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PubMed1991

[Does fetal reaction to vibro-acoustic stimulation depend on its activity state?].

The value of vibro-acoustic stimulation of the fetus in predicting fetal well-being remains controversial. This prospective randomised study comprised of 25 women with pregnancies ranging between 37 and 41 weeks. The fetal response in each case was investigated before and after a real and a sham stimulation. Each real stimulation led to immediate fetal movements (p less than 0.0001). The fetal reaction was independent of the preexisting behavioral state; vibro-acoustic stimulation can induce a change in the behavioral state. Fetal bradycardia following vibro-acoustic stimulation was not observed.

Arousal↗
PubMed2003

Evaluation of non-reassuring fetal heart rate patterns with fetal pulse oximetry combined with vibratory acoustic stimulation.

OBJECTIVE: To determine the value of fetal pulse oximetry and vibratory acoustic stimulation in the presence of non-reassuring fetal heart rate patterns during labor. DESIGN: Prospective study in women monitored by cardiotocography and fetal pulse oximetry during labor. MATERIALS AND METHODS: During a period of 18 months, 907 consecutive parturients in labor were monitored by cardiotocography. Out of these women, 63 were selected on the basis of a non-reassuring fetal heart rate tracing during the first stage of labor. In these cases, fetal pulse oximetry was applied. Vibratory acoustic stimulation was applied in fetuses without spontaneous reactivity in order to evaluate the fetal status. RESULTS: Our cases were classified into three groups, according to the lower fetal oxygen saturation levels, from the time of oximetry application until delivery. Group A consisted of 29 cases where fetal oxygen saturation levels were > or = 41%, group B (20 cases) with fetal oxygen saturation of 31-40% and group C (14 cases) with levels of < 30%. Spontaneous reactivity was observed in 15 fetuses of group A and seven of group B, while no case of reactivity was noted in group C. Vibratory acoustic-induced reactivity was associated with low fetal oxygen saturation levels. The mean umbilical artery pH levels were 7.29 +/- 0.051 in group A, 7.21 +/- 0.057 in group B and 7.04 +/- 0.05 in group C. CONCLUSION: Fetal pulse oximetry should be indicated not only in fetuses without any reactivity but also in those with induced reactivity, after the application of vibratory acoustic stimulation.

Acoustic Stimulation↗
PubMed2005

External inferior colliculus integrates trigeminal and acoustic information: unit responses to trigeminal nucleus and acoustic stimulation in the guinea pig.

The external nucleus of the inferior colliculus (ICx) receives ascending projections from both auditory and somatosensory nuclei. In the guinea pig, both the spinal trigeminal nucleus (TN) and the cochlear nucleus converge in the ventrolateral region of ICx. We investigated the function of trigeminal-collicular pathways by electrically stimulating the TN while recording unit responses from ICx. Pairing electrical stimulation with acoustic stimuli allowed us to investigate the function of converging auditory and somatosensory inputs, i.e. multisensory integration. Unit responses were recorded from ICx using a multi channel, single shank electrode. Electrical stimulation of the TN produced small changes above or below spontaneous rate, but resulted in significant suppression or enhancement of sound-evoked responses. Multisensory integration has been demonstrated in the dorsal cochlear nucleus (DCN), superior colliculus and sensory cortices and may play a role in plasticity that occurs after sensory deprivation.

Acoustic Stimulation↗
PubMed1990

Effect of vibratory acoustic stimulation on the duration of fetal heart rate monitoring tests.

The ability of vibratory acoustic stimulation to shorten the duration of antepartum fetal heart rate monitoring was investigated by a randomized controlled trial. Vibratory acoustic stimulation did not shorten the overall duration of testing. This failure to improve the performance of antepartum monitoring appeared to result from prolonged accelerations, which complicated one third of the tests in which vibratory acoustic stimulation was employed. Further investigation is warranted using less profound methods of fetal stimulation.

Acoustic Stimulation↗
PubMedDate not supplied

[Electrical activity of the cerebral ganglion of the mollusk Helix vulgaris upon acoustic stimulation of the statocyst].

