Thoughts on Newtown
13 years ago
My life mothering a child on the autism spectrum
"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."
"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."
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."
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.
"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."
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.