Sunday, July 11, 2010

A follow up on febrile seizures

Anonymous pointed out in response to my last post that pediatricians by and large think febrile seizures are not a big deal, and that is certainly true. If you visit the National Institute of Neurological Disorders and Stroke at the National Institutes of Health, you will find this fact sheet on febrile seizures.

It is clearly designed to reassure the worried parent. Here's what it says:

"Are febrile seizures harmful?

Although they can be frightening to parents, the vast majority of febrile seizures are harmless. During a seizure, there is a small chance that the child may be injured by falling or may choke from food or saliva in the mouth. Using proper first aid for seizures can help avoid these hazards (see section entitled "What should be done for a child having a febrile seizure?").

There is no evidence that febrile seizures cause brain damage. Large studies have found that children with febrile seizures have normal school achievement and perform as well on intellectual tests as their siblings who don't have seizures. Even in the rare instances of very prolonged seizures (more than 1 hour), most children recover completely.

Between 95 and 98 percent of children who have experienced febrile seizures do not go on to develop epilepsy. However, although the absolute risk remains very small, certain children who have febrile seizures face an increased risk of developing epilepsy. These children include those who have febrile seizures that are lengthy, that affect only part of the body, or that recur within 24 hours, and children with cerebral palsy, delayed development, or other neurological abnormalities. Among children who don't have any of these risk factors, only one in 100 develops epilepsy after a febrile seizure."


Does this sound reassuring to you? I can see why it might. After all it prominently says that "the vast majority of febrile seizures are harmless." That would explain of course why a pediatrician will always be dismissive if your child has one. That's because doctors play by statistics. If they have seen 80 patients with X, and they all turned out fine, you can bet that when your child shows up with it they will not think there is a problem.

I, however, am not reassured by this discussion. You know why? 2 reasons: 1) I review and edit corporate disclosures for a living, and for that reason, I am less influenced by "spin" than other people. 2) My son has autism, which means 2 things: a) I have already learned that when there is a 1% chance of something, that means it really can happen to my child. b) my child is in the group that is clearly described in the last paragraph as being at increased risk of epilepsy.

So, just for fun, I have re-written the last paragraph in a way that highlights rather than downplays the risk. I feel pretty confident that I have not altered the actual content. See what you think:

"Between 2 and 5 percent of children who have experienced febrile seizures go on to develop epilepsy. Some children who have febrile seizures face an increased risk of developing epilepsy, althouh the risk is small. Children who are more likely to develop epilepsy include those who have febrile seizures that are lengthy, that affect only part of the body, or that recur within 24 hours. In addition, children with cerebral palsy, delayed development, or other neurological abnormalities are also more likely to develop epilepsy. Other children, who don't have any of the risk factors listed above -- have a one in 100 chance of developing epilepsy after a febrile seizure."


Still think that they're not a big deal? Then you might ask yourself why they are still researching ways to treat and prevent them:

The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health (NIH), sponsors research on all forms of febrile seizures in medical centers throughout the country. NINDS-supported scientists are exploring what environmental and genetic risk factors make children susceptible to febrile seizures. Some studies suggest that women who smoke or drink alcohol during their pregnancies are more likely to have children with febrile seizures, but more research needs to be done before this link can be clearly established. Scientists are also working to pinpoint factors that can help predict which children are likely to have recurrent or long-lasting febrile seizures.

Investigators continue to monitor the long-term impact that febrile seizures might have on intelligence, behavior, school achievement, and the development of epilepsy. For example, scientists conducting studies in animals are assessing the effects of seizures and anticonvulsant drugs on brain development.

Investigators also continue to explore which drugs can effectively treat or prevent febrile seizures and to check for side effects of these medicines."


Now, of course this correlation between febrile seizures and epilepsy does not mean that the seizures "caused" epilepsy. It could be, I suppose, that these children already "have" epilepsy.

But I don't personally find this very reassuring, because as far as I can tell, all seizures are caused by a disturbance to the balance between excitatory and inhibitory neurons. See this discussion, for example, which states:

The Neurobiology of Seizures
Seizures can be caused by multiple mechanisms, and often they appear so diverse that one would suspect that no common theme applies. However, one principle that is often discussed is that seizures arise when there is a disruption of mechanisms that normally create a balance between excitation and inhibition. Thus, normally there are controls that keep neurons from excessive action potential discharge, but there are also mechanisms that facilitate neuronal firing so the nervous system can function appropriately. Disrupting the mechanisms that inhibit firing or promoting the mechanisms that facilitate excitation can lead to seizures. Conversely, disrupting the mechanisms that bring neurons close to their firing threshold, or enhancing the ways neurons are inhibited, usually prevents seizure activity.


