The management of female voiding dysfunction: Fowler's syndrome -- a contemporary update

PURPOSE OF REVIEW

Several aspects of voiding dysfunction in women remain under investigation, including standardization of the diagnosis and management of bladder outflow obstruction. This article describes a specific cause of urinary retention in young women, associated with a failure of urethral sphincter relaxation, and a treatment option that can restore voiding in this group of patients - sacral nerve electrical stimulation therapy. Recently there have been advances in the stimulator implantation technique, as well as in our appreciation of its mechanism of action.

RECENT FINDINGS

Advances include the use of ancillary investigations such as urethral function tests as well as better understanding of the clinical profile of these patients. Improvements in the surgical technique include better methods of lead fixation and a less invasive surgical approach. Research suggests the action of neuromodulation is on the afferent pathway, though it remains to be shown whether this is at a spinal or supraspinal level. It is likely that sacral nerve stimulation has an indirect modulatory effect on detrusor contractility rather than a direct effect on the sphincter.

SUMMARY

Experience of sacral nerve stimulation has increased over the past few years, and its application is expanding to other clinical domains. This knowledge has helped improve the therapy, which is particularly effective in the treatment of women with urinary retention. Although how it works is still not fully understood, this is something that is being addressed by ongoing research.

The role of electrodiagnostic techniques in the reprogramming of patients with a delayed suboptimal response to sacral nerve stimulation

Sacral neuromodulation is an approved therapy for frequency, urgency, urge incontinence and non-obstructive urinary retention. There are several recent reports on a subgroup of patients who are 'Iate failures' to therapy. This descriptive study aimed to determine whether the use of electrodiagnosis during reprogramming could provide objective data on device function in these patients and help direct therapy. We employed electrodiagnostic techniques to differentiate between those patients who could be reprogrammed in the office to a site of maximal response, those that required reoperation, and those in whom reoperation was unlikely to be successful. Our findings suggest that electrodiagnostic monitoring may help to direct future therapy in this group of patients who currently present a management challenge.

[Clinical Results of PNE Tests in 70 Patients with Different Bladder Dysfunctions]

PURPOSE

Prior to implantation of a sacral neuromodulator we carried out PNE tests (peripheral nerve evaluation test) with bilateral test stimulation to establish which patients might profit from this kind of therapy. In contrast to the original unilateral technique used by Tanagho and Schmidt, we performed bilateral PNE test stimulation. Moreover, we analysed the diagnostic characteristics of those patients who had positive PNE test results and could thus receive a chronic sacral neuromodulator.

MATERIALS AND METHODS

We performed bilateral PNE test stimulation in 70 patients (mean age: 53.6 yrs; 41 with retention symptoms and 29 with a hyperactive detrusor) over a minimum of 3 days. Retrospectively, we analysed the distribution of diagnostic characteristics (retention vs. overactive bladder and neurogenic vs. idiopathic) in the implant recipients.

RESULTS

All patients received bilateral PNE test stimulation, during which the stimulation amplitudes were adjusted individually for each side. 8 patients were treated with the original PNE-electrode (model 0 041 830 - 002, Medtronic Inc., USA) without success. Of the remaining 62 patients, who were treated with an improved electrode, the PNE test was successful in 32 cases (51.6 %). Twenty-seven of these patients suffered from a neurogenic bladder dysfunction, and, in 5 cases, the causes were idiopathic.

CONCLUSIONS

Bilateral PNE-test stimulation and the use of advanced PNE electrodes (model 3057, Medtronic Inc., USA) led to a positive PNE result in 51.6 % of the tested patients. Of these, the group with neurogenic bladder dysfunctions showed the highest response rate. Compared with the success rates in the multicenter study, we were able to increase the overall PNE response rate significantly. For this reason, we prefer a bilateral PNE-test with side-specific stimulation.

