Long-term result of Memokath urethral sphincter stent in spinal cord injury patients

Background

Memokath urethral sphincter stents are used to facilitate bladder emptying in patients with spinal cord injury, but long term follow-up has not been reported.

Methods

Case series of ten men with spinal cord injury who underwent insertion of Memokath stents and were followed for up to nine years.

Results

Within four years, the stent had to be removed in nine out of ten patients because of: extensive mucosal proliferation causing obstruction to the lumen of the stent; stone around the proximal end of the stent, incomplete bladder emptying, and recurrent urinary infections; migration of the stent into the bladder related to digital evacuation of bowels; large residual urine; concretions within the stent causing obstruction to flow of urine, and partial blockage of the stent causing frequent episodes of autonomic dysreflexia. In one patient the stent continued to function satisfactorily after nine years.

Conclusions

The Memokath stent has a role as a temporary measure for treatment of detrusor-sphincter dyssynergia in selected SCI patients who do not get recurrent urinary infection and do not require manual evacuation of bowels.

     

Mapping of spinal cord circuits controlling the bladder and external urethral sphincter functions in the rabbit

AIMS: A primary purpose of this study was to evaluate the rabbit as a model for studying the spinal circuitry controlling the bladder emptying. We aimed to map the locations of the neuronal circuitry controlling the external urethral sphincter (EUS) and the detrusor by stimulating at different spinal cord locations with a microelectrode, while recording the responses from these muscles. METHODS: Spinal cord microstimulation was performed in the intermediate zone of the gray matter at the L7-S4 spinal cord levels in eight rabbits with empty and full bladders. Bladder activity was measured as intravesical pressure (IVP) changes and EUS activity was measured via electromyographic (EMG) electrodes positioned within the urethra. RESULTS: Under both bladder conditions, EUS activation was produced from similar locations in the spinal cord comprising a continuous area in the intermediate zone of the S2-S3 spinal cord. This region extended 25 mm in the rostrocaudal dimension, at least 1 mm lateral to the midline, and 0.5-1 mm in the dorsoventral dimension at a depth of 2-3 mm beneath the dorsal surface. No locations in the intermediate zone produced EUS inhibition. The S2-S3 spinal region, stimulation of which produced the strongest EUS activation, also produced modest bladder contractions. CONCLUSIONS: Overall, the results indicate that spinal cord networks controlling bladder and EUS activation in the rabbit are overlapping and clustered into columns extending rostrocaudally. The lack of spinal locations producing EUS inhibition and large bladder contractions make the rabbit an unattractive model for studies of neuroprosthetic spinal control of micturition.     

Identification of androgen receptors in the motoneurons of the external urethral sphincter in the spinal cord of female rats

OBJECTIVES: In women, aging is associated with profound hormonal changes. Menopause has been implicated in the etiology of urinary tract complaints including incontinence, urgency and recurrent urinary tract infections. However, the use of hormone replacement therapy for these conditions has given conflicting and disappointing results. The role of androgen changes on urinary continence in perimenopausal women has not been studied. We studied the presence of androgen receptors in pudendal motoneurons controlling the external urethral sphincter of female rats. MATERIALS AND METHODS: A combination of retrograde labeling of pudendal motoneurons from the external urethral sphincter and immunohistochemistry for the N-terminal portion of androgen receptors on spinal cord sections was performed in adult female rats. RESULTS: Androgen receptors were identified in the nuclei of the ventral horn of the L5-L6 spinal cord. Pudendal motoneurons, retrogradely labeled from the external urethral sphincter, were identified in the dorsolateral nucleus of the ventral horn at the same levels. Confocal microscopy demonstrated the presence of nuclear and cytoplasmic androgen receptors in the cell bodies of these retrogradely labeled pudendal motoneurons. CONCLUSION: Our study demonstrated the presence of androgen receptors in the cell bodies of retrogradely labeled pudendal motoneurons controlling the urethral sphincter of female rats suggesting a role of androgens in the neuromodulation of urethral sphincter function at the spinal level.     

