Shaken baby syndrome
Synonyms and keywords: abusive head trauma, the battered-child syndrome, the whiplash shaken infant syndrome, nonaccidental head injury, nonaccidental head trauma, inflicted traumatic brain injury,  shaken impact syndrome

# Overview
Abusive head trauma (AHT), commonly known as shaken baby syndrome (SBS), is the injury to the skull/intracranial structures due to violent shaking and/or abrupt impact in children aged less than 5 years. AHT is caused by shaking injuries from repetitive and rapid flexion, extension, and rotation of the head and neck usually following parental frustration over an infant that does not stop crying. Retinal hemorrhages and subdural hematomas associated with spine injuries and/or bone raise high suspision for shaken baby syndrome. Noncontrast head CT is the initial radiologic workup for evaluating intracranial injury due to abusive head trauma (AHT). The prognosis of AHT is associated with the extent of damage seen on CT scan and MRI. The initial management of AHT is to maintain the patient's airway and circulation. Vital signs, oxygenation, and intracranial pressure (ICP) should be monitored. Increased intracranial pressure (IICP) and seizures should be managed. Decompressive craniectomy may be required.

# Historical Perspective
- In 1945, Dr. John Caffey reported pediatric cases with chronic subdural hematoma and long bone fractures.
- Later, Dr. Caffey discovered the association between traumatic shaking, subdural hematoma, and retinal hemorrhage.
- In 1962, Henry Kempe used the term 'the battered-child syndrome'.
- In 1974, Caffey used 'the whiplash shaken infant syndrome' for infants with injures from shaking the extremities with whiplash induced bleeding inside the brain and eye.
- 'Shaken baby syndrome' (SBS) has been used for decades to describe abusive head trauma (AHT) or inflicted traumatic brain injury on infants and young pediatric patients.
- Other terms for SBS include: nonaccidental head injury or trauma, inflicted traumatic brain injury, or shaken impact syndrome.
- The American Academy of Pediatrics and the Centers for Disease Control and Prevention (CDC) recommend the term 'abusive head trauma' (AHT).

# Classification
The modified grading system of abusive head trauma (AHT) is as the following:

# Pathophysiology
AHT is caused by shaking injuries from repetitive and rapid flexion, extension, and rotation of the head and neck and may result in:
- Tearing of the vessels due to the rapid striking of the brain on the skull result in bleeding. Consequently, the enlarging hematoma may cause pressure within the skull and lead to increased intracranial pressure (IICP) and additional injury to the brain.
- Sheering forces across the brain may injure nerve axons and lead to diffuse axonal disruption.
- Greater parenchymal movement
- The head may hit an object and result in lacerations, bruises, and fractures.
AHT includes primary and secondary injuries: 
- Primary injuries is the consequence of the initial direct trauma and may include:
Skull fracture
Epidural, subdural, subarachnoid, and intraparenchymal hemorrhages
Cortical contusion
Diffuse axonal injury
- Skull fracture
- Epidural, subdural, subarachnoid, and intraparenchymal hemorrhages
- Cortical contusion
- Diffuse axonal injury
- Secondary injuries are inflammatory changes causing impairments in neurons and the microcirculation of the brain and include the complications of the primary injuries:
Diffuse brain edema
Herniation
Infarction or cerebrovascular accidents
- Diffuse brain edema
- Herniation
- Infarction or cerebrovascular accidents
The neurometabolic cascade of AHT is similar to traumatic brain injury:
- Depolarization
- Release of excitatory neurotransmitters
- Potassium efflux
- Increased activity of membrane pumps
- Hyperglycolysis
- Lactate accumulation
- Calcium influx
- Decreased production of ATP
- Calpain activation and initiation of apoptosis
- Axolemmal disruption and calcium influx
- Neurofilament compaction
- Microtubule disassembly
- Axonal swelling and axotomy
Children are more susceptible to head injuries at younger ages because:
- The skull is easily compressed and therefore causes injuries to the underlying brain tissue.
- The head is larger (in proportion to the rest of the body) and as they fall it is usually injured first.
- The brain is more likely to suffer acceleration-deceleration injuries due to higher water content compared to adults.

# Causes
AHT is caused by shaking injuries from repetitive and rapid flexion, extension, and rotation of the head and neck.

# Differentiating Shaken Baby Syndrome from Other Diseases
Shaken baby syndrome must be differentiated from the following conditions:
- Accidental head trauma that may cause:
Epidural hemorrhage
Subdural hemorrhage
Subarachnoid hemorrhage
Cerebellar hemorrhage
Parenchymal hemorrhage
- Epidural hemorrhage
- Subdural hemorrhage
- Subarachnoid hemorrhage
- Cerebellar hemorrhage
- Parenchymal hemorrhage
- Bleeding diathesis
- Arteriovenous malformation
- Stroke
- Neoplastic conditions
- Metabolic disorders
- Glutaric aciduria
- Vitamin K deficiency
- Connective tissue diseases
- Osteogenesis imperfecta

# Epidemiology and Demographics
- The exact incidence of shaken baby syndrome/abusive head trauma (AHT) is unknown.
- In a population-based study, the incidence of AHT was reported to be 29.7 cases per 100,000 children younger than one year in the United States.
- In another study, the incidence of AHT was reported to be 24.6 cases per 100,000 children younger than one year in Scotland.
- Shaken baby syndrome/AHT is the leading cause of death due to head injuries in children younger than 2 years, worldwide.

