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Re: microcephalyFrom: DuBose, Terry (DuboseTerryJ@exchange.uams.edu)Thu May 13 10:13:55 1999
I agree, that biometrics may not indicate a real problem. I recall a British study of hydrocephalics that included a girl with sever hydro (only a few mm of cerebral cortex as I recall) but was attending school as a teenager and very good in math. There is a lot that we do not understand. Unfortunately, I have no data on microcephaly. My entering the discussion here was due to a statement suggesting that we can not measure the cranial volume..., which is incorrect. H. Jordaan of South Africa lamented the fact that sonography could not measure the vertical cranial diameter (VCD) as early as 1977 in the J Clinical Ultrasound, Obstetrics and Gynecology, and the Amer. J of Obstetrics & Gynecology. Jordan and Dunn recognized that, "...the ponderal size of the brain, which is a function of a three-dimensional or volumetric measurement". However, they went on to state that, "...no ultrasonic data on the vertical-auriculo-vertex diameter (VAV) are available in the literature." (Jordaan & Dunn: A new method of evaluating growth; Obstet Gynecol, 1977; 51:659-665) While this was true at the time of their publication, the VCD which very nearly approximates the VAV which Jordaan and Dunn had envisioned was published in 1985. It was their argument that convinced me that the 2D measurements of the head (BPD & transverse head circumference) simply were not sufficient for greatest accuracy. Because of the arrangement of the cranial sutures and fontanels, the VCD is the most dynamic of the three axes of the skull. My main concern is pregnancy dating. I find a 3D BPD Correction in the presence of dolichocephalic and brachycephalic shapes after 30 weeks consistently correlates better with the dates than other parameters. (DuBose TJ, FETAL SONOGRAPHY; W.B. Saunders Co., 1996, p. 157-199.) Of course, if the head is normally shaped, the a BPD is all that is needed; but if molding and head shape are a concern, then 2D measurements simply are not sufficient for greatest accuracy. I published the measurement of the growth of the cranial volume for normal fetuses in 1985. {DuBose T: FETAL BIOMETRY: Vertical Calvarial Diameter and Calvarial Volume. J Diag. Med. Sonography; 1985; 1(5) 205-217)}. In 1986 the Society of Diagnostic Medical Sonographers (SDMS) recognized the research by the presentation of the Kenneth Gottesfeld Award, JDMS 2(4): 181-182. The 3D BPD is also detailed in Berman & Cohen: Obstetrics & Gynecology, 2nd Edition, Chapter 19 "Assessment of Fetal Age & Size: Techniques & Criteria", Lippincott, 1997, p 375-384. Also see: http://www.io.com/~dubose/3d.html <http://www.io.com/~dubose/3d.html> I keep hoping some bright researcher will replicate this work in a center where such data may be available. In reality the advent of 3D sonographic equipment will make my type solid geometry analysis of the fetal cranial volume passe' before long. Peace, Terry J. DuBose, M.S., RDMS, FAIUM University of Arkansas for Medical Sciences Little Rock, AR, USA -----Original Message----- From: James S Smeltzer MD [SMTP:gaperina@mindspring.com] Sent: Wednesday, May 12, 1999 11:33 PM To: Multiple recipients of list ULTRASOUND Subject: RE: microcephaly Terry, Volume does not matter so much as it is neuronal pathway dysplasia that is the problem. I STILL maintain that you know the bad actors by the company they keep and that it is a rara avis that has ISOLATED microcephaly (by any measure) that has a problem. I've been wrong before (but not often). Vide supra! Semper fi! Show me the data of low school performance with ONLY microcephaly (perhaps from the british birth cohort project or the Collaborative perinatal project - which showed NO increased problems above the 1st %ile unless multiple problems other than hat size, as I recall. Is there anything from the Dutch Famine? I believe that the victims never caught up in head circumference but that their intelligence was normal. Jim S
At 12:11 PM 5/12/1999 -0500, you wrote:
>While I agree that microcephaly can and does exist without
ventriculomegaly,
>they can also be associated. However, I do disagree with the
and
> nonpathologic microcephaly without ventriculomegaly.
syndromes and
> genetic diseases with microcephally but no
ventriculomegally....the
> problem is when to label the small head "microcephalic"
Experience
> suggests that it is not usually possible until well into the
between
>inaccurate
not
>attempt to
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