Neuropeptide Y- and vasoactive intestinal polypeptide-containing nerves in the intrinsic external urethral sphincter in the areflexic bladder compared to detrusor-sphincter dyssynergia in patients with spinal cord injury

Specimens of urethra were obtained from patients with cervical and thoracic spinal cord lesion with detrusor-sphincter dyssynergia and from patients with lower motor neurone lesion with detrusor areflexia, undergoing transurethral sphincterotomy. Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in nerves associated with both the smooth and striated muscle components of the urethral sphincter were studied immunohistochemically and by immunoassay. In patients with detrusor-sphincter dyssynergia following cervical and thoracic spinal cord injury, NPY- and VIP-immunoreactive varicose nerve fibres were seen in both the smooth and striated muscle components of the urethral sphincter. In the smooth muscle, NPY- and VIP-immunoreactive nerves did not appear to have any particular orientation, but in the striated muscle region they were found to run along the length of individual muscle fibres. In patients with detrusor areflexia following lower motor neurone lesion, while the pattern, density and fluorescence intensity of NPY- and VIP-immunoreactive nerves in the smooth muscle of the sphincter mechanism appeared the same as seen in patients with detrusor-sphincter dyssynergia, there was a marked increase in the density of these nerves in the striated muscle region of the sphincter mechanism. Quantitation of the peptides by immunoassay was consistent with the histochemical findings, with significantly higher levels of both NPY and VIP in the striated muscle of patients with lower motor neurone lesion, compared to those with cervical and thoracic spinal cord lesion, p = 0.04. NPY and VIP levels in urethral smooth muscle were in the same range in lower motor neurone lesion patients and cervical and thoracic spinal cord lesion patients. We conclude that there are increased NPY- and VIP-containing fibres in striated muscle of the intrinsic external urethral sphincter in patients with areflexic bladder compared with those with detrusor-sphincter dyssynergia.     

Carbon dioxide urethral pressure profilometry before and after external sphincterotomy in spinal cord injury patients

Seven spinal cord injury patients were studied before and after transurethral external sphincterotomy with combined electromyographic and gas urethral pressure profilometry. The technique was simple, rapid, accurate and reproducible in evaluating the completeness of external sphicterotomy. A significant reduction in maximum urethral closure pressure, as well as in the residual urine volume, was a consistent after spincterotomy. The electromyographic profile showed evidence of periurethral striated muscle activity preoperatively in 2 patients with lower motor neuron lesions in whom the bulbocavernosus reflex could not be elicited. Thus, absence of the bulbocavernosus reflex did not eliminate sphincter reflex activity.     

Vasoactive intestinal polypeptide-, somatostatin- and substance P-immunoreactive nerves in the smooth and striated muscle of the intrinsic external urethral sphincter of patients with spinal cord injury

Specimens obtained by transurethral sphincterectomy from patients with spinal cord injury and carcinoma of the bladder were studied immunohistochemically. In the smooth muscle region of the sphincter, vasoactive intestinal polypeptide-, substance P- and somatostatin-immunoreactive fluorescent, varicose nerve fibers were seen. In the striated muscle region, VIP-immunoreactive nerves were found around striated muscle fibers and bundles, while somatostatin- and substance P-immunoreactive nerves were confined to nerve bundles. In both the smooth and striated muscle regions of the intrinsic external urethral sphincter, VIP-immunoreactive nerves were seen around blood vessels. No differences were observed in the immunohistochemical localization of these peptide-containing nerves in the two groups of patients. No immunofluorescence for [Met]enkephalin, bombesin, neurotensin or serotonin was found in any nerves in the urethra.     

Response of external urethral sphincter to high frequency biphasic electrical stimulation of pudendal nerve

PURPOSE: We optimized the axonal blocking effect of high frequency, biphasic stimulation on neurally evoked contractions of the external urethral sphincter (EUS) and further investigated the repeatability of the blocking effect during relatively long periods to evaluate any acute nerve damage. MATERIALS AND METHODS: Two stainless steel electrodes were positioned 5 to 10 mm apart on the decentralized pudendal nerve in alpha-chloralose anesthetized cats. The distal electrode was first tested at different frequencies (1 to 10 kHz) to search for the effective blocking frequency. At a fixed frequency (4, 6, 8 or 10 kHz) different stimulation intensities were then tested to evaluate their blocking effect. Sine waveform or biphasic pulses of a fixed pulse width were also tested. Finally, the proximal electrode was stimulated at 40 Hz for more than 40 minutes and during the same period the distal electrode (6 to 10 kHz) was repeatedly activated for 1-minute intervals in an attempt to block the EUS contraction induced by the proximal electrode. RESULTS: High frequency, biphasic stimulation (6 to 10 kHz) with a pulse width dependent on frequency is optimal to block EUS contractions compared with sine waveform or biphasic pulses of a fixed pulse width. Acute nerve damage caused by blocking stimulation was not observed on neurally evoked urethral pressure. CONCLUSIONS: Reversible block of EUS contractions by high frequency, biphasic stimulation of pudendal nerves is a potential method for suppressing detrusor-sphincter dyssynergia and improving voiding in spinal cord injured patients.     

