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Biomedical subjects

P Enck

Publications and source records attributed to P Enck.

At least 55 records · Page 3Linked to original sources
PubMed1999

Functional disorders of the anus and rectum.

In this report the functional anorectal disorders, the etiology of which is currently unknown or related to the abnormal functioning of normally innervated and structurally intact muscles, are discussed. These disorders include functional fecal incontinence, functional anorectal pain, including levator ani syndrome and proctalgia fugax, and pelvic floor dyssynergia. The epidemiology of each disorder is defined and discussed, their pathophysiology is summarized and diagnostic approaches and treatment are suggested. Some suggestions for the direction of future research on these disorders are also given.

Anus Diseases↗
PubMed1999

Influence of continuous, isobaric rectal distention on smooth muscle tone and cardiovascular activation in healthy volunteers.

UNLABELLED: Interactions between visceral, intestinal stimulation and autonomic cardiovascular function have received increasing attention over the last years. The aim of the study was to investigate the effect of long-term continuous rectal distention on rectal tone and cardiovascular function at the threshold for first sensation of distention and moderate urge to defecate compared to a resting period without distention. Continuous isobaric rectal distention was performed in 13 healthy volunteers with a ten minute pressure tracking procedure at each subject's predetermined individual threshold for either moderate urge or first sensation, separated by a ten minute resting period. Rectal volume, heart rate, systolic and diastolic blood pressure were determined continuously. RESULTS: Rectal tone decreased significantly over time at the threshold for moderate urge and first sensation. Cardiovascular measures remained stable over the distention procedures, except for a significant increase in systolic blood pressure at the threshold for moderate urge. DISCUSSION: The previously reported rectal accommodation response to rectal distention was confirmed. The increase in systolic blood pressure is most likely mediated through sympathetic efferent pathways.

Adaptation, Physiological↗
PubMed1998

Somatic and limbic cortex activation in esophageal distention: a functional magnetic resonance imaging study.

Little is known about the cerebral representations of visceral sensations in humans. Using functional magnetic resonance imaging (fMRI), we mapped the cortical areas of the human brain that were activated by mechanical stimulation of the esophagus in 5 healthy volunteers. Stimulation probes were placed into the distal part of the esophagus and inflated to produce a local distention. The cerebral activation pattern was related to the strength and quality of the stimulus. The weakest stimulus accompanied by a well-localized albeit weak retrosternal sensation activated only the parietal opercular cortices, probably including the secondary somatosensory cortex (SII). Additional activation of the primary sensorimotor cortex (SI) at the level of the face and mouth representation as well as of the right premotor cortex was found during repetitive distention of the esophagus at 0.5 Hz. Repetitive stimulation at 1 Hz additionally activated the insula bilaterally. The strongest distention stimulus, which caused a painful retrosternal sensation, resulted in an activation of the anterior cingulate cortex. Our findings demonstrate that SII is the primary cortical target of visceral afferents originating in the esophagus. Limbic structures become engaged when the visceral sensation is unpleasant or painful.

Adult↗
PubMed1998

Discharge patterns of intramural mechanoreceptive afferents during selective distension of the cat's rectum.

The afferent input from the rectum to the central nervous system (CNS) has yet to be thoroughly characterized. The characteristics of mechanoreceptive rectal afferents have been studied in unanaesthetized decerebrate cats. Following lumbo-sacral laminectomy, single-unit activity (occasionally multi-unit activity) was recorded from centrally cut filaments of the sacral dorsal roots (predominantly S2), while a balloon was inflated in the rectum. Starting from their background activities (mean 15.1 imp sec-1, SD 7.6 imp sec-1), afferent discharge rate increased with increasing balloon pressure (mean threshold 6.3 mmHg, SD 3.6 mmHg). The dependence of firing rate on intrarectal pressure began to flatten out at 25 mmHg (mean; SD 10 mmHg). For 22 out of 29 units (76%) complete saturation occurred at 35 mmHg (mean; SD 15 mmHg) with a maximum discharge rate of 31 imp sec-1 (mean; SD 12.6 imp sec-1). In a number of recording sessions, cyclical rectal contractions were observed. In these cases, changes in firing of the units were closely related to changes in intrarectal pressure. Pressure-related afferent activity could be enhanced by parasympathomimetic drugs which augmented rectal contractions. We conclude that sacral dorsal roots contain afferents from low-threshold mechanoreceptors located in the rectal wall, and that these afferents monitor the filling state and contraction level of the rectum.

