Developmental delay Vs developmental regression

Today I consulted on a 4-year-old boy who presented for evaluation of developmental delay.  As I tried to explain to the worried parents that their son had developmental delay due to a static encephalopathy, it dawned on me how hard it was for the parents to follow me. So here in this post I thought I would discuss the differences between developmental delay versus developmental regression. I shall also give an overview of the various causes of developmental delay and regression and how to go about investigating these children.

So lets keep this simple. What do we mean when we say developmental delay. Simple it means that the child is delayed in his or her developmental milestones. As we all know children acquire motor and language skills as they grow. These set of skills appear more or less at fixed times. For example a baby can sit by the age of about 8 months. Other motor developmental milestones include the age where the baby starts to support his head, crawl, roll over, stand, stand up without support, walk and so on. Pediatricians check for these milestones when you take the baby in for well baby visits. Similarly there are language milestones like when the child starts to speak  ma ma da da etc and when the child is able to form short sentences.

So it follows that developmental delay can be of a few types. A child may just have delay in the motor milestones, in others the motor milestones may have appeared at the right time but there is delay in language and other cognitive milestones. In still other there is delay in both motor and language skills (we refer to this as global devlopmental delay).

So what is developmental regression? Developmental regression is said to occur when a child who has been normal in his developmental and has met all the milestones starts to regress and starts losing the acquired milestones. Such a child may stop talking or stop walking and so forth.

As you can imagine the causes for developmental delay and those for developmental regression vary. Another couple of terms need clarification. We neurologists love to use terms called static encephalopathy and progressive encephalopathy in relation to developmental delay.

Static encephalopathy what does this mean? Let me explain with the aid of an example. Suppose you have a child who suffered some brain insult at or near the time of birth. Lets say he had hypoxia (lack of oxygen) to the brain. This child shall have developmental delayed but this shall remain static. The child is not going to progressively go downhill, infact as he ages if good intervention is carried out, it is more than likely that he would start to catch up wih his peers. He may never become completely ” normal” but he is not going to go downhill. His brain took a hit but now is trying to get back.

Progressive encephalopathy: let us assume another child. As compared to the first child, this child has a progressive neurological or systemic condition. Let us for example say he has a metabolic disease which leads to progressive brain damage. This child is going to go downhill as he ages. The brain is going to go “more bad” as time goes by.

Now that we have done with the medical jargon, let us try to make sense of some of the causes of developmental delay and developmental regression. There can be numerous causes of delay. The baby may have suffered some brain damage at or near the time of birth (during the antenatal period when the brain is developing or near the time of birth). Examples include conditions as diverse as mother abusing alcohol during the antenatal period (fetal alcohol syndrome), drugs used during the antenatal period may also harm the developing fetal brain. Hypoxia (lack of oxygen to the brain) is one of the common causes of cerebral palsy which presents as a static encephalopathy and developmental delay. This hypoxia may result from a difficult child birth or complications during labor and delivery. Inborn errors of metabolism, certain genetic disorders constitute other causes of developmental delay. Unrecognized seizures can also cause delay in development. Absence seizures is one such cause.

Developmental regression too has numerous causes.

How does one work up such children? The work up starts with a detailed history and physical examination. Your doctor shall go in depth into the birth history to find any cause. Family history is taken, where any drugs used during pregnancy? Then the child is examined to document is he delayed just in motor skills or is there global delay. After that the work becomes more complicated. Blood work to rule out inborn errors of metabolism, genetic and karotype testing, MRI scans of the brain and EEG may be ordered to zoom in to the diagnosis.

If the final cause is static encephalopathy, then there is nothing”active” to treat. What happened has happened. Now we need to concentrate on early intervention services to bring the child up to par. Physical therapy, language therapy, special education is what we need to stress on.

If the final cause is a progressive encephalopathy then of course depending upon the cause we need to treat. Is the cause treatable?

My advise to parents dealing with this difficult situation: find a good doctor, a pediatrician or pediatric neurologist who can help in getting to the bottom. Do not get disheartened, there are many interventions out there for your loved one. Seek treatment early rather than late as you want to halt a progressive encephalopathy early before too much irreversible brain damage occurs.

Nitin Sethi, MD