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Biomedical subjects

Simon Podnar

Publications and source records attributed to Simon Podnar.

17 recordsLinked to original sources
PubMed2007

Epidemiology of cauda equina and conus medullaris lesions.

The epidemiology of cauda equina and conus medullaris lesions is not well known, and this study aimed to provide further information on this topic. In the period 1996-2004, patients fulfilling the clinical, electrodiagnostic, and radiological criteria for such lesions were identified. For cauda equina/conus medullaris lesions an annual incidence rate of 3.4/1.5 per million, and period prevalence of 8.9/4.5 per 100,000 population were calculated. The values obtained are probably valid estimates of the incidence and prevalence of these lesions in developed countries.

Adult↗
PubMed2006

Which patients need referral for anal sphincter electromyography?

Needle electromyography (EMG) of lower sacral myotomes is useful in certain patients with urinary, bowel, or sexual dysfunction. The aim of the study was to identify the clinical profile of patients who require such testing. Medical records were retrospectively reviewed, and findings evaluated using bivariate and multivariate statistics. A neuropathic condition affecting the lower sacral segments was diagnosed by quantitative concentric needle EMG of the external anal sphincter (EAS) muscle. Neuropathic changes in the EAS were found in 85 (44%) of 193 patients studied. On ordinal logistic regression analysis, bladder-emptying difficulties and perineal sensory loss were significantly related to the presence of a neuropathic EMG. No guidelines for referral for anal sphincter EMG could be defined that would include all patients with neuropathic abnormalities in the lower sacral segments. However, patients with bladder-emptying difficulties and perineal sensory loss seem to be the most suitable candidates for testing.

Adolescent↗
PubMed2006

Sensitivity of motor unit potential analysis in facioscapulohumeral muscular dystrophy.

Template-operated motor unit potential (MUP) analysis has made quantitative electromyography (EMG) feasible, even in busy laboratories, but validation of this approach is still necessary. In the present study, the utility of multi-MUP analysis was assessed in patients with a molecular genetic diagnosis of facioscapulohumeral muscular dystrophy (FSHD). Manual assessment of muscle strength and concentric-needle EMG of the biceps brachii and vastus lateralis muscles were performed. The sensitivity for diagnosing myopathy (mean values and outliers) was tested for eight MUP parameters and four of their combinations. The group comprised 31 patients. Elbow flexion and knee extension strength was normal in 45% and 52% of patients, respectively. The most sensitive MUP parameter was thickness, followed by duration. A combination of three MUP parameters (thickness, amplitude, and duration/area) was needed for maximal sensitivity. The study demonstrated a high sensitivity of multi-MUP analysis in FSHD. Myopathic abnormalities were demonstrated in all weak biceps brachii muscles, and in 77% of biceps brachii muscles with normal strength.

Action Potentials↗
PubMed2006

Bladder dysfunction in patients with cauda equina lesions.

AIMS: Data on lower urinary tract (LUT) function obtained in larger, systematically studied populations of patients with cauda equina lesions are limited. We report urinary function in 65 patients with chronic lesions. METHODS: A urinary function questionnaire was used, and neurological examination, quantitative electromyography (EMG) of the external anal sphincter (EAS) muscles, EMG assessment of the sacral reflex, and conventional urodynamic measurements were performed. RESULTS: Severe LUT dysfunction was found in 14%/15%, moderate in 27%/46%, and mild in 46%/39% men/women. Urinary symptoms interfered with daily life in 88%/92% and sexual life in 72%/67% of sexually active men/women. Symptoms of disturbed bladder emptying were the most common (95%/92% men/women), followed by urinary incontinence (56%/71%) and symptoms of overactive bladder (40%/56%). Perianal sensation was abnormal in 96%, EMG of the EAS muscle in 88%, and sacral reflex in 84% of patients. In 40%/17% men/women, a postvoid residual (>100 ml) was found. On filling cystometry overactive bladder was found in 21%/0%, reduced detrusor capacity in 9%/15%, and during voiding phase an acontractile detrusor or detrusor underactivity were found in 59%/85% men/women. Using multiple linear regression analysis, perianal sensory loss (P=0.0001) and female gender (P<0.02) had a significant positive effect on urinary incontinence score. CONCLUSIONS: Our study demonstrated significant LUT dysfunction, which disturbed the life of the majority of patients with chronic lesions of the cauda equina. Due to poor correlation between patients' symptoms and urodynamic findings cystometric surveillance is proposed in all patients with significant cauda equina lesions.

Adult↗
PubMed2006

Non-neurogenic urinary retention (Fowler's syndrome) in two sisters.

