Patient Content

Shaken Baby Syndrome

Shaken Baby Syndrome (also known as Shaken Impact Syndrome) is a serious form of abuse inflicted upon a child.
  • AANS


Shaken Baby Syndrome (also known as Shaken Impact Syndrome) is a serious form of abuse inflicted upon a child. It usually occurs when a parent or other caregiver shakes a baby out of anger or frustration, often because the baby will not stop crying.

Babies have very weak neck muscles that cannot fully support their proportionately large heads. Severe shaking causes the baby’s head to move violently back and forth, resulting in serious and sometimes fatal brain injury. These forces are exaggerated if the shaking is interrupted by the baby’s head hitting a surface.

Shaking, with or without the sudden deceleration of the head when it impacts a surface, can cause the following:

  • Subdural hematoma, which is a collection of blood between the surface of the brain and the dura (the tough, fibrous outer membrane surrounding the brain.) This occurs when the veins that bridge from the brain to the dura are stretched beyond their elasticity, causing tears and bleeding.
  • Subarachnoid hemorrhage, which is bleeding between the arachnoid (web-like membrane surrounding the brain filled with spinal fluid) and the brain.
  • Direct trauma to the brain substance itself, caused when the brain strikes the inner surfaces of the skull.
  • Shearing off or breakage of nerve cell branches (axons) in the cortex and deeper structures of the brain caused by violent motion to the brain.
  • Further irreversible damage to the brain substance from the lack of oxygen if the child stops breathing during shaking.
  • Further damage to the brain cells when injured nerve cells release chemicals that add to oxygen deprivation to the brain.

Other injuries related to this abuse include:

  • Retinal hemorrhages ranging from a few scattered hemorrhages to extensive hemorrhages involving multiple layers of the retina.
  • Skull fractures resulting from impact when the baby is thrown against a hard or soft surface.
  • Fractures to other bones, including the ribs, collarbone and limbs; bruising to the face, head and entire body.

Prevalence and Incidence

This syndrome is primarily seen in children younger than age two, with the majority of cases occurring before the baby’s first birthday. The average victim is between three and eight months old. However, children up to age four have been victims of this abuse. The perpetrator of the abuse is most often the father, boyfriend of the mother, female babysitter or the mother. Parents experiencing stress because of environmental, social, biological or financial situations may be more prone to impulsive and violent behavior. Those involved with domestic violence and/or substance abuse may be at higher risk of inflicting this abuse.

The National Center on Shaken Baby Syndrome estimates that there are between 600 and 1400 cases in the U.S. a year. Because there is currently no reliable method of collecting these statistics, the true incidence is unknown. This syndrome is the most common cause of death and long-term disability in infants and young children who are victims of child abuse.


There is often no obvious external evidence of injury or physical sign of violence, resulting in under diagnosis of this syndrome. Caregivers and even physicians who are not aware of what has happened to a baby may not detect injuries that are primarily internal, attributing the baby’s fussiness to an underlying cause such as a virus.

Symptoms vary and are caused by generalized brain swelling secondary to trauma. They may appear immediately after the shaking and usually reach a peak within 4-6 hours. The following signs and symptoms may indicate shaken baby syndrome:

  • Altered level of consciousness
  • Drowsiness accompanied by irritability
  • Coma
  • Convulsions or seizures
  • Dilated pupils that do not respond to light
  • Decreased appetite
  • Vomiting
  • Posture in which the head is bent back and the back arched
  • Breathing problems and irregularities
  • Abnormally slow and shallow respiration
  • Cardiac arrest
  • Death

Physical Findings upon Medical Examination

  • Retinal hemorrhages
  • Closed head injury bleeding (subdural, epidural, subarachnoid, subgaleal)
  • Lacerations
  • Contusions
  • Concussions
  • Bruises to the face, scalp, arms, abdomen or back
  • Soft tissue swelling that may indicate a fracture to the skull or other bones
  • Abdominal injuries
  • Chest injuries
  • Abnormally low blood pressure
  • Tense fontanel (soft spot)

Suggested Diagnostic Studies

  • History
  • Optic fundus exam for retinal hemorrhages
  • Computed tomography scan (CT or CAT scan) of the head and abdomen
  • Magnetic resonance imaging (MRI) in select cases
  • Lumbar puncture with precautions
  • Skeletal survey
  • Nuclear scan
  • Drug screening
  • Routine blood samples

Prevent + Manage

The prognosis for victims of shaken baby syndrome varies with the severity of injury but generally is poor. Many cases are fatal or lead to severe neurological deficits. Death is usually caused by uncontrollable increased intracranial pressure from cerebral edema, bleeding within the brain or tears in the brain tissue. However, even babies with injuries that appear to be mild may show developmental difficulties. Typically, surviving babies with this syndrome may develop any of the following disabilities:

  • Cerebral palsy
  • Paralysis
  • Vision loss or blindness
  • Mental retardation
  • Epilepsy
  • Seizures

Shaken baby syndrome is completely preventable. Taking care of a baby can present challenges, especially for first-time parents. However, it is important to remember that it is never acceptable to shake, throw or hit a baby. The following tips may help prevent abuse:

  • Take a deep breath and count to 10
  • Take time out and let the baby cry alone
  • Call someone for emotional support
  • Call apediatrician – there may be a medical reason why the baby is crying
  • Never leave a baby with a caregiver, friend or family member in whom there is not complete trust
  • Always check references carefully before entrusting a baby to a caregiver or daycare center

Note from AANS

The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific neurosurgical advice or assistance should consult his or her neurosurgeon, or locate one in your area through the AANS’ Find a Board-certified Neurosurgeon online tool.