Urethral complications following ischiectomy in spinal cord injury patients: a urethral pressure study

Ischial ulcers are the most common pressure sores in spinal cord injury patients and ischiectomy often is used in the over-all management. Because a high percentage of spinal cord injury patients with total ischiectomy had complications of the membranous and proximal bulbous urethra, we evaluated urodynamically 15 ischiectomy patients in the supine and sitting positions to determine if pressure usually borne by the ischial tuberosities was transmitted to the membranous and proximal bulbous urethra. Of the 8 patients with a complete ischiectomy at least on 1 side 5 had problems of the membranous and proximal bulbous urethra, and the average urethral pressure increase from the reclining to the sitting position was 111 cm. water. The increase in urethral pressure was not related to any change in bladder or abdominal pressure. The average urethral pressure increase in the nonischiectomy patients was only 16 cm. water and none had any problems of the membranous and proximal bulbous urethra. Some retrospective clinical studies have implicated ischiectomy in the development of these urethral complications. Our urodynamic data lend some direct evidence that a more complete ischiectomy results in excessive urethral pressure with the patient in the sitting position, thereby predisposing the membranous and proximal bulbous urethra to problems related to ischemia. Five of the 8 patients with more complete ischiectomy and 1 with bilateral partial ischiectomy had high urethral pressures and complications, such as pseudodiverticulum, diverticulum and dilatation. More incomplete ischiectomy should be used to obviate this urethral damage.     

Adrenergic innervation of the striated muscle of the intrinsic external urethral sphincter from patients with lower motor spinal cord lesion

The adrenergic innervation of smooth and striated muscle components of the intrinsic external urethral sphincter from patients with suprasacral lesions and detrusor-sphincter dyssynergia has been described previously, when no adrenergic nerves were found associated with striated muscle fibers. In our study the intrinsic external urethral sphincter from patients with lower motor neuron lesions and detrusor areflexia was studied histochemically using the glyoxylic acid method to visualize catecholamines. Varicose adrenergic nerves were demonstrated in the smooth muscle. Adrenergic nerve fibers also were found along the edge of individual striated muscle fibers as well as around striated muscle bundles. Blood vessels in both regions of the urethral sphincter were innervated by adrenergic nerves. We conclude that in patients with lower motor neuron lesions and detrusor areflexia there is a substantial invasion by adrenergic nerve fibers in relation to smooth and striated muscle in the urethra, although the function of the nerve fibers is not known.     

Influences of external urethral sphincter relaxation induced by alpha-bungarotoxin, a neuromuscular junction blocking agent, on voiding dysfunction in the rat with spinal cord injury

OBJECTIVES: To determine whether external urethral sphincter (EUS) relaxation induced by alpha-bungarotoxin, a highly selective neuromuscular junction blocking agent, could ameliorate voiding dysfunction after spinal cord injury (SCI) in rats. METHODS: The effects of intravenous alpha-bungarotoxin (333 microg/kg) were evaluated during cystometry in decerebrate, unanesthetized female Sprague-Dawley rats (250 to 300 g) with spinal cords chronically transected at T7-9 (n = 7) or with normal spinal cords (NSC) (n = 7). Parameters measured included voided volume (VV), residual volume (RV), volume threshold for inducing micturition (VT), voiding efficiency (VE), micturition pressure (MP), pressure threshold for inducing micturition (PT), bladder contraction duration (BCD), and compliance (CP). RESULTS: In SCI rats, treatment with alpha-bungarotoxin improved voiding. The toxin increased VE (31%) and reduced RV (42%), MP (52%), BCD (14%), and VT (31%). VV, PT, and CP were not altered. In NSC rats, alpha-bungarotoxin decreased VE (23%), increased RV (63%), and decreased MP (36%), VV (38%), and VT (20%) but did not change BCD and CP. CONCLUSIONS: The results of our study demonstrated that alpha-bungarotoxin improved voiding in SCI rats by reducing urethral outlet resistance. However, in NSC rats, the toxin reduced voiding, probably by suppressing high-frequency phasic sphincter activity, necessary for efficient urine elimination in normal animals. The present results provide further support for the view that drugs that depress striated muscle activity can be useful in the treatment of voiding dysfunction after SCI.     