Responses in the cerebral ganglia to acoustical stimulation were studied at the frequencies 30, 60, 150, 300, 500, 1000 Hz. The lowest threshold of response was at the frequency 30 Hz 60 dB spl. The reaction was in the form of evoked response or different patterns of spike activity. Responses could take place at one frequency of stimulation or in the wide range of frequencies. The reaction lasted sometimes even after the stimulation had ceased. After 3-4 stimulations by one frequency the reaction disappeared as a rule. But if the stimulation continued, but with another frequency, the response restored. The acoustic stimulation of the statocyst evokes various types of response in the cerebral ganglia.

Acoustic Stimulation↗
PubMed1986

Fetal acoustic stimulation testing. II. A randomized clinical comparison with the nonstress test.

Antepartum fetal heart rate testing, specifically the nonstress test, is of accepted value in the antenatal surveillance of high-risk pregnancies. Fetal rest-activity cycles coupled with arbitrary test intervals appear to lead to falsely nonreactive tests. Methods to alter fetal behavioral states have not been uniformly successful. A retrospective analysis of the adjunctive use of acoustic stimulation at our institution demonstrated a 50% reduction in the number of nonreactive tests. Consequently a prospective randomized clinical trial was undertaken to compare the standard nonstress test with the fetal acoustic stimulation test. Those patients randomized to the fetal acoustic stimulation test underwent transabdominal acoustic stimulation with a Model 5C electronic artificial larynx. The incidence of nonreactive tests was 14% in the control group and 9% in the study group (chi 2 = 11.09, p = 0.004). A significant reduction in testing time was also observed. The fetal acoustic stimulation test offers advantages over the traditional nonstress test by lowering the incidence of nonreactive tests and reducing testing time.

Acoustic Stimulation↗
PubMed2005

Activation of astrocytes in brain of conscious rats during acoustic stimulation: acetate utilization in working brain.

To evaluate the response of astrocytes in the auditory pathway to increased neuronal signaling elicited by acoustic stimulation, conscious rats were presented with a unilateral broadband click stimulus and functional activation was assessed by quantitative autoradiography using three tracers to pulse label different metabolic pools in brain: [2-14C]acetate labels the 'small' (astrocytic) glutamate pool, [1-14C]hydroxybutyrate labels the 'large' glutamate pool, and [14C]deoxyglucose, reflects overall glucose utilization (CMR(glc)) in all brain cells. CMR(glc) rose during brain activation, and increased activity of the oxidative pathway in working astrocytes during acoustic stimulation was registered with [2-14C]acetate. In contrast, the stimulation-induced increase in metabolic activity was not reflected by greater trapping of products of [1-14C]hydroxybutyrate. The [2-14C]acetate uptake coefficient in the inferior colliculus and lateral lemniscus during acoustic stimulation was 15% and 18% (p < 0.01) higher in the activated compared to contralateral hemisphere, whereas CMR(glc) in these structures rose by 66% (p < 0.01) and 42% (p < 0.05), respectively. Calculated rates of brain utilization of blood-borne acetate (CMR(acetate)) are about 15-25% of total CMR(glc) in non-stimulated tissue and 10-20% of CMR(glc) in acoustically activated structures; they range from 28 to 115% of estimated rates of glucose oxidation in astrocytes. The rise in acetate utilization during acoustic stimulation is modest compared to total CMR(glc), but astrocytic oxidative metabolism of 'minor' substrates present in blood can make a significant contribution to the overall energetics of astrocytes and astrocyte-neuron interactions in working brain.

Acetates↗
PubMed1992

Vibro-acoustic stimulation does not alter the duration of high and low fetal heart rate variability episodes.