[Sacral neuromodulation in patients with nonobstructive, chronic urinary retention: relevance of the carbachol test and influence of associated nerve lession]

OBJECTIVE

Aim of this study was to evaluate whether the carbachol test and the nerve lesions responsible for bladder dysfunction possess predictive value in patients with chronic urinary retention who undergo temporary sacral neuromodulation (PNE test).

MATERIAL AND METHODS

In 1999 and 2000, PNE tests were performed in 24 patients with chronic urinary retention and acontractile detrusor previously assessed by urodynamics. In 18 patients, a carbachol test was performed during urodynamics. The diagnosis related to the acontractile detrusor was additionally assessed and compared to the successful outcome of the PNE test.

RESULTS

The PNE test was successful in 8 of the 24 patients (33.3 %). The bladder was completely emptied during the PNE test in 3 of the 10 patients with negative carbachol test and in 3 of the 8 patients with positive carbachol test. The highest success rate (80 %) was observed in patients after hysterectomy, whereas after lumbosacral pulposal prolapse or with a CNS tumor, it was only 20 - 33.3 %.

CONCLUSIONS

We conclude that sacral neuromodulation is an effective treatment option in patients with nonobstructive urinary retention. The carbachol test does not possess any definitive predictive value with respect to the success rate of sacral neuromodulation in patients with chronic urinary retention. The success rate more likely depends on the localisation of the nerve lesion. PNE tests should be performed in all patients with therapy resistent nonobstructive urinary retention, as no other predictive factors exist.

Improved sacral neuromodulation in the treatment of the hyperactive detrusor: signal modification in an animal model

OBJECTIVE

To investigate different stimulation signals for the peripheral nerve evaluation test (PNE, carried out before implanting a sacral neuromodulator for functional voiding dysfunction) in an animal model and to determine their efficacy, as up to 80% of patients do not respond to the PNE test.

MATERIALS AND METHODS

PNE foramen electrodes were placed in the S3 of 12 anaesthetized Göttingen minipigs. First, detrusor instabilities were induced by the intravesical instillation of formalin. A 10-min stimulation phase with both a quasi-trapezoidal (QT) signal and a rectangular signal followed. An interval of 30 min elapsed between the series of stimulations. The attained bladder pressure values were registered on a urodynamic unit and evaluated as contractions and amplitudes per minute. Six minipigs were treated in the same way but were not stimulated and served as a control group.

RESULTS

After formalin instillation, the mean (sd) number of involuntary detrusor contractions was 3.5 (0.8)/min and the sum of amplitudes 7.2 (1.1) cmH2O/min. Subsequent NaCl instillation and QT-stimulation reduced the contractions to 0.3 (0.3)/min and the sum of amplitudes to 0.8 (0.4) cmH2O/min. Stimulation with a rectangular signal, as used in the PNE test, followed after an interval of 10 min, giving 1.1 (0.1) contractions/min and a sum of amplitudes of 5.1 (2.4) cmH2O/min. Within the control group there was no significant reduction.

CONCLUSIONS

These results show that QT-stimulation suppresses uncontrollable detrusor contractions in the minipig more effectively than the conventional rectangular stimulation presently applied in sacral neuromodulation.

Mictunrition and the sacral reflex arc: lessons from electrophysiological techniques

Electrophysiological techniques applied either for diagnostic or therapeutic reasons have contributed to elucidation of the neurocontrol of micturition. But the ability of electrophysiological diagnostic tests to reveal neurogenic involvement in patients suffering from lower urinary tract dysfunction is limited, and has been overestimated. Furthermore, the correlation between a proven neurogenic deficit and the consecutive dysfunction is complex. The electrophysiological tests, however, may also be applied for testing the central nervous system integrative function, such as in testing reflex thresholds, excitability levels of motor nuclei, etc. The use of electrical stimulation for therapeutic purposes has instigated much physiological research. Insights related to micturition neurocontrol, as for instance that afferent inputs from lumbosacral and vesical sensory fibres modulate the micturition threshold, are being therapeutically exploited. It is expected that further use of electrophysiological techniques, being complementary to functional neuroimaging, will clarify particularly the temporal aspects of neurocontrol mechanisms involved in micturition.

