Is bridging vein rupture/thrombosis associated with subdural hematoma at birth?

BACKGROUND

The combination of bridging vein rupture/thrombosis and subdural hematoma in infants has recently gained attention as highly suggestive of abusive head trauma. While subdural hematomas are frequently observed at birth, there are no previous studies of bridging vein rupture/thrombosis prevalence in that context.

OBJECTIVE

To evaluate the prevalence of bridging vein rupture/thrombosis in newborns with and without subdural hematoma.

MATERIALS AND METHODS

This bicentric retrospective study (2012-2019) looked at all brain MRIs performed in neonates. We noted delivery method, demographic data and intracranial injuries and analyzed any clots at the vertex as potential markers of bridging vein rupture/thrombosis.

RESULTS

We analyzed 412 MRIs in 412 neonates. Age was (mean ± standard deviation [SD]) 5.4±2.2 days and 312 (76%) infants were full term (38.3±2.9 weeks from last menstrual period). The delivery method was vaginal birth for 42% (n=174), cesarean section for 43% (n=179), and unknown for 14% (n=59). Subdural hematoma was present in 281 MRIs (68.0%, [95% confidence interval = 63.3-72.5]). Six MRIs showed at least one clot at the vertex, assumed to be possible bridging vein rupture/thrombosis (1.5%, [0.5-3.1%]). Only one MRI showed more than two clots at the vertex, in a context of maternal infection. There was no significant difference in terms of gestational age at birth, delivery method or the presence of subdural hematoma or parenchymal injuries between those 6 infants and the 406 others.

CONCLUSION

Bridging vein rupture/thrombosis at birth is very rare and unlikely to be related to subdural hematoma.

Thrombosis is not a marker of bridging vein rupture in infants with alleged abusive head trauma

Aim

Thrombosis of bridging veins has been suggested to be a marker of bridging vein rupture, and thus AHT, in infants with subdural haematoma.

Methods

This is a non‐systematic review based on Pubmed search, secondary reference tracking and authors’ own article collections.

Results

Radiological studies asserting that imaging signs of cortical vein thrombosis were indicative of traumatic bridging vein rupture were unreliable as they lacked pathological verification of either thrombosis or rupture, and paid little regard to medical conditions other than trauma. Autopsy attempts at confirmation of ruptured bridging veins as the origin of SDH were fraught with difficulty. Moreover, microscopic anatomy demonstrated alternative non‐traumatic sources of a clot in or around bridging veins. Objective pathological observations did not support the hypothesis that a radiological finding of bridging vein thrombosis was the result of traumatic rupture by AHT. No biomechanical models have produced reliable and reproducible data to demonstrate that shaking alone can be a cause of bridging vein rupture.

Conclusion

There is no conclusive evidence supporting the hypothesis that diagnostic imaging showing thrombosed bridging veins in infants correlates with bridging vein rupture. Hence, there is no literature support for the use of thrombosis as a marker for AHT.

Venous injury in pediatric abusive head trauma: a pictorial review

Abusive head trauma (AHT) is the leading cause of fatal head injuries in children younger than 2 years. An intracranial pathology can exist even in the setting of a normal physical exam. A delay in the diagnosis of AHT can have serious life-threatening consequences for the child and increases the potential the child will be abused again. In this article, we review the traumatic subdural hematoma as well as various morpho-structural patterns of shearing injuries and thrombosis of intracranial bridging veins. This work serves as a summary of patterns of imaging features of intracranial venous injury in AHT, as described in the literature, to facilitate familiarity and early detection of abusive head trauma in the pediatric population. Essentially, in AHT there is a traumatic injury to the bridging vein with either partial or complete tear. This can secondarily result in thrombosis at the terminal end of the bridging vein with blood clots adjacent to the bridging vein.

