What is shaken baby syndrome and what are its consequences

Shaken Baby Syndrome (SBS) falls under the broader category of Abusive Head Trauma (AHT), as defined in 2009 by the American Academy of Pediatrics. This term emphasizes that not only shaking, but also blunt impact or a combination of both mechanisms, can lead to this condition.

SBS occurs when an infant is held by the torso and shaken violently. As a result, the baby’s head undergoes rapid rotational movements. Due to the head's relatively large size and the neck muscles’ immaturity, the brain moves rapidly within the skull, leading to acceleration–deceleration trauma. This can cause:

• Contusive brain injuries
• Nerve damage
• Rupture of blood vessels
• Intracranial hemorrhage

The peak incidence of SBS is between 2 weeks and 6 months of age, which coincides with the period when infant crying is most intense. At this age, babies have poor head control due to weak neck muscles, and their heads are heavy and proportionally large. The infant brain is soft and gelatinous, and can move inside the skull when shaken.

The main triggering factor is inconsolable crying that overwhelms parents or, more rarely, other caregivers. Often, those responsible for shaking the baby are already exhausted and emotionally distressed, feeling inadequate in their attempts to calm the child, unaware that their actions may cause permanent harm.

Additional risk factors identified in the literature include:

• Young maternal age
• Single-parent households
• Short intervals between births
• Premature birth
• Parental depression
• Socioeconomic hardship
• Substance abuse
• Low educational level
• History of domestic violence or previous abuse

Shaking is always dangerous, especially for infants under 1 year of age. Several anatomical and developmental characteristics make infants particularly vulnerable:

• The head is heavy and proportionally large compared to the body, and difficult for the infant to control
• The brain is immature and more susceptible to injury
• There is a significant size and strength imbalance between the infant and the person shaking them

Healthcare professionals should be alert to the following warning signs, which may indicate SBS:

• Lethargy, decreased muscle tone, or unusually long sleep
• Excessive irritability or inconsolable crying
• Poor feeding or vomiting without an obvious cause
• Bruising on the arms or chest (suggestive of gripping)
• Lack of smiling or vocalization
• Weak or uncoordinated sucking and swallowing
• Abnormal posture or stiffness
• Breathing difficulties
• Altered consciousness
• Seizures
• Enlarged head or forehead (disproportionate head circumference relative to weight and height)
• Bulging or pulsating anterior fontanelle
• Poor head control
• Difficulty following visual stimuli or unequal pupil sizes

The long-term outcomes of SBS depend on the severity and extent of central nervous system injury. Documented consequences include:

• Physical disabilities (hearing, speech, visual impairments)
• Learning difficulties
• Neuromotor impairments
• Cognitive disabilities
• Intellectual disability
• Behavioral disorders
• In severe cases: cerebral palsy, epilepsy, or death

The Italian Society of Neonatology, in collaboration with Terre des Hommes, has launched awareness campaigns to remind caregivers that crying is the newborn’s only means of communication.

Babies cry for many reasons: hunger, sleepiness, discomfort (too hot or too cold), the need to be changed, held, or comforted. However, it is crucial to remember: a baby should never be shaken.

Some practical tips for parents and caregivers:

• Check for any immediate needs (diaper, feeding, temperature)
• Rule out signs of illness or pain (fever, swelling)
• Talk or sing to the baby; sometimes “white noise” (vacuum, dryer, fan) can soothe them
• Offer a pacifier or a toy
• Breastfeed or offer a bottle
• Try swaddling or gentle rocking
• Go outside for a walk or a drive
• Ask a friend, neighbor, or family member for help to take a short break
• If no help is available, place the baby safely in the crib and leave the room for a few minutes to calm down

Regular well-child visits with a pediatrician are key for monitoring a baby’s development and health. While persistent crying between 2 weeks and 5 months is often normal, it’s best to consult a doctor if the infant seems unusual or shows any of the following additional symptoms:

• Fever above 38°C (100.4°F)
• Increased crying when moved or picked up
• Vomiting or refusal to eat/drink for over 8 hours
• Visible swelling or bruising
• Change in overall appearance or failure to gain weight
• Changes in stool patterns

Any parental concern should be discussed with the pediatrician without hesitation.