Several years ago I had the opportunity to be a plenary speaker for the World Congress of Autism in Monterrey, Mexico. My lecture was given late in the evening. The late hour gave me the opportunity to remain behind and answer question from the audience, primarily parents of children in the autism spectrum. The question and answer session ricocheted across a large number of subjects and before I knew it, two hours had passed and questions were still coming. It may have appeared that I was dealing with a hodgepodge of unrelated subjects such as diet, seizures, headaches, educational plans, etc. However, what caught my attention was three case histories from different parents all seemingly having in common an abnormality at the base of the skull and upper cervical (neck) region. Could this be regarded as a coincidence? In only one of the cases, was a clinical diagnosis already established. My clinical suspicion for all of them was a Chiari malformation. According to the Mayo Clinic a Chiari malformation is a condition in which brain tissues extend into the spinal canal (see references: Mayo Clinic, Chiari Malformation).
Upon questioning the parents at the World Congress of Autism it seemed that all of the patients had a similar history of complains including irritability and tantrums whenever they went to the bathroom, coughed, strained or had a sudden change in posture that involved head dependency (having your head at a lower level than the rest of your body). It seemed to me that the symptoms were due to headaches, or even neck pain, the nature of which was difficult to convey by non-verbal and cognitively impaired patients. In addition, the patients all exhibited torticollis (wry neck), and in one case, an awkward gait that resembled that of a drunken person.
In general, common symptoms of the Chiari malformation include, headaches, neck pain, dizziness, vertigo, disequilibrium, difficulty swallowing, sleep apnea, muscle weakness, impaired fine motor skills, chronic fatigue and painful tingling of the hands and feet. The symptoms are those characteristic of herniation of brain tissue through the opening of the skull, called foramen magnum, that defines the boundary between the hindbrain and the spinal cord. It was first described by Hans Chiari in 1891, and the disease now bears his name. The disorder arises from underdevelopment of the bone at the backside of the skull (occipital bone) causing that compartment to shrink in size. The hindbrain structure in this shallower compartment can’t be compressed and is therefore forced to try and escape through the hole at the base of the skull. The herniated tissue often blocks the circulation of fluid in the brain leading, in some cases, to the formation of a cavity (syrinx) within the spinal cord.
There are several types of Chiari malformation. All of them are present at birth but some take years to manifest themselves (including second and third decade of life). An increased prevalence has been reported among family members (transmisibility rate of 12%), so if you ever diagnose one individual with the abnormality you are required to take a closer look at the rest of the family. For some unknown reason, females with the disorder tend to outnumber males about 3:1. This is a common malformation affecting anywhere from 200,000 to 2,000,000 individuals in the US alone. Diagnosis is usually accomplished through MRI.
Figure: The posterior fossa of the brain in a normal (left panel) individual and one with the Chiari malformation (right panel). The Chiari malformation (type I) is characterized by a protrusion (herniation) of the cerebellum through the foramen magnum and into the spinal cord.
Figure: Magnetic Resonance Imaging (MRI) showing a sagittal cut through the brain of an individual with a Chiari malformation. The image shows the protrusion of the cerebellum through the foramen magnum. Clinical history in these patients is often a confusing mix of symptoms. Diagnosis is usually achieved through MRI.
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 (http://abclocal.go.com/wabc/story?section=news/health&id=5251975 ). 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 (http://bit.ly/167eZuR ).
The Chiari and Syringomyelia Foundation (CSF) is sponsoring a project to study the prevalence of the Chiari malformation within ASD (http://bit.ly/17HriiY ). According to their web page: “Children with Chiari frequently have tendency to headaches, neck pain, speech and swallowing difficulties, sensori-motor disorders, gastro-esophageal reflux, disordered respiration and sleep apnea – the same findings that characterize ASD. Other shared deficits include loss of smooth ocular pursuit, dysarthria, abnormal motor initiation, disordered neuro-endocrine modulation within the reticular activating system and possibly cerebellar mediated alterations of cerebral activity. This overlap of characteristics suggests that these disorders may be co-morbid conditions. Furthermore, in the course of routine surgical correction of Chiari disorders, members of CSF have measured substantial improvement in pain, function, and quality of life in ASD patients.”
If your child has ASD and unexplained neurological symptoms one possibility to keep in mind is the Chiari malformation. As many children with ASD have an MRI of their head done at some time during their lifetime, this could be a good opportunity to check for a Chiari malformation.
Mayo Clinic. Chiari Malformation, http://www.mayoclinic.com/health/chiari-malformation/DS00839
Milhorat TH, Bolognese PA, Nishikawa M, McDonnell NB, Francomano CA. Syndrome of occipitoatlantoaxial hypermotility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue. J Neurosurg Spine 7(6):601-9, 2007.
I was under the impression (though my knowledge of neuroscience may be too limited) that Chiari malformations usually involved the vermis of the cerebellum. When Eric Courchesne first published his MRI findings in the New England journal of medicine, he stated that the vermal hypoplasia he observed in lobules VI and VII were qualitatively different than what was found in chiari malformations. Margaret Bauman’s autopsy findings seemed to contradict this and the entire vermis of autistic cerebella were found to be normal including lobules VI and VII. Not sure what this means in terms of chiari malformations.
The Chiari malformation involves primarily the tonsils of the cerebellum, not the vermis. You are correct however, in that Bauman reported Purkinje cell loss in the cerebellar hemispheres but reported no abnormalities in the vermis. Courchesne tried to reproduce Bauman’s findings by doing an MRI study which unfortunately focused on the vermis. He did found some hypoplasia, and latter on changed his view saying that there was both hypo- and hyperplasia. Thanks for the comment.
if chiari malformation can exhibit in Autistic individuals
then the duplex kidney /deletion of T (shirt) gene that presents in Autistic individuals can be present also.
perhaps the encoding of genes regarding these issues are attached to the same Gene sequence?