Venous injury in pediatric abusive head trauma: a pictorial review

Abusive head trauma (AHT) is the leading cause of fatal head injuries in children younger than 2 years. An intracranial pathology can exist even in the setting of a normal physical exam. A delay in the diagnosis of AHT can have serious life-threatening consequences for the child and increases the potential the child will be abused again. In this article, we review the traumatic subdural hematoma as well as various morpho-structural patterns of shearing injuries and thrombosis of intracranial bridging veins. This work serves as a summary of patterns of imaging features of intracranial venous injury in AHT, as described in the literature, to facilitate familiarity and early detection of abusive head trauma in the pediatric population. Essentially, in AHT there is a traumatic injury to the bridging vein with either partial or complete tear. This can secondarily result in thrombosis at the terminal end of the bridging vein with blood clots adjacent to the bridging vein.

[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.

Traumatic macular retinoschisis in infants and children

PURPOSE

To provide detailed description of pediatric traumatic retinoschisis.

METHODS

The medical records of children with either abusive head trauma and traumatic macular retinoschisis seen at a single center from 1993 to 2006 were reviewed retrospectively. Clinical details were extracted from the record and photographic documentation. Evaluation regarding abuse excluded ophthalmology findings to avoid circular reasoning.

RESULTS

Of 134 patients with suspected abusive head trauma, 31 had retinoschisis. Mean age was 9 months. Of the 31, 22 (71%) offered a history of injury, and 9 (29%) were found unresponsive without history of injury; 6 were reportedly shaken. All patients had seizures, vomiting, and/or altered responsiveness. All had subdural hemorrhage, with cerebral edema in 17 (55%). In 10 (32%), there were findings of blunt force head injuries; in 4 of these there was no impact history. Retinal hemorrhages were present in all cases. Agreement between sidedness of retinoschisis and subdural hemorrhage was poor. Eleven patients had retinal folds, 3 of which had a hemorrhagic edge to the schisis. Nine patients had extracranial manifestations of abuse. Multidisciplinary team adjudications were as follows: of the 31 cases, 18 were suspicious for abuse, 11 were indeterminate, and 2 were possibly accounted for by accidental severe crush injury. Three children died, and 11 suffered neurological sequelae.

CONCLUSIONS

Traumatic retinoschisis in children is highly associated with subdural hemorrhage, neurologic symptoms, and poor outcomes. Even with a conservative approach to opinion formulation, traumatic retinoschisis was associated with likely abuse.

Parasagittal vertex clots on head CT in infants with subdural hemorrhage as a predictor for abusive head trauma

BACKGROUND

Abusive head trauma (AHT) is the most common cause of subdural hemorrhage (SDH) in infants younger than 12 months old. Clot formation in the parasagittal vertex seen on imaging has been associated with SDH due to AHT. There have been very few studies regarding these findings; to our knowledge, no studies including controls have been performed.

OBJECTIVE

To describe parasagittal vertex clots on head computed tomography (CT) in infants with SDH and AHT compared to patients with SDH and accidental trauma, and to evaluate for parasagittal vertex clots in the absence of SDH in the setting of known accidental head trauma.

MATERIALS AND METHODS

All infants younger than 12 months old with SDH present on CT scan were retrospectively identified from 2004 to 2014. Blinded, independent review of all CT scans for clot formation at the parasagittal vertex was performed by a pediatric neuroradiologist.

RESULTS

Ninety-nine patients were eligible for analysis. Mean age was 4 months. Fifty-seven (57.6%) were male. Fifty-five (55.6%) patients were identified as having AHT and 22 (22.2%) had accidental trauma. Forty-five (81.2%) patients with AHT had parasagittal vertex clots present on CT scan compared to 8 (36.4%) patients with accidental trauma. Compared to patients without parasagittal vertex clots, those with parasagittal vertex clots were more likely to have AHT (66.2% vs. 32.3%, P=0.001), no known mechanism of injury (69.1% vs. 32.3%, P=0.015), retinal hemorrhage (75% vs. 35.5%, P=0.002) and hypoxic-ischemic changes (25% vs. 0%, P=0.002). Patients with parasagittal vertex clots have eight times the odds of AHT compared to patients without parasagittal vertex clots. Age-matched control patients who underwent head CT scan due to a history of accidental head injury without SDH were identified (n=87); no patient in the control group had parasagittal vertex clots.

