Doc 0000022039

- ) . ·) ( APPRAISAL OF TWO REPORTS ON MATHEMATICAL ANALYSES OF HEAD INJURY ------~ ..... ------ ---·-·· __...,..-• ... 31 January 1972 -~- •. .. - J ~ -~~- -· 0 .• -............ ~:!1111 5 57 1~11-lf'!-l! .Fal-. ---&J-&-iZ- 2-2 -UJ-IU-I-I -----------·e- - --~-~--------- 1 .. ,, ·"""" ·-~ "'i.'.) •, .~ ... :. APPF(/\ISAL 01:- TWO REPORTS ON MATH~MATICAL ANALYSES OF HEAD INJURY Two papers concerned with ~athcmatica.l modeling of head injury dynan'-tics have;. bc~n submitt~d r.or biomedical appraisal. 1 • z Beth :reports define mathematical models of pr~ssure-accclerat.i<?n dynamics inside the skull during impact ~vent~ by assuming that; (I) The skull is a thin, isotropic, ho:nogenous, elastic, spherical shell. (2) The brain is an ideal compressible fluid. (3} _All impact loading is axisymmetric. ReferPnce 1 considers ths cavitation hypothesis of brain damage for head impact,_ and assumes a specific impacting load in addition to appropriate c~ns tants to define the primary assumptions noted above. The evolved model uses extensional shell theory and coupled differe~tial equations solved by finite difference .techniques to define the time-variable pressure field inside the shell. The autho4s feel that their model supports the cavitation hypothesis because the 1nodel indicates transient zones of negative pressure at the impact pole and the opposite (contrecoup) pole at different times after the start of irnpact. The authors acknowledge th-;~.t their work does not verify the cavita~ tion hypothesis and does not rule out other mechar.isms of brain damage from non-penetrating impact. Reference Z considers the pressure ef!ects of various impacting force wave~ 2 3 forms in :-elation to the previously proposed General Motors• Severity InJex. • The Severity Index is an nth power of impact acceleration, or force, integra- ted with respect to time for the duration of impact. Brief positive pulses of impact force in square, triangular, half sine and. eccentric waveforms were defined so as to have identical Sev·erity Index values, ind\cating that all the p11lses had roughly similar products of av-erage amplitude times duration. ./ - ·._ ; .. ,-._. . lk&. _i&J&G£ . 1!!1!'1 iMJI&L&& a;aw: .. • ... --.... -.·.·-· ;....:;:·-~-· r_ Tla~ fuul' pub<:s were used as inputs to the n1athcrnatic n1odel ck scribed ;\bovc, ;l:;cl the model show~~d that lhc pressure dy:namics of lhl; phy!ii<:al system would be 11ne3rly the s;unc11 for all pulses tested. From this finding, the author ::o con..: ludc, "The so rc sull:s indicate 1 The image displays a stylized representation of a vault door on the left, with a blueish glow emanating from it. To the right of the vault, text is presented against a black background. The title "THE BLACK VAULT" is prominently displayed in a white, stylized font. Below the title, several lines of white text describe the origin of the document as being from "The Black Vault," an online database of declassified government documents, specifically mentioning the "MKULTRA/Mind Control Collection" and its source as the Central Intelligence Agency (CIA). A brightly colored yellow hyperlink is provided as the access point for the collection. There are no photographs, handwritten annotations, stamps, forms, diagrams, tables, redactions, or visual evidence of experimental procedures present in this image. The document is a declassified CIA paper with what appears to be a title page. The title reads "APPRAISAL OF TWO REPORTS ON MATHEMATICAL ANALYSES OF HEAD INJURY". There are scattered handwritten marks, some lines appearing as an incomplete diagram. In the bottom right corner, the number "193" is circled in a hand-drawn ellipse. No photographs, stamps, forms, or tables are visible on this page. There are also no discernible redactions or visual evidence of experimental procedures, equipment, or facilities. The page seems to be an administrative or introductory document, possibly a cover page for a report. r_ Tla~ fuul' pub<:s were used as inputs to the n1athcrnatic n1odel ck scribed ;\bovc, ;l:;cl the model show~~d that lhc pressure dy:namics of lhl; phy!ii<:al system would be 11ne3rly the s;unc11 for all pulses tested. From this finding, the author ::o con..: ludc, "The so rc sull:s indicate 1 ha: the Ccncr:'ll J\.1ul ur a 1 