Investigation of Suspected Abusive Head Trauma in Children with subdural haemorrhages under 2 years old.
To detail recommended practice for the investigation of suspected abusive head trauma (AHT) involving sub-dural haemorrhages in children under two years of age at Cambridge University Hospital Foundation Trust .
Section A -To provide information, including a literature review of current papers concerning AHT involving sub-dural haemorrhage
Section B - To provide general practical guidelines
APPT activated partial thromboplastin time
CSF cerebrospinal fluid
CT computed tomography
FBC full blood count
FLAIR fluid attenuated inversion recovery
GA1 glutaric aciduria type 1
MRI magnetic resonance imaging
AHT Abusive head trauma
Non-AHT Non abusive head trauma
PT prothrombin time
SDH subdural haemorrhage
A1. Introduction AHT involving injury to or bleeding around the brain is one of the most serious forms of physical child abuse. It carries severe consequences for the child. Recently published population studies report a mortality of 8% in AHT cases with 53% of AHT cases having persistent neurological impairment at hospital discharge. AHT is the leading cause of death, in children who have been abused and 31-45% of children who survive experience ongoing problems.(1)
We have adopted the term ”Abusive Head Trauma” inline with recent nomenclature proposed by the Committee on Child Abuse and Neglect; American Academy of Paediatrics to include an inflicted injury to the head and its contents. Brain injury may well include elements of both impact and acceleration –deceleration injury. But the term AHT does not apply causality and in reality the causal mechanism is rarely confirmed. This should be used in preference to ‘Shaken Baby Syndrome’, “intentional head injury” or “non accidental head injury”.
AHT occurs most commonly in children under one year of age. It is estimated that between 20-24 per 100,000 infants under the age of one year are diagnosed with AHT in the UK. This rises to 36/100,000 in children under six months, on average a paediatrician in a district general hospital will see one case every one to two years but regional Paediatric Intensive care Units and Paediatric Neurologists will do so on a regular basis. Studies have found no association between ethnicity and AHT incidence, but AHT has been observed to be more common in lower socio-economic groups.(1)
Many children suffering AHT may have experienced previous episodes of physical abuse. Any suspicion of physical abuse of a baby or child must be fully investigated to identify the condition and prevent further abuse. However, it is also essential to give full consideration to differential diagnoses (discussed further in sections A8 and B4).
2011 guidance from the The Crown Prosecution Service states that AHT will usually be diagnosed by ‘the Triad’ of internal head injuries, namely retinal haemorrhages, subdural haemorrhages and encephalopathy(2).
A2. Involvement of the Professional Team Once a diagnosis of ‘possible AHT’ has been made, it is the duty of the consultant paediatrician responsible for the medical care to inform the Safeguarding Children Team. If the child is on PICU then this would the Intensivist. If the child is on the ward when the possibility of AHT is raised, then this would be general paediatrician, or the paediatric neurologist if the child is under the neurosurgery team. Referral to the CYPS (Children’s Social Care) should be made as soon as possible. See Child protection - safeguarding children procedure. Further assessment and investigations should then proceed in accordance with these guidelines, after the child has been clinically stabilised.
The child’s care and investigation will ultimetaly be lead by a lead local paediatrician, they should be identified and informed on the first working day after identification of SDH, with a consultant to consultant phone call, and clear decision on who is leading the below.
Relevant specialist teams should be contacted as usual with regard to the child’s clinical condition.
NICE guidance recommends that “A clinician with expertise in non-accidental injuries in children should be involved in any suspected case of non-accidental injury in a child”.(3). .
The on-call neurosurgical registrar will discuss any child referred for a neurosurgical opinion with subdural haemorrhage with their neurosurgical consultant.
Overall responsibility for the child protection investigation will lie with Social Care, who will liaise with relevant allied services e.g. the Police.
It is essential for all medical professionals involved in the child’s care to remember that good documentation is vital, as all findings may have to bear examination in court.
A list of useful contacts at CUHFT is provided in section B.
A3. Identification of Suspected AHT Children may present with clear signs of head injury, such as unconsciousness, fitting, paralysis or extreme irritability. However, some may present with less specific signs such as increased head circumference, poor feeding or excessive crying.
