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Biomedical subjects

D B Vodusek

Publications and source records attributed to D B Vodusek.

At least 19 recordsLinked to original sources
PubMed1999

Standardization of anal sphincter EMG: technique of needle examination.

The external anal sphincter (EAS) anatomy is complex, and no exact technique of needle electrode insertion into it for electromyography (EMG) has been described. To define optimal positions for needle electrode insertions, EAS muscle topography was studied by concentric needle EMG. Fifteen women without uroneurological disorders were examined. Perpendicular insertions were made superficially (just under the mucosa) at the mucocutaneous junction, 5 and 10 mm more proximally (toward the anus), and at the anal orifice. In addition, at the anal orifice, deeper insertions were made. Superficially, EMG activity was detected at the mucocutaneous junction in 9 (60%) subjects. In the remaining 6, the muscle was found either 5 mm (in 5) or 10 mm (in 1) more centrally. At the anal orifice, superficial EMG activity was present in 67% of women. On deep insertion (15-25 mm) at the anal orifice, muscle was always present. It is suggested that, in further studies, the portions of the EAS muscle examined should be specified.

Adult↗
PubMed1999

Standardisation of anal sphincter EMG: high and low threshold motor units.

OBJECTIVE: The anal sphincter muscle has a proportion of low threshold motor units (MUs) that are continuously active and other, recruitable high threshold MUs. In standard EMG recordings, motor unit potentials (MUPs) of the later seem to be of higher amplitudes. A quantitative EMG study was performed to assess possible consequences of sampling MUPs at different levels of sphincter activation. METHODS: Fifteen females without uroneurological disorders were studied. After insertion, standard concentric EMG needle was left in the anal sphincter muscle undisturbed for 1 min; then 30 s of the remaining continuous, and 1 min of voluntarily increased EMG activity were recorded on a DAT recorder. MUPs were collected and analysed by 'Multi-MUP' analysis. MUPs analysed during relaxation constituted the 'low threshold MUP pool'. MUPs sampled on activation were checked for those, already sampled during relaxation, (which were discarded), and the remaining MUPs constituted the 'high threshold MUP pool'. Parameters of both MUP pools were compared. RESULTS: High threshold MUPs were found to be significantly larger than low threshold MUPs. CONCLUSIONS: EMG investigator should be aware of the differences of MUPs sampled at various anal sphincter activity levels. For the technique of 'Multi-MUP' analysis sampling at an activity level which provides 3-5 MUPs per detection site would seem practical, providing a standardised approach suitable for comparing normative data with individual findings from most patients.

Adult↗
PubMed1999

Neurophysiological study of primary nocturnal enuresis.

The purpose of this study was to investigate nervous system involvement in primary nocturnal enuresis by using electrophysiological techniques. Nineteen boys with primary nocturnal enuresis and 25 boys without uroneurological abnormalities were included. Data about their psychomotor development, micturition, and defecation were obtained by interviewing the boys and their parents. The penile sensory threshold for electrical stimuli was determined. Single and averaged bulbocavernosus reflex (BCR), and averaged pudendal somatosensory evoked potentials (PSEP) to electrical stimulation, were recorded. The only statistically significant difference found in enuretic children was longer latencies of averaged BCR to single electrical stimulation (P = 0.03). No significant BCR latency differences to stimulation with double electrical pulses and no PSEP latency differences were found. By using electrophysiological techniques, differences between the enuretic and control group of boys were demonstrated. Our results can be interpreted as indicating hypoexcitability of sphincter nuclei. Along with the reported hyperexcitability of bladder motor nuclei, a minor dysfunction in the neurocontrol of the lower urinary tract, in at least a subgroup of enuretic children, can be postulated.

Adolescent↗
PubMed1998

Dysfunctional voiding in women: which muscles are responsible?

