OBJECTIVE: Subdural bleeding (SDB) in infants is considered an essential symptom of nonaccidental head injury (NAHI). Recently, this view has been challenged by the “unified hypothesis,” which claims that SDB in infants is related to hypoxia and brain swelling rather than to traumatic shearing of bridging veins. We analyzed a large series of infants' autopsies for the presence and causes of SDB, which should be a common event according to the unified hypothesis.
METHODS: Autopsy, clinical, and legal information for infants <1 year of age from a single institution over 50 years were analyzed regarding cause of death, presence, morphology, and cause of SDB, and brain weight.
RESULTS: From a total of 16 661 autopsies during the study period, 715 (4.3%) involved infants <1 year of age. Fifty (7.0%) of those had SDB. NAHI was identified in 17 patients. The most common cause of SDB was trauma (15 cases [30.0%]), with NAHI accounting for 14 cases. SDB was present in 82.4% of patients with NAHI but only 5.2% of infants with other causes of death. Four patients (8.0%) had unexplained SDB with no discernible cause of bleeding. Statistical analysis did not reveal any correlation between the presence of SDB and brain weight.
CONCLUSIONS: In the study population, unexplained SDB in infants was an extreme rarity. Moreover, a correlation between brain swelling and the presence of SDB could not be drawn. Our data argue strongly against the unified hypothesis and strengthen the association between SDB and NAHI in infancy.
Comments
Identifying mechanisms in undetermined subdural haematoma and effusion in infancy
Matschke et al (1) suggest subdural bleeding in infants of undetermined cause under one year is a rarity, and that most cases (30%) in their series were as a result of trauma. Hobbs et al (2) have previously described the aetiology of subdural haematomata and effusion in infancy. From their data, it would appear that just under 10% of cases are undetermined; the authors suggest that these are most likely a result of old injury presenting later. It follows from both studies that this is potentially an area where earlier detection would lead to a reduction in morbidity and mortality. A recent case we encountered highlights the need for extra vigilance by all front line professionals. A five week old infant presented to his general practitioner with a 24 hour history of crying, being off his feeds and vomiting. Further initial questioning did not elicit a cause; later it emerged that his mother had been in a road traffic accident in the antenatal period. Examination revealed a coincidental murmur only. The family left before a urinalysis was obtained but later presented as the infant had become drowsy and developed a squint. MRI confirmed bilateral subacute subdural haematoma. Preliminary investigations did not trigger full child protection procedures and follow up continues with the paediatric neurologist and ophthalmologist. It was thought that the event had occurred in the perinatal period. All professionals must remain alert to the possibility of injury in neonates, even if not immediately elicited on questioning and even if no external physical signs are apparent. Early referral is mandatory for further investigation. Mechanisms of injury have been hypothesised (3,4)but there is clearly a need for additional research and provision of guidelines in this area.
S Ross Shettleston Health Centre Glasgow Scotland UK Correspondence to: Dr S Ross, Shettleston Health Centre, Glasgow G32 7JZ, Scotland, UK; Samantha.ross@nhs.net
References 1. Matschke J, Voss J, Obi N, et al. Nonaccidental Head Injury Is the Most Common Cause of Subdural Bleeding in Infants <1 Year of Age. PEDIATRICS Vol. 124 No. 6 December 2009, pp. 1587-1594 2. Hobbs C, Childs A-M, Wynne J, et al. Subdural haematoma and effusion in infancy: an epidemiological study. Arch Dis Child 2005; 90(9): 952-955. 3. Goldsmith W et al. A biomechanical analysis of the causes of traumatic brain injury in infants and children. Am J Forensic Med Pathol, 2004;25(2):89-100. 4. Geddes J F et al Dural haemorrhage in non-traumatic infant deaths: does it explain the bleeding in ‘shaken baby syndrome’? Neuropathology and Applied Neurobiology. 2002; 29(1): 14-22.
Conflict of Interest:
None declared