Brain injuries may be asymptomatic but observed on radiological imaging performed if other non-accidental injury is suspected (e.g. rib fractures, unexplained bruising). Children can suffer non abusive head trauma by a variety of mechanisms. However, some features are particularly associated with AHT:
Table 1 From Kemp A (34)
Positive predictive values and OR for features associated with AHT
PPV (97.5% CI)
OR (97.5% CI), p
93% (73% to 98%)
17 (5 to 58), <0.001
73% (5% to 88%)
3 (0.7 to 13), 0.13
71% (48% to 86%)
3.5 (1.1 to 11), 0.03
66% (45% to 82%)
3 (0.7 to 12), 0.13
Long bone fractures*
59% (48% to 69%)
1.7 (0.8 to 3.6), 0.14
44% (22% to 68%)
0.85 (0.3 to 2.3), >0.2
Head and neck bruising
37% (4% to 90%)
0.8 (0.07 to 9), >0.2
* Estimates in this analysis are deemed to be conservative owing to missing data as children who have head trauma from non-abusive causes rarely have complete skeletal surveys or full ophthalmology examinations.
AHT, abusive head trauma; PPV, positive predictive value
Subdural haemorrhage – in three studies, 63%, 54% and 82% of cases of SDH were considered to be probable AHT (4-6).
Apnoea (1, 7) apnoea is significantly associated with AHT and appears to coincide with the fact that hypoxic ischaemic injury is commonly seen on MRI
Seizures – seizures have been shown to occur more frequently in AHT than Non-AHT and may exacerbate further hypoxic ischaemic damage to the brain
Rib fractures(1, 7) and long bone fractures have been found to be associated with AHT. The explanation for this is likely to be the fact that most cases of AHT include a combination of shaking injuries with or without impact
Retinal haemorrhages (RH) are strongly associated with AHT . Most studies identified retinal haemorrhages in 80-90% of confirmed AHT. RH have also been observed in severe Non-AHT but not in trivial accidental head injuries(5,8).
Skull fractures are more associated with Non-AHT. As most cases of non-AHT arise from falls or impact injuries that will predispose to skull fractures.
Bruises to the head and neck(1, 7) (N.B. please refer to the Addenbrooke’s Procedure for Bruising in Children not independently mobile)
Further detail concerning non-accidental head and spinal injury is available at Welsh Child Protection Systematic Review group - Neurological injuries in Children
NICE Clinical Guideline 89 When to suspect child maltreatment and the RCPCH Child Protection Companion provide useful information for identification of suspected NAHI.
A4. Subdural Haemorrhage Both accidental and non-accidental head injury can cause brain injuries of these types. The features seen in AHT include bleeding around the brain, most commonly subdural haemorrhages with or without sub-arachnoid haemorrhages.(1)
Features which may distinguish AHT from non-AHT:
SDHs over both halves of the brain, or interhemispheric SDH(1,7). Apart from in AHT, SDH in the interhemispheric fissures or posterior and middle cranial fossa has only been reported following severe accidental trauma or coagulopathy. (10)
Children may present with SDH’s of varying ages. Some legal cases have raised the possibility that this pattern may arise from rebleeding into older SDH’s. However, the volume of any such rebleed is considered unlikely to cause raised intracranial pressure and thus this explanation is not compatible with the usual presentation with increased ICP, encephalopathy or general unwellness.(10)
A5. Retinal Haemorrhage Presence of retinal haemorrhages is strongly associated with AHT but is not specific for the diagnosis.
AHT haemorrhagic retinopathy typically causes multi-layer retinal haemorrhages throughout the retina, from the posterior pole to the ora serrata. Superficial nerve fibre layer haemorrhages are flame shaped and usually resolve within days, deeper retinal and sub-retinal haemorrhages can take weeks or months to resolve. Sub-hyaloid haemorrhages (blood trapped between the posterior vitreous face and the retina) often have a fluid level and can take many months to resolve. Vitreous haemorrhage is frequent in severe cases.
Although retinal haemorrhages cannot be dated with precision, if deep retinal haemorrhages are present but no superficial nerve fibre layer haemorrhages are seen, the causative event is likely to have taken place more than 24 hours prior to the examination.(12)
A recent review has concluded that the overwhelming body of literature supports the conclusion that haemorrhagic retinopathy in otherwise previously well children who have not experienced severe accidental head injury have been submitted to abusive acceleration-deceleration trauma with or without head impact.(13)
Haemorrhagic retinopathy in NAHI can affect all retinal layers and haemorrhages of a variety of ages and stages may be present. Vitreous haemorrhage is common in NAHI, but otherwise rare. NAHI is also associated with retinoschisis, retinal detachment and dislocated lenses.(14)
Retinal haemorrhage may be unilateral or asymmetrical in terms of number and distribution, however, some victims have none at all (15-25%)(15). In severe life threatening trauma (motor cycle, great height) retinal haemorrhage was found in less than 3%.(15)
Convulsions and prolonged CPR are very unlikely to be the sole cause of retinal haemorrhages.
