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Biomedical subjects

P Enck

Publications and source records attributed to P Enck.

At least 73 records · Page 4Linked to original sources
PubMed1997

Cerebral evoked responses to gastrointestinal stimulation in humans.

Recent advances have permitted recording of evoked potentials (EPs) in response to electrical and mechanical stimulation of the gastrointestinal (GI) organs via methods used primarily in clinical neurophysiology. Current research involving stimulation of the esophagus, rectum, and colon, and recording the corresponding responses on the scalp, is being practiced in only a few laboratories. This review examines the engineering aspects of recording EPs, such as characteristics of the stimuli, placement of stimulus electrodes in the GI tract, and enhancement of evoked potential signals. We also discuss the physiological concepts involved in the generation of EPs, and how these compare with somatosensory evoked responses. Current experimental techniques employed by various investigators and results reported from their laboratories are compared. We believe that cerebral EPs to GI stimulation could be useful in studying a number of pathophysiological conditions such as gastroesophageal reflux disease, diffuse esophageal spasm, chronic inflammatory bowel disorders, chronic abdominal pain, and irritable bowel syndrome, among others. We hope that the present review will generate interest in the use of EPs arising out of GI stimulation, aiding in understanding their physiological implications in healthy subjects and in GI disorders.

Cerebral Cortex↗
PubMed1996

Comparison between intraluminal multiple electric impedance measurement and manometry in the human oesophagus.

Conventional oesophageal manometry and intraluminal electrical impedance measurement were simultaneously applied in eight healthy volunteers to study the effect of wet and semisolid bolus viscosities on oesophageal motility and bolus transit. Contraction front velocity measured by electrical impedance and manometry were identical for wet and semisolid swallows and highly associated. Bolus front velocity as measured by electrical impedance was significantly faster than contraction front velocity in both wet and semisolid swallows. Bolus front velocity during semisolid swallows was significantly slower compared to wet swallows. It is concluded that intraluminal electrical impedance measurement is a reliable technique to detect oesophageal motility as well as to differentiate between transit of wet and semisolid bolus consistencies.

Adult↗
PubMed1996

Electrically evoked cerebral potentials during esophageal distension at perception and pain threshold.

OBJECTIVE: To investigate esophageal sensory function in normal volunteers. METHODS: The method of evoking cerebral potentials (EPs) after electrical stimulation of the esophagus was applied in eight healthy male volunteers, 20-40 yr old. Electrical stimulation was obtained via bipolar Ag/AgCl electrodes attached to a latex balloon mounted on a catheter. The balloon was inflated stepwise to perception and pain thresholds. At the perception threshold for balloon distension, the intensity of electrical stimulation was increased stepwise to perception threshold for electrical stimulation, and subsequently to 2-fold, 4-fold, and 8-fold perception threshold. EPs were recorded from the vertex (Cz) and forehead (Fz, reference) and compared between the increasing electrical stimulation intensities and between perception and pain thresholds for mechanical stimulation. RESULTS: The results show that amplitudes of EPs significantly increased with increasing electrical stimulation intensities, whereas latencies of EPs were not affected. Latencies and amplitudes of EPs were comparable at perception and pain thresholds for esophageal distension. CONCLUSIONS: The study suggests that repetitive electrical stimulation of the human esophagus is predominantly mediated via vagal A-delta fibers. The unaltered EPs at the perception and pain thresholds suggest that vagal A-delta fibers are not involved in mediation of pain. The findings support the view that painful and nonpainful stimuli are mediated via different visceral afferents between the esophagus and brain in humans.

Adult↗
PubMed1996

Comparison of anal sonography with conventional needle electromyography in the evaluation of anal sphincter defects.

