A Question About Shaking Movements In Infants

Thanks J.R.F. of New York for your question about shaking movements in infants.

Babies (and children) who reportedly have shaking movements always catch my attention. The challenge is that there is an endless list of potential causes. Many movements that babies make are normal. Normal movements include a quivering chin, a startle reflex, and a trembling hand. Anytime shaking comes up though, so does the possibility of a seizure. (Keep in mind, all that shakes is NOT a seizure).

What is a seizure?

A seizure is an abrupt change in physical movement caused by an abnormal electrical firing in the brain. Seizures can involve the whole body (e.g., generalized tonic-clonic, grand mal) or a specific part of the body (e.g., focal seizure). There is further classification based on whether there is loss of consciousness, presence of fever, or shaking vs. just starring.

How do I tell if shaking is a seizure?

There are a couple of little tricks that can help you determine if the movement is a seizure. If the movement always happens only in certain circumstances (e.g., when you turn your baby’s head a certain way or change her diaper), then it is NOT a seizure. If you can easily make the movement stop (by distracting the child or gently touching the shaking limb), then it is NOT a seizure. If the movement is symmetric (same in all affected limbs), bilateral (both sides of the body), or rhythmic (same speed and intensity) that is more suggestive of a seizure.

If it’s not seizures, what else could it be?

Common causes of shaking, that can be mistaken for seizures include: fainting, breath-holding spells, myoclonus (body and facial twitching), and sleep disorders (e.g., night terrors, cataplexy, sleep walking). What the shaking looks like and the circumstances surrounding the shaking are the best indicators of the cause. Is the child awake, asleep, fevering, chilled, well, sick, etc? There are more rare causes of shaking (and frankly more concerning) including problems with the brain, muscular disorders, metabolic disorders, etc.

It’s a good sign if:

Generally speaking, it is a good sign if your child is growing normally, developing normally (appropriate milestones, etc.), and appears healthy. When shaking is due to one of the “bad causes,” babies/children most often start to show other signs of problems.

Should I see a doctor?

Because of the risk of something “bad,” I think most cases of shaking should be seen by your pediatrician. The likelihood of your child having one of the shaking episodes in the office is slim though, so I highly recommend videotaping the episode if at all possible so your doctor can see it.