To study the effect of vibro-acoustic stimulation on high and low fetal heart rate (FHR) variability episodes. Prospective control study, in 21 high risk pregnancies between 32 to 39 weeks gestation. FHR pattern was recorded with cardiotocograph (CTG). After 5 min low FHR variability a vibro-acoustic stimulator was activated in contact with or above the maternal abdomen (sham) on a random basis on two consecutive days, and CTG was continued to obtain a complete high and low FHR variability cycle. Complete high and low FHR variability cycles were obtained in 12 patients with mean recording time of 129.5 minutes (range 69-185 min). The mean baseline FHR increased by 32.5 +/- 9.4 bpm after contact vibro-acoustic stimulation, but remained unchanged after sham stimulation. Mean duration of high FHR variability was 56.6 +/- 32.9 min and 47.3 +/- 23.7 min, respectively, and mean duration of the consecutive low FHR variability episode was similar after contact and sham stimulation. The complete cycles were 71.1 +/- 34.7 min and 66.2 +/- 21.2 min, respectively. Vibro-acoustic stimulation induced an abrupt change from low to high FHR variability, but the complete cycle of high and low FHR variability was not altered, when compared with the corresponding cycle following sham stimulation on the same fetus.

Acoustic Stimulation↗
PubMed1992

Vibro-acoustic stimulation in high-risk pregnancies; maternal perception of fetal movements, fetal heart rate and fetal outcome.

Maternal perception of fetal movement in response to vibro-acoustic stimulation was compared with antenatal fetal heart rate monitoring as a test of fetal well-being in a population of gravidae with high-risk pregnancies (n = 517), admitted to the high-risk ward at Danderyd Hospital, Karolinska Institutet; a total of 2,015 tests were performed. The sensitivity and the specificity of the test compared to the fetal heart rate tracing was 81% and 89% respectively. If the test was performed within 24 hours of delivery, its predictive value for fetal asphyxia (i.e. a 5-minute Apgar score < 7) was 14% (7/49). Ten per cent of the patients felt no fetal movement in response to stimulation (irrespective of gestational age). In five cases where fetal heart rate tracings were pathological, stimulation nonetheless produced fetal movement and fetal outcome was good. Pathological heart rate tracings and no fetal movement in response to stimulation were present in 30 cases (out of 251 with no fetal movements at stimulation), in seven of which the infants had 5-minute Apgar scores < 7. Although many patients underwent repeated vibro-acoustic stimulation, there was no evidence of fetal habituation to the test. On 24 occasions (i.e. 1.2%), the patient denied vibro-acoustic stimulation, mostly because of previous discomfort due to vigorous fetal response. Where resources are limited, maternal perception of fetal movements in response to vibro-acoustic stimulation might be a useful alternative for preliminary screening of high-risk pregnancies.

Acoustic Stimulation↗
PubMed1988

Fetal acoustic stimulation in early labor in patients screened with the admission test.

Fetal heart rate reactions to the fetal acoustic stimulation test were investigated in 952 women in early labor. All had cephalic presentations (greater than 33 weeks of gestation) and were screened with a 15-minute fetal heart rate recording (admission test) before the sound stimulation was applied. Three different types of responses were observed: type I, an accelerative response; type II, a biphasic response with acceleration(s) followed by a deceleration; type III, no response or a prolonged deceleration (greater than 60 beats/min and greater than 60 seconds). A type I response was recorded in 98.0% of the women after a reactive admission test result, in 90.2% after an equivocal admission test result, and in 42.9% after an ominous admission test result. Fetal distress in labor occurred in these three groups in 2.0%, 22.2%, and 35.7% of cases, respectively. The risk for fetal distress was high after an ominous admission test and a type III response on the fetal acoustic stimulation test (75.0%). The fetal acoustic stimulation test might be of value in labor and give additional information about fetal well-being in patients previously screened by the admission test. Testing time can be shortened after an equivocal admission test.

Acoustic Stimulation↗
PubMed1987

Neonatal auditory acuity following in utero vibratory acoustic stimulation.

The fetal heart rate response to externally applied vibratory acoustic stimulation is currently being evaluated as a test of fetal well-being. We have examined the safety of this procedure by subsequent testing of the auditory nerve and brain stem evoked responses in the neonates. The results demonstrated no differences in auditory acuity when control infants were compared with infants previously exposed to antenatal vibratory acoustic stimulation.

Acoustic Stimulation↗
PubMed1995

Vibratory acoustic stimulation and fetal gasping.

