

As usual in autism, both extremes exist and so Microcephaly (small brains/heads) is also present.  The result is that in studies the average head size is meaningless.  Just as with many other possible markers, like cholesterol levels.  The same is true with signaling pathways like mTOR, Wnt, ERK and BDNF; both hypo function and hyper function exist and both can lead to “autism”.

Data from a series of 126 autistic children ages 2-16 years and referred to an Autism Diagnosis Unit in South-West France were examined. Macrocephaly (head circumference > 97th centile) was observed in 16.7% of the sample, a significantly higher proportion than that expected. Macrocephaly was more frequent among older subjects but was otherwise not associated with gender, developmental level, the presence of epilepsy or of medical disorders, or severity of autistic symptomatology. Microcephaly (head circumference < 3rd centile) was also significantly raised and found in 15.1% of the sample. Microcephaly was significantly associated with the presence of medical disorders. Results support those from recent studies suggesting a raised rate of macrocephaly in autism which, pooling published data, can be estimated to be 20%. It is argued that the raised incidence of microcephaly among low-functioning autistic subjects with medical disorders might have contributed to delay the recognition of an increased head circumference among a minority of subjects with idiopathic autism.

It is not hard to imagine what might happen if the brain is expanding faster than the skull is growing.  It would be reasonable to think that, in some cases, autism might cause Chiari malformation I.

Most people consider Chiari malformation I to be genetic.  In people with no underlying cause(s) of autism, the hernia itself may be the sole cause of the associated symptoms.

Since we know that autism is often caused by multiple “hits”, in some people the Chiari malformation might just be one of those handful of hits/triggers.  Oxidative stress and inflammation are both key drivers and consequences of autism; clearly hernia(s) growing in the spinal column are going to aggravate this.

To Treat or Not?

Surprisingly, some neurologists/neurosurgeons are unwilling to repair Chiari malformation I in children with autism.

If you recall my recent post on the history of autism, the reason becomes clearer.

Those neurologists/neurosurgeon hold the historical view that autism is untreatable and so how could surgery possible help?  It seems that in as many as 7% of autism cases, surgery might indeed help.  That is a surprise to me.

Fortunately, enough people with autism and Chiari 1 have been treated for it to be known that it does improve autism.

Since treatment involved a brain operation, it is not without risks.  Not treating the brain hernia likely also has risks.

Dr. Manuel Casanova on Chiari and Autism

Dr Casanova is a neurologist with a blog and an interest in autism. He is of the opinion that Chiari does not cause autism, but just makes it worse.

I am not a neurologist, but if you accept that autism, like cancer, is often caused by multiple hits, Chiari would seem like quite a dangerous hit, and perhaps more so than an immune over-reaction to childhood vaccines. In my recent autism history post we saw that for Hannah Poling the vaccine was enough to cause profound autism; she had two hits the first being a genetic mitochondrial dysfunction and the second an inflammatory reaction to the vaccines.

Over to Dr Casanova:-

"If you ever do a search through the internet you will find a lot of interest among multiple health boards on the possible correlation between the Chiari malformation and autism. Dr. Neil Felstein, Director of the Pediatric Neurosurgery Division of the Morgan Stanley Children’s Hospital, has seen many children with both conditions ( ). He believes that there is an association but can’t provide an explanation. Although a Chiari malformation is certainly not the cause of autism, it can aggravate the same. It may be worth noting that the Chiari malformation is seen as a comorbidity to both the Ehlers-Danlos and Marfan syndromes (Milhorat et al., 2007).  Both of these conditions manifest autistic symptomatology in a high percentage of cases ( )."

Head Circumference

Since data on head circumference is routinely collected during childhood, it would not be difficult to go back to the 125 cases studied by MRI in the research study, quoted at the start of this post.  You could then look for a correlations between head size, brain size and the Chiari hernia.

This might show that in autism the head was just not big enough at some critical point in time.

More links


It looks like you might want to add an MRI to those metabolic and genetic tests that most children with autism never receive, but perhaps should.