AIMS: To report for the first time occurrence of obstructed voiding due to excessive activity of the urethral sphincter (US) muscle in two sisters with polycystic ovaries (Fowler's syndrome). METHODS: In both patients precise micturition history was obtained. In addition, clinical neurological and gynecological examinations, cystometry, urethral pressure profile measurements, gynecological ultrasound, measurement of gonadotropic hormone levels, and concentric needle electromyography (EMG) of the US muscle were performed. RESULTS: Both sisters reported symptoms of severely obstructed voiding. Clinical examination, and filling cystometries were normal. Urethral pressures were increased (99-134 cm water). The first sister was not able to void, and the urinary flow was slow and intermittent in the second on voiding studies. Profuse complex repetitive discharges and decelerating burst activity were found on concentric needle EMG of the US in both of them. Both sisters had increased LH/FSH ratio (2.96 and 2.64), and ultrasonographic abnormalities compatible with polycystic ovaries. CONCLUSIONS: Diagnosis of Fowler's syndrome was made in both sisters. Due to very low incidence rate of this syndrome (0.2/100.000 per year), we think that it is highly unlikely to find it in two sisters just by chance. We suggest that the probable explanation is a genetic predisposition to polycystic ovaries, with which this condition has been shown to be associated.

Adult↗
PubMed2005

Comparison of different outlier criteria in quantitative anal sphincter electromyography.

OBJECTIVE: Analysis based on 'outliers' has been demonstrated to be a useful adjunct to mean value analysis in quantitative needle electromyography (EMG). However, the outlier criteria applied have been arbitrarily chosen. The aim of the present study was to determine the most useful outlier criteria in motor unit potential (MUP) analysis. METHODS: The external anal sphincter (EAS) muscles were examined by multi-MUP analysis. From 115 muscles of 64 normative subjects, the 0/100, 5/95, 10/90, 15/85, 20/80, and 25/75 percentile MUP parameter values were grouped individually. From these, the 5/95, 2.5/97.5, 1/99 and 0/100% confidence limits were determined. Thus, 24 sets of outlier limits were formed. To calculate sensitivity and specificity, data from 79 patients with cauda equina lesions (189 muscles), and from 77 controls (119 muscles) were compared to normative outlier limits. RESULTS: Sensitivities were highest with outlier limits formed from the 10-90 percentile ranges, followed by the 5-95 and 15-85 percentile ranges, while specificity was highest using the 15-85, followed by the 20-80, and 25-75 percentile ranges. On direct head-to-head comparison the 10-90 percentile ranges were more sensitive and 5-95 were more specific. CONCLUSIONS: The study demonstrated considerable differences in the sensitivity and specificity of outlier limits calculated from different percentile ranges, with outlier criteria calculated from the 10-90 and from the 5-95 percentile ranges appearing to be the most useful for detection of neuropathy in the EAS muscle. SIGNIFICANCE: In future EAS muscle EMG I propose that outlier criteria calculated from the 10-90 percentile ranges be used.

Adolescent↗
PubMed2004

Evaluation of the complexity of motor unit potentials in anal sphincter electromyography.

OBJECTIVE: Motor unit potential (MUP) morphology can be quantified using parameters describing electrophysiological size and shape (complexity). Traditionally, MUP complexity has been estimated using parameters number of phases and turns. Recently, 'irregularity coefficient' (IR), measuring the length of the MUP curve normalized with its amplitude, has been introduced. The aim of this study was to evaluate IR in the external anal sphincter muscle. METHODS: Sensitivity was examined in 61 patients with chronic cauda equina lesions, and specificity in 75 controls using a standard concentric EMG needle and EMG system with multi-MUP analysis. RESULTS: When evaluated separately the sensitivity of IR was 16% lower, and specificity 5% higher compared to number of turns, with both differences decreasing to only 2 and 1%, respectively, when each of these parameters was added to MUP area and duration. CONCLUSIONS: Our present results suggest that IR provides a similar diagnostic usefulness, but a more appropriate description of MUP complexity compared to traditional MUP parameters. SIGNIFICANCE: IR seems to be suitable to complement one of MUP parameters measuring electrophysiological MUP size in the future quantitative EMG.

Action Potentials↗
PubMed2004

Sphincter electromyography in diagnosis of multiple system atrophy: technical issues.

Possible technical reasons for the controversy over the role of sphincter electromyography (EMG) in the diagnosis of multiple system atrophy (MSA) were analyzed. In a review of the literature, a high sensitivity (>60%) was found reported in 11 studies that included late components, and no value of the test was found in 4 studies that excluded them. This was also corroborated in a pilot study of 5 patients with probable MSA. With late components included, the mean motor unit potential (MUP) duration was prolonged in all 4 patients with an adequate single-MUP analysis sample and, with late components excluded, in 2 of 5 patients on multi-MUP analysis. At least in diagnostic EMG of MSA patients, late components should be included in the measurement of MUP duration.

