In infants, pain from vaccinations shows up in brain activity

Infants show distinct, consistent patterns of brain activity in response to painful vaccinations, reports a study in the February issue of PAIN®, the official publication of the International Association for the Study of Pain. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

“We have shown that inoculation evokes, from the time of the first needle contact, a clearly defined EEG response in infants up to at least one year of age,” write Dr Madeleine Verriotis and colleagues of University College London. They believe this “brain-led approach” to assessing procedure-related pain in infants may help in developing improved vaccination techniques and pain-relieving treatments.

Brain Activity in Response to Shots in Infants…

The researchers performed elecroencephalography (EEG) in 15 healthy babies receiving routine vaccinations. A noninvasive and painless procedure, EEG is done to measure electrical activity in the brain, using electrodes placed in specific locations on the scalp. Twelve infants were tested during vaccinations at age one to two months, and five at age 12 months.

Dr Verriotis and colleagues compared the EEG findings with behavioral pain responses: facial expression, crying, and movements. Such behavioral responses are the standard method for assessing pain in preverbal infants. The researchers filmed the procedures to identify the precise timing of EEG responses to vaccination pain.

Sometimes the “ouch” of a vaccination doesn’t end when the needle’s out. Soreness or a low fever can sometimes appear afterwards, along with some fussiness.

What to Do About Side Effects
A warm compress applied after the shot can help reduce soreness, as can moving the arm or leg in which the shot was given (you can “bicycle” a baby’s leg to help bring relief, or encourage a toddler to do a few rounds of head-shoulder-knees-and-toes). A non-aspirin pain reliever such as acetaminophen (after age three months) or ibuprofen (after age six months) can help with residual achiness, as well as with any low-grade fever, so ask the doctor about that before you leave the office. Some doctors even recommend a dose of a non-aspirin pain reliever before the shot is given, to prevent these mild side effects in the first place.

The EEG recordings showed two clear waveforms, or “spikes,” which appeared within milliseconds after the first contact of the needle with the infant’s skin. Although the waveforms appeared in both age groups, they were significantly larger in one- to two-month-old infants than in one-year-olds.

In infants, pain from vaccinations shows up in brain activity In three infants studied at both ages, the EEG responses - particularly for the first waveform - appeared clearer and larger at age 12 months. The EEG patterns were also more reproducible in older infants. The researchers suggest that these age-related differences might reflect developmental changes in the brain during the first year of life: an increased number of neurons (nerve cells), a larger proportion of neurons being activated, or better synchronization of firing activity.

...But No Relation between EEG and Behavioral Pain Responses

Of course, infants of both ages showed strong and immediate behavioral responses to the vaccinations. However, there was no direct association between differences in the EEG waveforms and differences in the behavioral pain responses.

Vaccinations will protect your child from harmful infectious diseases. Vaccines must be given with a needle, which causes pain; this experience can be stressful for both babies and parents.

Below are some methods you can use to help reduce the pain and anxiety associated with having your baby vaccinated.

Planning ahead

Before your baby’s vaccination appointment, discuss your plan for pain reduction with your doctor so they can support you in this plan. All of the information below is based on scientifically proven research done by experts at SickKids and across Canada.
Before the vaccination
Use of topical anesthetics

Topical anesthetic creams or gels may be applied to the area where your child will receive their vaccine, in order to reduce pain. In Canada, these products are available over the counter; they must be applied between 30 to 60 minutes prior to injection. It is important to discuss this option with your doctor, and to ensure that the anesthetic gel or cream does not contain any ingredients that your child is allergic to.
Distract your baby

Take with you any items that you can use to distract your baby during their vaccination. These items might include toys, pacifiers or bubbles. You can also sing, talk or direct your baby’s attention to other things in the room in order to distract them from any pain that they might be experiencing.
Sugar water

