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Carole A. Jenny Professor of Pediatrics

Brown Affiliations

research overview

I am studying the biomechanics of accidental and inflicted head trauma in infants. The work involves using biofidelic infant crash test dummies to measure the biomechanical parameters of a variety of events.

research statement

Over the last three years, Dr. Carole Jenny has had the opportunity to work with the Aprica Childcare Institute on the issue of shaken baby syndrome and other pediatric head injuries. The experimental work at the Aprica Childcare Institute has been extremely productive. A list of presentations, research papers, and published documents concerning shaken baby syndrome and our research on biomechanics is appended (Appendix 1).

The types of head trauma researched include abusive head trauma, shaken baby syndrome, unintentional head trauma, and subtle forms of head trauma that may occur in the everyday environment of the infant. The research IS based on the infant anatomic testing devices (ATD) "Aprica 2.5" and "Aprica 3.4" at Aprica's research facility in Nara.

Data generated by the Aprica ATDs will be used to generate a finite element model of the effects of shaking on the infant retina. Modifications to the ATDs to study biomechanics of eye injuries with shaking will be studied.


Several factors make human infants particularly vulnerable to head trauma:

n They have poor head control and weak necks. They cannot use their neck muscles to protect their heads from excessive rotational and translational forces;
n they have softer brains than adults due to less myelination of their brain tissue;
n infants have more fluid around their brains, allowing movement of brain tissue within the cranium;
n they are physically weak and unable to protect themselves against assault or abuse or against environmental insults; and,
n they are entirely dependent on the adults around them to protect them from physical dangers.

Injuries to infants' brains reflect a continuum of forces applied to their heads leading to a spectrum of anatomic and physiologic results. At one end of the continuum we see shaken baby syndrome and other types of abusive head trauma where violent forces are purposefully applied to babies' heads by angry adults. The types of injuries we see in these children are similar to the injuries seen in infants involved in automobile crashes or multi-story falls from windows.

Some unintentional and inflicted head injuries can involve less injurious forces applied to the head, such as household falls or the hitting of the head with a bare hand. At the mildest end of the spectrum are head injuries that occur inadvertently in the child's environment. In my experience, I have seen significant head injury occurring in an infant riding in an 'off-road' vehicle over rough terrain and in an infant in her parents' 'back pack' on a 'mountain bike' traveling over a very rocky trail. Whether or not other types of vibrational forces can actually injure the infant brain is unknown. For example, can tossing a baby in the air and catching him cause subtle brain injuries? Can vigorously bouncing infants in an effort to calm them cause brain injuries? These questions continue to be asked.

1. We are examining the biomechanical forces applied to infants' heads during violent shaking, violent impact, impact plus shaking, and other events using the Aprica 3.4 ATD.

We have previously conducted a series of experiments to address the basic question comparing the biomechanical forces applied to the infant brain through shaking a child and impacting a child on a hard surface using Aprica 2.5. During this phase we will repeat some of those experiments with the Aprica 3.4 ATD. We will measure angular and linear acceleration during shaking and impact events. We will measure applied load during impact events.

The events to be enacted will be:
Shaking alone
Shaking with impact to floor
Shaking with impact to sofa
Slamming ATD to tatami mat without shaking
Rolling ATD off sofa to carpeted floor
Hitting ATD on the side of the head in a high chair, causing rotation of the head
Throwing ATD up in the air in a playful manner
Bouncing ATD on a knee.

In addition to recording the data from the internal accelerometers, we will again use accelerometers applied to the ends of the 'tibias' and 'ulnas' to measure acceleration of the ends of the long bone during violent shaking. Measurement of thoracic compression will also be noted due to the advanced features of the Aprica 3.6 ATD.

2. Compare the results of shaking and slamming experiments with the Aprica 3.4 ATD with results of simulated acceleration deceleration events in the laboratory.

The forces experience by the infant head in shaking has been compared to the forces experienced in car seats by young infants riding over very rough roads. Using the sled, we will simulate stops and starts at various speeds, and compare the acceleration experienced by the infant dummy head during driving events to the forces experienced by violent shaking of the dummy.

3. Finish the analysis of data from experiments with Aprica 2.5.

Because of concern over discrepancy between high-speed video recording of angular acceleration and calculations of angular acceleration derived from linear accelerometers, we have delayed the publication of results from the experiments with Aprica 2.5. We will reinterpret the original data and compare the results with the results from the experiments using Aprica 3.4.

4. Compare the linear and angular acceleration generated during shaking of the two ATDs and evaluate the effect of body weight on the results of violent shaking.

Many factors affect the amount of injury inflicted on infants during abusive head trauma events. Using the same person to violently shake the 3.4 kilogram dummy who took part in previous experiments (Mr. Mori), we will analyze the differential effect of the infant's size in approaching injury thresholds.

5. Work with the Aprica Childcare Institute to prepare an educational videotape on the dangers of shaking babies, featuring the video recorded during the laboratory research on shaking of the infant dummy, Aprica 2.5.

We have made significant progress on an educational video on shaken baby syndrome, but several things have to be done to finish the project, including identifying some new visual components. This project will continue to be a part of Phase III, with the goal of finishing the video within the first month of Phase III.

