External anal sphincter function in spinal patients. Electromyographic and manometric study

[Analysis of anorectal manometry data in central and peripheral neurological deseases: Review of the literature]

INTRODUCTION

Peripheral or central neurological deseases are providers of anorectal disorders of variable clinical expression (constipation, dyschezia, faecal incontinence (FI)…). Anorectal manometry (ARM) participates in their exploration to determine the underlying mechanisms, guide and optimize treatments. The objective of this work was to determine if there is a pattern of ARM data in neurological populations.

MATERIALS ET METHODS

Literature review from PubMed, Cochrane and Google scholar databases, using the following keywords: parkinsonian disorders; parkinson's disease; multiple slcerosis; neurolog*; spinal cord injury; spina bifida occulta; stroke; pudendal; endometriosis; peripheral nervous system diseases. 196 articles were isolated and finally 45 retained after reading the title and the abstract.

RESULTS

Data comparison was difficult due to the heterogeneity of techniques and thresholds used. In central lesions, resting and squeeze anal pressures were often altered. The presence of FI or constipation, the sex and the lesion level were factors influencing these data (low if complete injury, women or EDSS>5.5). In case of peripheral lesion, it is the anal tone and the contraction that varied the symptomatology. The sensory thresholds were variable regardless of the impairment.

CONCLUSION

This review did not identify a data pattern of ARM in central and peripheral neurological deseases. Gradual standardization of techniques and protocols will allow better comparison of data.

Recommendations for evaluation of neurogenic bladder and bowel dysfunction after spinal cord injury and/or disease

Objective: To provide an overview of clinical assessments and diagnostic tools, self-report measures (SRMs) and data sets used in neurogenic bladder and bowel (NBB) dysfunction and recommendations for their use with persons with spinal cord injury /disease (SCI/D).Methods: Experts in SCI/D conducted literature reviews, compiled a list of NBB related assessments and measures, reviewed their psychometric properties, discussed their use in SCI/D and issued recommendations for the National Institutes of Health (NIH), National Institute of Neurological Disorders and Stroke (NINDS) Common Data Elements (CDEs) guidelines.Results: Clinical assessments included 15 objective tests and diagnostic tools for neurogenic bladder and 12 for neurogenic bowel. Following a two-phase evaluation, eight SRMs were selected for final review with the Qualiveen and Short-Form (SF) Qualiveen and the Neurogenic Bowel Dysfunction Score (NBDS) being recommended as supplemental, highly-recommended due to their strong psychometrics and extensive use in SCI/D. Two datasets and other SRM measures were recommended as supplemental.Conclusion: There is no one single measure that can be used to assess NBB dysfunction across all clinical research studies. Clinical and diagnostic tools are here recommended based on specific medical needs of the person with SCI/D. Following the CDE for SCI studies guidelines, we recommend both the SF-Qualiveen for bladder and the NBDS for bowel as relatively short measures with strong psychometrics. Other measures are also recommended. A combination of assessment tools (objective and subjective) to be used jointly across the spectrum of care seems critical to best capture changes related to NBB and develop better treatments.

Altered Colorectal Compliance and Anorectal Physiology in Upper and Lower Motor Neurone Spinal Injury May Explain Bowel Symptom Pattern

OBJECTIVES

Supraconal spinal cord injury (SCI) and lower motor neurone spinal cord injury (LMN-SCI) cause bowel dysfunction; colorectal compliance may further define its pathophysiology. The aim of this study was to investigate rectal (RC) and sigmoid (SC) compliance and anorectal physiology parameters, in these subjects.

METHODS

Twenty-four SCI subjects with gut symptoms (14 RC, 10 SC) and 13 LMN-SCI subjects (9 RC, 4 SC) were compared with 20 spinal intact controls (10 RC, 10 SC). Staircase distensions were performed using a barostat. Anorectal manometry, including rectoanal inhibitory reflex (RAIR) measurement, was performed in all. Data presented as mean±standard error (SCI/LMN-SCI vs. controls).