OBJECTIVE: Vibratory acoustic stimulation (VAS) has been used to shorten the duration of antepartum fetal heart rate monitoring. Questions have been asked regarding the possible effects of VAS on the fetus. VAS was used to investigate whether the acute effect of VAS is associated with gasping in the normal fetus. STUDY DESIGN: Thirty-seven normal patients at 37-42 weeks' gestation with singleton fetuses were studied. All had normal amniotic fluid volume on ultrasound. These 37 subjects had a five-minute baseline sonographic assessment of fetal breathing and body movements. A fetal gasp was defined as an isolated, slow, irregularly occurring, deep, inspiratory-type movement, or series of them, of the chest and abdomen. Three-second VAS was then delivered with an artificial larynx placed directly over the fetal head. Fetal breathing, body and gasping movements were assessed at the time of this stimulus. RESULTS: A significant increase in fetal body movements (P < .001), a significant decrease in fetal breathing (P < .003) and absence of gasping movements were noted. CONCLUSION: The results suggest that gasping does not occur in response to VAS in the normal, term fetus.

Acoustic Stimulation↗
PubMed2004

Ultra-high-frequency acoustic stimulation and tinnitus control: a positron emission tomography study.

Ultra-high-frequency (UHF) external acoustic stimulation with the UltraQuiet device (UQ) has been reported to provide significant relief of severe disabling-type tinnitus. The nuclear medicine imaging technique of positron emission tomography (PET) was selected as a monitoring system to compare objectively metabolic alterations in brain function before and after UHF/UQ and to correlate the PET data with the subjective behavioral response of patients reporting tinnitus relief. PET of brain was completed on 6 patients randomly selected from a cohort of 15 patients included in a protocol to establish long-term tinnitus relief with UHF/UQ. Twelve specific regions of interest (ROI) were selected for PET of brain examination on the basis of results obtained with single-photon emission computed tomography (SPECT) of brain examinations recommended for patients with severe disabling-type tinnitus and demonstrating significant perfusion asymmetries in the right and left brain ROI of the primary auditory cortex; frontal, temporal, parietal, and medial temporal lobes; and cerebellum. PET of brain results included ratios of post- and pre-UHF/UQ stimulation that demonstrated no random response in the selected PET of brain ROI and ratios of post- and pre-UHF/UQ stimulation that demonstrated three categories of response in the selected PET brain ROI for all six patients: hypermetabolism in three patients; hypometabolism in two; and a mixed response in one. Correlation was established for each patient among PET and electrophysiological responses of alteration in minimal masking levels, the residual UHF neuronal response as reflected in the UHF audiogram, and the subjective reported behavioral responses of patients (obtained from outcome questionnaires for tinnitus relief, which focused on tinnitus intensity, annoyance, severity index, and a subjective scale of value of the UHF/UQ device for tinnitus relief. The subjective behavioral response for tinnitus relief with UHF/UQ was found to reflect a dual effect: acoustic stimulation of the residual neuronal function in the UHF range (10-14 kHz) and audiometric thresholds of 40-50 dB sound pressure level (SPL), and the metabolic activity at brain cortex for neuronal reprogramming. The PET of brain categories of response suggested that the UHF/UQ "masking" is predominantly reflective of neuronal reprogramming at the brain cortex. Nuclear medicine PET of brain imaging has provided an objective monitoring system for attempting to establish the efficacy of UHF/UQ for tinnitus relief. No complication of the tinnitus was reported secondary to the PET of brain examination. This limited PET of brain study supports the clinical recommendation of the efficacy of UHF/UQ external acoustic stimulation for a selected population of patients with tinnitus of the severe disabling type.

Acoustic Stimulation↗
PubMed2004

Motor cortex inhibition induced by acoustic stimulation.

The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following acoustic stimulation occurs at the level of the motor cortex through reticulo-cortical projections or subcortically, perhaps through reticulo-spinal projections. We compared the influence of acoustic stimulation on motor effects elicited by TMS over motor cortical areas to those evoked with subcortical electrical stimulation (SES) through depth electrodes in five patients treated with deep brain stimulation for Parkinson's disease. SES bypasses the motor cortex, demonstrating any interaction with acoustic stimuli at the subcortical level. EMG was recorded from the contralateral biceps brachii muscle. Acoustic stimulation was delivered binaurally through headphones and used as a conditioning stimulus at an interstimulus interval of 50 ms. When TMS was used as the test stimulus, the area and amplitude of the conditioned motor response was significantly inhibited (area: 57.5+/-12.9%, amplitude: 47.9+/-7.4%, as percentage of unconditioned response) whereas facilitation occurred with SES (area: 110.1+/-4.3%, amplitude: 116.9+/-6.9%). We conclude that a startle-evoked activation of reticulo-cortical projections transiently inhibits the motor cortex.

