Comparaison entre la latence distale motrice du nerf pudendal, la topographie de la douleur périnéale et le résultat d'infiltrations. Analyse pour 53 patients

AIM

The aim is to study the value of the pudendal nerve terminal motor latency (PNTML) testing, in respect to the painful side in patients with pudenda neuralgia, and to determine whether a possible increased latency in the painful side is predictive of a good result with the infiltration.

METHOD

This retrospective study included 53 outpatients (42 women, mean age 62) with suffering from pudendal neuralgia, who were seen between 2000 and 2004. The mean duration of the pain was 30+/-47 months. The PNTMPNL was measured by the Saint-Mark hospital technique, by the same operator. The following criteria have been were defined: significant increased latency greater than above 6 ms, significant difference of 2 ms in latency between 2 sides from 2 ms, and side of the infiltration corresponding to the side of the neuralgia. The infiltrations were performed either by perineal (30 cases) or transgluteal (8 cases) way. The results on pain were have been considered as good when a substantial reduction of the pain was observed for 6 months or more. Statistical analysis involved was done by the exact Fischer's test to seek for a possible relation between variables.

RESULTS

Of 53 patients (42 women, 11 men, mean age 62) suffered from a with perineal neuralgia. The duration of the neuralgia was 30+/-47 months. It was bilateral in 10 cases and unilateral in 43 cases. In 43 patients with When the pain was unilateral pain, PNTML we find that the MDLPN was increased in both sides in 39.5% of the population, in the painful side in 14% and in the side opposite side of the to pain in 11%. In 10 patients with the neuralgia was bilateral pain, in 10 patients. Among then, 4 had a bilateral increase of the latency, one patient had an increase only on the right side, and another one an increase only on the left side. We did not find any correlation between the increased of the PNTML TMPNL and, either neither the duration of the neuralgia nor the result of the infiltrations, whatever the method way of the infiltration.

CONCLUSION

The PNTML can be increased whether it corresponds or not to an entrapment of the pudendal nerve. Thus, the management of perineal pain is based mainly, from us, on clinical findings.

Magnetoencephalography in stroke: a 1-year follow-up study

Recovery after stroke is closely linked to cerebral plasticity. Magnetoencephalography (MEG) is a non-invasive technique, which allows location of cerebral cells activities. In the present work, a cohort of patients has been studied with MEG. Twelve patients with a recent ischemic or hemorragic stroke were included as soon as possible after onset of stroke. Neurologic assessment, including standard neurologic examination, functional independence measure (FIM) and Orgogozo's scale was performed for 1 year in addition to a study of the somatosensory evoked field (SEF) using a 37-channel Biomagnetometer system. No response could be recorded in five patients at the first SEF exploration. In three cases, no response was ever recorded during the study. All these patients had a bad recovery. The location of the SEF sources was always in the normal non-infarcted cortex of the postcentral gyrus. Sensory recovery seemed to be linked to the reorganization of the persistent functional cortex, which was a limiting factor for recovery. These observations confirm the experimental results obtained in animal models. After stroke it can be assumed that in the case of incomplete lesion, an intensive sensory peripheral stimulation could maximize the use of residual sensory function and then contribute to improve the sensory deficit. In case of total sensory loss other techniques have to be used, such as visual monitoring of hand activity in order to improve hand function.

Non-supervised spatio-temporal analysis of interictal magnetic spikes: comparison with intracerebral recordings

OBJECTIVE

Our main goal was to evaluate the accuracy of an original non-supervised spatio-temporal magnetoencephalography (MEG) localization method used to characterize interictal spikes generators.

METHODS

MEG and stereotactic intracerebral recordings (stereo-electro-encephalographic exploration, SEEG) data were analyzed independently in 4 patients. MEG localizations were performed with and without anatomical constraints.

RESULTS

We analyzed 1326 interictal spikes recorded using MEG. For each patient, 2-3 typical source patterns were described. These source configurations were compared with SEEG. SEEG findings and MEG spatio-temporal localization results were remarkably coherent in our 4 patients. Most of the MEG patterns were similar to interictal SEEG patterns from a spatio-temporal point of view.

CONCLUSIONS

We were able to evaluate the usefulness of our non-invasive localization method. This approach described correctly the part of the epileptogenic network involved in the generation of interictal events. Our results demonstrate the potential of MEG in the non-invasive spatio-temporal characterization of generators of interictal spikes.