RESULTS

SCI subjects had a higher RC (17.0±1.9 vs. 10.7±0.5 ml/mm Hg, P<0.05) and SC (8.5±0.6 vs. 5.2±0.5 ml/mm Hg, P=0.002). LMN-SCI subjects had a lower RC (7.3±0.7 ml/mm Hg, P=0.0021) while SC was unchanged (8.3±2.2 ml/mm Hg, P>0.05). Anal resting pressure was decreased in SCI (55±5 vs. 79±7 cmH2O, P=0.0102). Anal squeeze pressure was decreased in LMN-SCI (76±13 vs. 154±21 cmH2O, P=0.0158). In SCI and LMN-SCI, the amplitude reduction of the RAIR was greater (62±4% and 70±6% vs. 44±3%, P=0.0007).

CONCLUSIONS

Colorectal compliance abnormalities may explain gut symptoms: increased RC and SC contributing to constipation in SCI, reduced rectal compliance contributing to fecal incontinence (FI) in LMN-SCI. Reduced resting anal pressure in SCI and reduced anal squeeze pressure in LMN-SCI along with a greater RAIR amplitude reduction may be factors in FI. These co-existing abnormalities may explain symptom overlap, and represent future therapeutic targets to ameliorate neurogenic bowel dysfunction.

How sacral nerve stimulation works in patients with faecal incontinence

AIM

Sacral nerve stimulation (SNS) reduces incontinence episodes and improves the quality of life of patients treated for faecal incontinence. However, the exact mechanism of action of this technique remains unclear. The present article reviews the pertinent neuroanatomy and neurophysiology related to SNS and provides explanations for potential mechanisms of action.

METHOD

A systematic review of the literature was performed for studies of the potential mechanisms of action of SNS, using MEDLINE, PubMed, Embase and the Cochrane Library. Articles dealing with the technique, adverse events and economic evaluations of SNS, as well as literature reviews, were excluded, except for reviews dealing with the mechanisms of action of SNS. The following inclusion criteria were used to select articles: (i) articles in English, (ii) randomized, double-blinded, sham-controlled studies, and (iii) cohort studies. Case-control studies or retrospective studies were cited only when randomized or cohort studies could not be found.

RESULTS

We propose three hypotheses to explain the mechanism of action of SNS: (i) a somato-visceral reflex, (ii) a modulation of the perception of afferent information, and (iii) an increase in external anal sphincter activity.

CONCLUSION

The mechanism of action of SNS in patients with faecal incontinence almost certainly depends on the modulation of spinal and/or supraspinal afferent inputs. Further research on humans and animals will be required to gain a better understanding of the mechanisms of action of SNS.

Qualitative and quantitative analysis of rectoanal inhibitory reflex (RAIR) modulation in functional bowel disorders

BACKGROUND

Rectoanal inhibitory reflex (RAIR) is a physiological reflex implicated in anorectal continence. A lack of RAIR modulation is only described in spinal cord-injured patients with a lesion under L2. No quantitative data has been published concerning the normal modulation in amplitude and in duration in functional disorders.

METHODS

A retrospective analysis of anorectal manometry, performed in 40 safe-neurological patients, suffering from idiopathic constipation and/or faecal incontinence, has been done. RAIR were obtained by five successive rectal distensions (10-50 ml).Resting pressure, residual pressure, percentages of relaxation, slope and duration of inhibition were estimated. Four hypotheses of normal modulation in amplitude and duration were set up using these parameters. The cut-off values chosen for the hypotheses were similar to results obtained by calculating median value +/- 2SD of the parameters.

RESULTS

All the 40 patients had present RAIR. Concerning the modulation of RAIR, we tested the hypotheses with the aim of finding those applying to patient's largest number. Amplitude: 85% of the patients had a normal modulation defined by a difference >8 cm H2O between two non-consecutive residual pressure on three successive rectal distensions.

DURATION

77.5% of the patients had a normal modulation defined by a time difference >2 s between two non-consecutive durations on three successive rectal distensions.

