Biomedical subjects
Publications and source records attributed to P Guiheneuc.
Needle electromyography, nerve conduction velocity measurement and recording of T, H or F waves, are the most commonly used methods to investigate patients with polyneuropathies. The grade, distribution, and functional type of the lesions are to be determined. A classification is proposed according to acute or chronic character of the neuropathy course and to prevailing signs of demyelination or axonal degeneration.
(1) The sympathetic skin response (SSR) is a slow wave, generated in deep layers of the skin, resulting from reflex activation of the sudomotor sympathetic efferent fibres. The aim of this study was to define experimental conditions, best stimulation and recording procedures, and the criteria for validation of the responses. (2) Thirty normal subjects (aged 25-56) were tested. The stimulation was an electrical pulse train applied to the median nerve at the wrist, a binaural tone burst, or both simultaneously. Records were made with surface electrodes on hand and foot contralateral to the stimulated median nerve. (3) Response shape was most often biphasic in feet, biphasic or triphasic in hands. SSR amplitude was 3.1 +/- 1.8 mV in hands, 1.4 +/- 0.8 mV in feet. Normal mean onset latency was 1.5 +/- 0.08 sec for hand response, 2.05 +/- 0.10 sec for foot response. The mean conduction velocity along peripheral sympathetic nerve fibres was 1.40 +/- 0.14 m/sec in lower limbs. (4) Bimodal stimulation (burst + median) provided responses of larger amplitude. The influence of stimulation intensity was also investigated. A decrease in amplitude and lengthening of latencies were observed after 15-20 min of testing. (5) The criteria for validation of responses are discussed. The importance of central processing time in the response delay is pointed out. In good methodological conditions, SSR would appear to be a simple, effective means of assessing sympathetic sudomotor outflow in central and peripheral nervous system disorders.
The authors report a case of post traumatic tetraplegia at the C1-C2 level in a young man of 16 with total respiratory paralysis treated with mechanical ventilation and a tracheotomy. Thirty months after the accident, an Avery S 232(1) diaphragmatic pacemaker was surgically implanted by the mediastinal approach. The technique was rapidly successful and enabled satisfactory ventilation and phonation two months after the implantation. The patient is currently treated at home with no signs of diaphragmatic fatigue 20 months after the implantation of the stimulator.
In humans except for the postoperative state, electromyographic activity of the small bowel can only be recorded with intraluminal electrodes. The aim of this study was to validate the use of intraluminal electrodes in pigs by comparing the signal recorded from such electrodes to those recorded with surgically implanted electrodes. A polyethylene probe equipped with bipolar ring-shaped electrodes was placed in the lumen of the proximal jejunum of 6 pigs, at the same level as intramuscular implanted electrodes. The signals were recorded in conscious pigs fed normally. By comparison to the myoelectric activity recorded from the intramuscular implanted electrodes, the intraluminal electrodes provided reliable spike burst detection (sensitivity 85 p. 100; positive predictive value 91 p. 100) in the fasted and fed state, and good identification of migrating myoelectric complexes. Spectral analysis showed the same frequency patterns for signals obtained with both types of electrodes. In conclusion, intraluminal ring-shaped electrodes allow reliable detection of small bowel myoelectric activity and may represent a useful tool for motility studies in man.
Workers using vibrating tools are exposed to vascular and nervous symptoms called vibration syndrome (VS); moreover, the same subjects show increased prevalence of possible carpal tunnel syndrome (CTS). To determine the diagnostic criteria of both syndromes, we studied clinical and neurophysiological signs and differences in 18 patients with VS and in 18 with CTS; neither group had any other pathologic symptoms. Clinical symptoms clearly distinguished the 2 groups of patients: Raynaud's phenomena were mainly observed in patients with VS (83% of cases), whereas Tinel's sign was found exclusively in patients with CTS (56% of cases). Neurophysiological results were qualitatively similar in both patients groups compared to control group results, showing a significant decrease in median motor and sensory nerve conduction velocities (NCV), a significantly higher motor distal latency and a lower nerve action potential amplitude. These group results and the scattering of interindividual results did not allow us to classify any given patient in one group or the other. Nevertheless, statistical analysis showed differences between the 2 patient groups: median abnormalities were more severe, especially as revealed by the abductor pollicis brevis electromyogram, in patients with CTS, whereas ulnar motor distal latency and motor and sensory NCV were abnormal, exclusively in 50% of patients with VS. These results lend support to the assumption that the mechanical and vascular mechanisms responsible for lesions in both groups of patients may differ in nature or occur in a different sequence.
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Studies were carried out on 17 male workers with clinical vibration disease who had been working with different vibrating tools (compressed-air hammers, chain-saws, rock drills, grinders) for 2 to 39 years. Their neurophysiological results were compared with those of 20 healthy men (control group). Median motor nerve conduction velocity (NCV) between elbow and wrist was significantly reduced and motor distal latency (DL) significantly longer in 43% cases. A distinct decrease of the conduction velocity of distal (finger-wrist) median sensory fibers (in 56% of cases) as well as reduced amplitude of the sensory evoked potential (62% of cases) were found. EMG showed alterations only in patients with NCV abnormalities. These electrophysiological findings point to distal axonal as well as to demyelination damage. The results, which are discussed in relation to previously published work in this field and according to a pathogenetic hypothesis of this syndrome, allowed us to draw practical conclusions for the neurophysiological examination of patients with vibration disease.
