Functional and histological effects of intravaginal electrical stimulation on the pelvic muscles: a study in the rat

Spinal cord injury and degenerative cervical myelopathy

Spinal cord injury (SCI) often results in impaired respiratory function. Paresis or paralysis of inspiratory and expiratory muscles can lead to respiratory dysfunction depending on the level and severity of the injury, which can affect the management and care of SCI patients. Respiratory dysfunction after SCI is more severe in high cervical injuries, with vital capacity (VC) being an essential indicator of overall respiratory health. Respiratory complications include hypoventilation, a reduction in surfactant production, mucus plugging, atelectasis, and pneumonia. Respiratory management includes mechanical ventilation and tracheostomy in high cervical SCI, while noninvasive ventilation is more common in patients with lower cervical and thoracic injuries. Mechanical ventilation can negatively impact the function of the diaphragm and weaning should start as soon as possible. Patients can sometimes be weaned from mechanical ventilation with assistance of electrical stimulation of the phrenic nerve or the diaphragm. Respiratory muscle training regimens may also improve patients' inspiratory function following SCI. Despite the critical advances in preventing, diagnosing, and treating respiratory complications, they continue to significantly affect persons living with SCI. Additional studies of interventions to reduce respiratory complications are likely to further decrease the morbidity and mortality associated with these injuries.

Sacral Neuromodulation Changes Pelvic Floor Activity in Overactive Bladder Patients-Possible New Insights in Mechanism of Action: A Pilot Study

OBJECTIVES

To evaluate if electrodiagnostic tools can advance the understanding in the effect of sacral neuromodulation (SNM) on pelvic floor activity, more specifically if SNM induces changes in pelvic floor muscle (PFM) contraction.

MATERIALS AND METHODS

Single tertiary center, prospective study (October 2017-May 2018) including patients with overactive bladder syndrome undergoing SNM. Electromyography of the PFM was recorded using the Multiple Array Probe Leiden. The procedure consisted of consecutive stimulations of the lead electrodes with increasing intensity (1-3, 5, 7, 10 V). Recordings were made after electrode placement (T0) and three weeks of SNM (T1). Patients with >50% improvement were defined as responders, others as nonresponders. For the analyses, the highest electrical PFM response (EPFMR), defined as the peak-to-peak amplitude of the muscle response, was identified for each intensity. The sensitivity (intensity where the first EPFMR was registered and the normalized EPFMR as percentage of maximum EPFMR) and the evolution (EMFPR changes over time) were analyzed using linear mixed models.

RESULTS

Fourteen patients were analyzed (nine responders, five nonresponders). For nonresponders, the PFM was significantly less sensitive to stimulation after three weeks (T0: 1.7 V, T1: 2.6 V). The normalized EPFMR was (significantly) lower after three weeks for the ipsilateral side of the PFM for the clinically relevant voltages (1 V: 36%-23%; p = 0.024, 2 V: 56%-29%; p = 0.00001; 3 V: 63%-37%; p = 0.0002). For the nonresponders, the mean EPFMR was significantly lower at 8/12 locations at T1 (T0: 109 μV, T1: 58 μV; mean p = 0.013, range <0.0001-0.0867). For responders, the sensitivity and evolution did not change significantly.

CONCLUSIONS

This is the first study to describe in detail the neurophysiological characteristics of the PFM, and the changes over time upon sacral spinal root stimulation, in responders and nonresponders to SNM. More research is needed to investigate the full potential of EPFMR as a response indicator.

Electrotherapy for urethral modulation: Are extracellular matrix molecules and growth factors potential targets?

AIMS

To evaluate the expression of genes and proteins involved in the urethral components: vessels, nerves, and extracellular matrix, in female rats after trauma by vaginal distension (VD) and after electrical stimulation therapy (electrotherapy).

METHODS

We analyzed the urethras of three groups of 18 female rats 30 days posttrauma by VD: control (no interventions); trauma (animals that had VD); and electrotherapy group (those that had VD and were treated with electrical stimulation). We compared the expression of vascular endothelial growth factor (VEGF), nerve growth factor (NGF), collagen types I and III (COL1a1 and COL3a1), and lysyl-oxidase like 1 (LOXL1) among the groups. Real-time reverse transcription-polymerase chain reaction, Western blot, and immunohistochemistry were used for molecule quantification. We used the Kruskal-Wallis test and analysis of variance for statistical analyses with p < 0.05 for significance.

RESULTS

The COL1a1 gene expression was higher in the electrotherapy group than the trauma group (p = 0.036). COL3a1, VEGF, NGF, LOXL1 messenger RNA (mRNA) expression did not differ among the groups (p ≥ 0.05). COL1a1, COL3a1, VEGF, NGF, LOXL1 protein levels did not significantly differ among the groups (p ≥ 0.05) in Western blot analysis or immunohistochemistry assays.

CONCLUSIONS

Electrotherapy caused a long-term increase in the COL1a1 mRNA level but did not change COL1a1 protein expression or VEGF, NGF, COL3a1, and LOXL1 genes and proteins in the urethras of rats after trauma by VD.