Animals↗
PubMed1998

Autonomic dysfunction in patients with achalasia of the oesophagus.

It has been suggested that achalasia is associated with extraoesophageal sympathetic and parasympathetic dysfunction. In a prospective study we applied conventional ultrasonography and duplex sonography to investigate basal and postprandial peak systolic velocity (PSV), pulsatility index (PI) and resistance index (RI) of superior mesenteric artery and PSV of portal vein in nine patients with achalasia and 10 healthy controls (study I). In addition, in eight of these patients autonomic nervous function was investigated by pupillary function tests as well as cardiovascular reflex tests and compared with eight age- and sex-matched controls (study II). The results indicated that postprandial increase of PSV in the superior mesenteric artery was significantly lower, and postprandial decrease of PI and RI significantly higher in achalasia compared to healthy controls. In contrast, postprandial increase of PSV in the portal vein was not significantly different between both groups. Autonomic function tests revealed significant lower maximal pupillary contraction and redilatation velocities, significantly lower heart rate variation during orthostasis, deep respiration test and Valsalva manoeuvre in achalasia compared to controls. It is concluded that achalasia is associated with extraoesophageal autonomic nervous dysfunction that involves cardiovascular and pupillary function as well as regulation of mesenteric arterial blood flow.

Adult↗
PubMed1998

Anorectal functions in patients with spinal cord injury.

We wished to establish anorectal functions in patients with spinal cord lesions, related to the level of lesion and its completeness. We also wished to determine the value of neurophysiological tests for completeness of transsections in comparison with manometry and visceral sensory testing. In 32 patients (31.5 +/- 14.1 years, 25 males) with spinal trauma, completeness of transsection was assessed clinically. In 16 of these patients (30 +/- 15.6 years, nine males), a neurological work-up included recording of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) from the pudendal nerve within the first week after trauma. Also, anal sphincter EMG and pudendal nerve terminal motor latency (PNTML) were assessed. All patients also underwent conventional anorectal manometry and visceral sensory testing. Of all 32 patients, 15 were judged as 'complete' based on their clinical signs. Of those 16 tested neurologically, seven were labelled 'complete' since no MEP or SEP were detectable; one had pudendal SEP and MEP present, while SEP were present but delayed (47.0 +/- 8.8 msec) in the remaining patients. In four of these patients, also MEP were recorded (27.9 +/- 5.2 msec) and normal. PNTML was present in 12/16 patients independent of the completeness of lesion, and was rated normal in nine and delayed in three patients. EMG was normal in five, and pathological in 11 cases. In 5/15 cases of those judged as 'complete' (in 3/7 evaluated neurologically), visceral sensory testing revealed a minimal threshold for rectal perception of distension of 44 mL (range: 10-130), which sometimes was also perceived as urge to defecate. In a further case, manometry showed major voluntary action of the anal sphincter. These patients had lesions at all levels of the spinal column, ranging from cervical (C4,C6,C7) via thoratical (2 x T7,T8,T12) to lumbar segments. Anorectal function testing, and specifically visceral sensory testing may be superior to neurological assessment of 'completeness' of spinal cord lesions. It may be that visceral afferent pathways others than spinothalamic tract are involved in rectal perception that are less accessible to conventional neurophysiological diagnostic work-up.

Adolescent↗
PubMed1998

Spinal and pudendal nerve modulation of human corticoanal motor pathways.

