[Significance of abnormally high somatosensory evoked potentials (SEV)]. / Signification des potentiels évoqués somesthésiques (PES) d'amplitude anormalement élevée.

Data found in the literature and our own observations prompted us to consider the possibility that abnormally enlarged Somatosensory Evoked Potentials (SEPs) may have a diagnostic and physiopathological significance, particularly in a group of diseases which include common clinical features of encephalopathy with stimuli-sensitive myoclonus and epilepsy, whatever their etiology may be (degenerative or storage disease, metabolic, toxic or post-hypoxic encephalopathy...). We discuss the amplitude, morphology, diagnostic and therapeutic contribution of these 'giant' SEPs and pathogenic assumptions with reference to 'cortical reflex myoclonus'. Studies of back-averaged encephalogram, SEPs and long-loop reflexes allow some illustration of a functional hyperreactivity of the sensori-motor cortex, but no conclusive demonstration of its origin.

[Changes in somatosensory evoked potentials during EEG activation by bemegride in man]. / Modifications des potentiels évoqués somesthésiques au cours de l'activation EEG par bémégride chez l'homme.

The use of evoked potentials for the evaluation of neuronal mechanisms by which convulsant drugs activate epilepsy and produce seizure has been reported by many authors. Electrophysiological effects of bemegride with augmented responsivity of brain structure to sensory stimulation is well known, especially in experiments performed with implanted electrodes in animals. After recording evoked activity from parietal scalp following median nerve stimulation before and during 12 human EEG activations by bemegride, the authors find an increase in amplitude of cortical somatosensory evoked potentials. Changes in amplitude after diazepam administration are analysed, as well as morphological changes preceding and following grand mal seizures induced by bemegride administration. This variation in amplitude of evoked responses is compared with those recorded in animals with several convulsant drugs and in man affected with progressive myoclonic encephalopathies. A common action of these agents, beyond their effects on specific neurotransmitters (perhaps mediated by a blockade of neurotransmitter-induced chloride conductance increases), is discussed.

[Electrophysiologic study of Achilles areflexia of aged subjects]. / Etude électrophysiologique de l'aréflexie achilléenne du sujet âgé.

The elderly often presents loss of Achilles tendon reflex. In this electrophysiological study the authors examined 19 patients with loss of the ankle jerk and with no known etiology of peripheral neuropathy. They compared them with 24 subjects who had no areflexia. The study included measurement of the H reflex, of the tendon reflex, of the conduction velocity of Ia fibers and of motor conduction velocity of the tibial nerve. Amplitude of H and tendon response and H/M ratio are diminished in the areflexic group. In 4 cases the H reflex is preserved while the tendon reflex is abolished. The meaning of these impairments is discussed.

[Contribution of electromyography to the study of ulnar nerve lesions in the hand. Compression syndrome of the motor branch of the ulnar nerve (author's transl)]. / Apport de l'électromyographie a l'étude des lésions nerveuses du nerf cubital a la main. Le syndrome de compression de la branche motrice du nerf cubital.

Standard electromyographic investigations: detection and stimulodetection; segmental motor nerve conduction rate, distal motor latencies (interphalangeal V and I short abductor muscles), and distal sensory (antidromic) conduction time, were used to explore seven cases of distal paralysis of the ulnar nerve. Results enabled differentiation of elective lesions of the deep motor branch from those of the ulnar nerve in Guyon's canal. These two types of lesion correspond to precise anatomical features: the channel between the pisiform and unciform bones on the one hand and Guyon's canal on the other. The electroclinical syndrome of the deep branch should be considered as a separate true canalicular syndrome. Treatment is by surgery in most cases.