[Magnetocardiography: principles and potential uses in cardiology]

Magnetocardiography (MCG) is a non-invasive technique of studying cardiac electrophysiology activity. It appears that electric and magnetic measurements are not only complementary but provide independent information. Described over 25 years ago, recent technical progress in the field of supraconductivity has provided MCG with real clinical applications. It is still mostly used in research, but its clinical applications are beginning to develop. The most interesting clinical application of the MCG is certainly its capacity to provide a non-invasive anatomical localisation of the arrhythmogenic substrate or of accessory pathways. Nowadays, however, the accuracy of these localisations needs to be improved. When this has been accomplished, MCG could play a significant role in non-invasive cardiological investigation with well-defined clinical applications.

Model-based diagnosis of brain disorders: a prototype framework

This paper describes a prototype framework, named NEUROLAB, dedicated to research and diagnosis in the area of brain disorders. The diagnostic task uses a blending of factual knowledge, formal knowledge, and experiential knowledge. The prototype's first target clinical application is partial seizures in epilepsy. Diagnosis is carried out using qualitative electroencephalographic descriptions, clinical attack pattern descriptions, and pre- and post-ictal observations. From this information, the system builds explanations in the form of candidate epileptogenic foci and trajectories of the seizure spread. Hypothesis-testing and discrimination is based on minimal set coverage, and consistency-checking is performed using the general background knowledge. Upon completion, NEUROLAB will provide specific physiological knowledge for solving the so-called inverse problems in electroencephalography (EEG) and magnetoencephalography (MEG).

[Delay in the effect of antidepressive agents: pharmacologic approach]

A paradox which is not resolved in the use of antidepressants (ATD) is that in pharmacological studies of animal models of depression and in neurochemical studies, the onset of activity of all drugs is extremely rapid, whereas in human clinical practice the onset is delayed (15 days). An attempt is made to explain this in 3 ways, involving the synapse, transduction mechanisms, and cognition. Analysis of the impact of all ATDs shows that we are confronted with slow adaptive processes which are correlated with the delay observed in clinical practice. The interest of such considerations is that they may give rise to alternative therapies which are able not only to accelerate response, but also to increase it.

Surface electromyogram automatic analysis and Guillain-Barré syndrome follow up

An automatic and quantitative framework for the analysis of surface EMG interference patterns at maximal non-controlled force is described. The main contents are focused on different ways to represent surface EMG signals and to analyse collected data set through principal component analysis. The methods are tested on control individuals and on patients with Guillain-Barré Syndrome examined at different moments after the beginning of the disease (first week, three months, and one year). The results exhibit that a high diagnostic yield can be provided and furthermore that quantification and differentiation can be expected. Surface EMG interference pattern may be hoped to be a useful tool in daily practice.

Muscle fatigue unrelated to phosphocreatine and pH: an "in vivo" 31-P NMR spectroscopy study

Metabolic events were followed by 31-P NMR spectroscopy during mechanical exhaustion of directly stimulated rat gastrocnemius. During mechanical fatigue, phosphocreatine (PCr) and pH first declined but although stimulation continued high values were recovered without mechanical recovery. Total recovery was only observed after cessation of stimulation. Partial mechanical recovery was elicited by lowering stimulation rhythm; it was accompanied by decrease in PCr to a steady-state level without pH alteration. When exhaustive exercise was induced immediately after nonexhaustive exercise, failure of mechanical function occurred without decrease in pH. Major findings were: first, during exhaustive stimulations, the greater the muscle fatigue, and the higher the PCr level at the end of stimulation. Secondly, PCr and force levels did not depend on preceding levels of PCr and pH. Thirdly, acidosis was observed transiently during the first minutes of the first exercise period. These findings strongly suggested that electrical events and/or excitation-contraction (EC) coupling play a crucial role in this type of fatigue.

