Place of perineal electrophysiologic testing in multiple sclerosis patients.

At present, apart from visual evoked potential testing, clinical neurophysiological testing is rarely used in multiple sclerosis (MS) patients at all. In MS patients with lower urinary tract, bowel and/or sexual dysfunction, which are highly prevalent in MS, clinical neurophysiological tests of the sacral nervous system have been introduced in the past and reported as abnormal. Their usefulness is--in selected patients--to substantiate the suspicion of the neurogenic nature of the pelvic organ dysfunction, but there is no specific recommendation for MS patients. Concentric needle EMG of the perineal muscles, bulbocavernosus reflex latency measurement and pudendal SEP may be particularly useful in those rare patients in whom MS may affect the conus medullaris, to demonstrate "directly" this lesion of the lower sacral segments. Clinical neurophysiological testing retains the potential to further clarify interesting research questions of correlation of nervous system function and pelvic organ dysfunction, particularly relevant for application of sophisticated new rehabilitative methods including electrical stimulation of the nervous system.

Bayesian characterization of external anal sphincter muscles using quantitative electromyography.

OBJECTIVES: Based on the analysis of electromyographic (EMG) data muscles are often characterized as normal or affected by a neuromuscular disease process. The objective of this work was to compare the accuracy of Bayesian muscle characterization to conventional means and outlier analysis of motor unit potential (MUP) feature values. METHODS: Quantitative MUP data from the external anal sphincter muscles of control subjects and patients were used to compare the sensitivity, specificity, and accuracy of the methods under examination. RESULTS: The results demonstrated that Bayesian muscle characterization achieved similar accuracy to combined means and outlier analysis. Thickness and number of turns were the most discriminative MUP features for characterizing the external anal sphincter (EAS) muscles studied in this work. CONCLUSIONS: Although, Bayesian muscle characterization achieved similar accuracy to combined means and outlier analysis, Bayesian muscle characterization can facilitate the determination of "possible", "probable", or "definite" levels of pathology, whereas the conventional means and outlier methods can only provide a dichotomous "normal" or "abnormal" decision. Therefore, Bayesian muscle characterization can be directly used to support clinical decisions related to initial diagnosis as well as treatment and management over time. Decisions are based on facts and not impressions giving electromyography a more reliable role in the diagnosis, management, and treatment of neuromuscular disorders. SIGNIFICANCE: Bayesian muscle characterization can help make electrophysiological examinations more accurate and objective.

Impact of electromyographic findings on choice of treatment and outcome.

The subsequent clinical course of patients examined in the EMG laboratory has not been adequately studied before. It is not known how EMG findings in practice affect patients' final diagnosis, treatment and outcome. The aim of the present study was to test the hypothesis that EMG results have an important impact on the choice of patients' treatment and on outcome. Three years after EMG examination, a short questionnaire asking about initial symptoms, the final diagnosis, treatment and current symptoms was sent to 300 consecutive EMG patients. Responses concerning 186 of them (39% men) were received either from patients and/or from their referring physicians. Information obtained during EMG examination was also added. Data was analyzed using methods of bivariate and multivariate statistics. We found that patients with a pathologic EMG had a better clinical outcome 3 years later. Pathologic EMG has an independent effect, pointing to more favorable disease courses, which was further improved by more active treatment approaches received by these patients. The study demonstrated the important impact of EMG findings on the treatment choice and clinical outcome in population consisting mainly of patients with carpal tunnel syndrome and radiculopathy. Studies in other patient populations are needed.

Saddle sensation is preserved in a few patients with cauda equina or conus medullaris lesions.

Although saddle sensory deficit seems the most useful clinical sign in the diagnosis of a cauda equina or conus medullaris lesion, findings of previous studies were controversial. The aim of the present study was to try to resolve this issue. The data from the author's series of patients with clinical, electrodiagnostic and radiological findings compatible with a cauda equina lesion were reviewed. Of the 117 patients in the series, 11 (10 men) did not have a saddle sensory deficit. These 11 patients had less severe sacral dysfunction than the others, and none of them needed urgent surgical intervention. They all had electromyographic (EMG) signs of a significant motor fibre lesion, and in seven men the sacral (penilo-cavernosus) reflex was clinically abnormal. The study revealed normal saddle sensation in approximately 10% of patients with cauda equina or conus medullaris lesions. Dissociation between preserved touch sensation and abnormal EMG findings, as well as dissociation between preserved touch sensation and a non-elicitable penilo-cavernosus reflex might be explained by preservation of the thinner sensory nerve fibres, which are more resistant to compression. Although, saddle sensory loss seems to identify patients who might benefit from urgent spinal imaging and surgery, further diagnostic evaluation is also indicated in patients with normal saddle sensation, particularly due to the increased frequency of spinal tumours found in this subgroup.