Acoustic Stimulation↗
PubMed1991

The influence of contralateral acoustic stimulation on click-evoked otoacoustic emissions in humans.

Contralateral acoustic stimulation has the effect of reducing the amplitude and shifting the phase of click-evoked OAEs. This effect is thought to be mediated via the medial efferent system and, therefore, the presence of this effect could be used to test the integrity of the neural pathway from one cochlea to the other. With a clinical application in mind, a technique for demonstrating the influence of contralateral acoustic stimulation on click-evoked OAEs was designed to overcome fluctuations in patient and environmental noise. The results of this test on three normal subjects and a patient with a posterior fossa lesion are described.

Acoustic Stimulation↗
PubMed1993

Fetal acoustic stimulation for rapid intrapartum assessment of fetal well-being.

Fetal heart rate reactions to the fetal acoustic stimulation test (FAST) were prospectively studied in 140 women in early labor. Overall 45 of 140 patients (32%) had one or more complications of pregnancy. All were in the latent phase of labor with a singleton, vertex-presenting fetus. Gestational age ranged from 37-43 wks. The women were screened with a 15-20 min fetal heart rate recording (FHR admission test) before the acoustic stimulation was applied. Results of the FHR admission test and the FAST in women were compared with fetal outcome; which was considered poor when there was perinatal death, a 5 min Apgar score less than 7, fetal distress requiring cesarean section, thick meconium stained amniotic fluid or admission to the neonatal intensive care unit. FAST had better sensitivity (71.4% vs 42.8%), specificity (99.2% vs 97.7%), positive predictive value (83.3% vs 50.0%) and negative predictive value (98.5% vs 97.0%) for poor fetal outcome than the FHR admission test. Fetal acoustic stimulation test in the early intrapartum period may be used as a noninvasive screening method for rapid intrapartum assessment of fetal wellbeing. It may discriminate the compromised from the noncompromised fetus. This clinical application can be helpful in a busy labor room when rapid assessment of fetal health is required.

Acoustic Stimulation↗
PubMed1987

Intrapartum vibratory acoustic stimulation of the human fetus during episodes of decreased heart rate variability.

The effects of intrapartum vibratory acoustic stimulation during periods of decreased fetal heart rate variability were studied in 25 healthy term fetuses. Fetal monitoring and real-time ultrasound scanning were used simultaneously to detect fetal response. Vibratory acoustic stimulation was provided by an artificial larynx generating a signal at 85 dB and 85 Hz. This stimulus was applied for 5 seconds on the maternal abdomen over the fetal head after a 20-minute period of decreased fetal heart rate variability. All fetuses reacted with an immediate fetal heart rate acceleration of at least 10 bpm (range: 10 to 35 bpm, mean +/- SD = 18.4 +/- 7.0), and 19 fetuses also had sudden fetal body movement. A deceleration of the fetal heart rate after the initial acceleration was observed in nine fetuses (range: 15 to 70 bpm, mean +/- SD = 45.5 +/- 16.5). The implications of these findings are discussed in relation to the possible use of fetal vibratory acoustic stimulation for intrapartum surveillance.

Acoustic Stimulation↗
PubMed2001

[Effects of selective attention and contralateral acoustic stimulation on latency of distortion product otoacoustic emissions].

OBJECTIVE: To investigate the effects of selective attention and contralateral acoustic stimulation on latency of distortion product otoacoustic emissions. METHOD: Latency of DPOAE was recorded in 30 ears of 15 normal subjects with and without visual attention task, contralateral acoustic stimulation and combination of both forms of stimulus. RESULT: No significant change was observed in three form of stimulus. CONCLUSION: The effects of selective attention and contralateral acoustic stimulation on latency of DPOAE have to be further studied.

Acoustic Stimulation↗