CORRESPONDENCE

9. Harvey EN: Secondary damage in wounding due to pressure changes accompanying the passage of high velocity missiles. Sur- gery 1946;21:218-239.

10. Fackler ML: Wounding potential of the Russian AK-74 assault rifle. J Trauma 1984;24:263-266. 11. Lindsey D: The idolatry of velocity, or lies, damn lies, and ballistics. J Trauma 1980;20:1068-1069.

In Reply: In response to Dr Fackler's letter, we would like .to state

the following facts. All of the material in the text of the article is based on the references cited, and not on "imag- ination."

With regard to the practical aspects of the article, we re- spect Dr Fackler's contribution to our knowledge. Our own experience in treating more than 10,000 civilian gunshot wound victims in the past six years may suggest that expe- rience rather than "imagination '~ is involved. Dr Fackler

may want to consult the forensic lab of the Los Angeles Police Department, where the missiles discussed are on file for verification of the practical aspects of this article. For a presentation of clinical material representative of some of the points Dr Fackler questioned, the Editor may be inter- ested in publishing some of our own cases of, for example, mushrooming bullets that did not penetrate the skin; wounds due to nonjacketed, high-velocity bullets; irregular mushrooming of bullets producing a diameter propor- tionally greater than their Surface area; and large cavita- tional defects in relation to bullet diameter.

Readers are referred to a textbook by Dr Ordog entitled Gunshot Wounds (Traeger Scientifi c Division, WB Saun- ders), which is due for publication this year and provides more details of these discussions.

Gary J Ordog, MD Jonathan Wasserberger, MD Subramaniam Balasubramanium, MD Drew/UCLA School of Medicine Los Angeles, California

COWS Caloric Test

To the Editor: COWS is the time-honored caloric test for vestibular

function, Cold - - Opposite, Warm - - Same. Function of the vestibular portion of the eighth cranial

nerve is tested by instilling warm or cold water in the ear canal. Cold water directed against the tympanic membrane causes the endolymph to flow downward and away from the ampulla. Warm water produces the opposite reaction; endo- lymph flows toward the ampulla. This produces nystagmus away from (or toward) the stimulated ear and past-pointing

and falling as outlined in the figure. The reflex arc in vestibular nystagmus is as follows: laby-

rinth ---) vestibular nerve --) vestibular nucleus --) abducens nucleus --) abducens nerve --> external rectus muscle. Note that the fast component is actually the cerebral component, while the slow is the vestibular component.

Charles Webb, MD Owosso, Michigan

Caloric Test Warm Water

Cold Water

Nystagmus-Fast Component

Toward the ear stimulated "Same"

Away from the ear stimulated "Opposite"

Past-Pointing/Falling

Away from the ear stimulated

Toward the ear stimulated

Reaction

None

Asymmetric response of eyes in relation to each other No nystagmus (no fast component); eyes deviate to cold stimulated side

Disease Entity Disease of the eighth nerve Disease of the end organ of the eight nerve on that side Disease of the central connection of the eighth nerve on that side Ocular muscle pareses Pontine~esion Bilateral hemispheral disease

172/938 Annals of Emergency Medicine 14:9 September 1985