Neural control of the internal anal sphincter motility

Control mechanism of smooth muscle movement of the internal anal sphincter (IAS) by enteric and extrinsic neuvous systems in the dog was investigated. Responses of IAS muscle strips to electrical field stimulation (EFS) and neurotransmitter agents were recorded in vitro. The contraction response to norepinephrine or to EFS was inhibited by phentolamine. The relaxation induced by EFS was not affected by phentolamine, propranolol or atropine. The mechanical activity of smooth muscle in colon and anorectum during spontaneous defecation was recorded using strain gauge force transducers. The colon and anorectum showed the characteristic motility pattern during defecation: 1) The giant migrating contraction of the colon propagated to the rectum, 2) The relaxation of the rectum prior to the contraction, and 3) The IAS muscles continued to relax while the giant contractions of the colon were migrating to the rectum. Sacral nerves were stimulated electrically and the responses of smooth muscles in the rectum and IAS were recorded. The sacral nerve stimulation induced a relaxation followed by contraction of smooth muscle in the rectum and the relaxation in IAS. The mechanical responses of smooth muscle in the IAS were modulated by alpha-adrenergic excitatory and non-adrenergic, non-cholinergic inhibitory nerves. During defecation, the relaxation of IAS smooth muscle was associated with a characteristic motility pattern of the colon and anorectum. The enteric nervous systems may be organizing the motility of these muscles by way of the motor neurones under the control the extrinsic nervous systems.

[Magnetoneurographic registration of evoked summation action fields over lumbar vertebrae following transcutaneous tibial nerve stimulation]

Goal of this study was the development of a protocol for the registration of evoked magnetic fields over the lumbar spine using off-the-shelf equipment. Three subjects in a sitting position with their torso bent slightly forward were stimulated at the tibial nerve with a commercially available stimulator. Neuromagnetic fields were registered over a circular, 800 cm2 area of the lumbosacral spine using a 61-channel 4D-Neuroimaging biomagnetometer. After appropriate signal processing, dipolar magnetic fields with a field strength 5-17 fT peak-to-peak amplitude were detected in three out of four registrations. Location and orientation of these fields concurred with the expected evoked compound action currents along the course of the nerve fibers.

Spatial segregation within the sacral parasympathetic nucleus of neurons innervating the bladder or the penis of the rat as revealed by three-dimensional reconstruction

The purpose of the present investigations was (1) to examine the spatial organization of preganglionic neurons of the sacral parasympathetic nucleus in the lumbosacral spinal cord of male adult rats and (2) to search, in this nucleus, for a possible segregation of sub-populations of neurons innervating the penis or the bladder, respectively. To estimate their spatial organization, neurons of the sacral parasympathetic nucleus were retrogradely labeled by wheat germ agglutinin coupled to horseradish peroxidase applied to the central end of the sectioned pelvic nerve. The sub-populations of lumbosacral neurons innervating the corpus cavernosum of the penis or the dome of the bladder were identified using transsynaptic retrograde labeling by pseudorabies virus injected into these organs in different rats. In both wheat germ agglutinin-labeled and pseudorabies virus-labeled rats, serial coronal sections were cut through the spinal L5-S1 segments. Labeled neurons were revealed by histochemistry (peroxidase experiments) or immunohistochemistry (pseudorabies virus experiments). By means of a three-dimensional reconstruction software developed in our laboratory, three-dimensional models were calculated from each spinal section image series. They revealed the spatial organization of (i) preganglionic neurons and (ii) neurons innervating the bladder or the penis. The different three-dimensional models were subsequently merged into a single one which revealed the segregation, within the sacral parasympathetic nucleus, of the sub-populations of neurons. Neurons labeled by virus injected into the penis extended predominantly from the rostral part of the L6 segment to the rostral part of the S1 segment while those labeled by bladder injections were distributed predominantly from the caudal part of the L6 segment to the caudal part of the S1 segment. These results support the hypothesis of a viscerotopic organization of sacral neurons providing the spinal control of pelvic organs.