It has been suggested that non-NAHI-related retinal haemorrhages could occur as a result of coagulopathy. However, it appears that this occurs only with obvious severe coagulopathy.(13)
Retinal haemorrhages are seen in up to 75% of neonates born by vacuum-assisted delivery, and in up to 33% of spontaneous vaginal deliveries. The majority of these resolve by two weeks of age, but have been seen to persist until 6 weeks of age.(16) However, the series reporting the disappaearance of these by 6 weeks of age is small.
If AHT is suspected, an ophthalmologist should perform a retinal examination using mydriatic drops and an indirect ophthalmoscope Ideally whilst ventilated and sedated on PICU. If retinal haemorrhages are seen, a consultant ophthalmologist with paediatric sub-specialty interest should be asked to review, document and comment on the findings. Where possible retinal digital imaging should be performed but this is usually only possible when the baby is sedated.
A6. Spinal Injury Two patterns of spinal injury are described in the context of physical abuse: neck injuries and chest/lower back injuries.
Cervical neck injuries (mean age 5 months): When children sustain neck injuries from physical abuse they often have co-existing inflicted brain injury and/or retinal haemorrhages. In many cases, spinal injury may not be immediately obvious as co-existing brain injury makes the patient difficult to assess. In some cases, the child may be reluctant or distressed when the neck is moved, indicating the underlying injury.(17)
Thoraco-lumbar (T12-L2) Chest/lower back injuries (mean age 13 months). These are predominatly fracture dislocations associated with thoracolumbar deformity, kyphosis and swelling. Spinal cord injury presenting with paraplegia and urinary retention .
A recent study found a high incidence of clinically occult spinal SDHs in children with AHT on MRI. None of the spinal haemorrhages observed were surgically evacuated and all those followed up had resolved. Further work is required to evaluate potential long-term complications.(18) there was debate as to whether cervical blood could “flow over” from posterior fossa haemorrhage, therefore the lower the blood in the spine, the more significant it is thought to be (expert group Cambridge).
An MRI of the spine must be included in the standard imaging protocol when AHT is suspected (see section B1)
More information concerning spinal injuries in non-accidental injury can be found at Welsh Child Protection Systematic Review Group - Spinal injuries key messages.
A7. Bony Injuries There is a significant association between presence of multiple fractures and abuse.
In one study, 24% of children with suspected non-accidental injury had a positive skeletal survey.(19)
In children under 4 months of age, just over 50% of fractures are suspected to be abusive, whereas over the age of 4 months the majority of fractures are accidental.(20)
In comparison with children with accidental injuries, children with AHT were more likely to have a SDH in the absence of a skull fracture.(4) Skull fractures do not heal by callus formation and so dating of an injury is especially difficult. If the edges are round and smooth it is likely to be more than two weeks old(11).
No clear difference exists in the distribution of complex skull fractures between accidental and non-accidental injuries(21).
A typical non-skull fracture of child abuse is the metaphyseal fracture caused by twisting the limb. It can also occur from birth injury (eg breech extraction). The ‘bucket handle’ and ‘corner’ type metaphyseal fractures may be suggestive of physical abuse. It is very important to target x-ray imaging on the metaphyses, as wider imaging can miss fractures(11).
More information about patterns of fractures seen in non-accidental injury is available from Welsh Child Protection Systematic Review Group - Fractures key messages and a recent review published a list of features associated with possible child abuse (see box 2 in the linked article).
The Royal College of Radiologists recommends that a full skeletal survey must always be performed in children under 2 years when abuse is suspected. This should be the first imaging performed, unless head injury is suspected, when CT head should be performed first(22) (see section B1 for imaging protocol).
Full details of the recommended skeletal survey can be found in the Royal College of Radiologists Standards for Radiological Investigations of Suspected Non-accidental Injury. Note that a plain skull x-ray should be taken in addition to CT head, as linear skull fractures may not be identified on CT(23).
A8. Coagulation and Haematological Disorders The investigation of these disorders in the context of AHT, is challenging, and therefore all children should, be discussed with a paediatric (if available) haematologist prior to commencing.
It is essential to take a full haemostatic history of the patient and their family.