A型肉毒毒素注射治疗脊髓损伤后逼尿肌尿道外括约肌协同失调症

目的评价A型肉毒素（BTX-A）注射治疗脊髓损伤患者尿道外括约肌协同失调症（DESD）的临床效果。方法脊髓损伤致DESD患者15例。男12例,女3例,平均年龄37岁。临床表现排尿无力、排尿等待,需要压腹以助排尿。200 U BTX-A溶解于8 ml生理盐水,使用尿道镜注射针分8点二平面注射于尿道外括约肌,1ml/点。记录治疗前后排尿症状,尿动力学检查,并观察毒副作用。结果治疗后2个月,尿动力学检查结果显示膀胱贮尿和排尿功能有不同程度改善,15例最大尿流率由（9．2±5．0）ml/s增加至（16．2±7．0）ml/s,单次尿量由（182．5±52．0）ml/次增加至（235．5±40．0）ml/次,剩余尿量由（288．7±122．5）ml下降至（155．4±81．2）ml（P＜0．01）；最大膀胱测压容积、膀胱顺应性及充盈末逼尿肌压力术前分别为（113．0±64．8）ml、（15．2±2．0）ml/cm H2O、（52．7±19．2）cm H2O,术后分别为（205．5±75．6）ml、（22．5±9．3）ml/cm H2O及（37．1±7．3）cm H2O（P＜0．01,P＜0．05,P＜0．01）。治疗前需要坐位排尿的8例患者均可以直立排尿。随访2～7个月,疗效稳定。结论BTX-A注射是一种治疗脊髓损伤患者逼尿肌无反射伴DESD的有效方法,长期疗效有待观察。     

Long-term follow-up of spinal cord stimulation to restore cough in subjects with spinal cord injury

Abstract

Objective

To determine the long-term effects of the cough stimulation system.

Design

Nonrandomized clinical trial of subjects using the study device well beyond the period of close follow-up.

Setting

Use of the study device in the home setting.

Participants

Subjects (N = 10) implanted with the device for a minimum of 2 years (mean 4.6 ± 0.6 years).

Interventions

Application of daily stimulation.

Outcome measures

Airway pressure generation and other clinical assessments including ease in raising secretions, life quality, caregiver support, and incidence of respiratory tract infections were measured at 1 year and mean 4.6 years after implantation.

Results

Each subject continued to use the device on a regular basis. During SCS, mean maximum airway pressures were 103.1 ± 20.4 and 107.7 ± 23.0 cmH₂O at the 1-year and mean 4.6-year follow-up points, respectively (P < 0.05 compared with pre-implant and not significantly different (NS) compared with 1-year follow-up). Benchmarks related to ease in raising secretions and improvements in life quality related to respiratory care were maintained at the mean 4.6 year follow-up. The need for trained caregivers to provide other means of secretion management remained significantly below the pre-implant values (P < 0.05). The incidence of acute respiratory tract infections remained low at 0.2 ± 0.1 events/year, which is significantly below the pre-implant value of 1.4 ± 0.3 events/year (P < 0.05).

Conclusion

Subjects continued to use the system on a long-term basis beyond the period of close follow-up and to continued derive significant clinical benefits.     