Phosphocreatine and pH recovery without restoration of mechanical function during prolonged activity of rat gastrocnemius muscle: an in vivo 31P NMR study

Metabolic impairment in skeletal muscle was suggested to be involved in the development of local mechanical fatigue but until now results have dealt with short activity periods whereas little data on exhaustive and prolonged exercises are available. Stimulations of rat leg muscle lasting 45 min were induced by tetanic trains delivered via sciatic nerve at five different rhythms. Energy metabolism of the stimulated gastrocnemius muscle was followed by 31P NMR spectroscopy using surface coil while mechanical function was recorded. Our data showed a decrease in the force level to very low values a few minutes after exercise onset. This mechanical impairment only induced a transient metabolic failure followed by rapid restoration of high phosphocreatine (PCr) values and intracellular pH, without mechanical recovery. In addition, at the end of exercise, the PCr content was proportional to the fatigue level. As these experiments could not have impaired neuromuscular junction, the data would indicate that fatigue was maintained by a mechanism which does not appear to depend directly on muscle cell energy stores.

Water phases in rat striated muscles as determined by T2 proton NMR relaxation times

The spin echo decay curve of NMR protons in in-vitro rat muscle is two or three exponential as Hazlewood demonstrated in 1974. This author hypothesized that the longer T2 component is extracellular water and that the medium T2 is intracellular water. Our purpose was to test the histological significance of these two T2. Variations of water contents in two types of rat muscles were induced by electrical stimulation and osmotic diuresis and their incidence on the decomposition of the proton spin echo signal analysed. Decomposition of signal in resting muscles revealed two phases with T2 values similar to the Hazlewood's: a short phase, S, with T2 of 40 ms (20 MHz, 276 degrees K) representing 90-97% of the total signal and a long one, L, with T2 of 100-120 ms representing 3-10% of the signal. Increasing vascular volume appeared to increase the percentage of phase (L) in the total signal. Osmotic diuresis decreased the volume of the phase (S) and increased the volume of the phase (L). The use of Gd-DTPA allowed to differentiate the vascular compartment: Gd DTPA decreased in a great extent the T2 values of phase (L) and in low extent the T2 values of phases (S). From these results, it appears that phase (L) could correspond to vascular volume and that phase (S) would be interstitial and intracellular water. Elements of comparison with classical methods for determination of water compartmentation in tissues are given.

An attempt to differentiate female relatives of Duchenne type dystrophy from healthy subjects using an automatic EMG analysis

A new automatic EMG analysis and on-line assignment of MUAP into 8 dynamic cluster algorithm classes (P1......P8) were applied to female relatives of patients with Duchenne type dystrophy. Promising results are given. MUAP amplitude and duration differed significantly in the female relatives compared to the control subjects. MUAP distribution patterns found in the carrier population were significantly different from those found in controls; the carrier population exhibited higher percentages of MUAP (than healthy subjects) in the classes where were assigned the great majority of the potentials obtained from patients with Duchenne type dystrophy. All the known carriers and 55.5% of the possible carriers were detected using these methods. Nevertheless, the absolute accuracy of the results cannot yet be considered achieved because no recognizable distribution pattern was observed in carrier's daughters. No correlation was found between CK levels and EMG distribution.

[Automated analysis of motor unit potentials of a normal population]

The real-time and automatic system that we have developed, providing EMG signal acquisition, processing and storage, helps in decision making. This implies the formation of a reference signal set and the accurate determining of the influence of various parameters. Using data analysis methods, our normal population analysis investigates the effects of age, sex and muscle. Assignment tests have been carried out with learning classes (formed with signals obtained from healthy and myopathic subjects) to measure the variability of a possible aid-to-diagnosis procedure.

Automatic classification of electromyographic signals

The results of the application of classification methods to electromyograph signals of weak contractions in normal and myopathic subjects are described. Methods of pattern recognition, previously presented, allow the selection of representative motor unit action potentials. The analysis is done with ordinal qualitative variables obtained by identification of shape descriptive parameters (amplitude, duration, number of phases, number of extrema). From this analysis, characteristic classes for normality and myopathy appear, from which a diagnostic aid by assignment can be made.