A standard haematological screen is detailed in section B. This screen will exclude the most serious bleeding disorders but not all (for example factor XIII deficiency, usually seen in consanguineous families, which is not detected on the standard clotting screen and may be a cause of spontaneous intracranial haemorrhage).
If bleeding is still unexplained following this screen, further tests are possible and a paediatric haematologist should be consulted.
The results of these tests should be interpreted based on the age-specific normal ranges (detailed in Liesner et al, Blood Coag Fibrinolysis 2004 or on advice from Paediatric Haematology).
It should be remembered that factor XII deficiency may result in dramatically prolonged APTT, but does not cause a bleeding disorder in vivo.
Platelet function analysis may be performed but this is unreliable in children under 2 year of age except in the identification of severe platelet abnormalities such as Glanzmann’s thrombasthaenia.
Renal and liver function tests can be useful in exclusion of acquired coagulation defects.
It should be considered whether any diagnosed bleeding tendency actually relates to an injury or bruise, and it should also be remembered that children with bleeding diatheses may also have been abused.
A9. Differential Diagnoses There are many reported causes and associations of subdural haemorrhage, which must be considered in the production of a differential diagnosis. These include(11):
Traumatic labour – prospective examination of a cohort of neonates showed that presence of unilateral or bilateral SDH was not necessarily indicative of excessive birth trauma i.e. some babies with normal vaginal deliveries may have SDH. All haematomas had completely resolved by 4 weeks of age in one small series(24).
Arachnoid cysts/external hydrocephalus – SDH is an extremely rare complication of arachnoid cyst, and there is no generally acknowledged agreement that external hydrocephalus predisposes to SDH. For these diagnoses to be applicable, there must be evidence that the putative causative lesion was present prior to the development of the symptomatic SDH. This is obtainable by correct interpretation of imaging and head circumference measurements(25).
Glutaric aciduria type 1 (GA1) – this is a rare inborn error of metabolism which is associated with acute SDH and chronic subdural collections. Children with SDH int his condition do not have associated injuries such as fractures. It has been recommended that screening for GA1 should be added to the standard array of investigations for suspected NAHI. This screen involves urine organic analysis, glutarylcarnitine measurement on blood spots and plasma total and free carnitine estimations, (followed by confirmatory enzymology(26), if indicated by expert opinion) .
Menkes disease, is a severe neurological disorder that produces severe neurodegeneration in children over 6 months of age (normally occurs earlier). Therefore caeruloplasmin levels may be considered in children under 6 months and over that age with a previous history of neurological or developmental difficulties. Copper analysis is complex and is only done on recommendation of a consultant paediatric neurologist.
The ‘Unified Hypothesis’ - This states that SDH in infants could arise from a combination of factors as a ‘phenomenon of immaturity’ in the absence of head trauma(27). However, subsequent papers have concluded that unexplained SDH according to the unified hypothesis was ‘an extreme rarity’ and that NAHI was the most common cause of SDH in children <1 year.(28)
Further details of differential diagnoses and recommended investigations are detailed in section B.
A10. Timing of Injury In court, the paediatrician may be asked to give an estimate of the age of the injury. It must be appreciated that only approximations can be given.
It is not possible to accurately age a subdural haematoma on MRI scans(29) alone.
Accurate ageing of a subdural haematoma on CT scan is not possible after 1 week. There may some visible characteristics on CT which can suggest the age of a haematoma: acute (1-5 days) haematomas appear hyperdense relative to grey matter, whereas subacute (7-20 days) haematomas appear isodense and chronic (over 20 days) haematomas appear hypodense(30). However, other studies have shown that SDHs may remain hyperdense up to 11 days after injury, so this method of ageing injuries is not accurate(29). Advice should be sought from an experienced neuroradiologist.
Spectophotometry of subdural aspirate can identify presence of bilirubin, which suggests that bleeding occurred 24 hours – 3 days prior to aspiration(31).
CSF cytology and assessment of macrophage markers provide further tests for timing of bleeding. These investigations may be useful in assessing the consistency of a given injury with a reported/suspected cause e.g. birth trauma/accidental injury(11).
Xanthochromia from physiological jaundice of the newborn may persist in the CSF for up to 6 weeks(11).
A11. Legal Implications and Guidelines Recent guidelines have been issued by The Crown Prosecution Service regarding the prosecution approach to non-accidental head injuries(2). The salient points are listed below:
AHT cases will usually be diagnosed by a triad of internal head injuries, “the Triad”, consisting of subdural haemorrhages, retinal haemorrhages and encephalopathy.
