Presented at the Neonatal Society 2005 Spring Meeting.
Talbert D
ICSM, Queen Charlotte’s Hospital, London W12 ONN, UK
Introduction: In 1993 the American Academy of Pediatrics Committee on Child Abuse and Neglect reported that the syndrome of subdural-, and retinal haemorrhage, with little or no evidence of external cranial trauma, could only be explained by imposed trauma induced by shaking, and that a medical presumption of abuse should be made when a child younger than 1 year of age has intracranial injury.Shaken Baby Syndrome (SBS) (1). They noted that the shaken infant may have a history of poor feeding. However actual injuries do not always fit this description (2). Before the introduction of vaccination, similar injuries were seen to occur during paroxysmal coughing bouts in cases of whooping cough (Bordetella pertussis). Similarly, neonates being given ventilator support for RDS showed disturbances of cerebral artery flow if they coughed, but suppressing coughing by paralysis dramatically reduced the incidence of cerebral bleeding (3). Injuries in both situations were clinically attributed to vascular pressure changes induced by rapid consecutive contraction of the powerful abdominal muscles (4). Coughing is a vital protective mechanism which takes precedence over normal breathing control. To be effective very high expiratory pressures (>100mmHg) are required to produce the airflows necessary to drag mucus up the airways.
Methods: As there is no ethical method to investigate whether similar injuries could occur in infants during coughing fits induced by inhaled feed, vomit etc. the pulmonary detail of a software model of the infant, ”Caleb”, was extended to allow investigation of the interaction of respiratory and vascular pressures during extended rapid coughing.
Results: The high body cavity pressures add to the normal cardiac pressures, but within the body cavity perivascular pressures are equally raised, so net transmural pressures are minimally affected. Externally, e.g. in the head, there is no such compensation and these excessive vascular lumen pressures add directly to transmural pressures. It takes several stroke volumes to fill the head vasculature sufficiently to realise these high potential pressures so they do not materialise for single coughs, but in a rapid train of consecutive coughs reverse filling of venous beds, and highly hypertensive intracranial, retinal, and nasal arterial pressures are seen. Thus injuries similar to those seen in pertusis, but of accidental origin, (PCI), appear likely to be present in the population currently considered deaths from Shaken Baby Syndrome.
Conclusion: “The co-ordination of breathing, sucking and swallowing is a precarious skill” (5) which, if not satisfactorily acquired, would provide the trigger for PCI. It would explain the presence of prior feeding difficulties in some “shaken babies” and, if repeated in survivors, explain the apparent “late manifestations” of SBS (5). Could it be that PCI fatalities are the fatal tip of a dysphagic iceberg amongst the population of “shaken babies”?
References
1.American Academy of Pediatrics. Pediatrics 1993;92(6):872-875
2.Geddes,J.F.. et al Neuropathol. Appl. Neurobiol 2003;29:14-22
3. Perlman,J.M. Thach,B. N.Eng.J.Med.1988;81(3):399-403
4. Talbert,D.G.Medical Hypoth. 2005;64,8-13
5. Al-Sayed,L.E.;Schrank,W.I.;Thach,B.T. J.Appl.Physiol. 1994 ;77(1):78-83