Cerebral evoked potentials after endorectal mechanical stimulation in humans

1988 ◽  
Vol 254 (4) ◽  
pp. G477-G482 ◽  
Author(s):  
L. Collet ◽  
P. Meunier ◽  
R. Duclaux ◽  
S. Chery-Croze ◽  
P. Falipou
Keyword(s):  
Evoked Potentials ◽  
Mechanical Stimulation ◽  
Evoked Potential ◽  
Rectal Wall ◽  
International System ◽  
Rectal Sensation ◽  
Rectal Balloon ◽  
Female Age ◽  
Cerebral Evoked Potentials ◽  
Stimulation Of

Although numerous clinical studies have proved that impaired rectal sensation is a major factor in fecal continence dysfunctions, objective studies in this field are still lacking. To provide information on normal rectal afferents, a study of cerebral potentials evoked by mechanical stimulation of the rectal wall was carried out in 10 healthy volunteers (5 male, 5 female; age, 33–52 yr). The stimulating device consisted of a rectal balloon rhythmically inflated and deflated by means of an animal breathing ventilator. Recordings were obtained 2 cm behind the vertex (C'z, International system 10–20). The responses were averaged from 300 to 800 sweeps. The average was triggered either on inflation ("on effect") or on deflation ("off effect"). Inflation volume and pressure were adjusted to induce a clear but not painful pulsing sensation. Reproducible responses were recorded by both on and off effects. The evoked potentials were polyphasic with a succession of positive and negative waves (peak latencies between 78 and 310 ms). The shape of the response (morphology, latency, and amplitude) was perfectly reproducible in the same subject. With regard to intrasubject reproducibility, variability was displayed: only the early waves (latency less than 100 ms) were perfectly reproducible; late waves exhibited variable latency and morphology. The present findings are the first demonstration of the possibility of recording an evoked potential on the scalp after a mechanical stimulation of the rectum.

Octreotide reduces perception of rectal electrical stimulation by spinal afferent pathway inhibition

1995 ◽  
Vol 269 (6) ◽  
pp. G821-G826 ◽  
Author(s):  
W. D. Chey ◽  
A. Beydoun ◽  
D. J. Roberts ◽  
W. L. Hasler ◽  
C. Owyang
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Double Blind ◽  
Afferent Pathways ◽  
Normal Volunteers ◽  
Site Of Action ◽  
Cerebral Evoked Potentials ◽  
Pathway Inhibition ◽  
Irritable Bowel

Octreotide reduces perception of rectal distension in normal volunteers and irritable bowel patients. To localize octreotide's site of action, perceptual and evoked potential responses to rectal electrical stimulation were tested in seven normal volunteers after double-blind octreotide (100 micrograms 2) or placebo. After octreotide, the currents needed to elicit threshold perception of square-wave impulses delivered to the rectum were 29% higher than after placebo. When electrical stimulation was delivered at constant currents 50% above threshold, rectal perception scores were significantly reduced after octreotide compared with placebo. Rectal electrical stimulation led to characteristic and reproducible cerebral evoked potentials. Octreotide had no effect on latencies, but reduced peak-to-peak amplitudes by 35% compared with placebo. Rectal electrical stimulation also led to characteristic and reproducible spinal evoked potentials. Octreotide had no effect on spinal latencies, but reduced peak-to-peak amplitudes by 51%. In conclusion, octreotide reduces perception of rectal electrical stimulation, which is associated with inhibition of cerebral and spinal evoked potential amplitude, indicating effects on spinal afferent pathways.

Monitoring of Spinal Cord Stimulation Evoked Potentials during Thoracoabdominal Aneurysm Surgery

Neurosurgery ◽  
1991 ◽  
Vol 28 (2) ◽  
pp. 325-330 ◽  
Author(s):  
Richard B. North ◽  
Benjamin Drenger ◽  
Charles Beattie ◽  
Robert W. McPherson ◽  
Stephen Parker ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Conduction Block ◽  
Significant Risk ◽  
Thoracoabdominal Aneurysm ◽  
Direct Stimulation ◽  
Lower Extremity Ischemia ◽  
Extremity Ischemia ◽  
Stimulation Of

Abstract Repair of a thoracoabdominal aneurysm involves a significant risk of ischemic injury to the spinal cord. Standard monitoring of somatosensory evoked potentials, which relies upon peripheral nerve stimulation, becomes nonspecific and insensitive during this surgery when aortic cross-clamping produces lower extremity ischemia causing a peripheral conduction block. Techniques for the insertion of percutaneous epidural electrodes, developed originally for pain management, have been adapted to this setting to permit direct stimulation of the spinal cord for intraoperative monitoring of evoked potentials. The clinical outcome in patients monitored by this technique has been consistent with evoked potential findings.