OBJECTIVE: A comparison of anal sonography with conventional electromyographic mapping in the evaluation of anal sphincter defects was the aim of this study. METHODS: In 23 patients with defecatory problems referred for conventional needle electromyography (EMG), anal endosonography, with a 7.5-MHz, 355 degrees scanner, was performed before EMG to determine the structural integrity of the external anal sphincter. If lesions were found, they were described in terms of location and extent. Subsequently, concentric needle EMG of the external sphincter was performed circumferentially to locate muscle parts exhibiting normal and diminished or missing muscle activity. Lesions found by EMG were also described like those found by sonography. RESULTS: Of 23 patients, eight exhibited no abnormalities on EMG, and no muscle defects were identified endosonographically in any of these patients. In the remaining 15 patients, EMG showed either an incomplete pattern of interference or a complete absence of voluntary activity; in all of these patients endosonography also identified structural deficit. In 14 of these 15 patients, abnormalities were found at the same location with both endosonography and EMG. In the remaining patient, the two techniques identified structural and functional abnormalities at different locations. CONCLUSION: Although EMG is the gold standard for assessment of the functional relevance of muscle defects, anal endosonography yields a sensitivity and specificity of almost 100%.

Adult↗
PubMed1996

[Psychosocial factors in Crohn disease--an overview].

In more than 50 years of psychosomatic research on Crohn's disease, several research hypotheses have been generated, which are critically reviewed here: A disease-specific personality could never be identified, and an important role of psychiatric and psychopathologic personality traits in disease onset was never substantiated. Moreover, most abnormalities found in psychological tests have to be regarded as secondary to chronic illness. Effects of psychologic and social stress on symptoms have not been validated, but it may be that Crohn's patients may have developed less coping abilities with daily hassles. Psychotherapy may improve this, but does not affect the clinical course of the disease.

Adaptation, Psychological↗
PubMed1995

Speed and pressure characteristics of external anal sphincter contractions.

The principle of isochronism reflects constant contraction time for varying strengths of muscle contraction. This principle was studied for the innervation of the pelvic floor in humans using motor-evoked potentials (MEPs) and evoked pressure curves (EPCs) from the external anal sphincter muscle (EAS). MEPs and EPCs were simultaneously recorded after transcranial magnetic stimulation of the motor cortex. Voluntary contractions were also studied. Contraction times of the EAS were significantly longer in voluntary contractions (mean, 237 ms) than in EPCs (mean, 90 ms). Depending on either mode of contraction, contraction times varied only slightly despite a wide range of contraction strengths. It is shown that the contractile behavior of the EAS is a function of slow- and fast-twitch muscle fiber distribution and that the principle of isochronism governs motor performance not only of limb muscles but also of the EAS. There exists a unique optimal working range of each muscle to meet its individual function. Disturbance of this principle results in a less efficient contraction with either inappropriate basic tone or disturbed reflex activation in the EAS. Both are possible causes of incontinence.

Adult↗
PubMed1995

Gastrointestinal problems in airline crew members.

The presence of intestinal and extraintestinal symptoms was investigated by a symptom questionnaire in crew members (n = 190) - and as controls in age and sex matched ground based administrative employees (n = 100) - of a charter carrier and was related to the actual flight schedule of the flying staff during one month. In addition, health and illness behaviors and personal, job and life satisfaction were assessed and related to symptom scores and flight schedules. Flying staff did report significantly more dyspeptic symptoms than did ground staff, and this was found mainly with long-distance flying, since staff with short-haul experience only did not report as much upper intestinal complaints. Also, cabin crew reported significantly more intestinal symptoms than did cockpit members, and part of the upper GI symptoms could be explained by different eating behaviors, specifically more fibre intake in flying staff. With increasing intestinal symptom frequency, doctor visits and sick-days increased, and satisfaction with job and personal life decreased. Flying staff had, however, more awareness of the importance of health behaviors. It is concluded that frequent flying specifically on long distances may result in increased intestinal symptoms, presumably due to time-shift.

Absenteeism↗
PubMed1994

Long-term efficacy of biofeedback training for fecal incontinence.

PURPOSE: Biofeedback therapy in fecal incontinence has been reported to improve continence in more than 70 percent of patients, but most studies have followed patients for less than two years. METHODS: Patients treated by biofeedback training between 1985 and 1986 were given a questionnaire in 1991, as were incontinent patients who had not entered this treatment program. All were asked for the occurrence, frequency, and severity of incontinence events in the past two weeks. Anamnestic and anorectal manometry data from the initial visit were also compared. RESULTS: Eighteen of 24 treated patients and 40 of 71 untreated patients responded. Of those treated by biofeedback, 78 percent reported episodes of fecal incontinence as compared with 77.5 percent of those not treated by biofeedback. Severity of incontinence, however, was significantly less (P < 0.02) in the treatment group (mean number of events, 0.2/day) than in those without treatment (1/day). In biofeedback-treated patients, it was identical with the frequency and severity reported immediately after therapy. No differences were found with respect to initial clinical data and anorectal manometry between both groups. CONCLUSION: Biofeedback training improves continence in patients not only during treatment and within the first two years but also for several years after therapy.