Facilitation of monosynaptic reflexes by voluntary contraction of muscle in remote parts of the body. Mechanisms involved in the Jendrassik Manoeuvre

The facilitation of the tendon reflex of quadriceps, induced by voluntary contraction of a muscle group in the upper limb, evolves in the three phases and depends on several factos. These include the strength and type (ballistic or ramp) of the contraction. In the absence of any electromyographic activity in the conditioning muscle (from a lesion of its nerve trunk or by blockage of conduction by injection of xylocaine), a voluntary attempt to contract it causes only a moderate facilitation of the quadriceps motor nucleus; while reflex activation of the conditioning muscles, by vibration or sudden stretching. causes a more marked facilitation. Thus, it is concluded that at least two distinct mechanisms act sequentially. First, a general motor facilitation of supraspinal origin induces the first moderate phase of facilitations (phase I). This early facilitation precedes the onset of electromyographic activity in the conditioning muscle. Secondly, the more marked facilitation (phase II) is related to the stimulation of afferents originating from the conditioning muscles, either by fusimotor excitation in voluntary contraction or by manoeuvres which stimulate the spindle receptors mechanically. To investigate the transmission pathways of these facilitations, the latencies of these two phases were compared at two distant motor nuclei, the trigeminal motor nucleus and the quadriceps nucleus, following voluntary contractions of the tibialis anterior. Since the facilitations of the trigeminal motor nucleus precede those of the quadriceps motor nucleus, a slowly-travelling rostro-caudal facilitation is postulated during phase II when the facilitation is related to afferents coming from the contracting muscle. A long loop, therefore, is postulated to interpret the second phase of the facilitation curves.

Hypothetical role of long-loop reflex pathways

It is nowadays well known that there are reflex loops starting in the spinal cord, relaying in various supraspinal structures and descending back to the cord. These long-loops regulate motor responses and work in cooperation with segmental mono- and polysynaptic reflexes. The role of certain well-documented long-loop reflexes is reviewed. The existence of additional long-loop reflexes is hypothesized and preliminary results supporting this view are presented. In discussing the mode of action of spinal cord stimulation, the various ascending and descending pathways involved in long-loop regulation of motricity are to be taken into account.

Jendrassik maneuver vs controlled contractions conditioning the excitability of soleus monosynaptic reflexes

To analyze the factors that influence the conditioning of monosynaptic reflexes by the Jendrassik maneuver, the latter was replaced by a rapid, isolated, reproducible contraction of the wrist extensors; this procedure facilitated reflexes as effectively as the classical Jendrassik maneuver. The results were expressed quantitatively in relation to maximal motor response to allow comparisons to be made when different test reflexes were used. Identical selective contractions produced results that were reproducible in the same subject from one experiment to another. The facilitation depends on the time interval between the onset of the signal to contract and elicitation of the reflex. It develops in 3 distinct phases: the 1st, of moderate intensity, begins before electromyographic activity in the conditioning muscle; the 2nd, of much greater intensity, comes after the beginning of electromyographic activity, rapidly attains a maximum and then decreases progressively; the 3rd phase, of medium intensity, is stable until the end of the contraction. Facilitation also depends on the amplitude of the conditioned reflex and is most marked for one-half the maximum amplitude value and maximum tendon reflexes. The H-reflex is facilitated to the same extent as a tendon reflex of the same amplitude, but only during the 2nd phase. During the 3rd phase, facilitation of the H-reflex is no longer significant, but that of the tendon reflex is. Facilitation of alpha motoneurones may be assumed to explain the increases in amplitude during the 2nd phase but this mechanism alone cannot account for all the phenomena observed.

Reflex facilitation by remote contraction: topographic aspects

This study compares the facilitation of various lower limb reflex arcs brought about by a selective contraction of a well-defined upper limb muscle group in able-bodied healthy subjects. Quantitatively (results expressed as a percentage of maximal motor response), the quadriceps tendon reflex is facilitated more than the soleus and biceps femoris tendon reflexes. The time course of facilitation is similar for the 3 reflexes and exhibits 3 distinct phases. Electrically induced reflexes in the quadriceps are facilitated as much as the tendon jerk but only during the 2nd phase. Complementarily, the effects of contraction of different upper limb muscle groups on a single lower limb reflex (quadriceps tendon jerk) were also investigated. This reflex is facilitated more (especially in the 2nd phase) by contraction of thenar muscle than by that of deltoid muscles and more by wrist extensors than wrist flexors. Differences in facilitation are only apparent when the effects are quantified. They depend on the segmental level of the reflex under test (more marked proximally than distally) and on the conditioning muscle group; both facts must be taken into consideration in the interpretation of the functional role of remote contraction.