Shaken Baby Syndrome

Shaken baby syndrome, now more often called abusive head trauma, is inflicted brain injury in infants and young children caused by violent shaking, with or without impact. It typically produces subdural haemorrhage, retinal haemorrhage and encephalopathy.

It affects mainly infants under 1 year, peaking at 2 to 4 months, a time of peak crying. Reported incidence is about 14 to 40 in 100 000 infants under 1 year, depending on the setting. Perpetrators are most often a parent or male carer, and crying that provokes frustration is the commonest trigger.

Mortality is about 1 in 5 in hospitalised cases, and most survivors have lasting neurological, visual or cognitive deficits.

Pathophysiology.

Infants have weak neck muscles, a relatively large head and a high water content brain. Repeated acceleration and deceleration tears bridging veins, causing subdural haemorrhage, and shearing of axons causes diffuse injury.

Impact adds skull fracture and contusion. Hypoxic ischaemic injury from apnoea and cervicomedullary injury, with brain swelling, often cause more harm than the initial mechanical injury.

• Non-specific presentation: irritability, poor feeding, vomiting, lethargy, hypotonia, seizures and apnoea.
• Severe cases: coma, bulging fontanelle, rapidly increasing head circumference, bradycardia, hypotension and collapse.
• History of trauma is usually absent or is a minor fall inconsistent with the injury, with delayed presentation.
• Signs of other abuse: bruises on the head, face or trunk, rib and long bone fractures, and abdominal injury.

Red flags.

• Any infant with unexplained apnoea, seizures, encephalopathy or collapse.
• Retinal haemorrhages (especially multilayered and extending to the periphery), subdural haemorrhage of different ages, or rib and metaphyseal fractures.
• Inconsistent, changing or absent history.

• Urgent CT head to identify haemorrhage, swelling and fracture, followed by MRI brain and spine within days, to define the extent of injury, hypoxic ischaemic change and cervical cord or ligament injury.
• Dilated fundoscopy by an ophthalmologist within 24 to 48 hours, and documentation of retinal haemorrhages.
• Skeletal survey, repeated at 11 to 14 days.
• Blood tests: full blood count, coagulation screen, fibrinogen, liver enzymes, amylase, bone profile, vitamin K status and glucose. Urine organic acids when glutaric aciduria type 1 is a possibility.
• EEG if seizures or altered consciousness.

Differential diagnosis. Accidental head injury with major trauma, birth related subdural haemorrhage (usually resolves by 4 weeks), benign enlargement of the subarachnoid space with minor trauma, coagulopathy and vitamin K deficiency, glutaric aciduria type 1, meningitis, metabolic disease and hypoxic ischaemic injury.

Resuscitation and neuroprotection.

• Airway, breathing and circulation. Intubate for a Glasgow Coma Scale score of 8 or less, or when airway protection or oxygenation is poor.
• Treat seizures with levetiracetam 40 to 60 mg/kg IV or phenobarbital 20 mg/kg IV over 20 minutes.
• Raised intracranial pressure: head of the bed at 30 degrees in the midline, normal PaCO2 (4.5 to 5.0 kPa), osmotherapy with 3% sodium chloride 2 to 5 mL/kg over 10 to 20 minutes or mannitol 0.25 to 0.5 g/kg, and urgent neurosurgery review.
• Correct coagulopathy, anaemia, hypoglycaemia and hyponatraemia. Maintain normothermia.
• Neurosurgery for surgically treatable collections, decompression or intracranial pressure monitoring.

Safeguarding.

• Inform the senior paediatrician and local child protection services the same day. Admit and do not discharge. Hold a multi-agency discussion with social care and police, and record all findings carefully.
• Assess siblings. Consider medical causes through full investigation, rather than attributing injury to a single mechanism.

Monitoring. Neurological observation, intracranial pressure when invasive monitoring is used, sodium, glucose, and repeat imaging for deterioration. Long term follow up of development, vision, hearing, epilepsy and head growth.

Referral and escalation. Refer to paediatric intensive care, neurosurgery, ophthalmology, neurodevelopmental services and child protection teams.

Special groups. Infants born preterm or with disabilities are at increased risk and need the same assessment. Support for parents includes education on infant crying and coping strategies to prevent recurrence.