We investigated the effects of lumbosacral and pudendal nerve stimulation on the corticofugal pathways to the human external anal sphincter. In 11 healthy subjects, anal sphincter electromyographic responses, evoked to transcranial magnetic stimulation of the motor cortex, were recorded 5-500 ms after lumbosacral root or pudendal nerve stimulation. Lumbosacral and pudendal nerve stimulation alone evoked responses with amplitudes of 293 +/- 73 and 401 +/- 153 microV and latencies of 3.2 +/- 0.2 and 2.2 +/- 0.2 ms, respectively. Cortical stimulation also evoked responses with amplitudes of 351 +/- 104 microV and latencies of 20.9 +/- 1.1 ms. When lumbosacral or pudendal nerve stimulation preceded cortical stimulation, the cortically evoked responses were facilitated (P < 0.01), with the effect appearing greatest at 5-20 ms after both lumbosacral and pudendal excitation and at 50-100 ms after lumbosacral excitation alone. Our results demonstrate that cortical pathways to the external anal sphincter are facilitated by prior lumbosacral and pudendal nerve stimulation, indicating that sensorimotor interactions are important in the central neural control of sphincter function.

Adult↗
PubMed1998

[Hepatic encephalopathy: neuropsychological and neurophysiological diagnosis].

Hepatic encephalopathy (HE) is a metabolically induced, potentially reversible functional disorder of brain, that may occur during chronic and acute liver diseases. It is of special clinical relevance to identify latent or subclinical HE, when patients show no clinical signs, but exhibit changes of complex cerebral functions as well as subcortical psychomotor deficits in psychometric tests. Because patients experience significant limitations in everyday life and the presence of such deficits is of prognostic value concerning their life expectancy, detection of latent HE has clinical importance. Psychometric tests have gained most significance because they are easy to perform and demonstrate high sensitivity, being highest with the trail-making-test part B. Electrophysiological methods such as EEG, visual evoked potentials, and P300 currently have a secondary and complementary role. An integration of brain imaging and spectroscopic techniques, electrophysiological methods, and neuropsychological tests is necessary for a comprehensive description of the disturbance on functional and topographical level in the future.

Brain↗
PubMed1998

Postprandial changes of electrical activity of the stomach after different meals.

AIM: The aim of the study was to investigate the response of the electrical activity of the stomach (electrogastrogram, EGG) to meals, different with respect to consistency, nutrient and caloric composition. METHODS: EGG was recorded in ten healthy volunteers for 30 min before and 45 min after a meal. All subjects received three different meals: A standard 500 kcal solid, a 500 cc isocaloric liquid diet of identical composition (55% carbohydrates, 15% protein, 30% fat) or 500 cc water. Data were analyzed off-line for postprandial changes. RESULTS: Water as well as liquid diet induced a significant postprandial decrease, while solid food induced a slight initial decrease and a subsequent marked increase of the dominant frequency above the fasting level. The response to the solid meal was significantly different from both tap water and liquid diet, but there was no difference between liquid diet and water. All meals significantly increased the signal power with a more sustained effect over time for the liquid diet and water than the solid meal. CONCLUSION: EGG changes seem to be more dependent on the consistency than the caloric and nutrient composition. Because of the dissociation between the timing of EGG changes and the known emptying kinetics, EGG changes seem to reflect other gastric functions rather than being associated with gastric emptying.

Adult↗
PubMed1998

Temporal analysis of feeding behavior in miniature pigs.

The feeding behavior of four Munich miniature pigs (29-43 kg) housed in pairs of two, was observed for two consecutive weeks. Pigs were conditioned to operate a computer-controlled recording system equipped with feeders delivering a precise food release per response and were then fed ad libitum. In addition to the descriptive analysis of feeding behavior, Walsh-Fourier Spectral Analysis was utilized to investigate the temporal patterns of food ingestion and the synchronisation of feeding patterns between the animals housed together. The pigs had up to 48% of their daily energy intake during the dark cycle and there was a substantial reduction of food intake from the first to the second week. Furthermore, pigs housed together synchronized feeding behavior from week 1 to week 2. The recording system has been shown to be highly reliable and valid and provides an excellent tool for the investigation of ingestive behaviors in miniature pigs.

Animals↗
PubMed1998

Neurogastroenterology--information processing from the viscera to the brain in humans.

With the many new investigational possibilities allowing access to the gut-brain axis in humans, new techniques, mainly from neurology, as well as interdisciplinary approaches, have produced insights into afferent information processing from the gut to the brain. They have become research tools in recent years, but will eventually become clinical tools for diagnostic purposes in the future. Gut-brain interactions may be seen at different levels: rather simple research models such as recordable perception and pain, on the one hand, can be contrasted and/or supplemented with neurological stimulation and imaging techniques, and clinical models such as spinal cord injury. All have contributed to the development of a new subspecialty in medicine, neurogastroenterology.