And I think I have pretty good reason to find this disturbing, since there is material all over the place about how autism is also caused by a disturbance in this same balance. For example, this review from the Simons Foundation describes a couple of recent studies from last year:

"Together, the papers add heft to the hypothesis that an imbalance between excitatory and inhibitory neurons underpins autism. The high prevalence of seizures in individuals with autism is seen an indicator that the balance between excitatory and inhibitory circuits has gone awry in people with the disorder.

"The possibility is emerging that subtle changes in the numbers and proportions of this category of interneurons may result in a range of neurodevelopmental disorders, including schizophrenia, bipolar disorder and autism," says Anthony-Samuel LaMantia, lead investigator on the PNAS study and a neuroscientist at the University of North Carolina at Chapel Hill.

The studies also emphasize the essential role inhibitory interneurons play in the development of proper circuitry in the cortex. Restoring circuit balance may therefore be a plausible way to reverse autism, suggests Hensch, a neurobiologist at Harvard."


Now, again, let me point out that what this suggests is that autistic individuals are more likely to have seizures. It doesn't mean that a febrile seizure made them autistic.

But it is a rather far leap from there to conclude that febrile seizures do not harm an autistic person, either.

And how many studies have been done to ascertain the impact of a febrile seizure on an autistic person? I haven't seen anyone mention any. How would you design such a thing, I wonder? Who is your control group? Autistic children who didn't have one? How would you even know for sure who had had a seizure, since so many of them are undetectable? And how would you match them, given that autistic children have so many different levels of functioning, comorbid conditions, etc.?

So for me, I am back to common sense. I already have some pretty good reason to think that there is something wrong in my son's brain. And it is clear that he is at increased risk for febrile seizures.

And I dig deeper, and I find this from the CDC (emphasis added):

The 5%-7% of children who have either a personal history of convulsions or a parent or sibling with history of convulsions may be at increased risk for febrile convulsions after MMR vaccination (184). The precise risk has not been measured, but appears to be minimal. On the other hand, febrile seizures occur commonly among children in whom measles disease develops, and the risk for acquiring measles is substantial. Therefore, the benefits of administering MMR vaccine to children with a personal or family history of convulsions substantially outweigh the risks and these children should be vaccinated following the recommendations for children who have no contraindications.


This doesn't sound unreasonable to me. But this is NOT the same thing as saying there are no risks to the vaccine, or that it is perfectly safe.

I just can't see leaving this decision up to some stranger in Washington DC, or group of strangers, no matter how many degrees they have. I just can't understand how anyone could take this stuff lightly, I really don't.

2 comments:

  1. It has already been proven that environmental factors change the expression of many of our genes. In the field of epigenetics, the genes of identical twins were studied where one had autism and one did not.

    I believe that in some cases, the febrile seizure may alter the expression of one or more genes. I wonder if this could explain why some people with autism seem better when they have a high fever. Perhaps a genetic expression enables them to function better with a fever.

    Personally, I do not have a family member with autism, but I did a lot of reading when my son, who has Down syndrome, was getting vaccinated. Because he was getting Early Intervention services, and he is in daycare, we had to keep his vaccinations up to date. What I don't understand is why he was expected to follow the same schedule as a typical child when the autism rate among people with down syndrome is about 7-8%. Since the rate is many times higher than the typical population, I can't help but wonder what link there may be. Perhaps thyroid issues?

    Fortunately, at 3 1/2, there are still no signs of autism. However, I still want there to be a simple study which will show whether or not ajusting the vaccination schedule affects the occurence of autism.

    What if there were a study of 4 groups:
    - typical children on a regular schedule
    - children w/ Down syndrome on a regular schedule
    - typical children on a less agressive schedule (and thimerisol free flu vaccines)
    - children w/ Down syndrome on a less agressive schedule (and no thimerisol)

    I keep hearing the rise in cases of autism despite the elimination of thimerisol shows that there is no link. However thimerisol is still in the flu vaccine, and the vaccination schedule has added several items to the schedule. I just don't understand how people believe that this much exposure to viruses and chemicals can be safe for ALL children.

    Another comment that irks me is that people state that vaccines do not cause autism because a link has not been proven. Do people know how difficult it is to prove causality? How long has it taken for people to accept that smoking causes lung cancer? Actually, some are still arguing that it doesn't. Also, just because something has not been proven does not mean that it is not true. In this case it means that we still don't know the cause, so I'm not ruling out vaccines->febrile seizures as one of the possible causes.

    I agree, this is not something that should be taken lightly. I hope that epigenetics can help pinpoint some of the causes.

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  2. Yeah....nothing is without risk. It's just that there's either a small risk or a big risk. And ways of preventing them or not.

    What was that quote, again?

    “All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.”

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