Use of the artificial urinary sphincter in spinal cord injury patients

A total of 49 patients with neuropathic bladder dysfunction and urinary incontinence underwent implantation of the AS791/792 artificial urinary sphincter. Preoperative urodynamic evaluation allowed the bladder response to be categorized as hyperreflexia, areflexia and low compliance. The over-all success rate in obtaining total urinary continence in these patients was 70 per cent, although the type of bladder present did influence the degree of success. Although urodynamic evaluation is an essential prerequisite for sphincter implantation there were no clear-cut data that allowed an accurate prediction of the postoperative result. The only absolute contraindication to implantation of the artificial urinary sphincter is significant bladder fibrosis. Owing to the success in obtaining total urinary continence in this complicated group of patients, we believe that the artificial urinary sphincter should be considered in carefully selected patients with neuropathic bladder dysfunction secondary to spinal cord injury.     

A new approach to electromyography of the external urethral sphincter

Detailed electromyographic investigation of the external urethral sphincter was done as part of a urodynamic evaluation of 119 patients. The sphincter was located by inserting electrodes alongside the urethra. The electromyogram was viewed on an oscilloscope and recorded on paper. Normal and abnormal sphincter electromyograms were defined and the role of sphincter electromyography in urodynamic studies was discussed. It was observed that electromyographic activity does not always correlate with urethral resistance but must be interpreted in conjunction with other urodynamic parameters, such as urethral pressures, urinary flow rates and voiding cystourethrography. In addition, sphincter electromyography provides valuable information to define the various neural pathways involved in micturition and continence.     

Nitric oxide synthase in the external urethral sphincter of the sheep: immunohistochemical and functional study

PURPOSE: We studied the distribution of neuronal nitric oxide synthase (nNOS) and the effects of nitric oxide (NO) modulating drugs on contractile function of the external urethral sphincter of lambs. Gender differences were evaluated. MATERIALS AND METHODS: Longitudinal and transverse sections of the external urethral sphincter from 10 female and 10 male lambs were studied using reduced nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry and nNOS immunocytochemistry. Isometric contractile responses to electrical field stimulation were recorded from external urethral sphincter preparations from 47 female and 45 male lambs and the effects of NO modulating drugs were evaluated. RESULTS: We detected nNOS in the sarcolemma of some but not all striated fibers, where nNOS seems to be concentrated at the neuromuscular junction. In addition, nNOS was present in nerve fibers and intramural ganglia. The density of innervation decreased toward the distal part of the external urethral sphincter and was higher in male preparations. No significant functional effects of the NOS inhibitor NG-nitro-L-arginine (10 mM.) or the NO donors diethylamine and spermine NONOate (Sigma Chemical Co., St. Louis, Missouri) (5 mM. each) on external urethral sphincter isometric contractility were found in either gender. CONCLUSIONS: Despite the evidence for nNOS at the sarcolemma and nerve fibers of the external urethral sphincter the physiological relevance of these immunohistochemical findings remains to be determined.     

Cadaveric anatomy of pelvic fracture urethral distraction injury: most injuries are distal to the external urinary sphincter

PURPOSE: The anatomy of posterior urethral distraction injuries is controversial. We present a cadaver study of posterior urethral distraction injuries. To our knowledge this is the first study that establishes that the most common location is distal to the external urinary sphincter. MATERIALS AND METHODS: We performed an autopsy review of 10 male patients with posterior urethral distraction injuries. RESULTS: Urethral disruption occurred distal to the external urinary sphincter in 7 of 10 patients. It appeared to occur when the anterior pelvic ring and urogenital diaphragm complex were displaced caudal and rostrally, tearing the urogenital diaphragm off of the urethra. The average inner mucosal defect +/- SD was 3.5 +/- 0.5 cm, while the defect between the outer urethral layer (tunica of the spongiosum) was 2.0 +/- 0.2 cm due to mucosal retraction. Simple and complex injuries could be observed, according to the clinical classification proposed by Turner-Warwick in 1989. Simple injuries had less significant dislocation of the symphysis, general maintenance of urethral continuity and slightly shorter mucosal distraction (3.3 cm). Complex disruptions had significant symphyseal dislocation, complete disassociation of the urethral ends (often with interposition of other tissues) and a slightly longer mucosal distraction (3.8 cm). CONCLUSIONS: Posterior urethral distraction injuries appear to most commonly occur distal to the urogenital diaphragm, contrary to classic teaching. These injuries are on average between 3 and 4 cm, and they are more significant dorsal than ventral. They appear to occur as simple or complex injuries, mirroring the clinical findings seen in clinically simple and complex urethral strictures.