CONCLUSION

Determination of normal values of RAIR modulation in functional disorders is interesting in clinical practise, suggesting that the patients with a lack of normal RAIR modulation (in amplitude or in duration) may have a neurological disease.

Effects and mechanisms of anal electrical stimulation on anorectal compliance and tone in dogs

PURPOSE

This study was designed to investigate the changes in rectal compliance and tone during anal electric stimulation and the involvement of the alpha-adrenergic pathway in conscious dogs.

METHODS

Eight healthy dogs were studied in five randomized sessions. Anal sphincter pressure was quantified by using the area under the contractile curve. Rectal compliance and tone were measured in a pressure-controlled phasic and isobaric distention by using an electronic barostat. Anal electric stimulation was performed via a pair of ring electrodes attached to the catheter.

RESULTS

The electric stimulation-induced increase in sphincter pressure was lowered by the presence of an alpha(1)-adrenergic receptor antagonist, prazosin (18.6 +/- 7.4 vs. 45.4 +/- 9.7, P < 0.05), or alpha(2)-adrenergic receptor antagonist, yohimbine (10.2 +/- 8.2 vs. 38.3 +/- 7.6, P < 0.05), compared with the control. The threshold volume in rectoanal inhibitory reflex during electric stimulation was significantly higher than during baseline (27.5 +/- 0.9 vs. 22.5 +/- 1.9 ml, P < 0.05). There were no significant differences between the percentage drops in sphincter pressure with and without stimulation at a rectal distention level of 45 ml of air. Anal electric stimulation significantly increased rectal compliance reflected as reduced P(1/2) (11.1 +/- 1.5 vs. 16.7 +/- 1.1, P = 0.027) and reduced kappa (11.6 +/- 2.5 vs. 20.5 +/- 2.6, P = 0.0095), compared with the control session, but did not significantly alter rectal tone.

CONCLUSIONS

Anal electric stimulation increases anal sphincter pressure, mediated at least partially by the alpha-adrenergic pathway. It also increases rectal compliance but does not alter rectal anal inhibitory reflexes.

Anal electrical stimulation with long pulses increases anal sphincter pressure in conscious dogs

PURPOSE

This study was designed to investigate the effects and mechanisms of anal electric stimulation with long pulses on anal sphincter pressure in conscious dogs.

METHODS

The study was performed after enema in nine healthy female hound dogs and composed of four randomized sessions ("dose"-response, anal electric stimulation only, or with atropine or phentolamine). The anal sphincter pressure was measured by using manometry and quantified by using the area under the contractile curve (mmHg/sec). Anal electric stimulation was performed via a pair of ring electrodes attached to a manometric catheter. The stimulation parameters in all but dose-response sessions included a frequency of 20 ppm, pulse width of 200 ms, and amplitude of 3 mA.

RESULTS

The anal sphincter pressure was 55.7 +/- 6 at baseline and increased by 37 percent to 76.4 +/- 6.5 during electric stimulation (P = 0.009). The increase of anal pressure during stimulation was positively correlated with the stimulation energy (r = 0.395; P < 0.01). The excitatory effect of electric stimulation was sustained for at least 20 minutes. Atropine did not alter anal pressure and did not abolish the excitatory effect of anal electric stimulation on the sphincter. Phentolamine reduced anal pressure from the baseline value of 50.5 +/- 4.7 to 33.1 +/- 5.4 (P = 0.019). The electric stimulation induced increase in anal pressure was dropped from 19 +/- 2.6 to 9.9 +/- 2.8 (P = 0.029) at the presence of phentolamine.

CONCLUSIONS

Anal electric stimulation with long pulses increases anal sphincter pressure in an energy-dependent manner. The alpha-adrenergic but not the cholinergic pathway at least partially mediates the excitatory effect of anal electric stimulation.

Endosonography in the evaluation of anal function after primary repair of a third-degree obstetric tear

BACKGROUND

Disruption of the anal sphincter occurs in 0.6%-6% of women during delivery and almost half have persistent defecatory symptoms despite primary repair. Our aim was to prospectively analyse anal endosonography and rectoanal manometry after primary repair of a third-degree obstetric tear in order to compare the findings with the clinical outcome.