6. Work with AAP on the production and distribution mechanism for the shaken baby video.

7. Design database for evaluating free falls in infants and toddlers.

During Phase III, I plan to design data collection instruments for the scientific evaluation of the biomechanics of accidental infant and toddler falls. The instruments will be based on similar instruments used by NHTSA to evaluate car crashes. Specifically, I will create a system for the
systematic study of falls from windows. Thousands of American children fall from windows each year, often from multistory windows. These events provide a mechanism to study the effects of easily calculated gravitational forces on the bodies of infants and small children. Data collection instruments will include parameters such as the height of the fall, the position and attitude of the body on impact, the nature of the impacted surface, the body surfaces contacting the impacted surfaces, and the nature and severity of the resulting injuries. This project will give us tools to collect data that cannot be obtained in the laboratory.

Part B: Development of a Finite Element Model of the Eye and Orbit with Salient Features led by Dr. Levin and Dr. Ranga.

Retinal haemorrhaging is a cardinal manifestation of the Shaken Baby syndrome. Because of ethical concerns, it is impossible, however, to develop an understanding of the pathogenesis of retinal haemorrhage or a causal relationship between violent shaking and eye injuries through direct experiments with animals. We propose to develop a surrogate for the paediatric eye and develop the causal chain using the surrogate.

An initial planning meeting was held in Washington, DC on March 30, 2004 to discuss strategies to evaluate the link between shaking and eye injury. The meeting was attended by Drs. Alex Levin, Carole Jenny, Robert J. Bigge, Tariq. Shams, and N. Rangarajan. It was agreed that the following research strategy would be adopted:

1. We should first develop a finite element model of the eye and orbit with salient features. Collaboration with other centers such as ALGOR, University of Virginia, and University of Alabama will be sought and encouraged.
2. This model should be validated using data available in the literature and also using data that can be collected by Dr. Levin from patients undergoing eye surgery (for example, tensile strength of muscles, and translation distance of globe in and out of orbit).
3. The validated model should be exercised using input from shaking experiments conducted with Aprica 2.5 kg and 3.4 kg infant dummies. Sensitivity of model output to the following should be evaluated:
a. The presence or absence of various features in the eye model.
b. The level of detail of each feature in the model
c. The physical characteristics of each feature in the model (for example, strength of attachment of various muscles).
4. Conclusions from the finite element model sensitivity study should be used to decide on the features that are to be incorporated in the Aprica 2.5 and 3.4 dummies, and the measurements to be made using the dummies.
5. The enhanced dummies should be used in shaken baby experiments to evaluate the effect of shaking on various parts of the eye, optic nerve and orbital tissues.
6. Since this is a multi-year project it is hoped that more data will become available and it will be possible by the end of the project to draw the causal chain from shaking to eye injury, if such a chain exists.

The following tasks will be accomplished in the initial phase of this research proposal:

1. Study commercially available finite element calculation engines and make an appropriate choice to use in this project.

The choice of finite element models will depend on the availability of features such as solid/fluid interface, the range of material models available and any relevant experience of previous investigators.

Geometry can be obtained from non-invasive medical images. Physical properties of structures can be obtained directly from the literature or scaled from available data using normally accepted scaling methods.

funded research

1987-1989 National Institute of Justice, US Department of Justice. "Forensic Aspects of DNA Typing". Grant # 87-IJ-CX-0400, $203,000. C. Jenny, Principal Investigator.

2000 Rhode Island Department of Children, Youth and Families: "The Parent Support Project", $100,000, T. Roesler and C. Jenny, Co-Directors.

2001-2004 Centers for Disease Control and Prevention: "Cooperative Agreement for Surveillance of Child Maltreatment (Mortality). $49,469, C. Jenny and W. H. Hollinshead, Co-Principal Investigators.

2001-2004 U.S. Centers for Disease Control and Prevention: "Cooperative Agreement for Surveillance of Child Maltreatment (Morbidity). $271,816, C. Jenny and W. Hollinshead, Co-Principal Investigators.

2001-2002 Rhode Island DCYF: "Family Support Project", $134,477, T. A. Roesler and C. Jenny, Co-Directors.

2001-2002 Brown University Department of Pediatrics, "Departmental Support for Fellow's Research", $3,300.

2001-2002 Victims of Crime Act, through Rhode Island Governor's Justice Commission, "Family Support Project, $17,500, T. A. Roesler and C. Jenny, Co-Directors.

2002 U.S. Department of Justice: "Development of Guidelines for Law Enforcement on the Evaluation of Child Pornography, $26,127, C. Jenny, Principal Investigator.

2002 Aprica Kassai, Inc., Osaka, Japan: "Biomechanical Studies in Abusive Head Trauma", $54,913, C. Jenny, Principal Investigator

2003 Aprica Kassai, Inc., Osaka, Japan: "Biomechanical Studies in Abusive Head Trauma", $100,464, C. Jenny, Principal Investigator.

2005 Aprica Kassai, Inc., Osaka, Japan: "Biomechanical Studies in Abusive Head Trauma", $102,058, C. Jenny, Principal Investigator.