Spinal cord neuronal components involved in the reflex activity of female rat pubococcygeus motoneurons

Evoked EMG reflex activity from the pubococcygeus muscle of female Wistar rats has been reported, but has not been carefully analyzed. Here, we studied this reflex activity through mechanical stimulation of the clitoris, perigenital skin, caudal vagina and foot, all of which produced bilateral reflex multiunit electromyographic (MEMG) tonic "on" activity and displayed a rapid adaptation. However, deep vagina and cervical stimulation did not modify MEMG baseline activity even if it was combined with clitoris, perigenital skin and foot stimulation. Electrical stimulation of the dorsal nerve of the clitoris produced bilateral MEMG activity that when recorded at fast sweep speed, it was possible to observe that the ipsilateral response had an 8 ms latency, while the contralateral response had a 10 ms latency. These data suggest that bilateral reflex activation of pubococcygeus muscle motoneurons is produced by several sensory sources in which a specialized neural circuitry of afferent and efferent components and several spinal cord interneurons are involved. This is in accordance with the multi functionality of this muscle in reproductive and behavioral processes.

Electrical stimulation structurally affects the tissues of the rectum and anus of nulliparous rats

Considering that the muscles of the anus perform a critical role in maintaining continence, losses in their structure can negatively affect the physiological control of the intestinal contents. Anorectal electro-stimulation (ARES) has been reported to have a positive effect on the functionality of treated patients, but how ARES affects the structural tissues of the anorectal segment remains unknown. Because the study of how ARES structurally affects human tissues is not possible, this study aimed to clarify these effects in a murine model, which has a similar anorectal segment (structure and physiology) to humans. For the descriptive and comparative study, randomly selected nulliparous adult Wistar rats (n = 5) were submitted to 30 anorectal sessions of ARES with a biphasic current (700 μs, 50 Hz from 2 to 4 mA). After treatment, the animals were euthanized, and the anorectal segments were dissected and processed for histopathological analysis. Our results showed that ARES increased the widths of the mucosal, submucosal and muscle layers of the rectum, as well as the number of leukocytes in the mucosa. ARES also caused hyperplasia of the smooth muscle of the internal anal sphincter and hypertrophy of the external anal sphincter muscle. In conclusion, our results showed that ARES had not only a positive effect on the structure (morphology) of all tissues associated with the rectum and anus but, more importantly, on the structural gain of the muscles (hyperplasia and hypertrophy), which could point to a functional gain of the anal sphincter, reinforcing the applicability of ARES as a non-invasive treatment for anal incontinence.

Hormonal Treatment Effects on the Cross-sectional Area of Pubococcygeus Muscle Fibers After Denervation and Castration in Male Rats

We explore the interaction of muscle innervation and gonadal hormone action in the pubococcygeus muscle (Pcm) after castration and hormone replacement. Male Wistar rats were castrated and the Pcm was unilaterally denervated; after 2 or 6 weeks, the cross-sectional area (CSA) of Pcm fibers was assessed. Additional groups of castrated rats were used to examine the effects of hormone replacement. At 2 weeks post surgeries, rats were implanted with Silastic capsules containing either dihydrotestosterone (DHT), estradiol benzoate (EB) or both hormones, and the CSA of Pcm fibers was assessed after 4 weeks of hormone treatment. At 2 weeks post surgeries, gonadectomy without hormone replacement resulted in reductions in the CSA of Pcm fibers, and denervation combined with castration increased the magnitude of this effect; further reductions in CSA were present at 6 weeks post surgeries, but again denervation combined with castration increased the magnitude of this effect. Hormone replacement with DHT resulted in hypertrophy in the CSA of nondenervated muscles compared to those of intact normal males, but this effect was attenuated in denervated muscles. Hormone replacement with EB treatment prevented further castration-induced reductions in CSA of nondenervated muscles, but denervation prevented this effect. Similar to that seen with treatment with EB alone, combined treatment with both DHT and EB prevented further reductions in CSA of Pcm fibers in nondenervated muscles, but again denervation attenuated this effect. Thus, while hormone replacement can reverse or prevent further castration-induced atrophy of Pcm fibers, these effects are dependent on muscle innervation. Anat Rec, 300:1327-1335, 2017. © 2017 Wiley Periodicals, Inc.

Vaginal cone use in passive and active phases in patients with stress urinary incontinence

OBJECTIVE

To evaluate vaginal cone therapy in two phases, passive and active, in women with stress urinary incontinence.

METHODS

A prospective study was conducted at the Department of Obstetrics and Gynecology, São Paulo University, Brazil. Twenty-four women with a clinical and urodynamic diagnosis of stress urinary incontinence were treated with vaginal cones in a passive phase (without voluntary contractions of the pelvic floor) and an active phase (with voluntary contractions), each of which lasted three months. Clinical complaints, a functional evaluation of the pelvic floor, a pad test, and bladder neck mobility were analyzed before and after each phase.

RESULTS

Twenty-one patients completed the treatment. The reduction in absolute risk with the pad test was 0.38 (p<0.034) at the end of the passive phase and 0.67 (p<0.0001) at the end of the active phase. The reduction in absolute risk with the pelvic floor evaluation was 0.62 (p<0.0001) at the end of the passive phase and 0.77 (p<0.0001) at the end of the active phase. The reduction in absolute risk of bladder neck mobility was 0.38 (p<0.0089) at the end of the passive phase and 0.52 (p<0.0005) at the end of the active phase. Complete reversal of symptomatology was observed in 12 (57.1%) patients, and satisfaction was expressed by 19 (90.4%).

CONCLUSION

Using vaginal cones in the passive phase, as other researchers did, was effective. Inclusion of the active phase led to additional improvement in all of the study parameters evaluated in women with stress urinary incontinence. Randomized studies are needed, however, to confirm these results.