Adolescent↗
PubMed1994

Anatomy of the anal sphincters. Comparison of anal endosonography to magnetic resonance imaging.

PURPOSE: A recent application of endosonography in the evaluation of anal sphincter morphology has led to controversy about the possibility of precisely assessing the diameter of external and internal anal sphincter muscles. On the other hand, magnetic resonance imaging (MRI) has been proposed to allow a more detailed view of the anatomy of the pelvic floor. However, both techniques have not yet been compared directly. METHODS: Eight healthy volunteers (age range, 25-40 years; 5:3, male:female) participated. Anal ultrasound was performed using a 7.5-MHz rectal transducer which produced a transversal panorama display of 360 degrees, allowing an image perpendicular to the anal canal. Imaging of the diameter of the internal and external anal sphincter muscles was performed with the transducer placed in the midanal canal, and measurement was always performed by the same investigator in dorsal projection. MRI was performed using a 1.5 Tesla Magnetom (Siemens, Erlangen, Germany) to obtain sagittal and angled axial (perpendicular to the anal canal) planes for consecutive 3-mm slices which were evaluated by four independent raters. RESULTS: Muscle thickness of the sphincter muscles in dorsal projection was 1.96 +/- 0.61 mm for the internal sphincter and 6.35 +/- 1.07 mm for the external sphincter using ultrasound. It was 1.72 +/- 0.13 mm and 3.99 +/- 0.99 mm, respectively, using MRI. When both measures were compared, only the internal sphincter data correlated significantly (r = 0.818, P = 0.0023) between both measures. Sagittal resonance imaging of the anal canal did not allow for differentiation of both muscles at all. Differentiation among mucosa, submucosa, and internal anal sphincter is not possible with MRI but may well be performed with high-resolution ultrasound. CONCLUSION: Anal ultrasound carries the potential of becoming a routine clinical procedure for evaluation of the anal anatomy and morphology in defecation disorders, but current MRI assessment of the anal anatomy is elaborate, costly, and does not provide any further insights.

Adult↗
PubMed1994

Nutrient ingestion increases rectal sensitivity in humans.

To determine the effect of nutrient ingestion on rectal perception thresholds (first sensation, consistent urge to defecate, pain), rectosigmoid balloon distentions were performed with a computerized automated pump in eight healthy volunteers (four males, four females, 31.6 +/- 6.02 years). Two measurements of rectal balloon distention were performed on 2 separate days. Day 1 served as a control condition with no meal. On day 2 the subjects received a 600 kcal liquid meal. On the control day, determination of perception thresholds was performed two times with a 10-min break between measurements. On the experimental day, threshold determinations were made before and after the ingestion of the liquid standard meal. The order of the experimental days was counterbalanced. Distention volumes at the urge to defecate and the pain threshold (maximum tolerable volume) were significantly reduced following the meal. The average change from pre- to postprandial measurements of the threshold for urge to defecate was -20.55 +/- 4.22% and for the maximum tolerable volume it was -16.09 +/- 4.4%. These results extend data previously reported from animal studies using similar experimental methods.

Adult↗
PubMed1994

Prevalence of gastrointestinal symptoms in diabetic patients and non-diabetic subjects.