CONCLUSION

The finding of parasagittal vertex clots on CT scans should raise suspicion for abuse and prompt further investigation, especially in the setting of no known, uncertain or inconsistent mechanism of injury.

In Vivo Demonstration of Traumatic Rupture of the Bridging Veins in Abusive Head Trauma

OBJECTIVE

In victims of abusive head trauma, bridging vein thrombosis is a common finding on magnetic resonance imaging. We aimed to evaluate the utility of high-resolution coronal susceptibility-weighted imaging (SWI) in depicting bridging vein thrombosis as well as to verify the morphology of the bridging vein thrombosis on axial SWI. We additionally analyzed the correlations between bridging vein thrombosis or bridging vein deformation and other magnetic resonance imaging findings that often occur in association with abusive head trauma.

METHODS

Seventeen patients with abusive head trauma were retrospectively evaluated for the presence of thrombosis on axial SWI. The affected veins were localized on coronal SWI, and the strength of association between the presence of bridging vein thrombosis on axial versus high-resolution coronal SWI was determined.

RESULTS

Of 11 patients identified with thrombosis on axial SWI, high-resolution coronal SWI verified bridging vein thrombosis in four individuals (36%). The previously reported "tadpole sign" on axial images did not predict bridging vein thrombosis on coronal SWI (odds ratio = 0.3 [0.02, 5.01], P = 0.538). Volumetric coronal SWI disclosed additional irregularities of the bridging vein walls which was associated with the presence of subdural hematoma on magnetic resonance imaging (P = 0.03), suggesting traumatic injury.

CONCLUSION

Coronal SWI confirmed thrombosis of the bridging veins only in a minority of cases. Diffusely irregular contours of the veins observed on high-resolution coronal SWI was a major finding in our study. Disruption of the normal anatomy of the bridging veins in abusive head trauma further supports the traumatic nature of the disease.

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.

Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

Update on injury mechanisms in abusive head trauma--shaken baby syndrome

Violently shaking a baby leads to clinical presentations ranging from seizures to cardiopulmonary arrest. The main injuries sustained are retinal hemorrhages, subdural hemorrhages, and sometimes fractures and spine injury. It is important to have a global view of the injuries sustained by the infant to correctly discuss the biomechanical aspects of abusive head trauma. Recent works based on finite element models have shown that whiplash-shaking alone is enough to generate vitreo-retinal traction leading to retinal hemorrhage and to cause the rupture of bridging veins leading to subdural hemorrhage. We will review the main papers dealing with the mechanisms of shaken baby syndrome and present the most relevant hypothesis concerning the biomechanical aspects of injuries related to shaken baby syndrome.

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.

Investigating the possibility and probability of perinatal subdural hematoma progressing to chronic subdural hematoma, with and without complications, in neonates, and its potential relationship to the misdiagnosis of abusive head trauma

The high incidence of subdural hematoma (SDH) from birthing was first identified with MRI by Looney in 2007 and was then more accurately determined by Rooks in 2008. Rooks screened 101 "normal" deliveries and demonstrated that 46% of the babies in her series and by inference, approximately 46% of the 4 million born normally in the US have SDH that formed in the perinatal (birthing) period during labor. Both metabolic strain and physical forces exerted on the head damage the capillaries within the dura (the intradural capillary bed), which is the source of the blood in the SDH that results from labor and delivery or at times from labor alone. While child abuse pediatricians relying on Rooks, maintain that no permanent complications result, her study was limited to 101 subjects and the sole criteria for resolution was the resolution of the SDH as seen on follow-up MRI. In fact, Rooks did have one patient (1%) who had complications that lead to symptoms and findings often associated with abuse. The purpose of this article is to explore if there is a complication rate for perinatal (PSDH) that supports that 1% of complications that are definable by different criteria. Next, if there are complications, how many of the roughly 2,000,000 cases of perinatal acute subdural hematoma every year in the United States will suffer them? Then, what are the clinical manifestations of the complications if they occur? Lastly, do the complications cause or mimic some or all of the findings that are offered by board certified child abuse pediatricians as evidence of child abuse? The article argues that a small percentage, but significant number of neonates, suffer birth related complications and findings secondary to the development of chronic subdural hematoma CSDH) that are often misdiagnosed as abusive head trauma.