Excitatory synaptic currents in lumbosacral parasympathetic preganglionic neurons evoked by stimulation of the dorsal commissure

Excitatory pathways from the dorsal commissure (DCM) to L(6)-S(1) parasympathetic preganglionic neurons (PGN) were examined using whole-cell patch-clamp recording techniques in spinal cord slices from neonatal rats. PGN were identified by retrograde axonal transport of a fluorescent dye injected into the intraperitoneal space. Excitatory postsynaptic currents (EPSCs) were evoked in PGN by stimulation of DCM in the presence of bicuculline methiodide (10 microM) and strychnine (1 microM) to block inhibitory pathways. Electrical stimulation of DCM evoked two types of inward currents. In the majority of PGN (n = 66), currents (mean amplitude, 47.9 +/- 4.7 pA) occurred at a short and relatively constant latency (3.8 +/- 0.1 ms) and presumably represent monosynaptic EPSCs (Type 1). However, in other neurons (n = 20), a different type of EPSC (Type 2) was noted, consisting of a fast monosynaptic component followed by a prolonged inward current with superimposed fast transients presumably representing excitatory inputs mediated by polysynaptic pathways. Type 1 EPSCs were pharmacologically dissected into two components. A fast component was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 microM) and a slowly decaying component was blocked by 2-amino-5-phosphonovalerate (APV, 50 microM). The fast component of Type 1 EPSCs had a linear current-voltage relationship and reversed at a membrane potential of -7.6 +/- 1.3 mV (n = 5). The fast component of Type 2 EPSCs was also blocked by 5 microM CNQX and the remaining slower component was blocked by 50 microM APV. When the DCM was stimulated in the presence of 50 microM APV, the time to peak and decay time constant in Type 1 EPSCs were 1.9 +/- 0.2 and 4.1 +/- 0.8 ms, respectively. Examination of the NMDA receptor-mediated component of the EPSCs in the presence of 5 microM CNQX revealed a current-voltage relationship that had a region of negative slope conductance (from -20 to -80 mV), which was abolished in Mg(2+)-free external solution. The time to peak and decay time constant of this component were 14.2 +/- 2.0 and 91.0 +/- 12.4 ms, respectively. Type 1 EPSCs in some PGN responded in an all-or-none manner and presumably represented unitary synaptic responses; whereas Type 2 EPSCs always exhibited a graded stimulus intensity-response relationship. Paired-pulse facilitation (50-ms interstimulus intervals; 141 +/- 5.6% increase, n = 8) of EPSCs was observed. These results indicate that PGN receive monosynaptic and polysynaptic glutamatergic excitatory inputs from neurons and/or axonal pathways in the DCM.

Examination of the variations of lateral femoral cutaneous nerves: report of two cases

The origins, courses and relations of lateral femoral cutaneous nerves (LFCNs) were examined bilaterally in 28 cadavers, and the variations were observed in two. On the right side of one cadaver, the ventral rami of the first and second lumbar spinal nerves were united and then this nerve was divided into four branches. From medial to lateral, these branches were the obturator nerve, the femoral nerve, the medially located LFCN and the laterally located LFCN. On the left side of another cadaver, there were three LFCNs. All of these nerves pierced the psoas major muscle anterolaterally. Two of these nerves, which pierced the psoas major muscle more proximally than the third, united with each other by a communicating branch anterior to the iliacus muscle. These types of variations are very important, especially in the presence of paresthesias or pain in the anterior thigh, lateral thigh and gluteal region. In these cases, surgeons must always remember the possible variations of the LFCN during surgical procedures in order to prevent injury and the occurrence of meralgia paresthetica.

