Magnetic resonance imaging in acute non-accidental head injury

Spinal cord injury as an indicator of abuse in forensic assessment of abusive head trauma (AHT)

Abusive head trauma (AHT) in children is notoriously one of the most challenging diagnoses for the forensic pathologist. The pathological “triad”, a combination of intracranial subdural haematoma, cerebral oedema with hypoxic-ischaemic changes and retinal haemorrhages, is frequently argued to be insufficient to support a corroborated verdict of abuse. Data from all available English-language scientific literature involving radiological and neuropathological spinal cord examination is reviewed here in order to assess the contribution of spinal cord changes in differentiating abusive from accidental head trauma. In agreement with the statistically proven association between spinal subdural haemorrhage (SDH) and abuse (Choudhary et al. in Radiology 262:216–223, 2012), spinal blood collection proved to be the most indicative finding related to abusive aetiology. The incidence of spinal blood collection is as much as 44–48% when all the spinal cord levels are analysed as opposed to just 0–18% when the assessment is performed at cervical level only, in agreement with the evidence of the most frequent spinal SDH location at thoracolumbar rather than cervical level. In this review, the source of spinal cord blood collection and how the age of the child relates to the position of spinal cord lesions is also discussed. We concluded that the ante mortem MRI examination and post mortem examination of whole-length spinal cord is of fundamental interest for the assessment of abuse in the forensic setting.

Shaken Baby Syndrome: Magnetic Resonance Imaging Features in Abusive Head Trauma

In the context of child abuse spectrum, abusive head trauma (AHT) represents the leading cause of fatal head injuries in children less than 2 years of age. Immature brain is characterized by high water content, partially myelinated neurons, and prominent subarachnoid space, thus being susceptible of devastating damage as consequence of acceleration–deceleration and rotational forces developed by violent shaking mechanism. Diagnosis of AHT is not straightforward and represents a medical, forensic, and social challenge, based on a multidisciplinary approach. Beside a detailed anamnesis, neuroimaging is essential to identify signs suggestive of AHT, often in absence of external detectable lesions. Magnetic resonance imaging (MRI) represents the radiation-free modality of choice to investigate the most typical findings in AHT, such as subdural hematoma, retinal hemorrhage, and hypoxic-ischemic damage and it also allows to detect more subtle signs as parenchymal lacerations, cranio-cervical junction, and spinal injuries. This paper is intended to review the main MRI findings of AHT in the central nervous system of infants, with a specific focus on both hemorrhagic and non-hemorrhagic injuries caused by the pathological mechanisms of shaking. Furthermore, this review provides a brief overview about the most appropriate and feasible MRI protocol to help neuroradiologists identifying AHT in clinical practice.

[Bridging vein injuries in shaken baby syndrome : Forensic-radiological meta-analysis with special focus on the tadpole sign]

Shaken baby syndrome is a common variant of the abusive head trauma in infants and toddlers and is still subject of intensive research. In recent years, a number of radiological studies on the diagnostic and forensic relevance of injured bridging veins were conducted using different imaging modalities. The present article will give an overview on the current state of research in this field and will discuss the forensic implications. The meta-analysis of the seven currently existing studies revealed that injuries of the bridging veins and bridging vein thromboses, respectively, frequently appear as rounded, enlarged, and/or tubular structures. The "tadpole sign" may serve as a valuable tool for the identification of these formations. Especially, T2*/SWI (susceptibility-weighted imaging) sequences allow for good detectability of these lesions and should always be generated when abusive head trauma is suspected. In conclusion, it can be recommended that the presence of radiologically detectable bridging vein injuries should give reason to search for other manifestations of physical child abuse.

Pediatric abusive head trauma

Abusive head trauma (AHT), used to be named shaken baby syndrome, is an injury to the skull and intracranial components of a baby or child younger than 5 years due to violent shaking and/or abrupt impact. It is a worldwide leading cause of fatal head injuries in children under 2 years. The mechanism of AHT includes shaking as well as impact, crushing or their various combinations through acceleration, deceleration and rotational force. The diagnosis of AHT should be based on the existence of multiple components including subdural hematoma, intracranial pathology, retinal hemorrhages as well as rib and other fractures consistent with the mechanism of trauma. The differential diagnosis must exclude those medical or surgical diseases that can mimic AHT such as traumatic brain injury, cerebral sinovenous thrombosis, and hypoxic-ischemic injury. As for the treatment, most of the care of AHT is supportive. Vital signs should be maintained. Intracranial pressure, if necessary, should be monitored and controlled to ensure adequate cerebral perfusion pressure. There are potential morbidity and mortality associated with AHT, ranging from mild learning disabilities to severe handicaps and death. The prognosis of patients with AHT correlates with the extent of injury identified on CT and MRI imaging. The outcome is associated with the clinical staging, the extent of increased intracranial pressure and the existence of neurological complications such as acquired hydrocephalus or microcephalus, cortical blindness, convulsive disorder, and developmental delay. AHT is a potentially preventable disease, therefore, prevention should be stressed in all encounters within the family, the society and all the healthcare providers.

