Technological diseases -2 (Sonograms)

[Guest guest]

Ultrasound and fetal brain damage

 

In yesterdays post on ultrasound, the increased usage of ultrasound

was the main issue, despite its safety being proven by adequate

evidence. The desire to see the baby is natural, and possibility of

discovering some abnormality at earliest also drives this rush, while

forgetting that this "look" itself may cause harm. In this post

author examines some published literature and view points on this

issue. Nowadays, some health providers are persuading a sonogram at

every monthly visit. This is an alrming trend, at least in India.

 

We close our ears even if some one is about to fire a cracker twenty

feet away from us. The sound energy released is high, though for a

few milliseconds. The effects of terrorist blasts is well known in

most countries these days. Ultrasound is a form of energy—sound waves

vibrating at approximately a hundred times the frequency of normal

sound (normal range of audio frequencies is in 50 Hz to 5 Khz range,

some people with excellent ear can hear upto 20 kHz) —and the waves

can affect tissue in a variety of ways. Heat is one effect. The

energy of waves is proportional to square of amplitude and frequency.

In addition, although ultrasound itself does not produce audible

noise, secondary vibrations can produce noises as loud as 100

decibels, causing fetuses to move. [1] Other effects include tiny

bubbles in tissue (a process known as cavitation), sheering forces

within tissues, induced flows within fluids, and creation of minute

quantities of toxic chemicals. [2] Ethical restrictions on

the `direct study of ultrasound effects on humans' makes scientists

use animal studies as well as data from populations of humans exposed

to ultrasound in the past.

 

Temperature increases of 4.5 degrees Centigrade (8.1 degrees

Fahrenheit) were measured in the brain of late-gestation live guinea-

pig fetuses insonated in utero for 2 minutes by pulsed Doppler-type

ultrasound. [3] Other guinea-pig studies have shown adverse effects

on cell division in bone marrow following ultrasound exposure. [4].

In October 2004, Pasko Rakic, Chairman of the Neurobiology Department

at Yale University, announced that he and his colleagues had observed

disruption of normal migration of cells in the brains of fetal mice

following exposure to ultrasound. Rakic is now conducting a $3

million study to see if the same effects occur in the offspring of

monkeys scanned during pregnancy. In humans, such disruption is known

to be caused by certain viruses, mutations, and drugs, and it is

linked to a range of disorders including autism and learning

disabilities.[5]

 

In 2001, a team of Polish researchers published actual temperature

readings obtained from an adult human brain during ultrasound

exposure. The results showed no temperature increase, causing the

researchers to hypothesize that the human brain enjoys better cooling

capacities than the brains of smaller mammals.[6] But rapidly

developing brain of the human fetus is similarly protected from

ultrasound-induced heat? To determine whether such heating may

produce subtle brain damage in humans, comparison of the health

histories of children exposed to ultrasound and the same data for

children not exposed is presented in[7]

 

To date, studies of humans exposed to ultrasound have shown the

following possible adverse effects: growth retardation, dyslexia, and

delayed speech development[8]. But only one effect, a higher rate of

left-handedness among boys exposed to neonatal ultrasound, has been

observed in at least three separate studies.

 

Left-handedness is statistically linked to many cognitive and

developmental problems ranging from learning difficulties to autism

to epilepsy. Secondly, many researchers suspect that other types of

minor brain damage may also arise. According to medical reporter

Robert Matthews, the increase in left-handedness associated with

neonatal ultrasound exposure could be the result of subtle brain

damage causing people who ought genetically to be right-handed to

become left-handed[9].

 

The left-handedness findings were based on children of mothers who

underwent lower-voltage scanning in the late 1970s and early 1980s.

But by the mid-1990s, average exposure levels had risen

significantly. In 2003, the ECMUS Safety Committee noted that

intensity in the most common ultrasound scanning mode, "are now up to

1000 times greater than those reported in the 1970s." [10].

Scientists need to repeat the left-handedness studies, as well as

studies of other possible effects, on this younger, more intensively

exposed population. To date, such follow-up studies have not been

done.[11] Thus, claims that "there has never been a harmful effect

shown" simply do not apply to today's ultrasound equipment. Author

strongly urges the academic researchers to undertake the link if any

between ADHD and ultrasound, due to alarming rate of rise of

proportion of children suffereing from ADHD, since about 1990.

 

Risk Levels uncreased:

 

A milestone came in 1993 when the FDA raised the maximum output of

ultrasound machines used in obstetrics eightfold, from 94 up to 720

milliwatts per square centimeter[12]. The FDA was persuaded that

operators needed greater flexibility, especially when confronting

life-and-death situations such as determining blood flows in tiny

coronary arteries in the midst of an ongoing heart attack.