Bilateral sacral spinal nerve stimulation for fecal incontinence after low anterior rectum resection

BACKGROUND AND AIMS

The somatomotor innervation pattern has been shown to differ in patients undergoing percutaneous nerve evaluation for sacral nerve stimulation. In some patients bilateral stimulation might improve clinical outcome; however, only single-channel pulse generators have until now been available. We report a patient with fecal incontinence after surgery for rectal carcinoma in whom a dual-channel, individually programmable, pulse generator permitted implantation of neurostimulation electrodes bilaterally.

PATIENTS AND METHODS

Intractable fecal incontinence developed in a 48-year-old man who underwent low anterior rectum resection, owing mainly to reduced internal anal sphincter function. The morphology of the anal sphincter was without defect. Based on the findings of unilateral and bilateral temporary sacral nerve stimulation the patient underwent placement of foramen electrodes on S4 bilaterally. Both electrodes were connected to a dual-channel impulse generator for permanent low-frequency stimulation.

RESULTS

The percentage of incontinent bowel movements decreased during unilateral test stimulation from 37% to 11%, during bilateral test stimulation to 4%, and with chronic bilateral stimulation to 0%. The Wexner continence score improved from 17 preoperatively to 2, and quality of life (ASCRS score) was notably enhanced. Anorectal manometry revealed improved striated anal sphincter function; the internal anal sphincter remained unaffected.

CONCLUSION

Sacral nerve stimulation can effectively treat incontinence after rectal resection, and bilateral stimulation can improve the therapeutic effect.

Predictive factors for sacral neuromodulation in chronic lower urinary tract dysfunction

OBJECTIVES

To investigate data from 211 patients who underwent a trial stimulation (percutaneous nerve evaluation [PNE]) to determine the clinical parameters that can enhance the prediction of PNE success. The advantageous effect of sacral neuromodulation depends on the accurate identification of suitable candidates during the preimplantation PNE.

METHODS

A total of 211 patients (161 women and 50 men), with refractory urge incontinence, urgency-frequency syndrome, and urinary retention, underwent a PNE. Patient data (demographics, medical history, urologic investigations, and diagnosis) were collected. The PNE results were evaluated from a voiding diary and patient history. More than 50% improvement of voiding parameters was considered a successful PNE, and those patients were selected for implantation. Logistic regression analysis was performed. The factors tested for predicting the test result were sex, patient age, diagnosis, previous surgery, neurogenic bladder dysfunction, duration of complaints, and previous treatments.

RESULTS

The PNEs were positive in 85 patients (40.3%) and negative in 105 patients (49.8%). In 18 patients (8.5%), the test electrode had migrated; 3 more patients were not assessable and were also excluded. Missing data on the variable "duration of complaints" reduced the number of patients in the analyses from 190 to 174 patients.

CONCLUSIONS

Intervertebral disk prolapse, duration of complaints, neurogenic bladder dysfunction, and urge incontinence were found to be significant predictive factors. However, a PNE remains necessary to evaluate a patient's chance of implant success objectively.

[Sacral nerve stimulation in fecal incontinence]

INTRODUCTION

Sacral nerve stimulation for the treatment of faecal incontinence has gained increasing use in Europe over the last two years. Experience with the first patients treated in Denmark is described here.

MATERIAL AND METHODS

Fourteen patients with severe faecal incontinence were given sacral nerve stimulation. The first treatment was temporary, and if this was successful they had a device for permanent stimulation implanted.

RESULTS

The result of the test stimulation was good in ten of the 14 patients and a permanent system was implanted. After a median of 4.5 months' stimulation, nine of the ten patients continued to respond to respond well.

DISCUSSION

Sacral nerve stimulation in the treatment of faecal incontinence shows promising results. Compared to other more advanced forms of treatment, this method is minimally invasive.

Sacral neuromodulation as an effective treatment for refractory pelvic floor dysfunction

OBJECTIVES

To determine the long-term efficacy and complications of sacral nerve stimulation as an alternative therapy for pelvic floor dysfunction. Pelvic floor dysfunction is a complex problem that can be refractory to current treatment modalities. Conservative therapy rarely results in a durable cure of patients, and various surgical procedures have significant side effects and less than optimal results.

