The buccinator muscle: an original morphogenetical study.

The buccinator muscle, a cutaneous muscle derived from the second arc, is innervated by the facial nerve. It is made of 3 bundles extended into the cheek, from the pterygo-mandibular ligament to the modiolus. It is used for diverse buccal functions. This study attempts to give a better insight of the embryogenesis and the development of the muscle. After taking samples by microdissection under binocular microscope, of this region of embryos and foeti, we performed histological sections. They were then coloured by Masson's trichome for their observation under photon microscopy. From seventieth week we observed the presence of a peri-mucous mesenchyma between the cartilaginous condensation of the "pre premier arc" and Meckel's cartilage. The buccinator presents an insertion on the modiolus, sliding under the latter it runs forwards, it is at the origin of the formation of the orbicularis internus of the lips (musculus orbicularis oris). This muscle displaces its posterior insertion downwards, with the development of the face in the child and the adolescent, notably with the modification in vertical dimension due to the arrival of the deciduous teeth before the permanent dentition. Furthermore it appears that buccinator does not play a role as a sphincter in the secretion of the parotid glands.

Heart rate variations in five-month-old children during interactions in a controlled environment.

UNLABELLED: This paper reports the first data of a study on heart rate variations of 13 5-mo-old infants seated in special chairs. Their electrocardiograms and behaviour were continuously recorded during sessions that were set up with their mother and a mother-child dyad that they met for the first time when the first session was organized. The protocol comprised two interaction phases between the infants and their mothers and two with one another. The same pairs of mother-child dyads were studied a second time 1 wk later. During the first session, the infants' heart rate variability increased significantly from the mother-infant interaction phases to the infant-infant interaction phases. During the second session, the variability was higher during the mother-infant phases than in the corresponding phases of the first session. This could be linked to changes in the mothers' behaviour and the infants' idea and excitement of meeting the child from the first session again. However, the variability was significantly lower during the infant-infant phases than during the mother-infant phases and the corresponding infant-infant phases of the first session. This corresponds to the development of affiliative behaviours in the infants. CONCLUSION: When two 5-mo-old infants were seated by their mothers in special chairs, significant differences were observed in their heart rate variability when they became familiar with each other, whether they were interacting with their mothers or with one another.

Study of central and peripheral conductions to the diaphragm in 22 patients with definite multiple sclerosis.

Involvement of the diaphragm was evaluated electrophysiologically in 22 patients with definite multiple sclerosis. Magnetic transcranial stimulation (MTS), magnetic cervical stimulation at C4 level (MCS) and electric stimulation of the phrenic nerve at the neck (EPS) were performed for measuring latencies, motor conduction times and amplitudes of the responses recorded with a pair of surface or subcutaneous electrodes located at the xiphoid and the 8th costal interspace on the anterior axillary line. Latency of the motor evoked potentials (MEPs) was abnormal: in 9 patients following MTS, in 6 following MCS, in 2 following EPS. The motor conduction time between the cortex and the cervical spine, we called CMCT1, was abnormal in 11 patients and the motor conduction time between the cortex and the neck, we called CMCT2, was abnormal in 8 patients. However CMCT1 was more often unmeasurable than CMCT2 because the MEPs following MCS were unreliable in 4 patients. The conduction time between the cervical spine and the neck was abnormally long in 2 patients but it was paradoxically abnormally short in 3, probably because of the difficulties in locating exactly the place of the stimulation at the cervical C4 level. The MEP amplitude was not considered a reliable parameter because of the large range of the values in our controls, although the mean amplitude was significantly lower in the patients than in the controls. The amplitude of the compound muscle action potential (CMAP) following EPS was below the lower limit of the normal in 9 patients. The percentage of abnormal MEP latencies and CMCTs when both sides were combined was higher for the hemidiaphragms than for the upper limbs and was roughly the same for the hemidiaphragms and the lower limbs. Moreover electrophysiological study of the diaphragm was abnormal in 5 patients without pulmonary symptoms and with normal pulmonary function tests, demonstrating that this study is useful for revealing infraclinical demyelinating lesions on the central motor pathways down to diaphragm. In addition, alterations of the CMAPs in some patients suggest a possible extension of the lesions towards the anterior horns and anterior roots.