Proof of AHT usually requires the triad of injuries plus supporting evidence (see CPS guidelines for details of supporting evidence).
CPS policy is to resist challenges to the Triad diagnosis based on the ‘Unified Hypothesis (see (27)).
Careful and efficient documentation of all findings is essential.
The diagnosis of ‘suspected AHT’ has to be confirmed or rebutted on the basis of subsequent investigations. The degree of suspicion will then be qualified by a degree of certainty(11):
Probable (on a balance of probabilities, greater than 50% chance)
Possible/questionable (legally not provable at the time)
Not AHT(suspicion not sustained)
Section B – A Practical Guide to Investigation
As always, the first objective on acute presentation is clinical stabilisation of the child. Following stabilisation, if AHT is suspected social care should be informed at the earliest available opportunity via telephone and followed up in writing within 24 hours. Care should be taken to inform Social Care of any other children living within the same household and if possible their current whereabouts. Within working hours the Safeguarding Children Team should be informed. The following protocol for investigation followed. Relevant specialist teams should be contacted as normal with regard to the child’s clinical condition. Remember that good documentation is essential. A ‘checklist’ to assist with tracking of investigations is provided in appendix 2, which can be attached to the patient’s notes to provide a quick-glance overview of what investigations have been performed.
Concerns that AHT is a possibility should be shared with key professionals at the earliest opportunity, this includes Childrens Social Care, the Safeguarding Children team at CUHFT, Police and the local District Paediatrician (see section A2.i). Strategy discussions will be held in accordance with the wishes of The Social Care department and Police. Trust staff may be invited to participate in these discussions. The responsible paediatrician will be asked for an opinion about the nature of the injuries and may need to introduce the subject with specific mention of the 14 day investigation period, it should be established at that time whether interim reports are required . It is the responsibility of the consultant in charge of the patient to liaise with social care and police on a regular daily basis whilst safeguarding procedures continue. The allocated Social worker may convene a further strategy meeting to be held in the hospital setting in order to gather more information and plan further investigations. A senior member of the medical team caring for the patient should attend to represent CUHFT or ensure that up to date information is available and comprehensible to the relevant team members.
B1. Imaging Protocol The protocol for head imaging recommended in guidelines published by the Royal College of Radiologists in association with the Royal College of Paediatrics and Child Health is shown below(22):
It is important to perform diffusion-weighted MRI as this is capable of detecting secondary ischaemic sequelae of NAHI which may be occult on routine sequences(22).
An MRI of the spine should be performed.
A full skeletal survey should also be performed, including a plain skull x-ray.(22). Full details of the views to be taken are available from the Royal College of Radiologists Standards for Radiological Investigations of Suspected Non-accidental Injury (p20) along with further details and guidance concerning head imaging.
A repeat chest x-ray should be performed at 14 days from putative injury date.
If a child with confirmed NAHI has a sibling under 2 years of age, a skeletal survey for the sibling should be considered(23).
Radiation risk: a recent study found a small, statistically non-significant increase in risk for all cancers following diagnostic radiography in early infancy.(32)
B2. Haematology Protocol A haemostatic history is essential and should include the following:
History of bleeding in the child (ask specifically about circumcision or other surgery, particularly ENT or dental procedures)
Blood group (essential for interpretation of vWF results)
Note the interpretation of the PFA and TEG is difficult under the age of 2yrs, and must always be done in discussion with the paediatric haematologist.
Minimum volumes required (all citrate samples) are as follows:
Coagulation screen – 1.2ml
Factor assays – 1.2-2.4ml
TEG (for α2 antiplasmin) 1.2ml.
PFA – ideally 4ml (must be analysed within 4 hours)
These may need to be done in stages.
It is important to ensure that there is no contamination with heparin (potentially problematic e.g. if drawn from arterial lines in PICU)
Ideally, send 6x1.4ml citrate (green) bottles before any blood products are given or as soon as possible and send to haematology lab within four hours for spinning and freezing.
Results of these tests should be based on the age-specific normal ranges, which can be found in Liesner et al, Blood Coag Fibrinolysis 2004, or on request from Paediatric Haematology.
If bleeding is still unexplained after these tests, discuss with the consultant paediatric haematologist who will recommend further tests. The laboratory does have a standard NAI screen which can be requested.
Please discuss with the Specialist Haemostasis lab before taking samples to arrange suitable time for lab to process tests, usually within normal working hours. If child is moribund or situation dictates that samples cannot wait, then arrange with lab for samples to be spun down and frozen immediately, to be analysed at a later date.