METHODS

Sixty-four patients, 54 women and 10 men, with various forms of voiding dysfunction for whom other forms of therapy had failed underwent placement of the Medtronic Implantable Pulse Generator sacral nerve implant. The mean age was 47 years. The presenting complaint was frequency, urgency, and urge incontinence in 44 patients and chronic nonobstructive urinary retention requiring self-catheterization in 20 patients. Forty-one patients also had chronic pelvic and perineal pain associated with their voiding symptoms. The mean duration of symptoms was 69 months. All patients underwent percutaneous nerve evaluation before the permanent implant and demonstrated more than 50% improvement in their symptoms. All patients were evaluated at 1, 3, 6, 12, and 24 months, and yearly thereafter. The assessment of the voiding symptoms was done both subjectively by patient symptoms and objectively using voiding diaries recorded for 3 days. A validated verbal rating pain scale was used to evaluate pain levels.

RESULTS

Eighty percent of the patients had 50% or greater improvement in their presenting symptoms and quality of life after the procedure, with a mean follow-up of 24 months. Patients with frequency-urgency showed a reduction in the number of voids per day with a significant increase in voided volumes. Patients with urge incontinence showed a reduction in leaking episodes from 6.4 to 2.0/24 hr, with a decrease in the number of pads used from 3.5 to 1.2/day. Sixteen of 20 patients with urinary retention were able to void with a residual volume of less than 100 mL. Patients with chronic pelvic pain showed a decrease in the severity of pain from a score of 5.8 to 3.7. Complications were minimal and encountered in 18.7% of the patients.

CONCLUSIONS

Sacral nerve stimulation is an effective and durable new approach to pelvic floor dysfunction with minimal complications. Test stimulation provides a valuable tool for patient selection.

Influences of pelvic floor structures and sacral innervation on the response to distension of the cat rectum

The contributions to the rectal response to distension of the pelvic floor structures surrounding the rectum and of the sacral spinal innervation have never been studied. Using paralysed intercollicularly decerebrate, anaesthesia-free cats, we studied pressure-volume relationships during slow ramp distensions of the rectum. Results obtained from animals with intact pelvic cavities were compared with those following mobilization of the rectum from the pelvic floor musculature. To assess the influences of spinal outflow and afferent input, rectal pressure-volume relationships were measured in the mobilized rectum following bilateral sequential transection of the spinal roots S1 to S3, first dorsal, then ventral. Isolation of the rectum from the pelvic floor structures resulted in a decrease in balloon volume in the lower range of distension pressure but did not affect volumes at higher pressures. The only afferent effect was seen after sectioning of dorsal roots S1, which resulted in a decrease in balloon volume. The only efferent effect was seen after sectioning of ventral roots S3, which decreased balloon volume further. In conclusion, the rectal response to distension depends on the properties of the rectal wall. It may be influenced by somatic inputs, inputs from the myenteric nervous plexus, and from the parasympathetic and sympathetic nervous systems. Afferent inputs and spinal autonomic reflexes may decrease the tone of the rectal musculature during distension.

Alterations of cortical electrical activity in patients with sacral neuromodulator

OBJECTIVES

Sacral neuromodulation represents chronic stimulation of the sacral (S3) nerve. So far, the mode of action and neuro-anatomical basis is unclear. Sacral reflex mechanisms as well as pontine or cortical centers of modulation have been postulated. Our aim was to evaluate possible alterations in electroencephalogram (EEG) activity as an indicator of a supraspinally mediated mechanism of sacral neuromodulation.

MATERIALS AND METHODS

We analyzed serial EEGs (apparatus: Kölner Vitaport System) using electrodes placed at Fz, Cz, Cz' and Pz in 10 patients. Subsequently, the sacral (S3) nerve was stimulated by means of an impulse generator (Medtronic, Interstim 3023) using an on-off paradigm with a 1.5s "on" interval followed by a 10s stimulation break. Raw data were analyzed using both Matlab 4.0 software and a specially developed averaging routine.