Action Potentials↗
PubMed2004

Criteria for neuropathic abnormality in quantitative anal sphincter electromyography.

For the external anal sphincter muscle, both normative values and an optimal set of motor unit potential (MUP) parameters have been defined. However, criteria for the diagnosis of neuropathic conditions have not yet been validated. Therefore, in this study, sensitivity was examined in 86 patients with cauda equina lesions (227 muscles), and specificity in 77 controls (119 muscles), using multi-MUP analysis. Six previously defined diagnostic criteria (mean values and outliers for MUP area, duration, and number of turns) were used. An increase in the number of diagnostic criteria required for muscle abnormality (two and three instead of one), and the application of more stringent normative limits resulted in a progressive increase in specificity from 74% to 99% (controls), and a decrease in sensitivity from 70% to 21% (patients). The data suggest that no single cut-off diagnostic criterion has both satisfactory sensitivity and specificity. Introduction of the diagnostic categories of "possible," "probable," and "definite" neuropathic abnormalities into quantitative electromyographic analysis is proposed.

Adult↗
PubMed2004

Usefulness of an increase in size of motor unit potential sample.

OBJECTIVE: It is known that the sensitivity of quantitative electromyographic (EMG) analysis of motor unit potentials (MUPs) improves with an increase in MUP sample size to more than 20. However, no normative data and estimate of sensitivity have been published. METHODS: In the present study sample sizes of 5, 10, 15, 20, 30 and 40 MUPs were obtained from the external anal sphincter (EAS) muscles of 81 controls and 70 patients with cauda equina lesions. For each sample size normative limits and sensitivities for mean values and 'outliers' were calculated for 8 MUP parameters. RESULTS: As the size of the MUP samples increased, normative limits narrowed and sensitivities increased for both statistics of all MUP parameters (sensitivities were 26% at 10, 44% at 20, and 67% at 40 MUPs with mean values and outliers of MUP area, duration and number of turns). CONCLUSIONS: Our results confirmed a substantial increase in the sensitivity of MUP analysis by enlargement of the MUP sample size to more than 20 MUPs. The gain in sensitivity seem to be greater than the increase obtained by examination of contralateral EAS muscle. SIGNIFICANCE: Findings might be useful to clinical neurophysiologists planning strategies for electrodiagnostic evaluation of lower sacral segments.

Anal Canal↗
PubMed2004

Bilateral vs. unilateral electromyographic examination of the external anal sphincter muscle.

AIM OF THE STUDY: In patients with cauda equina or conus medullaris lesions, bilateral electromyographic (EMG) examination of the subcutaneous external anal sphincter (EAS) muscles has been suggested. In spite of its circular shape, EAS should be considered as two separate semicircular muscles. The aim of the present study was to test the hypothesis that information obtained by bilateral examination of the EAS muscle outweighs inconvenience due to additional needle insertions. PATIENTS AND METHODS: A group of 67 patients with clinical and radiological data supportive of cauda equina or conus medullaris lesion was studied. From the subcutaneous EAS muscles motor unit potentials (MUPs) were sampled by the standard concentric EMG needle electrode, and an advanced EMG system with template operated multi-MUP analysis. Severity of EMG abnormalities was determined, and compared in 48 pairs of the left/right subcutaneous EAS muscles. RESULTS: In 18 patients, bilateral EMG abnormalities were found, in five of them asymmetry of involvement was demonstrated. Unilateral MUP abnormalities were found in 22 patients. The sensitivity of unilateral EMG analysis was 57% and of bilateral examination, 83%. CONCLUSION: In patients with suspected cauda equina lesions, as a rule, bilateral EMG of the subcutaneous EAS muscle is recommended.

Adult↗
PubMed2003

Size of motor unit potential sample.

In quantitative electromyography (EMG), a sample size of 20 motor unit potentials (MUPs) is standard. The effect of increase in the number of MUPs above 20 is not known, although advanced MUP analysis techniques make such samples practical. In the present study, using multi-MUP analysis, pools of 3,720 neuropathic and 2,526 control MUPs were obtained from external anal sphincter muscles. From each pool, 10,000 random samples of 5, 10, 15, 20, 30, 40, 50, and 100 MUPs were obtained by a computer. For each sample size, 95% normative limits for mean values, SDs, and "outliers," and sensitivities were calculated for eight MUP parameters. As the magnitude of MUP samples increased, normative limits narrowed and sensitivities increased (at 5: 20-30%; at 20: 30-55%; at 100: 80-100%) for all statistics of all MUP parameters. Our results demonstrated a substantial increase in sensitivity by increasing the MUP sample to more than 20. This option deserves consideration in an attempt to improve the usefulness of quantitative EMG.