The "Shaken Baby" syndrome: pathology and mechanisms

The "Shaken Baby" syndrome (SBS) is the subject of intense controversy; the diagnosis has in the past depended on the triad of subdural haemorrhage (SDH), retinal haemorrhage and encephalopathy. While there is no doubt that infants do suffer abusive injury at the hands of their carers and that impact can cause catastrophic intracranial damage, research has repeatedly undermined the hypothesis that shaking per se can cause this triad. The term non-accidental head injury has therefore been widely adopted. This review will focus on the pathology and mechanisms of the three physiologically associated findings which constitute the "triad" and are seen in infants suffering from a wide range of non-traumatic as well as traumatic conditions. "Sub" dural bleeding in fact originates within the deep layers of the dura. The potential sources of SDH include: the bridging veins, small vessels within the dura itself, a granulating haemorrhagic membrane and ruptured intracranial aneurysm. Most neuropathologists do not routinely examine eyes, but the significance of this second arm of the triad in the diagnosis of Shaken Baby syndrome is such that it merits consideration in the context of this review. While retinal haemorrhage can be seen clinically, dural and subarachnoid optic nerve sheath haemorrhage is usually seen exclusively by the pathologist and only rarely described by the neuroradiologist. The term encephalopathy is used loosely in the context of SBS. It may encompass anything from vomiting, irritability, feeding difficulties or floppiness to seizures, apnoea and fulminant brain swelling. The spectrum of brain pathology associated with retinal and subdural bleeding from a variety of causes is described. The most important cerebral pathology is swelling and hypoxic-ischaemic injury. Mechanical shearing injury is rare and contusions, the hallmark of adult traumatic brain damage, are vanishingly rare in infants under 1 year of age. Clefts and haemorrhages in the immediate subcortical white matter have been assumed to be due to trauma but factors specific to this age group offer other explanations. Finally, examples of the most common causes of the triad encountered in clinical diagnostic and forensic practice are briefly annotated.

Imaging of nonaccidental injury and the mimics: issues and controversies in the era of evidence-based medicine

Because of the controversy involving the determination of child abuse, or nonaccidental injury (NAI), radiologists must be familiar with the issues, literature, and principles of evidence-based medicine to understand the role of imaging. Children with suspected NAI must receive protective evaluation along with a timely and complete clinical and imaging work-up. Imaging findings cannot stand alone and must be correlated with clinical findings, laboratory testing, and pathologic and forensic examinations. Only the child protection investigation may provide the basis for inflicted injury in the context of supportive clinical, imaging, biomechanical, or pathology findings.

Neuroimaging of nonaccidental head trauma: pitfalls and controversies

Although certain neuroimaging appearances are highly suggestive of abuse, radiological findings are often nonspecific. The objective of this review is to discuss pitfalls, controversies, and mimics occurring in neuroimaging of nonaccidental head trauma in order to allow the reader to establish an increased level of comfort in distinguishing between nonaccidental and accidental head trauma. Specific topics discussed include risk factors, general biomechanics and imaging strategies in nonaccidental head trauma, followed by the characteristics of skull fractures, normal prominent tentorium and falx versus subdural hematoma, birth trauma versus nonaccidental head trauma, hyperacute versus acute on chronic subdural hematomas, expanded subarachnoid space versus subdural hemorrhage, controversy regarding subdural hematomas associated with benign enlarged subarachnoid spaces, controversy regarding hypoxia as a cause of subdural hematoma and/or retinal hemorrhages without trauma, controversy regarding the significance of retinal hemorrhages related to nonaccidental head trauma, controversy regarding the significance of subdural hematomas in general, and pitfalls of glutaric aciduria type 1 and hemophagocytic lymphohistiocytosis mimicking nonaccidental head trauma.

