Autism and Sensory Responses to Pain

Autism and pain

Many parents ask if their children are the only Autistic children that seem to have a higher or lower pain thresholds than the “normal” person. The answer is no they are not. Many children with Autism experience reduced or heightened pain sensitivity. It is actually widely reported to be a common feature of children with Autism. Sensory abnormalities in Autism are well known; they are even part of the diagnostic criteria for the condition. But few investigators have looked into how people with Autism experience pain. The ones who have base their conclusions of reduced and heightened pain in children with Autism on anecdotal observations and questionable measures of pain reported by parents. My son is among the Autistic children that are affected by this.

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My son has a crazy high pain threshold. When he was 18 months old he broke his arm and never cried. When he lost teeth growing up he’d rip the tooth next to it out within 24 hours because of sensory issues with the missing spot in his mouth. I have become desensitized to his lack of pain as well. It used to surprise me, now when he rips the skin off of his fingers and toes or bites his nails down until they bleed- I take him to the doctor and talk to him about bleeding and how it is supposed to hurt. I have to remind him that he shouldn’t bleed. As extreme as that may sound to the parent of a non-Autistic child, to us seasoned special needs parents we know this is a common issue. So, whether your child cries over everything or doesn’t seem to feel anything at all, don’t feel alone.

Low Thresholds of Pain

If you don’t believe me, let me show you the science. A study published in The Clinical Journal of Pain was aimed at proving just this. The motivations of the study were to “(1) characterize the behavioral response of children with Autism experiencing a venipuncture using objective observational measures of pain and distress, (2) examine parents’ assessments of pain behavior in children with and without autism, including comparison of the relationship of parental reports with behavioral measures, and (3) compare the behavioral reactions and parental assessments of children with autism with children without autism undergoing venipuncture.”

The methods of the study were basically straight forward. In an effort to measure the pain reactions of Autistic children the invasive procedure of venipuncture was videotaped, systematically described and compared in 21 children with Autism whom were between 3 and 7 years old and 22 nonimpaired children. “The latter providing a chronological age and gender equivalent comparison group.” If you don’t know, venipuncture is when they puncture your vein as part of a medical procedure. Sometimes this is as simple as a little blood draw, sometimes it is more invasive. The parents of the children were present and provided the observer with reports of pain. Facial activity was also used as an objective behavioral measure of pain.

It was reported that the children with Autism displayed “a significant facial pain reaction in response to the venipuncture procedure; however, there was a lack of concordance between parental reports of pain and observed pain responses for the children with Autism. This wasn’t the only study of it’s kind. A study brought to light by ScienceDirect.com acknowledges that there is a lack of knowledge about pain reactions in children with Autism Spectrum Disorders (ASD), who have often been considered as insensitive to pain. The objective of this study was much like that of the other.

They wanted to describe the “facial, behavioral and physiological reactions of children with ASD during venipuncture and to compare them to the reactions of children with an intellectual disability and nonimpaired control children.” They also examined the relation between developmental age and pain reactions. This sample included “35 children with ASD, 32 children with an intellectual disability, and 36 nonimpaired children.” It is reported that much like the earlier study the children were videotaped during venipuncture. This time their heart rate was recorded as well. Again, they recorded facial reactions, this time using the Child Facial Coding System (CFCS). The children’s behavioral reactions were scored using the Noncommunicating Children’s Pain Checklist (NCCPC).

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Per the study, “a linear mixed-effects model showed that children’s reactions increased between baseline and venipuncture and decreased between the end of venipuncture and the recovery period. There was no significant difference between groups regarding the amount of facial, behavioral and physiological reactions. However, behavioral reactions seemed to remain high in children with ASD after the end of the venipuncture, in contrast with children in the 2 other groups.” Researchers also observed a “significant decrease in pain expression with age in nonimpaired children, but no such effect was found regarding children with ASD. The data reveal that children with ASD displayed a significant pain reaction in this situation and tend to recover more slowly after the painful experience. Improvement in pain assessment and management in this population is necessary.”

To sum it up for you. Parents and clinicians report “difficulties in pain assessment in children with autism because of sociocommunicative deficits.” These studies show that children with Autism Spectrum Disorders are more reactive to pain during venipuncture as developmentally delayed and typically developing children. Though studies show that children with Autism are more reactive to pain, I assure you that there are studies that prove that they can also be less reactive to pain.

High Thresholds of Pain

In a study released by spectrumnews.org, “17 adults with Autism and 16 unaffected adults were laid in a functional magnetic resonance imaging (fMRI) scanner with a small piece of metal strapped to one calf. The metal heated up over three seconds to 49 degrees Celsius (120 degrees Fahrenheit) — hot enough to hurt, but not to cause injury. The metal stayed hot for 12 seconds, then cooled to room temperature. The researchers measured participants’ brain activity through a dozen of these cycles of pain and relief.”

In this study, they used the brain imagery and the knowledge that the brain’s response to pain has three phases: early, intermediate and late to prove a delayed response to pain in individuals with Autism. During this study, throughout the early phase, roughly corresponding to the study’s warm-up and the first seven seconds of heat, people with Autism “show similar levels of brain activity to controls in areas known to be involved in pain processing, such as the somatosensory cortex, a brain region that governs touch.”

However, during the last five seconds of heat and the cooldown, the control group of non-Autistic individuals still showed brain activity in these areas. But among those with Autism “all of the activation in the pain network was just gone,” said Michelle Failla, a postdoctoral researcher in Carissa Cascio’s lab at Vanderbilt University in Nashville, Tennessee, who presented the work. She continued on to point out that the differences between the groups persist for 10 seconds after the painful stimulus ceases. “In people without Autism, the brain is still responding: ‘Hey, you were just in pain.’ But in Autism, that is completely gone,” says Failla.

These patterns suggest that the brain’s initial processing of pain may be normal in Autism, but later steps in pain processing, having to do with cognitive and emotional evaluation of pain, stop. Individuals with Autism vary in their brain responses to pain, the study shows. Some have unusually low activity in the brain’s pain network, whereas pain activity in others is relatively high. This is not surprising, given that individuals with autism may also be either “hyper- or hypo-sensitive to non-painful sensory inputs.” The researchers plan to examine the relationship between brain activity and facial grimaces in response to pain. “If we could combine brain imaging with other ways of determining pain experience, like facial expressions, we might be able to provide even more clarification,” says Failla.

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