OBJECTIVE: To analyse the striated external urethral sphincter (EUS) and pelvic floor muscles using two different electromyography (EMG) techniques in women with dysfunctional voiding and/or urinary retention. PATIENTS AND METHODS: Fifteen women (mean age 38.2 years, range 18-61) with dysfunctional voiding and/or unexplained voiding dysfunction associated with urinary retention were examined neurologically and urologically; urodynamics and kinesiological EMG of the bilateral pubococcygeal and external urethral striated sphincter muscles were obtained. In an additional neurophysiological session, concentric-needle EMG of the external urethral sphincter was performed. RESULTS: Kinesiological EMG recordings revealed inappropriate pelvic floor muscle activation during voiding in 11 and EUS activation in four women. Concentric needle EMG of the EUS revealed complex repetitive discharges in the four women with inappropriate urethral sphincter activation recorded by kinesiological EMG during voiding. Biofeedback training led to improvement in women with inappropriate pubococcygeal activation but not in those with urethral sphincter complex repetitive discharges. CONCLUSION: Urodynamic examinations in combination with kinesiological EMG examination of the pubococcygeal and external urethral sphincter muscles revealed two groups of women with dysfunctional voiding. Further diagnostic evaluation of such patients with concentric-needle EMG is mandatory. The differentiation of the two groups is therapeutically relevant.

Adolescent↗
PubMed1997

A method of uroneurophysiological investigation in children.

Characteristics and reproducibility of bulbocavernosus reflex (BCR) and pudendal somatosensory evoked potentials (PSEP) elicited by mechanical stimulation in children were tested. Twenty-five male children aged 5-14 years without uroneurological complaints were enrolled in the study. In addition to electrical stimulation, a specially constructed electromechanical hammer triggered by an oscilloscope was used for mechanical stimulation of distal penis. All responses were detected by surface electrodes. The latencies and amplitudes of averaged as well as latencies of single BCR on single and double electrical stimuli were determined. Mechanical stimulation was described as much less unpleasant than electrical stimulation. Both mechanical/electrical stimulation elicited consistent and reproducible responses in high percentages of children (BCR: average, 80%/71%, single, 94%/100%; PSEP: 96%/96%, respectively). BCR latencies were significantly longer and PSEP amplitudes were significantly higher on mechanical stimulation. The compliance with mechanical was much better than with the electrical stimulation and the former can be recommended for clinical use. The effective mechanical stimulus delivered by a particular mechanical stimulator has a characteristic 'delay' (as to the actual point of triggering the oscilloscope ray) which influences the latency reading of responses; appropriate control data are therefore necessary.

Adolescent↗
PubMed1997

Electromyogram, evoked sensory and motor potentials in neurourology.

To test the integrity of the sacral neuromuscular system, the concentric needle electromyogram (EMG) is suggested as the established method to provide information on denervation and reinnervation. The electrophysiologically recorded bulbocavernosus reflex is more sensitive than the clinically performed test; its latency is, however, not a sensitive test to assess axonal lesions. Pudendal cerebral somatosensory evoked potentials (SEP) can be considered promising in patients with conus involvement. Motor evoked potentials (MEP) in perineal muscles can only be considered investigational. True sensitivity and specificity of uroneurophysiological tests is difficult to establish due to the lack of a 'gold standard' test to define the underlying neurological lesion. Therefore, good (age stratified) reference values have to be established.

Electromyography↗
PubMed1997

Intraoperative recording of the bulbocavernosus reflex.

OBJECTIVE: To demonstrate the feasibility of intraoperative monitoring of the bulbocavernosus reflex (BCR) as an indicator of the functional integrity of sacral nervous structures to aid in preventing their intraoperative injury. METHODS: Intraoperative BCR was elicited by electrical stimulation of the dorsal penile/clitoral nerve in 119 patients anesthetized with propofol, fentanyl, and nitrous oxide, with short-acting relaxant. Thirty-eight patients underwent surgery without risk, whereas 81 underwent surgery with risk of damage to sacral structures. Different patterns of stimuli were applied through silver/silver chloride disc electrodes placed on the dorsal aspect of the penis in males and over the clitoris (cathode) and adjacent labia (anode) in females. Recordings were made from the anal sphincter using intramuscular wire electrodes introduced within a 27.5 gauge needle, with two electrodes each inserted in the right and left hemisphincter muscles. Preoperatively, some patients had minor urinary problems in controlling their sphincters. RESULTS: The BCR was reliably recorded without habituation under this anesthetic regime. Optimal stimulating parameters were found to be double pulses (0.5-ms duration), with an interstimulus interval of 3 ms, stimulating rate of 2.3 Hz, and intensity of 20 mA. With these parameters, it was possible to record the BCR intraoperatively in all patients. Isoflurane and nitrous oxide significantly suppressed the BCR, and muscle relaxant completely abolished it. CONCLUSION: We demonstrated that it is feasible, under certain anesthetic regimes, to intraoperatively monitor the BCR in both children and adults (24 d to 74 yr of age) who did not have significantly affected function in sacral nervous structures.