Giving your baby a small amount of sugar water before vaccination has been shown to reduce perceived pain. You can make sugar water by mixing 1 packet of sugar with two teaspoons of water. Using a syringe or dropper, place the sugar water one drop at a time, into the side of your baby’s mouth (between the tongue and cheek). You can also dip your baby’s pacifier into the sugar water. Only use sugar water for this purpose. Using water on an ongoing basis is NOT safe in babies.
During the vaccination
Hold your baby

Holding your baby helps to provide comfort during the vaccination process, and will also help them to remain still.
Breastfeed your baby

Like giving sugar water, breastfeeding before, during and after vaccination reduces perceived pain. Breastfeeding provides the benefits of distraction, holding and sweet taste, which all work to soothe your baby.
Stay Calm

If you are feeling anxious before and during your baby’s vaccination, this might increase feelings of anxiety in your baby. Even though you may feel stress related to vaccination, try your best to remain calm; use your normal speaking voice, and take slow, deep breaths.

This may have at least partly reflected the fact that behavioral pain responses were close to maximal (8 on a 10-point scale) in most infants. Dr Verriotis and coauthors write, “Cortical EEG activity…shows that the noxious stimulus is being processed in the brain, with some individual variability, but is not necessarily a direct read-out of the amount of pain perceived.”

Vaccinations are the most common cause of procedural pain in children. Although it may seem harmless, pain from frequent vaccinations is a source of anxiety and distress for the child, and a concern to parents as well as healthcare providers. “There is emerging evidence that fear of needles in both parents and children affects medical care,” the researchers note. Improved pain management during routine vaccinations is therefore an important goal.

The new study, by showing a “clearly defined EEG response” to shots in infants up to one year of age “may provide a quantitative measure of cortical pain activity that could be used to investigate the efficacy of pain relieving interventions,” Dr Verriotis and colleagues conclude. They add that future studies tracking pain responses over time may help in understanding the long-term development of pain processing in the infant brain.

Click here to read “Cortical activity evoked by inoculation needle prick in infants up to one-year old.”


Article: “Cortical activity evoked by inoculation needle prick in infants up to one-year old” (DOI: 10.1097/01.j.pain.0000460302.56325.0c)

About PAIN

PAIN is IASP’s official journal. Published monthly, PAIN presents original research on the nature, mechanisms, and treatment of pain. Available to IASP members as a membership benefit, this peer-reviewed journal provides a forum for the dissemination of multidisciplinary research in the basic and clinical sciences. It is cited in Current Contents and Index Medicus.

About the International Association for the Study of Pain

IASP is the leading professional forum for science, practice, and education in the field of pain. Membership is open to all professionals involved in research, diagnosis, or treatment of pain. IASP has more than 7,000 members in 133 countries, 90 national chapters, and 20 special interest groups (SIGs). IASP brings together scientists, clinicians, healthcare providers, and policymakers to stimulate and support the study of pain and to translate that knowledge into improved pain relief worldwide.

About Wolters Kluwer Health

Wolters Kluwer Health is a leading global provider of information, business intelligence and point-of-care solutions for the healthcare industry. Serving more than 150 countries worldwide, clinicians rely on Wolters Kluwer Health’s market leading information-enabled tools and software solutions throughout their professional careers from training to research to practice. Major brands include Health Language®, Lexicomp®, Lippincott Williams & Wilkins, Medicom®, Medknow, Ovid®, Pharmacy OneSource®, ProVation® Medical and UpToDate®.

Wolters Kluwer Health is part of Wolters Kluwer, a market-leading global information services company. Wolters Kluwer had 2013 annual revenues of ˆ3.6 billion ($4.7 billion), employs approximately 19,000 people worldwide, and maintains operations in over 40 countries across Europe, North America, Asia Pacific, and Latin America.maintains operations in over 40 countries across Europe, North America, Asia Pacific, and Latin America. Wolters Kluwer is headquartered in Alphen aan den Rijn, the Netherlands. Its shares are quoted on Euronext Amsterdam (WKL) and are included in the AEX and Euronext 100 indices. Wolters Kluwer has a sponsored Level 1 American Depositary Receipt program. The ADRs are traded on the over-the-counter market in the U.S. (WTKWY).


Connie Hughes
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