To determine the frequency of gastrointestinal symptoms in diabetic patients, 190 patients, consecutively referred to the Diabetes Research Institute, reported their gastrointestinal symptoms on a standardized symptom list. One hundred and eighty non-diabetic healthy subjects served as (matched) controls. Finally, 75 patients with Type 1 (insulin-dependent) diabetes mellitus (33 male, 43 female; age 34,1 (18-60) yrs, diabetes duration: 11,1 (0,3-41) yrs) and 68 patients with Type 2 (non-insulin-dependent) diabetes mellitus (31 male, 37 female, age: 61,4 (37-88) yrs, diabetes duration: 10,7 (0,3-40) yrs) were studied and compared with two cohorts of controls of the same size. There were no differences in prevalence of symptoms referrable to the upper and lower GI-tract in type 1 diabetic patients as compared with controls. Among patients with type 2 diabetes the main gastrointestinal complaint was constipation (22,1% vs 10,3%; p < 0.05). Upper gastrointestinal symptoms were also more frequent among Type 2 diabetic subjects (nausea 11,8% vs 2,9%, p < 0.05). There was a tendency for an increased symptom prevalence with higher age in both type 1 and type 2 diabetes. Presence of peripheral neuropathy was associated with a higher symptom prevalence in type 1 diabetes. After stratification, diabetes duration and glycaemic control (HbA1c) did not influence the frequency of symptoms. Thus, gastrointestinal symptoms occur frequently among both diabetic patients and non-diabetic subjects. However, significant differences were found only in type 2 (non-insulin-dependent) diabetes, the commonest symptom being constipation. These findings support the need of a nondiabetic control group in epidemiological studies evaluating symptom prevalence in diabetes mellitus.

Adolescent↗
PubMed1994

Endosonography of the anal sphincters: incontinent and continent patients and healthy controls.

It has previously been shown that in healthy subjects anal sphincter functions as assessed by anorectal manometry and anal sphincter anatomy as measured by endoluminal ultrasound are poorly correlated. It remains to be shown, however, whether this is true for a larger series of patients with anorectal dysfunctions such as incontinence, and what is the clinical relevance of anal sonography. Anal sonography was performed in 42 consecutive patients with fecal incontinence, in 19 patients with constipation and/or anal pain, and in 15 healthy volunteers to determine anal sphincter integrity and the dorsal diameter of the internal and external anal sphincter muscles. Conventional multilumen anorectal manometry was performed in all subjects and patients to determine, among others, external and internal sphincter (EAS, IAS) performance at rest and during squeezing. It was shown that healthy subjects exhibit significantly higher muscle diameters of the IAS than both patient groups, but the EAS was similar in all groups. In 11/42 cases of incontinent patients, in 3/19 constipated patients, but in none of the controls a muscle defect of the EAS was found with sonography. Thirteen of these 14 patients were women with previous birth traumas. EAS but not IAS muscle thickness and muscle performance (squeezing and resting, respectively) were significantly correlated. Across all groups, women had smaller EAS muscle diameters than men. It is concluded, that in incontinent patients anal sonography may reveal additional information of clinical relevance in a substantial fraction of patients, and, thus, both anal manometry and anal ultrasound are of clinical value.

Adult↗
PubMed1994

Colonic and anorectal dysfunction in a patient with the tethered cord syndrome.

Although visceral dysfunction is commonly encountered in the tethered cord syndrome, alteration of intestinal motor and sensory function has not yet been specifically addressed in this neurological disorder. We report the case of a 54-yr-old woman with a rare form of adult onset tethered cord syndrome who presented to us for preoperative assessment of marked constipation, urinary and fecal incontinence, and a rectal prolapse. It is shown that the tethered cord syndrome causes complex clinical patterns of bowel dysfunction and that careful efforts are mandatory to differentiate their underlying pathology. Specific diagnostic procedures directed to intestinal motility and perception were of decisive importance in enabling us to apply the appropriate treatment to our patient.

Colon↗
PubMed1994

[Biofeedback treatment of fecal incontinence and constipation].

In summary, studies published in recent years on biofeedback training in defecation disorders--fecal incontinence and constipation--have presented convincing evidence that this method which derives from psychological learning theory has found clinical importance and relevance. Future research will need to demonstrate the mechanisms involved in its efficacy, the best clinical diagnosis and treatment modalities, and the long term effects of such management.

Adult↗
PubMed1993

Biofeedback training in disordered defecation. A critical review.

For 20 years now, biofeedback applications in the treatment of fecal incontinence and, more recently, chronic constipation in adults have proven that improvement of anorectal function can be achieved in a majority of patients. Despite this evidence, the definitive mode of action of biofeedback training remains obscure but may include improvement of both motor and sensory functions of the anorectum. In addition, behavioral modification of individual defecatory behavior in these patients may be effective as well. The long-term results of such treatment need to be tested in future research.

Anal Canal↗