Brain↗
PubMed1997

Anal endosonography and manometry: comparison in patients with defecation problems.

PURPOSE: Correlations between anal sphincter function as assessed by anorectal manometry and anal sphincter anatomy measured by endoluminal ultrasound have been reported in the literature both for patients and for healthy individuals but have not been confirmed by other authors. METHODS: For a larger series of patients (152 consecutive patients, mean age 54.1 +/- 15.5 years; female:male ratio, 111:41) with anorectal dysfunctions such as incontinence (n = 92), constipation (n = 37), and other symptoms (n = 23), diagnostic work-up included conventional multilumen anorectal manometry to evaluate internal sphincter pressure at rest, maximum external sphincter squeeze pressure during contraction, and endoanal sonography to determine anal sphincter integrity and to measure dorsal, left lateral, and right lateral diameter of the internal anal sphincter (IAS) and external anal sphincter (EAS) muscles. RESULTS: Maximum squeeze pressure was significantly correlated to muscle thickness of the EAS (P = 0.001). No association was found between resting pressure and IAS diameter. Women had significantly lower resting and squeeze pressures than men (P = 0.008 and P = 0.003, respectively), but age-related changes of function were only found for resting pressure. Endosonographic values of IAS and EAS did not differ between genders but were significantly correlated with age (P = 0.008 and P = 0.02, respectively). Because all correlations were rather weak, they only can explain a small portion of data variance. CONCLUSION: Anal manometry and anal ultrasound, therefore, are of complementary value and are both indicated in adequate clinical problems.

Adult↗
PubMed1997

Biofeedback therapy for defecation disorders.

Biofeedback therapy is a useful adjunct to conventional treatment for many patients with refractory defecation disorders. This article provides an overview regarding the historical evolution of this treatment together with current perspectives regarding the principles and techniques of performing biofeedback therapy and an assessment of its outcome in adults and pediatric patients with defecation disorders.

Biofeedback, Psychology↗
PubMed1997

Pathophysiology of diabetic gastroparesis.

Our understanding of the nature of diabetic gastroparesis has advanced in the last decade due to new investigational procedures (electrogastrography, visceral evoked potential recording), and transferring these insights into clinical routine will be our task in the future. Meanwhile, the clinical relevance of gastroparesis--whether overt or silent--remains unquestioned: proper gastric emptying is a prerequisite for adequate metabolic control, and its disturbance may result not only in further progression of the chronic complications of the disease, but also in the false assumption that these patients are not compliant with their doctor's management--the patients just may have delayed emptying of their stomach without noticing it.

Age Factors↗
PubMed1997

How reproducible are measures of the anal sphincter muscle diameter by endoanal ultrasound?

UNLABELLED: Anal endosonography is an imaging technique for the anal sphincter system and offers analysis of its muscular integrity. It is generally assumed that measurement of the thickness of muscle layers is provided by sonography; however, reproducibility of such measurements have not yet been investigated. METHODS: Study 1: In 10 healthy volunteers, endoanal ultrasound was performed independently by two experienced investigators with two different ultrasound machines, and thickness of the muscle layers of the internal and external anal sphincter was assessed in the position of the intermediate dorsal anal canal in a randomized cross-over fashion. Study 2: In a study of similar design, sonography was performed in nine healthy volunteers by two investigators independently using a single ultrasound machine in three standardized positions (proximal/intermediate/distal anal canal) and the sphincter layers assessed in the left, right, and dorsal segment. RESULTS: Study 1: Both the same investigator with different ultrasound scanners and different investigators with the same machine failed to obtain reproducible results with respect to internal and external anal sphincter muscle layer diameter (four bivariate correlations, all with p > 0.05). Study 2: Standardization of the probe position did not improve the agreement (2 x 9 bivariate correlations, all but two p > 0.05). CONCLUSION: At present, therefore, endoanal ultrasound does not provide reliable morphometric data on anal sphincter muscle diameter. This could explain previously conflicting observations of associations between anal sphincter morphometry and function.

Anal Canal↗