Bowel dysfunction in patients with cauda equina lesions.

Despite their serious sequels on bowel function, lesions of the cauda equina have not been previously systematically studied in larger patient populations. This was the aim of the present report. From the registrars of a diagnostic and rehabilitation centres 67 patients with clinical, electrodiagnostic and radiological findings supportive of the cauda equina lesions were recruited. The Slovene versions of the standard questionnaires for anal incontinence and constipation were used. The responses were scored, impairments categorized and previous treatments noted. Neurological examination, electromyography (EMG) of lumbo-sacral myotomes, quantitative anal sphincter EMG and electromyographic evaluation of the sacral reflex were performed. Severe anal incontinence/constipation was reported by 18%/0%, moderate by 36%/33%, and slight by 28%/43% of our patients. Twenty-one per cent of patients wore pads continuously and 14% occasionally. More than half of the patients (60%) reported changes in their lifestyle due to anal incontinence. No patient had completely normal findings on neurological examination. Perianal sensory loss correlated (P < 0.05) with anal incontinence and gender with constipation (women > men). Only two patients had received medical attention for bowel dysfunction. Study thus demonstrated significant bowel impairment in patients with lesions of the cauda equina, which has received insufficient medical attention.

Critical reappraisal of referrals to electromyography and nerve conduction studies.

A large number of examinees referred to electromyographic (EMG) laboratories do not have symptoms or signs suggestive of a peripheral nervous system disorder, and the aim of the present study was to check this. All examinees evaluated by the author in a "general" EMG laboratory in the first 4 months of 2002 were included. Data on examinees, referral physicians and diagnoses, clinical symptoms and signs, and electrodiagnostic findings were statistically evaluated. Three hundred examinees, 42% men, were included. A neurological diagnosis was provided in 55% of referrals. Electrodiagnostic abnormalities were found in 45% of examinees. Using multivariate statistics, a positive effect of neurological referral diagnosis, history of paraesthesias and of weakness and sensory loss on examination, and a negative effect of history of pain on pathological electrodiagnostic findings were found. Except 20 patients with carpal tunnel syndrome, no patient with normal clinical examination had abnormal electrodiagnostic findings. Our study confirmed the inappropriateness of referrals to electrodiagnostic examination to screen patients for peripheral nervous disorders. We propose electrodiagnostic examination mainly of patients with unequivocal clinical signs of a peripheral nervous system lesion and of patients with typical symptoms of the carpal tunnel syndrome.

Electrodiagnosis of the anorectum: a review of techniques and clinical applications.

Electrodiagnostic tests may be valuable in the assessment of patients with anorectal dysfunction and are complementary to imaging and manometry. While the latter delineate morphological and functional sphincter changes, respectively, electrodiagnostic methods document, help to localize and assess the severity and mechanism of neural injury. These data are important for the treatment of patients and for estimating their prognoses. Among electrodiagnostic tests, concentric needle electromyography of the external anal sphincter is the most important. It demonstrates muscle denervation, quantitatively estimates muscle reinnervation, estimates the level of motor neuron excitability and assesses several kinesiological parameters. In addition, measurement of the bulbocavernosus reflex is often useful, while pudendal somatosensory evoked potentials are sometimes useful. Use of single tests of sacral nervous system by workers less familiar with theoretical principles of clinical neurophysiology is discouraged. In patients with suspected neurogenic bowel disorders, comprehensive electrodiagnostic approach, performed by clinical neurophysiologists experienced in application of these tests to the sacral nervous system, should complement data obtained by other methods and guide patient management.

Sexual function in men with cauda equina lesions: a clinical and electromyographic study.

OBJECTIVE: To investigate the effects of cauda equina lesions on sexual function in men. METHODS: Sexual function was investigated in 46 men with long standing cauda equina/conus medullaris lesions. All had clinical and radiological findings supporting the diagnosis. The validated Slovene translation of the international index of erectile function (IIEF) was used. The responses were scored and sexual dysfunction categorised as absent, mild, moderate, or severe. The number of patients receiving help for sexual dysfunction was noted. Neurological examination of the trunk and lower limbs, electromyographic (EMG) evaluation of the sacral reflex, and quantitative EMG of the external anal sphincter muscles were done. RESULTS: Severe sexual dysfunction was reported by 35% of patients, moderate dysfunction by 24%, and slight dysfunction by 26%; normal sexual function was reported by 15%. Orgasmic function was slightly more impaired than erectile function, and sexual desire slightly less. The patients' age, but no findings on clinical neurological or EMG examination, correlated with sexual function. Only five men had received medical attention for sexual dysfunction. CONCLUSIONS: There is significant sexual impairment in men with lesions of the cauda equina or conus medullaris. This is poorly correlated with neurological and EMG findings and has received insufficient medical attention.

