Anencephaly and the nature of fetal response to vibroacoustic stimulation.

The fetal response to vibroacoustic stimulation has been used in recent years as a measure of well being. Vibroacoustic stimulation theoretically may evoke both tactile and auditory responses in the fetus. In clinical practice, it is important to distinguish which type of response is actually activated. An answer may be suggested through observation of two anencephalic fetuses who demonstrated no response to such stimulation. Neuroanatomic considerations are discussed that suggest which auditory mechanisms are involved in the fetal response to vibroacoustic stimulation.