Venous injury in abusive head trauma

BACKGROUND

Abusive head trauma (AHT) is an important cause of serious brain injury in infants and young children who have characteristic clinical and imaging findings that are discordant with the clinical history provided. Recent attention has focused on abnormalities of the cranial venous sinuses and cortical veins, both on MRI and at autopsy. Although many have interpreted these to be secondary to the AHT, some have recently argued that these venous abnormalities represent primary cortical sinus and venous thrombosis that leads secondarily to subdural hemorrhage and secondary brain injury. Direct trauma to the veins and sinuses has been reported at autopsy in AHT, but there has been no systematic study of venous abnormalities in cases of AHT.

OBJECTIVE

The purpose of this study was to define the incidence and characteristics of venous and sinus abnormalities in AHT.

MATERIALS AND METHODS

We included all children <36 months of age who were diagnosed with abusive head trauma between 2001 and 2012 and who had MRI and magnetic resonance (MR) venography as part of their diagnostic workup. We analyzed age, gender and clinical findings. MRI and MR venography were analyzed independently by two neuroradiologists with a focus on abnormalities involving the intracranial veins and venous sinuses.

RESULTS

A total of 45 children were included. The median age was 3 months (range 15 days to 31 months) and 28 were boys (62%). Clinical findings included retinal hemorrhage in 71% and extracranial fractures in 55%. CT or MRI demonstrated subdural hemorrhage in 41 (91%); none had subdural effusions. In 31 cases (69%) MR venography demonstrated mass effect on the venous sinuses or cortical draining veins, with either displacement or partial or complete effacement of the venous structures from an adjacent subdural hematoma or brain swelling. We also describe the lollipop sign, which represents direct trauma to the cortical bridging veins and was present in 20/45 (44%) children.

CONCLUSION

Evidence of displacement or compression of cortical veins and sinuses from subdural hemorrhage or edema on MR venography was present in the majority of children with abusive head trauma. Evidence of direct trauma to the veins (lollipop sign) was identified in nearly half of cases. It is important to understand the superimposed effects of subdural hematoma and brain swelling on the veins and sinuses to differentiate it from cortical sinus and venous thrombosis.

Imaging of bridging vein thrombosis in infants with abusive head trauma: the "Tadpole Sign"

OBJECTIVES

Abusive head trauma (AHT) in infants is usually diagnosed using a multi-disciplinary approach by investigating the circumstances and identifying morphological indicators, for example, subdural hematomas (SDHs), subdural hygromas (SDHys), retinal haemorrhages and encephalopathy. The present morphological study investigates the incidence, radiological characteristics and non-radiological co-factors of bridging vein thrombosis (BVT) in infants with AHT.

METHODS

From 2002 to 2013, computed tomography (CT) and magnetic resonance imaging (MRI) material of 628 infants aged 0-2 years were analysed retrospectively. If available, medicolegal expert opinions were additionally considered. Cases with SDHs and/or SDHys were identified and systematically evaluated as to the presence and characteristics of BVT.

RESULTS

SDHs and/or SDHys were present in 29 of the 81 cases exhibiting morphological abnormalities in the initial CT. Among these, 11 cases (40%) had BVT (mean age = 5.0 months). BVT could be best depicted in the T1-weighted spin echo and T2*/susceptibility-weighted MRI. In one case, BVT could be depicted indirectly using time-of-flight MR venography. The predominant (73%) BVT shape was found to be tadpole-like ("Tadpole Sign").

CONCLUSIONS

In the absence of appropriate accidental trauma, BVT appears to be a strong indicator of AHT. Therefore, the BVT/Tadpole Sign represents compelling cause to search for other signs of AHT.

KEY POINTS

• BVT is an excellent indicator of AHT in SDH/SDHy cases. • Accidental trauma must be ruled out before diagnosing AHT. • The Tadpole Sign appears to be the most characteristic shape of BVT. • BVT can be depicted using CT, MRI and MR venography. • The Tadpole Sign suggests searching for other signs of AHT.

Multifocal Signal Loss at Bridging Veins on Susceptibility-Weighted Imaging in Abusive Head Trauma

Identifying abusive head trauma (AHT) in infants is difficult because often there are no externally visible injuries and symptoms are nonspecific. The radiological finding that usually raises suspicion of AHT--especially when found with retinal hemorrhage and inappropriate history--is subdural hematoma (SDH). In addition to that, bridging vein thrombosis, assessed by imaging or autopsy, has been reported as a sign of the traumatic cause of SDH. Here we present two cases of AHT-associated SDH in infants, in which multifocal signal loss at bridging veins was present on susceptibility-weighted imaging without signs of venous infarction. As susceptibility-weighted imaging has been reported to be more sensitive for blood products than gradient-echo T2-weighted imaging, we propose that it might help to identify clot formation on injured bridging veins and therefore increase the sensitivity of imaging studies for a traumatic cause of SDH, helping to identify AHT that is considered to be caused by violent shaking.