Shaken baby syndrome: the quest for evidence

Shaken baby syndrome (SBS), characterized by the triad of subdural haemorrhage, retinal haemorrhage, and encephalopathy, was initially based on the hypothesis that shaking causes tearing of bridging veins and bilateral subdural bleeding. It remains controversial. New evidence since SBS was first defined three decades ago needs to be reviewed. Neuropathology shows that most cases do not have traumatic axonal injury, but hypoxic-ischaemic injury and brain swelling. This may allow a lucid interval, which traumatic axonal injury will not. Further, the thin subdural haemorrhages in SBS are unlike the thick unilateral space-occupying clots of trauma. They may not originate from traumatic rupture of bridging veins but from vessels injured by hypoxia and haemodynamic disturbances, as originally proposed by Cushing in 1905. Biomechanical studies have repeatedly failed to show that shaking alone can generate the triad in the absence of significant neck injury. Impact is needed and, indeed, seems to be the cause of the majority of cases of so-called SBS. Birth-related subdural bleeds are much more frequent than previously thought and their potential to cause chronic subdural collections and mimic SBS remains to be established.

A hypothesis of cerebral venous system regulation based on a study of the junction between the cortical bridging veins and the superior sagittal sinus

Object

The cerebral venous regulation involved in various physiological and pathological processes has received little attention. Here the authors describe the anatomy of the junction between the cortical vein and the superior sagittal sinus (SSS) and propose a new theory of cerebral venous regulation.

Methods

Ten adult human cadaveric heads (20 sides), including five specimens into which stained latex had been injected, were used for anatomical study. Formalin-fixed cadaver heads were dissected to demonstrate the cortical veins along the SSS. The characteristics of the cortical bridging veins and their openings into the SSS were established by anatomical, histological, immunohistochemical, and ultrastructural study of the junction.

Results

After their subarachnoid course, the cortical bridging veins penetrated the SSS at different points in the dura mater depending on their rostrocaudal position. The venous endothelium stretched beyond the sinus endothelium. The orientation of the collagen fibers changed at the level of the venous openings, with the luminal diameter becoming narrow and oval-shaped. The major finding was the organization of the smooth-muscle cells at the end of each cortical vein. At this site and particularly in the frontoparietal region, the vessel resembled a myoendothelial “sphincter.” The authors hypothesize that this organization is involved in cerebral venous system regulation.

Conclusions

The point of convergence between the cortical veins and the SSS is a key area. The authors also hypothesize that the myoendothelial junction acts as a smooth sphincter and that it plays a role in cerebral venous hemodynamics and pathological conditions.

Inflicted head injury in infants

There is scant neuropathological information in the child abuse literature; even the best reviews include assumptions based on the findings of a few inadequate early studies. Our recent series of 53 fatal cases (Brain 124 (2001) 1290, 1299 [1,2]) demonstrated age-related patterns of brain injury and showed the substrate of severe encephalopathy in the infants to be hypoxic brain damage, not diffuse traumatic axonal injury ('DAI'), as had previously been thought. About one-third had craniocervical injuries, particularly in the brain stem, suggestive of stretch injury to the neuraxis. Our interpretation was that this finding implied a mechanism of injury--brain stem damage from stretch injury to the neck with resultant apnoea--that could account for the clinical scenario in many cases, and for which violence would not necessarily be required. Since publishing this study we have turned our attention to the subgroup of infants who die without objective signs of injury, such as skull fracture or impact, whose carers are accused of abuse, usually, "violent shaking", on the pathologic findings alone. Given the striking discrepancy that there often is in such cases between the relatively trivial findings in the brain and the accusations of violence, we have been looking at the pathogenesis of the typical intracranial bleeding. A histologic study of dura from 50 paediatric autopsies, none of whom had suffered a head injury, has led us to propose that the subdural and retinal bleeding in such cases may well have a physiological aetiology, rather than being caused directly by trauma.

