Single-fiber electromyography correlates more closely with incontinence scores than pudendal nerve terminal motor latency

Clinical relevance of neurological evaluation in patients suffering urinary retention in the absence of subvesical obstruction

PURPOSE

Clinical relevance of neurological evaluation in patients suffered urinary retention in the absence of subvesical obstruction. Determining whether (1) women complaining residual bladder volume without prolapse and obstruction always suffer pudendal nerve damage; (2) neurogenic damage can be linked to patients history/clinical examination; (3) therapy alters regarding to neurological findings; and (4) electromyography (EMG) of musculus sphincter ani externus (MSAE) can be omitted with electronically stimulated pudendal nerve latency (ESPL) as the standard investigation.

METHODS

Women with urinary retention without ≥stage 2 prolapse or obstruction have neurological investigation including vaginally and anally pudendal terminal nerve latency (PTNL) (>2.4 ms considered abnormal) and EMG seen 7/2005-04/2010.

RESULTS

(1) 148/180 (82.2%) suffered at least moderate neurogenic damage and (2) severe neurogenic damage occurs with urge odds ratio (OR) = 3.1 or age (OR = 3.2). Correlations: spasticity with therapy changes (OR = 11.1), latencies. (a) Anally: (i) right and peripheral neuropathy (PNP) (OR = 2.5), chemotherapy (OR = 5.0); (ii) left and PNP (OR = 3.9), chemotherapy (OR = 4.8); (iii) left or right with PNP (OR = 3.9), chemotherapy (OR = 6.8); and (iv) left and right with chemotherapy (OR = 5.0). (b) Vaginally: (i) right with age >60 (OR = 3.2), radical operation (OR = 10.6); (ii) left with diabetes mellitus (OR = 2.5); and (iii) left or right with age (OR = 3.3), radical operation (OR = 8.7). (3) 19.6% therapy changes (36 patients). (4) Neither EMG nor ESPL can be replaced one by another (p = 0.12 anal, p = 0.05 vaginal).

CONCLUSION

Red flags are neurogenic damage, age >60, chemotherapy, PNP, radical operation or diabetes. In unclear situations, EMG and ESPL need to be performed to gain relevant information.

Prolonged pudendal nerve terminal motor latency is associated with decreased resting and squeeze pressures in the intact anal sphincter

AIM

To determine the contribution of the pudendal nerve to the anal continence mechanism by determining the correlation between pudendal nerve terminal motor latency (PNTML) and resting and squeeze anal canal pressures.

METHOD

In all, 1051 patients were investigated with anorectal physiology studies between January 1998 and July 2010. Of these, 213 patients had intact anal sphincters on endoanal ultrasound and had undergone PNTML testing and anal manometry with measurement of resting and squeeze pressures. The relationship between PNTML and mean resting and squeeze pressures was compared in these patients with an intact anal sphincter. Values were compared using a two-sample t test with equal variances. A P value of < 0.05 was considered significant.

RESULTS

Of these patients 40.8% had normal PNTML bilaterally, 9.9% had slow PNTML bilaterally and 21.6% had a unilateral slow PNTML. Mean resting pressure was significantly reduced in patients with unilateral slow and bilateral slow PNTML compared with normal. The magnitude of the reduction was 28% and 19% respectively. Mean squeeze pressure was significantly reduced in patients with unilateral slow and bilateral slow PNTML compared with normal. The magnitude of the reduction was 18% and 23% respectively.

CONCLUSION

In patients with an intact anal sphincter, either unilaterally or bilaterally prolonged PNTMLs are associated with significantly decreased resting and squeeze pressures. Our results suggest that both internal and external sphincter function is impaired with pudendal nerve injury. The inhibition of internal sphincter function may be due to damage of autonomic, principally sympathetic fibres carried in the pudendal nerve.

Anal sphincteric neurogenic injury in asymptomatic nulliparous women and fecal incontinence

While anal sphincter neurogenic injury documented by needle electromyography (EMG) has been implicated to cause fecal incontinence (FI), most studies have been uncontrolled. Normal values and the effects of age on anal sphincter motor unit potentials (MUP) are ill defined. The functional significance of anal sphincter neurogenic injury in FI is unclear. Anal pressures and EMG were assessed in 20 asymptomatic nulliparous women (age, 38 ± 5 yr; mean ± SE) and 20 women with FI (54 ± 3 yr). A computerized program quantified MUP duration and phases. These parameters and MUP recruitment were also semiquantitatively assessed by experienced electromyographers in real time. Increasing age was associated with longer and more polyphasic MUP in nulliparous women by quantitative analysis. A higher proportion of FI patients had prolonged (1 control, 7 patients, P = 0.04) and polyphasic MUP (2 controls, 9 patients, P = 0.03) at rest but not during squeeze. Semiquantitative analyses identified neurogenic or muscle injury in the anal sphincter (11 patients) and other lumbosacral muscles (4 patients). There was substantial agreement between quantitative and semiquantitative analyses (κ statistic 0.63 ± 95% CI: 0.32-0.96). Anal resting and squeeze pressures were lower (P ≤ 0.01) in FI than controls. Anal sphincter neurogenic or muscle injury assessed by needle EMG was associated (P = 0.01) with weaker squeeze pressures (83 ± 10 mmHg vs. 154 ± 30 mmHg) and explained 19% (P = 0.01) of the variation in squeeze pressure. Anal sphincter MUP are longer and more polyphasic in older than younger nulliparous women. Women with FI have more severe neurogenic or muscle anal sphincter injury, which is associated with lower squeeze pressures.