Adolescent↗
PubMed1997

Preservation of pudendal afferents in sacral rhizotomies.

OBJECTIVE: To assess the effectiveness of pudendal afferent mapping as a tool to minimize the risk of postoperative bowel, bladder, and sexual dysfunction in patients undergoing selective posterior rhizotomies in whom the S2 roots are candidates for rhizotomy. METHODS: One-hundred fourteen children with the diagnosis of cerebral palsy and debilitating spasticity were selected to undergo selective posterior rhizotomies at New York University Medical Center during 1991 through 1995. There were 72 male and 42 female patients with a mean age of 3.8 years. At the time of surgery, none of the patients had clinically relevant bladder dysfunction. Dorsal root action potentials were recorded intraoperatively to map the distribution of pudendal afferent fibers in S1-S3 roots bilaterally before performing the rhizotomies. RESULTS: Pudendal afferent mapping was successful in 105 of 114 patients. In the majority of these patients (56%), the distribution was asymmetrical. S1 roots contributed 4%, S2 roots 60.5%, and S3 roots 35.5% of the overall pudendal afferent activity. The pudendal afferent distribution was often confined to a single level in 18% of the patients or even to a single root in 7.6%. Fifty-six percent of the pathologically responding S2 roots during rhizotomy testing were preserved because of the significant afferent activity, as demonstrated during pudendal mapping. None of the 105 patients so mapped developed long-term bowel or bladder complications. CONCLUSIONS: Pudendal afferent mapping identifies S2 roots that carry a significant number of fibers involved with genital sensation. The preservation of such roots during surgical procedures may be important for sexual function and may also contribute to decreasing postoperative bladder and bowel disturbances.

Action Potentials↗
PubMed1996

Motor evoked potentials during brain surgery.

In order to obtain a robust method for intraoperative monitoring of motor pathways, different stimulation patterns to elicit muscle motor evoked potentials (MEPs) were studied during neurosurgical procedures in 3 patients. MEPs were recorded by a catheter electrode in the subdural space and/or by needle electrodes in limb muscles. For stimulation single pulses and trains consisting of two to five pulses were used. Muscle MEPs were only obtained after trains of at least 3 stimuli while single/double stimuli were inefficient. Simultaneous subdural recordings showed that single and double stimuli only elicited D-waves, whereas trains of 3 or more stimuli generated I-waves, as well. We propose that train stimulation can overcome the depressive effects of anesthesia on cortical motoneurons.

Brain↗
PubMed1996

Mechanically evoked bulbocavernosus reflex and pudendal somatosensory responses in children.

Electrophysiological investigations of sacral functions are unpleasant and as such rarely performed in children. A novel approach is presented: bulbocavernosus reflex and pudendal cortical somatosensory evoked potentials were studied on mechanical stimulation of the penis and compared with their electrically evoked counterparts in 21 (5-14 years old) boys. An electromechanical hammer was used and only surface electrodes applied. Children preferred mechanical stimulation which also evoked reliable responses in more boys. Reflex responses on mechanical stimulation were found to be of longer latency, however no latency differences between cortical evoked responses to either stimulation were found. We suggest the use of mechanical stimulation in uroneurophysiological testing of children.

Adolescent↗
PubMed1996

Evoked potential testing.

Electrophysiologic tests of the sacral neuromuscular system and its suprasegmental control may be divided into EMG and methods involving stimulation (i.e., evoked potential and sacral reflex testing). The latter group of methods tests the function of defined parts of the motor or sensory nervous system, or reflex arcs. There already is ample experience with testing the somatic sensory pathways (pudendal SEP) and the (somatic) sacral reflex arc, whereas other methods (testing the motor system and tests involving visceral afferents and sympathetic efferents) need further study to establish their proper place in everyday clinical diagnostics. The application of these methods in research has led to important advances in our understanding of nervous system involvement in different pathologic conditions leading to neurogenic sacral dysfunctions. If applied in individual patients, these methods should however, be used and interpreted with restraint; they should be considered in patients with probable or proved nervous system lesions, those in whom additional clarification regarding proof of, localization of, and the nature (i.e., axonal versus demyelinative) of the lesion is relevant for diagnosis and prognosis. If applied in patients with central nervous system involvement, evoked potential studies may be used on their own; but, in the author's opinion, in patients with putative peripheral nervous system involvement these tests should be considered, as a rule, only as an extension of a needle EMG exploration. It is expected that further experience will clarify the sensitivity and specificity of the available methods. The already available methods certainly will gain a place in the operating room helping the surgeon in selected procedures involving the pelvis and particularly conus and cauda equina better to identify neuromuscular structures and to monitor their function throughout the operation in order to prevent subsequent development of lesions.