S!,!vcrity Index is a useful means of determining the s<'vcrity of vastl}' diiL.:rl!nt pnlscs appliC'd In lin"'ar syniCil"J,S. 11 The authors go on In ~aulion, bowc-vi"J", that "these results do not necessarily indicate that the Severity Index is a valid means of predicting the hazard or injury potential of diff,·rcnl pulses. be An evaluation such as that m.ust accomplished 'Jy furtiter experimentation and clinical investigations • II Comments 1. The two papers appear to be ingenious examples of ana lytical modeling technique applied to the complex dynamics of (luid filled spheric<3;l shells subjectec to impact. z. Reference 1 shows that, under the assumed conditions, transient negative pressures will occur at both the impact :md conlr•· coup poles of t!1e impacted shell. 3. Reference Z shows that, under the assumed conditions, similar impact forces (differing mainly in waveform) selected to have identical General Motors' Severity Indices will cause similar dynamic pressure patterns .. 4. It is unfortunate that neither report mentions the Gctailw results of Lindgren who measured the dynamic pres sure patterns -i of flu1d filled spheres and human cadaver heads subjecLed to impact. Lir.dgren recorded negative pressures at both the contrecoup and impact poles, as well as similar pressure patterns arising from 5imilar ilnpar:t forces. 5. With regard to the concussion lhresholci probl~m, it would be· extremely interesting to see the po,vcrful analytic ·~chniques of Reference 1 and 2 used in a retrospective S·~arch for a useful common dcr.oxninalor in a large number of the published investigations on experimental concussion. - 2- r ~( _/ .. ~ . . -. ~--~i ....... : ••: . -. / REFERENCES 1. Bcn~dict, J. V., Harris, E. f-1. and von Rosenberg-, D. U., "An An<f. lytical Investigation of the C<llvilation l-~ypothcsis of Drain Dan"lage," Journal of D01slc Engineering, September 1970, pp 597-603-. (UNCL) I z. 'Be:1edict, J. V. end Lin, Do J., "Analytical [nvcstigalian of the General Motors' Severity Index, 1 ASME Publication 71-WA/ ' BHF-6, American Society o£ Mechanical Engineers, New York, !9 7 1. (UNCL) 3. Gadd, C. W., "Use of a Weighted-Impulse The document is a typescript page with a border on the left side, which appears to be a perforation margin for a binder. There are several handwritten marks at the top of the page, including a dash and what looks like a rough sketch of a "J" shape, possibly notes or annotations by a reader. The text discusses mathematical analyses of head injury, referencing two papers. There are no photographs, diagrams, stamps, or filled-in forms visible on this page, and no redactions are apparent. of D01slc Engineering, September 1970, pp 597-603-. (UNCL) I z. 'Be:1edict, J. V. end Lin, Do J., "Analytical [nvcstigalian of the General Motors' Severity Index, 1 ASME Publication 71-WA/ ' BHF-6, American Society o£ Mechanical Engineers, New York, !9 7 1. (UNCL) 3. Gadd, C. W., "Use of a Weighted-Impulse C;-itcrion for Estimating Injury Hazard, 11 in Proceedings of the Tenth ?t<tnp C;u Crash Conference, Society of Automotive Engineers, New York, 1966, pp 95-100. (UNCL) 4. LinC.gren, S. 0., · "Experimental Studies of Mechanical Effects in Head Injury, 1 ' Acta Chb-urgica Scandinavica 1 Supplement 360, 1966, pp 1-100. (UNCL) The page is covered in text, with some faint marks from the original document and the copying process. There are no photographs, diagrams, or tables present on this page. The most prominent visual element is the text itself, which appears to be a scanned document with some bleed-through from the back of the page. There are no handwritten annotations, signatures, official stamps, or filled-in forms visible. There are some small, dark circular marks at the top of the page, likely from the binding or original filing of the document. The document is a page of references with numbering from 1 to 4. There are handwritten annotations in the form of lines and curves in the top right corner, possibly indicating corrections or notes. The text is predominantly typed and refers to various engineering journals and publications. There are no photographs, diagrams, forms, or stamps visible on this page. The bottom center of the page has a handwritten number "-3-" enclosed in a bracketed box, likely a page number.