Any parent can recognize that their child develops in an amazing fashion during this time, growing from a newborn baby who is totally dependent on their parent(s) to a toddler who is walking, talking, and eating on their own. The development that occurs during these first 2 years is quite remarkable. In children with TSC, however, the onset of seizures early in life can interfere with the pace of brain development. This also appears to be associated with an increased likelihood of cognitive and behavioral difficulties, particularly if seizures are not controlled. 

TSC is prototypical of a genetic disorder that can cause epileptic encephalopathy, a description used by epileptologists to indicate that, in addition to the epilepsy, the seizures themselves contribute to the developmental impairments. This is also true of other genetic-related causes of epilepsy. Terminology such as developmental and epileptic encephalopathy has recently been suggested, which underscores that genetic variants not only may be influential in the epilepsy and its sequelae but also might contribute independently to developmental encephalopathies.

I often use the analogy of the brain as a computer to describe epileptic encephalopathy. Imagine that a seizure is similar to your computer freezing up. When a computer freezes, it has to be shut down and rebooted for it to work again, but it often does not function as well after that, especially with multiple freezes/reboots. 

Now consider the fact that the brain grows to 80% of its adult size during the first 2 years of life. If a child’s developing brain suddenly freezes up because of a seizure—and this happens approximately 50 or 100 times per day in patients with TSC—and it has to be shut down and rebooted each time, this constant rebooting interferes with developmental progress and leads to the developmental delays that you see in these young patients with TSC. In anybody with seizures, especially in individuals whose brains are still developing, the seizures need to be stopped as soon as possible to prevent or reduce the seizure-induced encephalopathy or developmental delays.