Protocol for clinical neurophysiologic examination of the pelvic floor.

Clinical neurophysiologic examination of the pelvic floor is performed worldwide, but there is no consensus on the choice of tests, nor on technical details of individual methods. Standardized methods are, however, necessary to obtain their valid application in different laboratories for the purpose of collection of normative data, comparison of patient data and organization of multi-center studies. It is proposed that in patients with suspected "lower motor neuron" type lesions concentric needle electromyography (CNEMG) is the most informative test to detect pelvic floor denervation/reinnervation, and the external anal sphincter (EAS) muscle is the most appropriate muscle to be examined (either in isolation-when a selective lesion is suspected-or in addition to examination of other muscles). An algorithm consisting of standardized tests including a standardized approach to CNEMG examination of the EAS is presented. The proposed electrophysiologic assessment consists of a computer-assisted analysis of denervation and reinnervation features of the CNEMG signal, a qualitative assessment of reflex and voluntary activation of EAS motor units, and of electrical (or mechanical) elicitation of the bulbocavernosus reflex in those patients in whom manual anogenital stimulation failed to elicit a robust response in the EAS. The proposed protocol could serve as a basis for further studies on validity, sensitivity and specificity of electrophysiologic assessment in patients with different types of "lower motor neuron" involvement of pelvic floor muscles and sacral dysfunction.

Standardization of anal sphincter electromyography: utility of motor unit potential parameters.

Advanced electromyography systems offer quantitative analysis of a number of motor unit potential (MUP) parameters. However, only limited data are available on the diagnostic usefulness of these parameters. In the present study, we compared the sensitivities of MUP parameters in revealing "neuropathic" changes in the external anal sphincter (EAS) muscles in 56 patients examined 5-240 months after damage to the cauda equina or conus medullaris. Using multi-MUP analysis, 20 MUPs were obtained from patients' EAS muscles. Their MUP parameters were compared with normative data from 64 controls. The diagnostic sensitivities of mean values/"outliers" of MUP parameters for detecting neuropathic EAS muscles were calculated (area 25%/30%; number of turns 18%/29%; size index 13%/24%; thickness 18%/18%; amplitude 17%/17%; spike duration 20%/9%; duration 15%/12%; number of phases 15%/11%; and their combination 51%/52%). Altogether, the cumulative sensitivity of multi-MUP analysis using both mean values and "outliers" was 62%. The combination of MUP parameters improves the diagnostic yield of MUP analysis, but the influence on specificity remains unknown.

Reinnervation of anal sphincter muscle by low and high-threshold motor neurones.

The external anal sphincter (EAS) has continuously active low-threshold and recruitable high-threshold motor units (MUs), the latter being 'larger'. On performing concentric needle electromyography (EMG) of the EAS, the high-threshold MUs seemed to reveal more neuropathic changes than the low-threshold MUs. To verify this hypothesis, low- and high-threshold motor unit potentials (MUPs) were compared in patients with neuropathic EAS and controls. Fifteen subjects without pelvic disorders and 29 patients with sequela after cauda equina lesions were studied. In patients, only muscles ipsilateral to severe perianal sensory loss were included. MUPs were sampled using multi-MUP analysis during relaxation ('low-threshold'), and on activation ('high-threshold' MUs). MUP parameters of low- and high-threshold MUs from controls and patients were compared, as was the sensitivity and specificity with which MUPs were classified as normal or pathological (using discriminant analysis). MUP changes due to reinnervation, and the sensitivity and specificity in classifying MUPs as normal or pathological were not significantly different between the low- and high-threshold MUPs. Stronger activation of EAS does not improve discrimination between neuropathic and normal MUPs. New EMG techniques for sampling sphincter MUPs at higher activation levels would seem not to yield additional information.

Standardization of anal sphincter electromyography: normative data.

OBJECTIVES: Electromyography (EMG) of the external anal sphincter (EAS) is important in the evaluation of conus/cauda lesions, the differential diagnosis of parkinsonism and anal incontinence. The aim of our study was to establish normative data in a sufficiently large group of healthy subjects, using a rigorously standardized examination technique. METHODS: Sixty-four subjects (aged 19-83 years) without pelvic or neurological disorders were included. Motor unit potentials (MUPs)/interference pattern (IP) samples were obtained from the EAS using multi-MUP and turn/amplitude analyses, respectively. The effect of age, gender, parity, and constipation on MUP/IP parameters was studied. For MUP parameters the lower/upper limits for mean values, and 'outlier' limits, and for IP parameters normal 'clouds' were calculated. RESULTS: From 112 muscles 15-30 MUPs were sampled. As no effect of evaluated factors on mean values could be demonstrated, common reference values were calculated. Lower/higher limits for mean values were: amplitude 148/661 microV, duration 3.2/7.8 ms, area 87/625 microVms, and number of phases 2. 3/3.7. 'Outlier' limits for individual MUPs were: amplitude 84/1315 microV, duration 1.6/13.8 ms, area 46/1222 microVms, number of phases 2/6. From 95 muscles 2706 IP samples were obtained. CONCLUSIONS: The presented normative data should allow valid quantitative EMG of the EAS muscle in patients.

