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Baby shaking summary of responses

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  • Baby shaking summary of responses

    Dear Colleagues,
    The archives do not seem to have the summary of replies to my question about
    baby shaking (which I sent two years ago, maybe to the wrong destination).
    Anyway, here is the summary again. The replies were very valuable to those
    defending the case in Alameda County, California. I will post another

    Dear Biomechanicers,
    Thank you all who responded to my request for help
    about a baby-shaking case. A summary follows.
    This case is ongoing, and I intend to post
    any more information that I think will
    be of general interest.

    Derek Hendry.

    "I have a "baby-shaking" case. The prosecution is
    going to say that the baby was in my client's care when the baby stopped
    breathing (true). At the hospital, the red blood cell count was decreasing,
    showing that the system had not yet stabilized, showing,
    in turn, that the injury was "recent." An expert witness is going
    to say that brain swelling was continuing when the baby was examined in the
    hospital. The baby had no external injuries.

    "The prosecution is going to use these facts and testimony to conclude
    that the baby was shaken by my client. I have strong reasons to
    believe that the baby was NOT shaken by my client.

    "I want to understand the biomechanics and physiology of intracranial
    Some important questions relate to the time course
    of the symptoms of brain damage.
    Other important questions relate to the effects of various kinds
    of mechanical insult. What is the danger threshold of acceleration
    of the head? What physical events produce dangerous levels
    of head acceleration?

    "My client, myself, and my colleagues will appreciate information, data,
    and leads.

    " I will post a synopsis of all helpful replies.


    Date: 94-06-09 04:25:08 EDT

    Dear Derek,

    I read your message with respect to "baby-shaking". I must say I
    have never heard of this before (apart from a custom in this part
    of the Netherlands where the neigbours come by to shake a newborn
    kid; gently that is). From your message I conclude the baby you
    mentioned has had brain damage and that the suspicion is someone
    has caused this brain damage by violently shaking the baby.
    Personally I find it highly unlikely that manually shaking a baby
    can induce brain damage. I have several reasons for this.

    With respect to manually exerting the acceleration force :
    I am sure measurements have been done to determine accelarations
    which the adult brain can stand. The area to look would be
    aeronautical engineering. I know that pilots of high performance
    aircraft can stand up to 5g without blacking out, and I think at
    least up to 9g while blacking out but recovering immediately as
    soon as the accelerations have decreased again. This means 9-10g
    is not yet the limit where brain damage would occur. I suppose the
    young growing brain of a baby can not take as much. Still, accelerating
    to 10g a mass of, say 4 kilograms, would require a force of 400 Newton.
    To give you an idea : benchpressing a 90-lb weight.

    With respect to accelerating the head :
    Sorry this sounds somewhat technical/mechanical; I am aware of
    the fact babies are not merely masses or objects.
    Suppose somebody is shaking a baby. He or she will hold the body,
    presumably under the armpits, but not the head. Also, the baby
    would be held out forward. The range of movement is hereby
    restricted because of the limited arm length. Because babies do
    not have strong neck musculature, the head will not follow the
    exact movements of the body. Mechanically : The body-neck-head can
    for this purpose be considered as a system consisting of a large
    mass, to which a small mass is connected by a spring-damper. If
    the large mass is accelerated, the small mass will generally not
    undergo the same acceleration as the large mass. Theoretically it
    is possible to bring the small mass into resonance which could
    raise the level of acceleration to a value above the acceleration
    of the small mass. In the case of the baby, this would in my
    opinion require deliberate "careful" action, if it is possible
    at all.

    Limitation of the forces which can be delivered to the head :
    As mentioned above, the neck musculature of babies is not very
    well developed yet. This means the head is supported mainly by
    passive structures (vertebrae and ligaments). Anybody who has
    ever held a small baby knows the head must be supported in order
    to protect the neck. As far as I know there have been cases of
    young children who have been put in a bicycle-seat before their
    necks were strong enough, which caused neck lesion when the cycle
    hit a hole in the pavement. The point is this. Suppose that
    a baby is shaken vigorously enough to induce accelerations which
    would cause brain damage. In my opinion the neck would break long
    before actual brain damage could ever occur. The pilots flying the
    aircraft I mentioned before do not break their neck because their
    musculature is better developed, and sideways support of their
    head is provided so that the neck is not loaded in transverse

    Of course the matter is changed completely if the head would be
    struck by or against another object. The accelerations occurring
    in this case would be much higher than by "just" shaking. I
    assume that evidence of impact would normally have to be present
    in this case though. Absence if this kind of evidence would
    at least require deliberate action of molesting and hiding the
    evidence (use of sandbags or the like).

    I hope some of this may be useful to you.

    Yours sincerely,

    Edsko Hekman
    Twente University
    Fac. Werktuigbouwkunde - BW
    Postbus 217Date: 94-06-08 23:19:56 EDT
    7500AE Enschede
    The Netherlands

    Date: 94-06-09 03:06:25 EDT
    Subj: Baby-shaking
    To: Dhendry

    Hi Derek,

    Re your Biomch-L posting about baby shaking, have you talked to
    Werner Goldsmith in the mechanical engrg dept at Berkeley? He is
    an expert on head injuries due to impact, so he should have data
    on accelerations and injuries.

    Best regards,
    Date: 94-06-09 07:33:06 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    I think someone at University of Strathclyde, Scotland was working on this
    about 10 years ago, with reference to potential damage to babies from
    putting them in those baby-bouncers hanging from doorways - don't know any
    more details but might be a useful lead.