Electric Stimulation↗
PubMed1994

Botulinum toxin in the treatment of neurological disorders.

Botulinum toxin therapy is safe and effective in the treatment of different movement disorders, especially focal dystonias. We reviewed botulinum toxin treatment of 97 patients: 36 had blepharospasm, 41 had torticollis, and 20 had diverse movement disorders. Patients with blepharospasm and torticollis improved markedly after botulinum toxin injections. The most common side effect in BS patients was ptosis (44.4%); in TC patients, it was dysphagia (29.3%). The mean duration of the improvement in both groups was 3.4 months. Very promising results were obtained also in the heterogeneous group including patients with other focal dystonias and cerebral palsy. On the basis of these results, we concluded that BTA injections must now be considered the mainstay of therapy for focal dystonias and other involuntary movement disorders.

Adolescent↗
PubMed1994

Pelvic floor activity patterns: comparison of nulliparous continent and parous urinary stress incontinent women. A kinesiological EMG study.

OBJECTIVE: To introduce neurophysiological methods to search for damage to neuromuscular structures involved in sustaining continence in women who experienced stress urinary incontinence during pregnancy and/or after delivery. PATIENTS AND METHODS: Eight stress urinary incontinent parous women (mean of 2.75 vaginal deliveries [range 2-4] median age 45.3 years [range 31-60]) were examined using simultaneous electromyogram recordings of the left and right pubococcygeus muscle via wire electrodes. Comparisons were made with 10 nulliparous continent women (median age 27.2 years [range 22-32]). RESULTS: Individual muscle activation patterns in stress urinary incontinent parous women were in principle similar to those observed in the continent nulliparous women, with two significant exceptions: (i) voluntary 'squeeze' showed significant differences in the holding time between the parous stress urinary incontinent patients and the nulliparous continent controls, with an empty bladder (49.0 s versus 193.9 s median value) and a full bladder (39.2 s versus 198.4 s); (ii) asymmetrical and uncoordinated levator activation patterns were demonstrated in four of eight parous stress incontinent women, i.e. inhibition of motor unit firing on coughing (n = 3) and dissociated recruitment of motor units during voluntary and reflex activation (n = 1). CONCLUSION: Childbirth appeared to induce both quantitative and qualitative changes in the pelvic floor which jeopardized the continence mechanism. Sphincter weakness appeared to result not only from the loss of motor units but also from altered activation patterns in the remaining units: shorter activation periods, lack of response or paradoxical inhibition. Kinesiological EMG recordings revealed behavioural abnormalities which appeared relevant for planning treatment.

Adult↗
PubMed1993

Activity patterns of pubococcygeal muscles in nulliparous continent women.

Simultaneous electromyographic (EMG) recordings from the left and right pubococcygeal muscles were obtained in 10 continent nulliparous women (aged 22-32 years) via wire electrodes inserted percutaneously. During relaxation, sustained motor unit firing was obtained in 14 and no EMG activity in 4 of the 20 recorded muscle sites. During voluntary squeeze, stopping urine in midstream and coughing there was always bilateral recruitment of motor units that was gradual in the recording sites with ongoing EMG activity and brisk in the sites without EMG activity; the 2 different patterns of activity were called "tonic" and "phasic" respectively. Voluntary squeeze led to activation of motor units sustained for 26 to 647 s (median 193.9) with the bladder empty and 25 to 600 s (median 198.4) with a full bladder. A marked decrease in ongoing tonic motor unit activity was seen during the attempt to urinate. Bladder filling caused an increase in tonic activity in 7 females bilaterally and in 1 unilaterally, whereas there was no change in 3 women. During the Valsalva manoeuvre, simultaneous motor unit recruitment was seen in all subjects bilaterally with the bladder empty and in all but one with the bladder full: in the latter case the motor unit recruitment with an empty bladder changed into simultaneous bilateral inhibition of firing of motor units with a full bladder (both in the supine and erect position); this pattern changed to bilateral recruitment of motor units again after bladder emptying. It is important to be familiar with the normal patterns of activity of the pubococcygeal muscles in continent nulliparous women since the denervation injury caused by childbirth might not only weaken these muscles but also influence their behaviour.

Adult↗