Standardization of anal sphincter electromyography: effect of chronic constipation.

Severe chronic constipation has been implicated as a cause of damage to the pelvic floor innervation. The aim of the present study was to examine the role of mild to moderate chronic constipation, a condition more relevant for clinical electromyographers, because this complaint is common in patients sent for evaluation of possible neurogenic dysfunction of lower sacral myotomes. A group of 59 subjects without major uroneurological dysfunction, proctological disorders, or neurological abnormalities participated in the study, which involved concentric needle electromyography of the external anal sphincter (EAS). Motor unit potentials (MUPs; sampled using multi-MUP analysis) and interference pattern (IP, sampled using turn/amplitude analysis) of chronically constipated and control subjects were compared. No effect of chronic constipation on MUP/IP parameters compatible with neurogenic injury was found. Our results suggest that mild chronic constipation does not cause damage to the EAS innervation, and that no separate reference values are needed for this group of subjects.

Anal sphincter electromyography after vaginal delivery: neuropathic insufficiency or normal wear and tear?

The study was performed to evaluate the potential role of vaginal delivery on innervation of the external anal sphincter (EAS) muscle. Forty-four women, 18 nulliparous and 26 of varying parity (1-4), without genitourinary prolapse, major urogynecological, anorectal, or neurological dysfunction were included. Participants' histories were evaluated by a questionnaire. Quantitative concentric needle electromyography (EMG) using multi-MUP analysis for sampling motor unit potentials (MUPs) in all volunteers, and "turn/amplitude" analysis for interference pattern (IP) analysis in 13 nulliparous and 23 parous women were applied. Pools of MUPs and IPs of parous and nulliparous women were formed and compared using the Mann-Whitney U test. Multiple linear regression analysis was used for evaluation of parity and obstetric variables. No difference between the groups was found in any MUP parameter, while a significant difference was found in two of five IP parameters. On multiple linear regression analysis, the number of deliveries was related to several MUP and IP parameters: the time elapsed since last delivery to MUP, and slight stress urinary incontinence to IP parameters. A group of parous women with (slight) stress incontinence had less "pathologic" MUP parameters, compared to those without. Vaginal delivery is indeed related to EAS muscle EMG abnormalities. However, these are minor and seem not to indicate loss of sphincter function. Our study casts some doubt on the commonly accepted preconception that significant damage to peripheral innervation of the EAS occurs even during uncomplicated deliveries.

Hyperreflexia in a patient with motor axonal Guillain-Barré syndrome.

We report a patient who presented after an episode of diarrhoea with ascending, symmetrical weakness without sensory loss, and without sphincter or other autonomic dysfunction. On clinical examination there were no cranial nerve deficits. Hyperreflexia of tendon jerks without other upper motor neurone signs was found. Electrophysiological examination demonstrated acute distal symmetrical motor axonal polyneuropathy. No electrophysiological signs of peripheral nerve demyelination or central nervous system involvement were found. Albuminocytologic dissociation was present in the cerebrospinal fluid. Stool culture and serological tests were inconclusive. Our patient's clinical picture was, apart from hyperreflexia of tendon jerks throughout the disease, characteristic of Guillain-Barré syndrome. This is the first such patient reported in Europe. The aetiology remained unclear. We suggest that selective axonal motor fibre affection, with possible mild pyramidal involvement, caused tendon jerk hyperreflexia.

Standardization of anal sphincter electromyography: uniformity of the muscle.

The different parts of the external anal sphincter (EAS) are usually regarded as one muscle with common EMG characteristics. This assumption was addressed by comparing the number of continuously firing motor units (MUs) during relaxation, as well as the parameters of motor unit potentials (MUPs) and interference pattern (IP) in the subcutaneous and the deeper parts of EAS. MUPs and IPs were analyzed in 44 subjects (2008 MUPs and 3014 IPs) without uroneurological or proctological disorders, and the number of continuously active MUs in 34 of these subjects was recorded (221 positions). No significant difference was found in IP and most MUP parameters between the two parts of the EAS muscle, but the number of continuously firing MUs was lower in the deeper part. As far as MUP and IP characteristics are concerned, the whole EAS can be considered as one muscle, but some differences in patterns of activation of MUs may exist in different regions.

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.

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.

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.