Electrical stimulation of tooth pulp in humans. I. Relationships among physical stimulus intensities, psychological magnitude estimates and cerebral evoked potentials

Pain ◽  
1982 ◽  
Vol 14 (3) ◽  
pp. 207-232 ◽  
Author(s):  
Vera M. Fernandes de Lima ◽  
Gian Emilio Chatrian ◽  
Ettore Lettich ◽  
Robert C. Canfield ◽  
Colin R. Miller ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Tooth Pulp ◽  
Physical Stimulus ◽  
Cerebral Evoked Potentials ◽  
Stimulation Of ◽  
Magnitude Estimates

Motor Evoked Potentials from Transcranial Stimulation of the Motor Cortex in Humans

Neurosurgery ◽  
1984 ◽  
Vol 15 (3) ◽  
pp. 287-302 ◽  
Author(s):  
Walter J. Levy ◽  
Donald H. York ◽  
Michael McCaffrey ◽  
Fred Tanzer
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Sensory Modality ◽  
Motor Evoked Potential ◽  
Transcranial Stimulation ◽  
Direct Stimulation ◽  
Stimulation Of

Abstract Electrical monitoring of the motor system offers the potential for the detection of injury, the diagnosis of disease, the evaluation of treatment, and the prediction of recovery from damage. Existing evoked potentials monitor one or another sensory modality, but no generally usable motor monitor exists. We have reported a motor evoked potential using direct stimulation of the spinal cord over the motor tracts in cats and in humans. To achieve a less invasive monitor, we used transcranial stimulation over the motor cortex in the cat, thus stimulating the motor cortex. We report here the initial application of this method to humans. A plate electrode over the motor cortex on the scalp and a second electrode on the palate direct a mild current through the motor cortex which will activate the motor pathways. This signal can be recorded over the spinal cord. It can elicit contralateral peripheral nerve and electromyographic signals in the limbs or movements when the appropriate stimulation parameters are used. In clinical use to date, this has been more reliable than the somatosensory evoked potential in predicting motor function in patients where the two tests differed. It offers a number of possibilities for the development of valuable brain and spinal cord monitoring techinques, but requires further animal studies and clinical experience. Studies to date have not demonstrated adverse effects, but evaluation is continuing.

The long-latency component of cerebral evoked potentials in anesthetized cats

1986 ◽  
Vol 65 (3) ◽  
pp. 392-397 ◽  
Author(s):  
Kyu Ho Lee ◽  
Jun Kim ◽  
Jin Mo Chung
Keyword(s):  
Evoked Potentials ◽  
Sural Nerve ◽  
Evoked Potential ◽  
Afferent Input ◽  
Late Component ◽  
Content Type ◽  
C Fibers ◽  
Long Latency ◽  
Fine Print ◽  
Stimulation Of

✓ A late component of the cortical evoked potential elicited by somatosensory afferent input was studied in cats anesthetized with α-chloralose. Cortical evoked potentials were recorded from the somatosensory-motor cortex during stimulation of the sural nerve with graded intensities. The stimulus intensity was adjusted to activate Aαβ fibers only, then both Aαβ and Aδ fibers, and both A and C fibers, as judged by afferent volleys monitored from the sural nerve proximal to the stimulating site. In addition to early components reported previously, a very late component was identified at a latency of 400 to 600 msec following stimulation of the sural nerve with intensities above threshold for Aδ fibers. A further increase in stimulation intensity to include activation of C fibers did not reveal any more components. This late component was depressed by a systemic intravenous injection of morphine (2 mg/kg), and intravenous naloxone (0.1 mg/kg) reversed the effect of morphine. The late component of the evoked potential could also be recorded from subcortical tissue after decortication of the sensorimotor cortex. From these results, it appears that a very late component of the cortical evoked potential can be recorded from cats anesthetized with α-chloralose. The late component is evoked by activation of peripheral Aδ fibers. Furthermore, its morphine sensitivity suggests that this component may be elicited by nociceptive afferent fibers. If further investigations prove this, the late component, which is analogous to human long-latency potentials, could be used in an experimental model for pain research.