 

As a safety measure, FDA began requiring manufacturers to add two on-

screen safety indexes. One measures the heating of bone or tissue;

the other including cavitation caused by the expansion of gas

bubbles, sheering forces within tissues, and induced flows within

fluids. It was expected that a well trained sonographer using the on-

screen safety indexes properly would not subject patients to greater

levels of ultrasound exposure than under the previous system of

regulation. But then the FDA failed to ensure that sonographers are

properly trained. According to ultrasound experts, the actual state

of sonographer training is dismally inadequate. Dr. Jacques

Abramowicz, Professor of Obstetrics and Gynecology and Radiation at

the University of Chicago, said, "Only two to three percent of the

population doing ultrasound really know what the thermal index and

the mechanical index mean."

 

Even trained operators are confused by the complexity of interactions

between sound waves and human tissues, the ways different ultrasound

modes affect exposure, and the different responses caused in

different parts of the body. Bones respond differently than muscles,

for example. And bone is extremely sensitive to ultrasound heating:

the skull of a third-trimester fetus heats up 50 time more quickly

than brain tissue when exposed to ultrasound.[13]. This means that

brain structures lying close to the skull, such as the pituitary and

the hypothalamus, are especially at risk of secondary heating.[14].

 

The difference in sensitivity between fetal tissue and adult tissue

is also important: fetal brain tissues are more sensitive to

disturbance because of the developmental changes taking place. When a

storm comes, we see small fruits and leaves of trees falling quickly,

but branches may remain intact. Similarly, large trees with thick

trunk may remain unaffected but younger trees with thin trunk may

collapse.

 

Even when operators are perfectly trained, according to Dr.

Abramowicz, the actual amount of tissue heating may exceed the level

predicted by the safety index by a factor of 2 to 6. Thus, actual

heating may reach a dangerous level even when the safety index shows

otherwise. This is similar to the hot spot on metal where welding is

carried out. Rest of the metal is cool.

 

Finally, researchers cannot agree where to set the "safety baseline"

for temperature effects. Most researchers regard a temperature rise

of .5 degrees Centigrade to be safe. But according to John Abbott,

PhD, director of standards communication for Philips Medical Systems,

the indexes "cannot be considered as absolute measures of

anything.They apply to the machine, transducer and operating

condition in use at the time. A thermal index of 4 is more than a

thermal index of 3. That's all." Let us consider this issue in

simple but scientific way. How we become concerned if baby gets a

fever. After all fever is overall temperature rise by just 4 to 5

degrees F. And we try to reduce the fever by putting cold salt packs

on forehead. Why forehead only? because forehead houses brain. We

very well know what happens if a children fever exceeds 5 degrees F.

And sonograms produce local heating approximately 8 deg. F.

 

Despite the uncertainties, doctors continue to use medical ultrasound

because the diagnostic benefits are believed to outweigh any

potential harm. Some doctors accept that there may be risks, but they

believe that medical ultrasound remains a beneficial practice when

performed by a trained operator for diagnostic purposes. According to

Dr. Joshua Copel, Professor of Obstetrics and Gynecology and

Pediatrics at Yale University, "It's impossible to prove ultrasound

is completely safe, but if you're getting medically helpful

information, then the tradeoff is reasonable."

 

As for keepsake fetal portraits, Dr. Copel says,"We don't know what

equipment they're using, what the acoustic output is, and what the

training of the personnel is."

Because tissue heat increases over the length of exposure, well-

trained sonographers limit the duration of any medical ultrasound

procedure. But in multiple investigations of keepsake fetal portrait

studios, FDA investigators found patients being exposed to higher

machine settings for as long as an hour in order to obtain fetal

pictures, much longer than is considered prudent. [15]

 

Under a passive FDA, the ultrasound industry is openly flouting

regulations. Despite the official ban on non-diagnostic use of

ultrasound equipment, most keepsake fetal portrait studios routinely

advertise non-diagnostic examinations.

 

At the center of the fetal portrait fad are the simple, normal

desires of expectant parents to be reassured about the health and

well being of their new baby. Sadly, that very desire for reassurance

and enjoyment makes parents vulnerable to sales pitches for

technologies whose safety remains uncertain. Ultrasound, of course,

plays a vital role when needed for a legitimate medical purpose. But

as with any powerful technology, caution is advised. Says Dr.

Abramowicz: "I recommend against keepsake ultrasounds. The principle

is simple. You should not use a medical device for a non-medical

purpose."

 

Meanwhile, the issue of prenatal ultrasound has highlighted a serious

gap in the regulatory system. Unlike new drugs, medical devices are

not subjected to rigorous animal and human testing prior to being

released. While it is reassuring that researchers are finally

beginning to understand just how ultrasound may affect brain

development, the best time for such research would have been before

the FDA loosened the ceilings on ultrasound exposure. Since 1993,

when the rules were changed, some 28 million pregnant women have been

exposed to ultrasound.