METHODS

Twenty-one women aged 27-41 (mean 31.5 years) who had undergone primary suture of a third-degree disruption of the anal sphincter were interviewed on their pelvic floor function and explored by manometry and endosonography 4 months after delivery.

RESULTS

Twelve women had anal incontinence. External sphincter defect was identified on endosonography in 22% continent and in 91% incontinent women (P < 0.01). The presence of an external sphincter defect was associated with anal incontinence in 91.7%. Surgical repair was identified on endosonography in 88% continent women and in 25% incontinent women (P < 0.03). The combination of a visible surgical repair and absence of defect was highly associated with normal continence (91.7%). Squeezing pressures were higher in continent women (87 +/- 23 cm H2O) than in incontinent women (48 +/- 36 cm H2O; P = 0.04), but no anal pressure threshold could achieve better results than endosonography in predicting the clinical outcome.

CONCLUSION

After primary repair of a third-degree obstetric tear, endosonographic pattern of the anal sphincter correlates with the continence status.

Evidence for supraspinal nervous control of external anal sphincter motility in the cat

The aim of this study was to investigate the role of noradrenergic descending nervous pathways in external anal sphincter motility. For this purpose, the effects of intravenously injected adrenoceptor antagonist and agonist on the tonic electrical activity of this sphincter were studied in anesthetized cats. The effects of stimulating the region of the locus coeruleus and the effects of intravenous, intracerebroventricular and intrathecal injection of the above drugs on the electromyographic responses of this muscle to pudendal nerve stimulation were also investigated. The tonic sphincteric activity and the reflex response triggered by electrically stimulating pudendal afferent nerve fibers were inhibited by alpha1-adrenoceptor antagonist nicergoline and enhanced by alpha1-adrenoceptor agonist phenylephrine. Stimulation of the locus coeruleus area either inhibited or enhanced the reflex responses. Intracerebroventricular and intrathecal injection of the alpha2-adrenoceptor agonists, morphine and leu-enkephalin decreased the amplitude of these reflex responses. All the effects of opioids were blocked by naloxone and by spinalization performed at the cervical and lumbar levels. The direct response elicited by stimulating the sphincteric motor axons was not affected either by these drugs or by the brainstem stimulation. These results suggests the existence of a pontine neuronal network controlling the motility of the external anal sphincter via noradrenergic and opioid neurons.

Pelvic floor function in patients with clinically complete spinal cord injury and its relation to constipation

PURPOSE

Constipation is a common problem in patients with spinal cord injury. The aim of this study is to analyze the role of pelvic floor dysfunction in the development of constipation.

METHODS

Twenty-five patients with clinically complete supraconal spinal cord injury were studied by means of colonic transit time, anal manometry, electrophysiologic testing, and sensory-evoked potentials.

RESULTS

Sixteen patients had prolonged total and segmental colonic transit times (Group C), and nine patients had normal colonic transit times (Group NC). Basal pressure and anal pressure during coughing, Valsalva's maneuver, and rectal distention were diminished in all patients, but no differences were observed between Group C and Group NC. Rectal sensation was preserved in eight patients, but this was not related to the absence of constipation. In seven of these eight patients, somatosensory-evoked potentials could be recorded, which indicated an incomplete cord lesion. Synergic relaxation of the pelvic floor during straining was never observed; dyssynergia was seen in ten (7 in Group C and 3 in Group NC; P = not significant) patients. Associated peripheral nerve damage was present in 40 percent of patients but did not predispose these patients to constipation.

CONCLUSIONS

Loss of rectal sensation, dyssynergic pelvic floor contraction during straining, associated peripheral nerve damage, and insufficient rise of intraabdominal pressure could not be held responsible for constipation as a result of spinal cord injury. A prolongation of the colonic transit time is the most important mechanism, and therapy should be directed toward it.