RESULTS

All patients demonstrated a cortical potential complex following sacral root stimulation with an early electronegative component at 50 ms with a mean amplitude of 23 microV followed by a late potential component with a mean latency of 253 ms and a mean amplitude of 5 microV, both with a maximum at Cz, corresponding to the post-central gyrus. This finding occurred irrespective of patient's reports of actually feeling the neuromodulator being switched on and off.

CONCLUSION

In neuromodulation responders, both short and long latency cortical potentials can be reproduced with a maximum at the sensory cortical area. Although these potentials are similar to cognitively mediated "event-related potentials", they are clearly distinct from any subjective sensory or even painful response since several patients of this series have not been able to feel any neuromodulator action. Therefore, this pilot study indicates a supraspinally mediated site of modulation, most probably in sensory cortex areas.

Recent innovations in the management of fecal incontinence

The importance of having a reproducible scoring system to objectively assess the severity of fecal incontinence and its response to treatment is stressed, and a number of methods are described. The approach to conservative treatment and investigation is outlined. Recent advances in the surgical management of fecal incontinence including the electrically stimulated gracilis neosphincter, sacral nerve stimulation, the artificial anal sphincter, internal anal sphincter augmentation, rectal augmentation, and antegrade colonic irrigation are described in detail.

Assessment of sphincter muscle function before and after posterior sagittal anorectoplasty using a magnetic spinal stimulation technique

PURPOSE

The authors used a magnetic spinal stimulation technique to assess both the preoperative sphincter function and the effect of operative intervention on the sphincter muscle in patients with anorectal malformations.

METHODS

The authors examined 5 patients with an anorectal malformation consisting of 4 high-type cases and 1 intermediate-type case, that all had undergone posterior sagittal anorectoplasty during the previous 2-year period. Control data also were obtained from 11 age-matched healthy children. A contraction of the external anal sphincter (EAS) was evoked by magnetic stimulation of the sacral roots with a figure-of-eight coil at the level of the lumber and sacral segments. EAS electromyograms then were recorded at the anal verge.

RESULTS

The preoperative motor latencies at L4 stimulation increased significantly more in the patients than in the controls (5.9 +/- 0.5 msec v 4.1 +/- 0.7 msec during left side recording). In the postoperative examination (1 to 5 months after operation), the mean maximum amplitude decreased slightly without any significant difference, where as the latency was almost identical to the preoperative data.

CONCLUSION

These results suggest that the neurologic function of EAS was congenitally disturbed, and the current operative technique had no significant effect on the sphincter function.

Diagnostic value of electrical stimulation of lumbosacral roots in lumbar spinal stenosis

OBJECTIVES

This paper compares the diagnostic sensitivity of two tests in lumbar spinal stenosis (LSS): lumbosacral root stimulation with needle electrodes and needle electromyograph (EMG).

MATERIAL AND METHODS

Twenty patients with LSS were assigned to two groups: Patients with 'neurogenic intermittent claudication' (NIC) only (n=11), and patients with 'neurological signs' (n=9). Ten normal subjects were also examined. The effects of direct stimulation of the lumbosacral roots and conventional EMG recorded from important muscles [rectus femoris (RF): L4, tibialis anterior (TA): L5, soleus muscle (SOL): S1], were compared with each other and correlated with their respective clinical findings and radiological images.

RESULTS

Needle EMG and nerve conduction study revealed pathology in 15/20 patients, and electrical stimulation of the roots in 17/20 patients. Agreement in radiological findings with electrical stimulation of the roots and EMG was found in 12 patients. The other patients were harmonic with radiological findings either in EMG or in electrical stimulation of the roots.

CONCLUSIONS

Electrical root stimulation revealed more abnormalities in patients with LSS in comparison with needle EMG. However, both methods seemed to complement each other to show additional pathology in a given patient.