Sustained improvement in the anal sphincter function following surgical plication of rabbit external anal sphincter muscle

BACKGROUND

We recently found that the anal canal function and external anal sphincter contraction can be enhanced by surgically adjusting the EAS muscle sarcomere length in rabbits. A 20% length plication of the external anal sphincter muscle results in significant increase in the anal canal pressure and EAS muscle stress without affecting its passive tension. The durability of the beneficial effect of external anal sphincter muscle plication on the anal canal function is not known.

OBJECTIVE

We studied the long-term effects of optimal length external anal sphincter plication on the anal canal pressure, external anal sphincter sarcomere length, and anal canal histology.

DESIGN

Female rabbits (n = 16) were anesthetized and either sham (n = 4) or external anal sphincter plication (n = 12) surgery was performed.

MAIN OUTCOME MEASURES

The effect of external anal sphincter plication on the anal canal pressure was determined every 2 weeks for 6 months in 6 animals. Anal canal was harvested for sarcomere length and histological assessment.

RESULTS

External anal sphincter plication resulted in 50% to 60% increase in the anal canal pressure, and 80% to 90% increase in external anal sphincter muscle stress (during maximum electrical stimulus). The effect of plication was durable for the entire study period of 24 weeks. Sarcomere length increased from 2.11 ± 0.08 μm to 2.59 ± 0.03 μm immediately after plication and was 2.35 ± 0.08 μm at the end of 6 months. Histology revealed no significant differences in the muscle (30% vs 29%) or connective tissue components (70% vs 71%) of the anal canal between control and chronically plicated animals.

CONCLUSIONS

Normal external anal sphincter muscle plication results in long-term enhancement of the anal canal function without any untoward effects on the tissue architecture in the rabbit. External anal sphincter muscle plication could be an important strategy to improve the anal canal function in patients with anal incontinence.

Evaluation of the role of the puborectal part of the levator ani muscle in anal incontinence: a prospective study of 78 female patients with anal incontinence

BACKGROUND

Anal incontinence is most often linked with sphincter rupture and/or stretching the pudendal nerves.

OBJECTIVE

The aim of our study was to investigate the involvement of the puborectal part of the levator ani muscle in anal incontinence.

PATIENTS AND MAIN OUTCOME MEASURES

Seventy-eight female patients were studied by anorectal manometry, 3-dimensional ultrasound examination, and concentric needle electromyography of the external anal sphincter, puborectal muscle, and bulbocavernous muscles, completing with the evaluation of the pudendal nerve terminal motor latencies. Damage to the puborectal muscle was defined by an abnormal ultrasound and/or abnormal electromyography.

RESULTS

Rupture of the anal sphincter apparatus and puborectal muscle was found in 23% and 3.8%. The EMG showed damage to the puborectal part in 39 cases: this was isolated in 4 cases and combined with external anal sphincter damage in 35 patients. Unilateral or bilateral increase in the terminal motor latencies of the pudendal nerves was found in 36% (28/78) of the patients. The frequency of peripheral neurogenic lesions varied from 36% to 90% according to the electromyographic tests used. There was no correlation between puborectal part damage and resting pressure, perception threshold, and maximum tolerable rectal volume. The mean Wexner index score was not increased by the existence of a defect involving the puborectal part found by echography or by damage to the puborectal part shown by the EMG. Investigating puborectal muscle lesions reduced the percentage of idiopathic anal incontinence to 2.5%.

CONCLUSION

Our study confirms the feasibility and usefulness of combined electromyography and 3-dimensional ultrasound examination of the puborectal muscle in anal incontinence.

Novel applications of external anal sphincter muscle sarcomere length to enhance the anal canal function

BACKGROUND

Our recent studies show that the external anal sphincter muscle (EAS) operates at a sarcomere length range which is below optimal. In this study, we tested the hypothesis that by surgically increasing sarcomere length and bringing it close to the optimal length, EAS muscle function and anal canal pressure can be enhanced.

METHODS

Rabbits (n = 25) were anesthetized and subjected to either a sham or an EAS plication of different length by placing sutures at two locations, at a distance of 13%, 20%, 28%, or 35% of the circumferential length of the anal canal. Anal canal pressures were recorded before and after the plication. Anal canal was harvested and the EAS muscle sarcomere length was measured using laser diffraction.

KEY RESULTS

Electrical stimulation of the EAS muscle resulted in a stimulus-dependent increase in the anal canal pressure (mmHg) and EAS muscle stress (mN mm(-2)). A significant increase in maximal pressure (212 ± 13 after compared with 139 ± 22 before plication) as well as stress (166 ± 10 after as compared with 88 ± 14 before plication) was recorded at 20% plication length. Passive anal canal stress at 20% plication was not significantly different compared with the sham group. The mean sarcomere lengths with sham and 20% plication were 2.11 and 2.60 μm, respectively.

CONCLUSIONS & INFERENCES

EAS plication resulted in a length-dependent increase in EAS muscle sarcomere length with an optimal sarcomere length at 20% plication. These considerations may help guide repair of anal sphincter muscle defects in the humans.

Fecal Incontinence: a woman's view

Fecal incontinence (FI) has a prevalence of 2-7% in the general community and increases substantially in hospitalized patients and nursing home residents. Incontinent patients often isolate themselves from society for fear of having an incontinent episode in public. Few of these patients ever discuss this ailment with their doctor, despite a significant increase in depression and anxiety. Women have gender-specific medical and surgical conditions that predispose them to FI such as pregnancy, scleroderma, MS, IBS, childbirth, and pelvic surgeries. This article will address multiple facets of FI, but will focus specifically on issues related to women.