Biomedical subjects
Publications and source records attributed to P Guiheneuc.
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.
We tried to appreciate the maturation of the peripheric nervous system, in children from two days to five years old, by electrophysiological technics. Hoffmann's monosynaptic reflex is recorded on the soleus muscle and conduction velocity is calculated on the motor tibial nerve. So, we can follow the conduction velocities on the proximal and distal part of this nerve, from birth to five years of life. The conduction velocities develop in a parallel and approximately exponential way. The proximal conduction velocity remains always faster than the distal one but their difference decreases during the first 18 months of life and then remains constant. The evolution of the proximal conduction velocity explains that the conduction time slightly but significantly decreases during the first year of life in contrast to the increase of the nerve length. So, during the first year of life, nervous system maturation gets on very quickly and anticipates the skeletal growth.
The Hoffmann monosynaptic reflex was recorded in the soleus muscle in 105 healthy children aged between 2 days and 5 years. From this the nerve conduction velocity in the proximal segment of the sciatic nerve was calculated. The tibial nerve conduction velocity (motor) was also measured in 59 of these children. The conduction velocity in the proximal and distal parts of the nerve develop in parallel and in an exponential manner but the conduction velocity in the reflex arc (afferent and efferent) is always faster than the motor conduction. Conduction time slightly but significantly decreases during the first year despite the increase in length of the nerve. Thereafter the conduction time slowly increases and by 5 years the values are similar to those in the neonatal period.
H reflex on the soleus muscle and motor tibial nerve conduction velocity are used to study peripheral nervous system maturation in 68 healthy children, from birth to 4 years of age. Proximal an distal conduction velocities develop in a parallel and approximately exponential way but proximal conduction velocities remain always faster. The latencies slightly decrease during the first 18 months of life and then increase very slowly.
The Hoffman (H) reflex of the soleus muscle has been used to study peripheral neurological disorders in 79 cases of chronic renal insufficiency prior to the initiation of haemodialysis, and in 94 cases of chronic alcoholism. In both groups, care was taken to ensure that the subjects examined could not be suspected of any other type of neuropathy. The results have been compared with those obtained in 42 normal subjects. The nerve conduction velocity in the reflex pathway was evaluated by an H index formula in which the conduction time (interval between M and H responses) is related to the length of the nervous pathway (a function of the subject's height). This method demonstrated a marked reduction in the conduction velocity of the proximal parts of the peripheral nerves, in both uraemic and alcoholic subjects. The maximal amplitude of the reflex response was evaluated in relation to the maximal amplitude of the direct motor response (H max/M max). It was shown that this ratio diminishes very greatly and very rapidly in the course of alcoholic polyneuritis, while, at comparable conduction velocities, the amplitude of the reflex response is much less changed in chronic renal insufficiency. These results prove that there is a noteworthy difference between uraemic and alcoholic polyneuropathy. Its significance is discussed in the context of currently knwon histopathological and electrophysiological data on the polyneuritides. From a practical point of view, the H reflex appears to be an effective tool for the investigation of peripheral neuropathy in man.
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The authors review critically a series of cases, followed up by the authors, of acrodynia and trophic ulcers occurring either in alcoholics (119 cases) or in diabetics (28 cases), who were also often alcoholic as well. The symptoms were similar in both groups. However, the poor nutrition was generally more market in the alcoholics. The trophic disorders were very similar, together with the sensory disorders. However, the deep sensitivity was less rarely involved in diabetics. Above all, the study of the rate of conduction of the motor nerve fibers showed axonal involvement in alcoholics and segmental demyelinisation in diabetics. The treatment was mainly dietary, together with proper hygiene and immobilisation of the foot.
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