Feeding alters cerebral evoked potentials in response to rectal balloon stimulation

1995 ◽  
Vol 108 (4) ◽  
pp. A580
Author(s):  
YK Chan ◽  
GK Herkes ◽  
CA Badcock ◽  
JE Kellow
Keyword(s):  
Evoked Potentials ◽  
Rectal Balloon ◽  
Cerebral Evoked Potentials

The functional anatomy of middle-latency auditory evoked potentials: thalamocortical connections

1992 ◽  
Vol 68 (2) ◽  
pp. 425-431 ◽  
Author(s):  
S. Di ◽  
D. S. Barth
Keyword(s):  
Electrical Stimulation ◽  
Auditory Cortex ◽  
Evoked Potentials ◽  
Linear Combination ◽  
Evoked Potential ◽  
Medial Geniculate Body ◽  
Cortex Area ◽  
Medial Geniculate ◽  
Potential Complex ◽  
Stimulation Of

1. An 8 x 8-channel microelectrode array was used to map epicortical field potentials from a 4.375 x 4.375-mm2 area in the right parietotemporal neocortex of four rats. Potentials were evoked with bilaterally presented click stimuli and with electrical stimulation of the ventral and dorsal divisions of the medial geniculate body. 2. Epicortical responses to click stimuli replicated earlier findings. The responses consisted of a positive-negative biphasic waveform (P1a and N1) in the region of primary auditory cortex (area 41) and a positive monophasic waveform (P1b) in the region of secondary auditory cortex (area 36). Two potential patterns, one at the latency of the N1 and the other at the latency of the P1b, were used to represent activation of cells within areas 41 and 36. A linear combination of these patterns was sufficient to explain from 90 to 94% of the variance of the evoked potential complex at all latencies. 3. In the same animals, epicortical responses to electrical stimulation of the ventral and dorsal divisions of the medial geniculate body were also localized to areas 41 and 36, respectively. A linear combination of potential patterns from these separate stimulation conditions was sufficient to explain from 80 to 93% of the variance of the original click-evoked potential complex at all latencies. 4. These data provide functional evidence for anatomically defined topographical thalamocortical projections to primary and secondary auditory cortex. They suggest that short-latency cortical evoked potentials (10-60 ms poststimulus) are dominated by parallel thalamocortical activation of areas 41 and 36.

Geophysical Variables and Behavior: XL. Electromagnetic Stimulation of ‘Extrasensory’ Evoked Potentials

1987 ◽  
Vol 64 (3) ◽  
pp. 1015-1018
Author(s):  
Robert G. Kunzendorf
Keyword(s):  
Evoked Potentials ◽  
Signal Detection ◽  
Evoked Potential ◽  
Cortical Response ◽  
Auditory Evoked Potential ◽  
Electromagnetic Stimulation ◽  
Long Latency ◽  
Psychophysiological Testing ◽  
And Behavior ◽  
Stimulation Of

In psychophysiological testing with 10 subjects, an electromagnetic stimulus evoked a long-latency cortical response similar to the long-latency component (P300) of an auditory evoked potential. On a signal-detection test, the electromagnet elicited no conscious sensations.

Effects of the somatostatin analogue octreotide on rectal afferent nerves in humans

1993 ◽  
Vol 265 (4) ◽  
pp. G742-G751 ◽  
Author(s):  
V. Plourde ◽  
T. Lembo ◽  
Z. Shui ◽  
J. Parker ◽  
H. Mertz ◽  
...  
Keyword(s):  
Visceral Pain ◽  
Rectal Wall ◽  
Receptive Fields ◽  
Inhibitory Effect ◽  
Visceral Afferents ◽  
Somatostatin Analogue ◽  
Rectal Sensation ◽  
Rectal Balloon ◽  
Analgesic Effects ◽  
Analogue Octreotide

Somatostatin (Som) administered intrathecally to humans has been shown to exert potent analgesic effects on somatic pain, and anecdotal evidence suggests that Som may also relieve visceral pain. In the current study, we used rectal balloon distension in seven healthy volunteers to evaluate the effect of the Som analogue octreotide (Oct; 1.25 microgram/kg sc) on four pathways mediated by different visceral afferents that originate in the rectum: conscious perception, receptive relaxation, reflex inhibition of internal anal sphincter, and a viscerosomatic reflex. Rectal mechanoreceptors were stimulated either by distending the rectum tonically (volume ramp at 20-40 and 400 ml/min) or phasically (intermittent pressure steps of 60 s duration). Pressure thresholds for nonnoxious and noxious sensations in response to slow tonic distension were increased in the presence of rectal lidocaine (20 ml of 2% solution), whereas those to phasic distension were unaffected. Oct significantly increased pressure and volume thresholds for nonnoxious and noxious sensations in response to slow tonic distension but did not further increase thresholds in the presence of intrarectal lidocaine. In contrast, no effect of Oct on rectal sensations was observed during rapid tonic or phasic distension. Oct had no effect on any of the monitored reflex responses. The effect of Oct on rectal sensation in the concentration used in this study was not associated with changes in the rectal wall pressure-volume relationship during any distension protocol. These findings indicate that the inhibitory effect of Oct on rectal sensation is likely to represent a direct effect on a subset of extrinsic primary afferent neurons, with receptive fields in the mucosa

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