Single fibre electromyography in multifocal motor neuropathy with persistent conduction blocks.

OBJECTIVE: To study the process of denervation-reinnervation in multifocal motor neuropathy with persistent conduction blocks in clinically affected and unaffected muscles. METHOD: Volitional single fibre electromyography (SFEMG) was performed in the extensor digitorum communis (EDC) of seven patients. The jitter, the fibre density, and the mean interpotential interval were determined. The results before and after treatment with intravenous immunoglobulin (IVIg) between the unaffected EDC and affected EDC examined during the same SFEMG session were also compared. In addition the values of jitter, fibre density, and mean interpotential interval were analysed for correlation with the strength score on the MRC scale, the duration of the neuropathy, the number of IVIg treatment periods, and the radial nerve conduction block values. RESULTS: Mean jitter, percentage of jitters >60 micros, and impulse blocking percentage, were higher than normal in both the affected EDCs and to a lesser degree in unaffected EDCs. Jitter decreased significantly after IVIg and correlated only with the MRC score. Fibre density and mean interpotential interval were higher than normal equally in the affected EDC and unaffected EDCs, but no correlation was found with strength, duration of the neuropathy, number of treatment periods, and conduction block values. CONCLUSION: The major finding is the presence of SFEMG abnormalities in clinically unaffected EDCs. This shows a process of denervation-reinnervation even in the absence of clinical symptoms, probably more frequent than commonly supposed in this neuropathy. The rapid clinical improvement after IVIg infusions could be due to remyelination after demyelination and to an interference of IVIg with the blocking effect of antibodies on the Na+ channels at the motor nerve endings.

[Electrophysiological development under thalamic stimulation of post-traumatic persistent vegetative states. Apropos of 25 cases]. / Evolution électrophysiologique sous stimulation thalamique des états végétatifs persistants post-traumatiques. A propos de 25 observations.

We have studied the electrophysiological evolution, with the aid of long-term, quantitative E.E.G. (Holter method) and sensory evoked potentials (visual, auditory and somatosensory) on 25 severe traumatic head injury patients (initial Glasgow scale--between 3 and 5) aged from 5 to 42 years having evolved towards a persistent vegetative state and being object of a protocol of thalamic stimulation. Electrophysiological exploration was practised before placement of the stimulation, then at 2 weeks, 1 month, 2 months and finally 3 months after. The electrophysiological parameters appear to have no predictive value on the clinical evolution after stimulation. However, changes such as long-term quantitative EEG as well as evoked potentials mostly precede clinical progress when present. Cortical evoked potentials are the first to change significantly (J15) followed by long-term quantitative EEG and brain stem evoked potentials (J30); the latter improving more completely. Also the consideration of the chronobiological aspects of the recordings of the long term EEG allow the proposal of "waking targeted" stimulations at the most favorable moments of the nyctohemeral period.

Diagnostic and prognostic value of electrophysiologic tests in meralgia paresthetica.

Electrophysiologic diagnosis of unilateral meralgia paresthetica is usually assessed by side-to-side comparison of SNAP amplitudes, SNCVs, and SEP latencies following stimulation of lateral femoral cutaneous nerves. To determine the relevance for diagnosis of these tests and side-to-side comparison, the results were compared in patients with unilateral meralgia paresthetica and normal subjects. The long-term outcome was also considered, in order to determine whether electrophysiologic findings contribute to the prognosis. In our study, SNAP amplitude comparison was found to be more useful for diagnosis than SNCV and SEP latency comparisons. However the value of the SNAP amplitude on the affected side, just as the results of the other tests, was not found to be predictive of the outcome. Also the results of the tests depend on the methods used and on the nerve's route.

Brainstem auditory evoked potentials in icteric fullterm newborns: alterations after exchange transfusion.