# Risk Factors
Common risk factors in the development of shaken baby syndrome/AHT include factors that increase the risk of child abuse and may include:
- Infantile colic
- Inconsolable cry
- Child Disability
- Lack of parental frustration tolerance
- Lack of prenatal and childcare experience
- Low education level
- Low socioeconomic status
- Single-parent families
- Young parents without support
- Community isolation
- Limited recreational facilities
- Poverty

# Screening
There is insufficient evidence to recommend routine screening for shaken baby syndrome.

# Natural History, Complications, and Prognosis
Children with AHT are more likely to experience the following compared to children with accidental head trauma:
- Worse outcomes
- Cardiorespiratory compromise
- Diffuse cerebral hypoxia-ischemia
- Deeper brain injuries
- Death
Complications of AHT may include:
- Blindness
- Seizures
- Attention deficit
- Behavior difficulties
- Learning difficulties
- Sensory impairment
- Motor dysfunction
- Severe handicaps
- Decreased quality of life
- Death
The prognosis of AHT is associated with the extent of damage seen on CT scan and MRI.

# Diagnosis
Retinal hemorrhages and subdural hematomas associated with spine injuries and/or bone raise high suspision for shaken baby syndrome.

## Clinical Evaluation
The clinical work-up of shaken baby syndrome should include:
- Comprehensive history
- Physical examination
- Laboratory tests
- Imaging
- Consultation with specialists

## History and Symptoms
History
The following should be considered in the history of shaken baby syndrome/AHT:
- Open-ended questions should be asked by physicians
- Caretakers should be interviewed separately
- An inconsistent or changing history may suggest AHT or child abuse
- The most common history suggestive of abusive head trauma (AHT) are:
History of non-accidental trauma
History of falling from a low height
- History of non-accidental trauma
- History of falling from a low height
Symptoms
Symptoms of shaken baby syndrome/AHT may include:
- Vomiting
- Poor feeding
- Decreased interaction
- Irritability
- Sleepiness and lethargy
- Hypothermia
- Bradycardia
- Respiratory distress
- Apnea
- Seizures

## Physical Examination
The following signs should be considered on the physical examination of shaken baby syndrome/AHT:
- Decreased level of consciousness
- Cardiovascular collapse
- Bulging fontanel
- Hydrocephalus
- Microcephaly
- Subdural hematoma
- Retinal hemorrhages
- Fractures in long bone, metaphysis, and rib
- Lack of external injury
- Bruises (ears, neck, or trunk)

## Laboratory Findings
Laboratory tests for shaken baby syndrome should include:
- Complete blood cell count (CBC) with platelet count
- Prothrombin time (PT)
- Partial thromboplastin time (PTT)
- Chemistry panel
- Aspartate aminotransferase (AST)
- Alanine aminotransferase (ALT)
- Amylase
- Lipase
- Urinalysis

## Electrocardiogram
There are no ECG findings associated with shaken baby syndrome.

## X-ray
There are no specific x-ray findings associated with shaken baby syndrome, however, in order to identify child abuse in children aged less than two years with unexplained trauma,  a skeletal survey should be performed with radiographs of the:
- Skull
- Spine
- Ribs
- Long bones

## Echocardiography or Ultrasound
There are no echocardiography or ultrasound findings associated with shaken baby syndrome.

## CT scan
Noncontrast head CT is the initial radiologic workup for evaluating intracranial injury due to abusive head trauma (AHT). CT is helpful in detecting:
- Skull fracture
- Intracranial hemorrhage
- Ischemic changes
- Brain edema

## MRI
MRI may be helpful in:
- Detecting subacute and chronic subdural bleeding
- Evaluating the extent of injuries in the parenchyma
- Differentiating chronic subdural from subarachnoid collections