Or, as put in today’s study:-

“The study reinforces the importance of a comprehensive medical evaluation designed to elucidate neurological findings in children with impaired communication abilities and suggests the judicious use of neuroimaging.”


  1. My son developed a large head 97%+ after age 1 and was 25-50th percentile in weight and height. He most likely had some form of macrocephaly. However, he had an MRI as a teenager due to small stature (especially looking at pituatary). They did not mention Chiari 1 in the report so should I assume that it confirmed he didn't have it? Thanks!

    1. As long as they looked at the lowest part of the brain, when they did the MRI, it would be fair to assume that there is no Chiari 1. If 7% have Chiari 1 it means that 93% do not have it.

    2. I have Chiari. I have three sons with chiari. Two of them we were told did not because the radiologists missed it on their MRI/measured incorrectly. We are still working through the consequences of under informed radiologists. It is very common to hear of it being missed. You can request the images then watch YouTube videos from chiari specialists that tell you how to measure.

  2. I didn’t realize that it's 7%. Just found a blog about twins diagnosed with ASD as toddlers, but only after MRI done years later and surgery (some kind of minimally invasive technique is apparently used in Barcelona) they acquired receptive language and other skills. All sounds like a clear recommendation for MRI.

    One thing from my own history of mistakes and missed chances: when you do an MRI in a child with ASD and especially also with intellectual disability it’s good to ask for MR spectroscopy done at the same time for creatine deficiencies GAMT/AGAT. Seems like many hospitals are able to do this, but it may look like here: no one recommends it for a child with autism and “routine MRI”. I was later told that it would not have been any problem for a kid nor for a hospital to extend MRI with this test. GAMT/AGAT are supposedly rare, but treatable.

    1. I think there are other ways to test for GAMT/AGAT, but MR spectroscopy is a good one.

      Tests which are useful in screening for creatine defects in patients with suspected creatine deficiency syndromes include:

      Proton MRS —absence or reduction of creatine signal in the brains of affected individuals

      Measurement of metabolites—guanidinoacetate (GAA), creatine and creatinine in urine, plasma or cerebrospinal fluid

      Molecular genetic testing

      Enzyme activity levels in fibroblasts (GAMT) and lymphoblasts (GATM)

      Creatine uptake study in fibroblasts (creatine transporter defects).

  3. Hi Peter
    Thanks for putting up chiari on your blog I did follow up withy neurologist as suggested
    He has referred me to a neurosurgeon as my sons is quite large 1.5 cm they think it is acceptable for less than 6 mm
    Also I wanted to share that my son tested positive for strep I remember agnieska above and another user had commented on it I did not have to do any panel simple oral swab and it was positive and he had no symptoms so think all parents should get the simple swab done I wish I had done it earlier as he has some symptoms like sudden onset etc our Ped started us on amoxicillin
    If any one knows better options please share

    Also have you heard anti striated muscle antibody my sons came back 8 times normal but we're told it is typically seen in mystania graves not autism

    1. It seems that many people carry strep with no ill effects. In some people strep can trigger PANS/PANDAS and it is for this that there is a diagnostic panel referred to by Agnieszka. Clearly it is better to be strep free.

      I have not come across anti striated muscle antibody connected to autism.

  4. Hi Peter,
    Would like to know how many kids with ASD did get their Chiari 1 operated on and if it helped, posting to see if any readers of the blog might know.
    The neurosurgeon I met recommended it based on the size and that it extended to the second vertebra and it is showing some effect of csf flow (no flow posterior to cerebellum), but was not sure how many of the symptoms it will help. He thinks it will mostly help with posture, strength than speech, cognition. So trying to decide as this is a major procedure

    1. If you google chiari 1 autism you will find comments from parents. They do seem to be glad they had the procedure. I don't think you will find statistics, but there are lots of anecdotes. It is probably the only surgical procedure that could improve autism. Depending on its severity, living with autism can be very tough on the individual and their family. If you can lighten this burden, even by an unknown amount, you really have an opportunity.


Post a comment