Nerve conduction velocity (NCV), according to age, was studied in normal children. Motor distal ulnar NCV (in 63 children, from 1 day to 4 years of age), motor distal tibial NCV (in 93 children, from birth to 15 years of age), proprioceptive tibial NCV (in 59 children, from birth to 5 years of age) and proximal CV (in 133 children from birth to 15 years of age), as well as VIIth superior branch CV (in 67 children) and XIIth CV (in 56 children) from birth to 3 years of age, were measured. These measurements showed that NCV changes were similar; NCV was 45-50% of the adult value during the first month of life. Then NCV increased very quickly, the progression being 90% of the first month's value during the first 18 months of life. The adult value was reached between 2 and 5 years of age. Proprioceptive NCV was 8-13 m/sec higher than motor NCV; proximal NCV was also 10-13 m/sec higher than distal motor tibial NCV. Ulnar NCV remained higher than tibial NCV, although changes in velocity as a function of age remained parallel. These NCV measurements proved significant in some diseases. The were useful for diagnosis of Krabbe's disease or of metachromatic leucodystrophy and to calculate the degree of disturbance in toxic polyneuritis, polyradiculoneuritis and some cranial nerve injuries; they were also useful in following up children undergoing chronic haemodialysis. In each case, NCV was only one aspect of a more complete neurophysiological study.
The blink reflex was elicited in 50 children from birth to 3 years of age. In the awake state, the R1 response was always obtained; R2 responses, especially contralateral ones, were more difficult to elicit under 9 months of age. R1 latency and VIIth motor nerve conduction variations were a good witness of the peripheral nervous system maturation. The influence of the different states of waking and sleeping on these reflex responses was studied. These results and some of the mechanisms that underlie these changes are discussed.
A new method is described, to perform repeated measures of twitch and tetanic tensions during isometric contractions of the tail's extensor muscles, in anesthetized mice. The results obtained from 20 normal and 15 dystrophic (S57 BL/6J dy/dy) mice are presented. This method may be a good tool for long term therapeutic trials in dystrophic mice.
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We compared plasma-membrane proteins of dystrophic and normal mouse skeletal muscle. The membrane protein concentrations were higher in dystrophic muscle than in normal muscle. The percentages of two of the protein bands on an SDS gel were different in normal and dystrophic muscle. Isaxonine (N-isopropyl-amino-2 pyrimidine) phosphate significantly increased plasma-membrane proteins in dystrophic muscle but not in normal muscle. The relative proportions of these two protein bands of dystrophic plasma membrane were modified by isaxonine phosphate. There was no change in the membrane proteins of normal muscle.
Fifteen patients with Hodgkin's disease were examined before and after each administration of vincristine sulfate (2 intravenous injections of 1.4 mg/m2 of body surface, during the first week of each month for 3 months). Moreover, each patient received daily, according to a double blind protocol, either 4 capsules of 375 mg of isaxonine, either 4 capsules filled with lactose used as placebo. At the end of treatment, analysis revealed that 8 subjects were given isaxonine and 7 the placebo. Motor, sensory and reflex conduction velocities, amplitudes of potentials evoked by stimulating motor, cutaneous sensory, or primary afferent fibres, were determined in each electrophysiological examination session. The data and pecularly those obtained from reflex studies, show a significant lesser degree of distal axonal degeneration, in patients receiving a placebo. These results support evidence for a protective effect of the drug against vincristine induced peripheral nerve lesions.
Electrophysiological methods available for routine study of polyneuropathies are briefly described. From some typical cases, interpretation of results is exemplified and explained. The interest of electrophysiological explorations is pointed out in comparison to clinical and histological findings.
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The excitability of the monosynaptic reflex pathway was tested in infants and children from birth to four years of age during waking and sleeping. The H reflex, evoked in the soleus muscle, was used to calculate the ratio, maximal H to maximal M, construct recruitment curves and test reflex excitability by the paired stimulus method. The excitability of the monosynaptic reflex pathway during the waking state is greatest at birth; it diminishes gradually during the first years of life without reaching the average level observed in adults by the end of the fourth year of age. From birth, regardless of age, sleep always depresses excitability. The mechanism that underlie this change with age, and with waking or sleeping, are discussed.
Ten patients with Hodgkin's disease were examined before and after each administration of vincristine sulfate (2 intravenous injections of 1.4 mg/m2 of body surface during the first week of each month for 3 months). The motor conduction velocity of the peroneal nerve, the conduction velocity in palmar sensory fibres of the median nerve, and the conduction velocity in the H reflex pathway remained unchanged. The amplitude of distal muscle (extensor digitorum brevis) and sensory nerve (median) potentials decreased, while the maximal response of more proximal muscles (soleus) was not significantly modified. The soleus T response quickly decreased, although at the same time the H response was increased in the days following administration of vincristine. Thus the T/H ratio seems to be the only convenient electrophysiological method of evaluating the functional impairment of primary afferent distal segments. These results show that vincristine induces a transitory excitability enhancement of the monosynaptic reflex. It is suggested that the drug may cause an increase in the firing rate in proximal segments of injured Ia fibres. Apart from this phenomenon the electrophysiological results lead to the conclusion that vincristine induces distal axonal degeneration, similar to that in other toxic neuropathies (e.g. acrylamide or n-hexane) where a dying-back process has been clearly demonstrated.
Hoffman's reflex was evoked in the soleus muscle of 105 normal children from birth to age 5 years. This technique made it possible to determine conduction time and to estimate conduction velocity over the reflex arc. For 59 children, proprioceptive and motor distal nerve conduction velocities were calculated for the tibial nerve trunk. These measurements enabled the common changes for these three velocities to be described in terms of an exponential curve. Proximal conduction velocity has similar values to those of proprioceptive distal nerve fibres: it is always higher than motor nerve conduction velocity, but the difference gradually diminishes, remaining constant after the eighteenth month. Conduction time diminishes between birth and one year of age, whereas height increases. Then conduction time increases slowly, reaching at about age 5 years, when average height is 1050 mm, the value it had just after birth. For the child born at term, maturation of the nervous system is thus especially rapid during the first year of life.