## Other Imaging Findings
There are no other imaging findings associated with shaken baby syndrome.

## Other Diagnostic Studies
There are no other diagnostic studies associated with shaken baby syndrome.

# Treatment

## Medical Therapy
- Vital signs should be monitored.
- The initial care of AHT is to maintain the patient's airway, breathing, and circulation.
- Patients without impairment of consciousness may be managed with supportive care.
- Hypotension is treated with fluids.
- Intubation and mechanical ventilation are required in patients with moderate impairment of consciousness, severe respiratory insufficiency, or hemodynamic instability.
- Oxygenation should be monitored with a pulse oximeter.
- Intracranial pressure (ICP) should be monitored.
Maintain ICP below 20 mmHg and minimal cerebral perfusion pressure (CPP) over 40 mmHg.
The age-dependent CPP is recommended as the following:
50 mmHg for 2-6 years
55 mmHg for 7-10 years
60 mmHg for 11-16 years
- Maintain ICP below 20 mmHg and minimal cerebral perfusion pressure (CPP) over 40 mmHg.
- The age-dependent CPP is recommended as the following:
50 mmHg for 2-6 years
55 mmHg for 7-10 years
60 mmHg for 11-16 years
- 50 mmHg for 2-6 years
- 55 mmHg for 7-10 years
- 60 mmHg for 11-16 years
- Increased intracranial pressure (IICP) should be decreased in order to prevent secondary brain injury by:
Hyperventilation
Maintain the PaCO2 at 25-30 mmHg (since excessive hyperventilation and hypocapnia result in vasoconstriction and decreased cerebral perfusion, capnography is recommended to monitor end-tidal CO2)
Raise the head to 30 degree
Improves venous return without affecting cerebral blood flow
Hypertonic agents may be used in moderate IICP.
3% hypertonic saline bolus 2-6 ml/kg, followed by 0.1-1 ml/kg/hour till the upper limit of serum osmolarity 360 or sodium level 155 g/dl.
Mannitol
0.25-1 gm/kg IV every 4-6 hours with the upper limit of serum osmolarity 320.
Sedation with barbiturates may be needed in persistent IICP.
Barbiturates decrease cerebral metabolism and in turn decrease cerebral blood flow and therefore, reduce ICP.
Thiopental or pentobarbital
- Hyperventilation
Maintain the PaCO2 at 25-30 mmHg (since excessive hyperventilation and hypocapnia result in vasoconstriction and decreased cerebral perfusion, capnography is recommended to monitor end-tidal CO2)
- Maintain the PaCO2 at 25-30 mmHg (since excessive hyperventilation and hypocapnia result in vasoconstriction and decreased cerebral perfusion, capnography is recommended to monitor end-tidal CO2)
- Raise the head to 30 degree
Improves venous return without affecting cerebral blood flow
- Improves venous return without affecting cerebral blood flow
- Hypertonic agents may be used in moderate IICP.
3% hypertonic saline bolus 2-6 ml/kg, followed by 0.1-1 ml/kg/hour till the upper limit of serum osmolarity 360 or sodium level 155 g/dl.
- 3% hypertonic saline bolus 2-6 ml/kg, followed by 0.1-1 ml/kg/hour till the upper limit of serum osmolarity 360 or sodium level 155 g/dl.
- Mannitol
0.25-1 gm/kg IV every 4-6 hours with the upper limit of serum osmolarity 320.
- 0.25-1 gm/kg IV every 4-6 hours with the upper limit of serum osmolarity 320.
- Sedation with barbiturates may be needed in persistent IICP.
Barbiturates decrease cerebral metabolism and in turn decrease cerebral blood flow and therefore, reduce ICP.
Thiopental or pentobarbital
- Barbiturates decrease cerebral metabolism and in turn decrease cerebral blood flow and therefore, reduce ICP.
- Thiopental or pentobarbital
- Continuous EEG (cEEG) monitoring should be performed and antiepileptic drug may be used to reduce the risk for early posttraumatic seizures (EPTS).
Seizure may occur at any stage.
- Seizure may occur at any stage.
- Stepwise hypothermia keeps the body temperature between 32 C and 33 C for 48 hours and neuromuscular blockade may be helpful in preventing shivering.
Therapeutic hypothermia may reduce:
Inflammation
Cell death
Excitotoxicity
Acute seizures
Cerebral metabolic demands
- Therapeutic hypothermia may reduce:
Inflammation
Cell death
Excitotoxicity
Acute seizures
Cerebral metabolic demands
- Inflammation
- Cell death
- Excitotoxicity
- Acute seizures
- Cerebral metabolic demands

## Surgery
Decompressive craniectomy (limits secondary brain injury by removing part of the skull and allowing brain swelling which ) is indicated when there is:
- No response to prior treatments
- Neurologic deterioration
- Signs of herniation

## Primary Prevention
Prevention of AHT includes:
- Decrease in child abuse and maltreatment
- Parental education with public service announcements, family resource centers, and home visit programs in:
Parenting
Child development
Dealing with a child's cry
Parental resilience
Danger of shaking a baby
Social support
- Parenting
- Child development
- Dealing with a child's cry
- Parental resilience
- Danger of shaking a baby
- Social support

## Secondary Prevention
Retinal hemorrhages and subdural hematomas associated with spine injuries and/or bone raise high suspision for shaken baby syndrome.
Healthcare providers should report suspected child abuse to child protective services.