Representation of cerebral bridging veins in infants by postmortem computed tomography

The postmortem diagnosis of shaken baby syndrome, a severe form of child abuse, may be difficult, especially when no other visible signs of significant trauma are obvious. An important finding in shaken baby syndrome is subdural haemorrhage, typically originating from ruptured cerebral bridging veins. Since these are difficult to detect at autopsy, we have developed a special postmortem computed tomographic (PMCT) method to demonstrate the intracranial vein system in infants. This method is minimally invasive and can be carried out conveniently and quickly on clinical computed tomography (CT) systems. Firstly, a precontrast CT is made of the infant's head, to document the original state. Secondly, contrast fluid is injected manually via fontanel puncture into the superior sagittal sinus, followed by a repeat CT scan. This allows the depiction of even very small vessels of the deep and superficial cerebral veins, especially the bridging veins, without damaging them. Ruptures appear as extravasation of contrast medium, which helps to locate them at autopsy and examine them histologically, whenever necessary.

From the archives of the AFIP. Child abuse: radiologic-pathologic correlation

In the United States, roughly one of every 100 children is subjected to some form of neglect or abuse; inflicted injury is responsible for approximately 1,200 deaths per year. Child physical abuse may manifest as virtually any injury pattern known to medicine. Some of the injuries observed in battered children are relatively unique to this population (especially when observed in infants) and therefore are highly suggestive of nonaccidental, or inflicted, injury. Worrisome injuries include rib fracture, metaphyseal fracture, interhemispheric extraaxial hemorrhage, shear-type brain injury, vertebral compression fracture, and small bowel hematoma and laceration. As noted, however, virtually any injury may be inflicted; therefore, careful consideration of the nature of the injury, the developmental capabilities of the child, and the given history are crucial to determine the likelihood that an injury was inflicted. The majority of these injuries are readily detectable at imaging, and radiologic examination forms the mainstay of evaluation of child physical abuse. Detection of metaphyseal fracture (regarded as the most specific radiographically detectable injury in abuse) depends on high-quality, small field-of-view radiographs. The injury manifests radiographically as a lucent area within the subphyseal metaphysis, extending completely or partially across the metaphysis, roughly perpendicular to the long axis of the bone. Acute rib fractures (which in infants are strongly correlated with abuse) appear as linear lucent areas. They may be difficult to discern when acute; thus, follow-up radiography increases detection of these fractures. For skull injuries, radiography is best for detecting fractures, but computed tomography and magnetic resonance imaging best depict intracranial injury.

Postmortem radiological investigation of bridging vein ruptures

In the usual method of brain removal in forensic autopsies, the upper bridging veins were invariably torn. There are several types of head injuries, in which ruptures of these vessels are the predominant intracranial injury. For the past 5 years we have investigated nearly all cases of lethal head injuries by a simple X-ray method (axial X-ray after instillation of contrast material into the superior sagittal sinus). The evaluation of the 350 X-rays which were available until today can be summarized by the following statements. (a) Anatomy of the parasagittal bridging veins: regarding the numbers and diameters of the veins, we can separate cases with many bridging veins of small diameter from a group with few veins of a large diameter. (b) Causes of injury and direction of impact: bridging vein ruptures resulted more often from frontal than from occipital, parietal and lateral impacts and occurred in traffic accidents in the majority of our cases.