    David Pickles
    Date: 94-06-09 08:39:35 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    What are your strong reasons for believing that your client did not shake
    the baby?
    Date: 94-06-09 10:15:51 EDT
    Subj: Biomechanics of Baby-shaking
    To: Dhendry

    This has to be a very important issue to try to resolve. I would
    contact Professor Donald Huelke at the University of Michigan Transportation
    Research Institute (313) 764-4367 to see if he has any good leads for you.
    He has considerable experience in impact and whiplash injuries and may
    know of a good neurologist. I presume you are familiar with the HIC,
    but I don't know whether it has been validated in the pediatric population.
    Date: 94-06-09 09:23:00 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    Check with Al King at Wayne State. Al has been working with head injury in
    auto accidents and has a great deal of experience in closed head injury.
    -Good Luck,
    Please let me know what you find out.
    -Mark Redfern
    University of Pittsburgh
    Date: 94-06-09 15:39:40 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    There was a paper written by Thibault, Margulies, Duhaime and some
    others, in Journal of Neurosurgery in 1984 which might be useful
    to you. Sorry, I haven't got the exact reference, but the gist
    was that a normal human being can't shake a baby hard enough to
    cause diffuse axonal injury. You could look it up.

    -Lynne Bilston

    Date: 94-06-09 18:45:42 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    While acknowledging the seriousness of your case, I believe your
    first step should be to inquire who on this list might be available
    for hire as your expert witness.

    Date: 94-06-09 19:05:06 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    Derek! I was acting as a consultant in the similar case of "baby - shaken"
    syndrome. The literature search provide very limited amount of information
    can used. From our research it is clear that the adult can shake the baby
    which will result in fatality. However, one has carefully examine clinical
    evidences of the pathology in order to come to definite conclusion. I hope
    this is helpful. Sincerely.

    *................................................. ........................*
    * " There are no shortcuts to any place worth going....." *
    * *
    *================================================= ========================*
    * Professor Arkady Voloshin *
    * Department of Mechanical phone: 610-758-4118 *
    * Engineering and Mechanics fax: 610-758-6224 *
    * Lehigh University email: AV01@LEHIGH.EDU *
    * 19 Memorial Drive West *
    * Bethlehem, PA 18015 USA *

    Date: 94-06-09 19:07:50 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    Dear Derek:
    You have posed many serious questions regarding head injuries and head injury
    mechanisms.. After studying head injuries and head protection for many years,
    we still don't have solid answers to many of your questions. Given that you
    are acting on behalf of your client, I would STRONGLY recommend that your
    client retain the services of an expert in the area of head injury and head
    injury mechanisms. There are many qualified people who do this kind of work
    for a living and are quite adept at providing expert witness testimony.

    I should also warn you that consulting with these people is not cheap.

    In any event, if I haven't convinced you to obtain some outside expert
    consulting, you may want to refer to Biomechanics of Head Injuries, edited by
    Dr. Alan Nahum and Dr. John Melvin, 1992.

    Good Luck,

    Terry Smith
    USC Head Protection Research Laboratory
    Los Angeles, California

    Date: 94-06-09 19:56:18 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    Dear Mr. Hendry,

    I am intrigued with your Baby-shaking case. My name is Scott McClellan.
    I have an MS in Bioengineering and am currently a doctoral candidate at
    the University of Utah. I recently finished a project for the United
    States Diving Foundation, a subsidiary of the United States Olympic
    Committee which was directly involved with the human limits and tolerances
    for head (brain) injury. I was asked to determine the biomechanics of head
    injury for platform impacts and provide them with a research protocol to
    increase safety and reduce the risk for serious head injury.

    Most of my experience has been in the analysis of head impacts. While your
    case does not require "impact" analysis, acceleration is still acceleration
    independent of its source. There are several standard curves
    used in industry as thresholds for survivable and or serious head injury
    due to high accelerations and short impulse durations. Several of these are:

    HIC Head Injury Criterion
    WST Wayne State Tolerance Curve
    BPT Brain Pressure Tolerance Curve
    MSC Maximum Strain Criterion

    It may be possible to determine the maximum accelerations a child could
    sustain under shaking by a normal adult person and apply these values to
    the established head injury curves to reach conclusions about the severity
    or probability of shaking. However, small children and infants have
    unique cranial characteristics which differ significantly from adult
    humans other than size and mass. Some potential differences are stiffness
    of the cranial suture joints, meninges development and attachment (which
    can change brain shear), as well as general neck muscle laxity. All of
    these variables will effect the potential cerebral acceleration magnitude
    and should be considered.

    Since I do not have any specific facts from your case I will refrain from
    speculating. If you are interested in discussing the matter further I can
    be reached at:

    Date: 94-06-10 08:08:43 EDT
    Subj: Re: Biomechanics of Baby-shaking
    To: Dhendry

    > Other important questions relate to the effects of variouskinds
    > of mechanical insult. What is the danger threshold of acceleration
    > of the head? What physical events produce dangerous levels
    > of head acceleration?

    You could try Mailing, Mr. Chris Snook is an
    engineer who, in collaboration with others, has done a significant amount
    of testing using human head models to determine impact magnitudes to
    falling heads. This was done for playground surfaces, in relation to
    legalities of head injuries and for car impacts. He has a knowledge of
    the likely accelerations etc, that the head is subjected to and is trying
    to associate this knowledge with a data base of car/pedestrian impacts.

    The general model used in such trauma modelling is a function of both time
    and acceleration imparted. That is, the amount of trauma potential is
    normally represented by a function incorporating time and is therefore an
    integral or a numerical integral of data. High acceleration, if imparted
    for short periods of time, does not cause significant injury, whereas a
    lower acceleration over a period of time may well cause trauma.