Anal Canal↗
PubMed2003

Electromyography of the anal sphincter: which muscle to examine?

Electromyographic examination of the deeper external anal sphincter (EAS) muscle is far more uncomfortable than of the subcutaneous muscle, so we tested the need for its examination. We compared the findings in 85 paired examinations of ipsilateral subcutaneous and deeper EAS muscles in 67 patients with a cauda equina lesion. When the other muscle was normal, the deeper or subcutaneous muscle was pathological in 18% or 13% of pairs, respectively. In addition, the subcutaneous EAS muscle was usually more severely affected than the deeper EAS muscle. Thus, examination of the deeper EAS muscle did not increase the sensitivity of MUP analysis significantly, and did not seem clinically necessary.

Adult↗
PubMed2002

Comparison of quantitative techniques in anal sphincter electromyography.

Data comparing results and utility of different quantitative electromyographic (EMG) techniques are limited. In the present study, we analyzed the EMG signal from the external anal sphincter (EAS) muscle using three techniques of motor unit potential (MUP) analysis, and a technique of interference pattern (IP) analysis. We examined 56 patients with damage to the cauda equina or conus medullaris, and 64 control subjects. Using manual-MUP and multi-MUP analysis about 20 MUPs, using a single-MUP technique about 10 MUPs, and using turn/amplitude (T/A) analysis about 20 IP samples were obtained. The sensitivities of these techniques in distinguishing neuropathic from control muscles were calculated. The single-MUP technique detected 63%, manual-MUP 57%, and multi-MUP analysis 62% of neuropathic muscles, and MUP parameters obtained by each of these differed significantly from the other. The sensitivity of T/A analysis of IP was 29%. Our results confirm the need for separate MUP normative data for each of the MUP analysis techniques, and favor them over the IP analysis technique. The normative data presented for the EAS muscle should improve and promote quantitative EMG in patients.

Adult↗
PubMed2002

Predictive power of motor unit potential parameters in anal sphincter electromyography.

The diagnostic utility of motor unit potential (MUP) parameters is usually based exclusively on their diagnostic sensitivity, disregarding specificity. In the present study, advanced statistical methods were used to determine MUP parameters with the highest predictive power for the separation of neuropathic and normal external anal sphincter (EAS) muscles. Using multi-MUP analysis, 3,720 MUPs from 138 muscles of 52 patients with cauda equina lesion and 2,526 from 112 muscles of 64 controls were obtained. Only two principal components (PCs), which put weight on the MUP area and amplitude, were needed to explain all the data variability. On logistic and probit regression analyses, MUP area, duration, and number of turns gave results identical to all MUP parameters. Our results suggest that only these three MUP parameters are needed, and that they are as effective as PCs, in MUP analysis of chronic neuropathic EAS muscles. Reduced number of MUP parameters is expected to simplify MUP analysis and increase its specificity.

Anal Canal↗
PubMed2002

Standardization of anal sphincter electromyography: quantification of continuous activity during relaxation.

AIM: Sphincter motor units (MUs) are continuously firing during relaxation. The quantification of this activity is a potentially useful electromyographic (EMG) parameter related to the number of MUs innervating the muscle and the level of motor neuron excitation. The aim of the present study was to develop a reliable, quantitative measure of continuous sphincter muscle activity during relaxation. METHODS: EMG activity was analyzed during relaxation, 1 minute after insertion of the concentric needle electrode into four sites in the external anal sphincter (EAS) muscle. In 10 control subjects, 8 interference pattern samples were obtained by "turn/amplitude" analysis. In 35 control subjects, a multi-MUP count of continuously firing motor unit potentials (MUPs) was used, quadruplets with scores of 0-6 obtained, and the lower reference limits (95th percentile) calculated. This approach was then evaluated in 57 patients (182 muscles) with cauda equina or conus medullaris lesion (CECML) and 7 patients (13 muscles) with "idiopathic fecal incontinence." RESULTS: The lower reference ("outlier") limits for MUP count were 0 0 6 6 and 0 1 2 2 for the subcutaneous, and 0 0 0 6 and 0 0 1 1 for the deeper EAS muscles. Both patient groups had a significantly diminished number of continuously firing MUPs, which was below the reference range in 43% of the EAS muscles from CECM patients and in 85% of muscles from patients with idiopathic fecal incontinence. In patients with CECML, the decrease in MUP count correlated with the severity of the lesion, as defined by the sensory deficit. CONCLUSIONS: MUP count in sphincter muscles during relaxation is technically feasible, and it is a promising tool, particularly in patients with idiopathic fecal incontinence.

Adult↗