Brainstem auditory evoked potentials (BAEP) were studied in five fullterm newborns before and during an exchange transfusion (ET) for hyperbilirubinemia and 1, 24, 48 hours after, in order to evaluate the changes of BAEP following acute decreases in bilirubinemia. Hyperbilirubinemia was due to ABO incompatibility. The newborns were free of other risk factors known to alter BAEP. In comparison with our normal laboratory data, we observed significant differences in pre-ET recordings for latencies I and V (p less than 0.01), and for interpeak latency V-III (p less than 0.01). After ET, there was a tendency towards shortening of all mean latencies and interpeak latencies in correlation with the acute decrease in bilirubinemia, but post-ET BAEP alterations consisted predominantly of a wave V latency and of a wave V-I interval shortening (p less than 0.01). In four patients, during the 48 hours post-ET we observed modifications of the wave V-I interval related to variations of bilirubinemia. At 12 months, BAEP were normal. Even acceptable increase of bilirubinemia in otherwise normal newborns may have a deleterious influence on BAEP and this could have implications for the determination of a so-called threshold of bilirubin neurotoxicity. Our results suggest that bilirubin neurotoxicity is rapidly reversed by ET, but it seems important to verify BAEP in the follow-up of hyperbilirubinemic newborns.

Neurotoxicity of iohexol vs iopamidol in lumbar myelography. Clinical, electrophysiological and brain CT scan correlations.

The potential neurotoxicity of iohexol and iopamidol in lumbar myelography was investigated in 20 patients using three criteria: clinical symptoms, EEG recordings with spectral analysis and CT scans of the brain. There was no significant difference in clinical side-effects between the two groups (Iopaminol, Iohexol). In 10 patients (iopaminol 4, iohexol 6) CT scans revealed an important penetration of the contrast media into the subarachnoid spaces at 3 hours and into the cerebral cortex at 24 hours. This cerebral contamination was unrelated to the headaches experienced by the patients or to the electrophysiological disturbances observed. Spectral analysis in brain-contaminated subjects showed a reduction of delta, beta 1 and beta 2 bands with iohexol. This reduction suggests that EEG activation is less pronounced with this agent than with iopaminol.

[Visual evoked potentials in elderly subjects (author's transl)]. / Potentiels évoqués visuels chez les sujets agés.

Study of visual evoked potentials by contrast stimuli (VEPL) and by luminance stimuli (VEPC) in 28 subjects aged between 65 and 95 years (mean age: 81.8 years). Changes related to aging in regard to VEP involve: an increase of latencies of VEPL affecting the early components and an increase in the maximum amplitude of VEPL. The course of EP as age progresses introduces a difference in topographical organisation with a deterioration of responses in the left occipital regions and a change in potentials recorded at the vertex. Aging would appear to cause more marked inter-individual differences which could have clinical implications by making it possible to demonstrate individual differences in the biological processes of aging.

[Emotional and attentive interferences and slow cerebral potentials (CNV-P 300) (author's transl)]. / Interférences émotionnelle et attentive et potentiels lents cérébraux (V.C.N.-P 300).

A study was conducted to establish possible correlations between electrophysiological indices and performance under neutral situations and those involving completing a double task of increasing complexity, by studying CNV and P 300 in young healthy men. The results demonstrated that: 1. After habituation, the CNV amplitudes were not related to performance. A significant correlation was noted only during the most complex tasks. 2. The CNV appears to depend mainly on endogenous factors, that is to say the aptitude and readiness of an individual to treat the information, rather than on the performance resulting from this treatment. 3. The amplitude of the P 300 is related to performance, as a function of detection rate and the complexity of the tasks. The functional duality of the CNV and the differences between it and the P 300 have been emphasized. The indices obtained from slow potentials appear to be of value for an evaluation of behaviour. Rather than analyzing the characteristics of the potentials in a supposedly "neutral" situation it would appear preferable to establish, from the indices, profiles of individual reactivity and adaptation to different experimental situations.