Natural history of traumatic meningeal bleeding in infants: semiquantitative analysis of serial CT scans in corroborated cases

BACKGROUND

The natural history of posttraumatic meningeal bleeding in infants is poorly documented, and the differences between inflicted head injury (IHI) and accidental trauma (AT) are debated. Autopsy findings have suggested that anoxia also plays a role in bleeding; however, these findings may not reflect what occurs in live trauma patients.

PURPOSE

We studied the natural history of traumatic meningeal bleeding in infants using serial computed tomography (CT) scans in corroborated IHI and AT.

MATERIALS AND METHODS

From our prospective series, we selected corroborated cases (confessed IHI or AT having occurred in public), who underwent at least three CT scans in the acute phase. We performed a semiquantitative analysis of meningeal bleeding using a four-tier scale (absent, faint, frank, and thick) derived from the Fisher grading for aneurysmal bleeding in four regions of interest (convexity, falx cerebri, sagittal sinus, and tentorium cerebelli).

RESULTS

We studied 20 cases: ten IHI and ten AT. Bleeding was maximal at the convexity initially, then increased along the falx and sagittal sinus, and then along the tentorium. Decrease and disappearance of blood was variable according to the site and the initial quantity of blood. We found no difference between IHI and AT.

CONCLUSION

Our findings suggest that the primary site of meningeal bleeding in infantile head trauma is the convexity of the brain; blood cells then migrate toward the midline following the flow of cerebrospinal fluid circulation and inferiorly following gravity. The pattern of bleeding in traumatic cases appears similar in IHI and AT but different from anoxic lesions.

Neuroradiological aspects of subdural haemorrhages

AIMS

To review the neuroimaging of a series of infants and young children admitted to hospital with subdural haemorrhage (SDH).

METHODS

Neuroradiological investigations of 74 children under 2 years of age, from South Wales and southwest England, in whom an SDH or subdural effusion had been diagnosed between 1992 and 2001, were reviewed. Two paediatric neuroradiologists blinded to the original radiological report reviewed all the relevant images.

RESULTS

Neuroradiological review of images identified radiological features which were highly suggestive of non-accidental head injury (NAHI). Interhemispheric haemorrhages and SDHs in multiple sites or of different densities were almost exclusively seen in NAHI. MRI was more sensitive in identifying SDHs of different signal characteristics, posterior and middle cranial fossa bleeds, and parenchymal changes in the brain. CT scans, if performed with suboptimal protocols, were likely to miss small subdural bleeds.

CONCLUSIONS

Guidelines for neuroimaging in suspected NAHI are recommended. A radiologist with experience in NAHI should report or review these scans. The initial investigation should be CT, but MRI will also be necessary in most cases. Head CT should be an integral part of the skeletal survey in all infants less than 6 months of age referred for child protection investigation, and in children less than 2 years where child abuse is suspected and there are neurological signs, retinal haemorrhages, or fractures.

Inner calvarial erosion from traumatic subdural haematoma in infancy

CASE REPORT

This is a report of a case of a subdural haematoma in infancy of possible non-accidental aetiology with raised pericerebral pressure, which we postulate has eroded the inner table of the cranial bones and resulted in leakage of marrow precursor cells into the extradural space.

RESULT

Subdural tapping via the fontanelle has created a channel allowing subsequent ingress of nucleated red cell precursors into the subdural space. This addition to the subdural collection has prolonged its course necessitating subduro-peritoneal shunting.

Apnoea and brain swelling in non-accidental head injury

AIMS

(1) To identify whether infants and young children admitted to hospital with subdural haematomas (SDH) secondary to non-accidental head injury (NAHI), suffer from apnoea leading to radiological evidence of hypoxic ischaemic brain damage, and whether this is related to a poor prognosis; and (2) to determine what degree of trauma is associated with NAHI.

METHODS

Retrospective case series (1992-98) with case control analysis of 65 children under 2 years old, with an SDH secondary to NAHI. Outcome measures were presenting symptoms, associated injuries and apnoea at presentation, brain swelling or hypoxic ischaemic changes on neuroimaging, and clinical outcome (KOSCHI).

RESULTS

Twenty two children had a history of apnoea at presentation to hospital. Apnoea was significantly associated with hypoxic ischaemic brain damage. Severe symptoms at presentation, apnoea, and diffuse brain swelling/hypoxic ischaemic damage were significantly associated with a poor prognosis. Eighty five per cent of cases had associated injuries consistent with a diagnosis of non-accidental injury.

CONCLUSIONS

Coma at presentation, apnoea, and diffuse brain swelling or hypoxic ischaemia all predict a poor outcome in an infant who has suffered from SDH after NAHI. There is evidence of associated violence in the majority of infants with NAHI. At this point in time we do not know the minimum forces necessary to cause NAHI. It is clear however that it is never acceptable to shake a baby.