 

Concerned citizens should push for full enforcement of the existing

rules on ultrasound, so that prenatal ultrasound is limited to

appropriate medical uses. But action needs to go further than that.

The approval process needs to be changed so that medical devices,

including the new higher intensity ultrasound machines, are fully

tested before being put into widespread use. Just like full fledged

double blind randomized drug trials.

 

Dr Bhate

 

1. Eugenie Samuel, "Fetuses can hear ultrasound examinations," New

Scientist, Vol. 10, No. 4, Dec. 4, 2001. Mostafa Fatemi, Paul L.

Ogburn, Jr., James F. Greenleaf, "Fetal Stimulation by Pulsed

Diagnostic Ultrasound," Journal of Ultrasound in Medicine, Vol. 20,

2001, 883-889.

2. S.B. Barnett, "Can diagnostic ultrasound heat tissue and cause

biological effects?" In S.B. Barnett and G. Kossoff, eds., Safety of

Diagnostic Ultrasound (Carnforth, UK: Parthenon Publishing, 1998), 30–

31.

3. M.M. Horder, S.B. Barnett, G.J. Vella, M.J. Edwards, A.K.W.

Wood, "Ultrasound-induced temperature increase in the guinea pig

fetal brain in utero: third-trimester gestation." Ultrasound in

Medicine and Biology, Vol. 24, No. 5, June 1998, 1501-10; M.M.

Horder, S.B. Barnett, G.J. Vella, M.J. Edwards, A.K.W. Wood, "In vivo

heating of the guinea pig fetal brain by pulsed ultrasound and

estimates of Thermal Index," Ultrasound in Medicine and Biology, Vol.

24, No. 5, June 1998, 1467-74.

4. S.B. Barnett, M.J. Edwards, P. Martin, "Pulsed ultrasound induces

temperature elevation and nuclear abnormalities in bone marrow cells

of guinea pig femurs." Proceedings of the 6th World Congress on

Ultrasound Medicine, No. 3405 (Copenhagen, Denmark: WFUMB, 1991).

5. Jim Giles, "Ultrasound scans accused of disrupting brain

development," news, 10/27/2004 at www.nature.com

<http://www.nature.com/news/2004/041025/pf/4311026a_pf.html>.

6. Z. Mariak, J. Krejza, M. Swiercz, T. Lyson, J. Lewko, "Human brain

temperature in vivo: lack of heating during transcranial color

Doppler US," Journal of Neuroimaging, Vol. 11, No. 3, 2001, 308-312.

7. D. Marinac-Dabic, C.J. Krulewitch, and R.M. Moore, Jr., "The

safety of prenatal ultrasound exposure in human subjects."

Epidemiology, May 13, 2002 (2 Supplement): S19-22.

8. K.A. Salvesen, L.J. Vatten, S.H. Eik-Nes, K. Hugdahl, L.S.

Bakketeig, "Routine ultrasonography in utero and subsequent

handedness and neurological development," British Medical Journal,

Vol. 307, 1993, 159-64. H. Kieler, O. Axelsson, B. Haglund, S.

Nilsson, K.A. Salvesen, "Routine ultrasound screening in pregnancy

and children's subsequent handedness." Early Human Development, Vol.

50, 1998, 233-45.

9. Robert Matthews, "Ultrasound Scans Linked to Brain Damage in

Babies," Epidemiology, Vol. 12, Dec. 2001, 618.

10. ECMUS Safety Committee, "Diagnostic Ultrasound Exposure," EFSMB

Newsletter, Jan. 2003.

11. Carol Rados, "FDA cautions against ultrasound `keepsake' images,"

FDA Consumer, Jan.-Feb., 2004.

12. Carol Rados, "FDA cautions against ultrasound `keepsake' images,"

FDA Consumer, Jan.-Feb., 2004.

13. S.B. Barnett, "Can diagnostic ultrasound heat tissue and cause

biological effects?" In S.B. Barnett and G. Kossoff, eds., Safety of

Diagnostic Ultrasound (Carnforth, UK: Parthenon Publishing, 1998), 28.

14. S.B. Barnett, "Sensitivity to diagnostic ultrasound in

obstetrics," In S.B. Barnett and G. Kossoff, eds., Safety of

Diagnostic Ultrasound. (Carnforth, UK: Parthenon Publishing, 1998),

58.

15. Carol Rados, "FDA cautions against ultrasound `keepsake' images,"

FDA Consumer, Jan.-Feb. 2004.

 

 

ayurveda, Darla Wells <lethe9@g...>

wrote:

> Dr. Bhate,

> There is another issue with the "recreational" ultrasound: what

> happens if parents stumble on some visible, horrible defect in the

> fetus? I don't think these types of ultrasound are justified, ever.

> The overuse of medical ultrasound is another issue and another thing

> driving our healthcare costs up and up.

> Darla Wells