Stress-induced analgesia in humans: endogenous opioids and naloxone-reversible depression of pain reflexes.

The cumulative effects of a repetitive stress induced by anticipation of pain (noxious foot shock) were studied on the threshold of a nociceptive flexion reflex of the lower limb. The threshold of the nociceptive reflex progressively increased with the repetition of the stress. This effect was reversed by naloxone, which even produced hyperalgesia, since a rapid and significant decrease in this threshold, below the initial values, was noted. Tha data provide evidence for involvement of endogenous opioids in the phenomenon of stress-induced analgesia in normal man.

Imitation synkinesia and sensory control of movement.

Immitation synkinesia is usually associated with thalamic or parietal lesions. Analysis of three cases shows that the lesions may affect the posterior columns of the spinal cord or even the peripheral nervous system. In our cases, two facts stand out, a large measure of integrity of motor activity and predominant disturbances of lemniscal sensation. Imitation synkinesia should therefore not be seen as due to a lesion of a particular structure but to the disorganization of the lemniscal system at any level. Functional interconnection between the lemniscal and motor systems occurs only in the cerebral cortex. In the light of this fact, imitation synkinesia can be interpreted as the loss of particular functions in the principal cortical motor neurons.

Congenital insensitivity to pain and the "morphine-like" analgesic system.

Congenital insensitivity to pain remains without a satisfactory physiopathological explanation. In an electrophysiological study on a nociceptive flexion reflex of the lower limb, the effects of naloxone and of placebo were compared in 8 normal subjects and in a patient with congenital insensitivity to pain. In normal subjects, no significant change in the reflex threshold was observed with naloxone or with placebo. In contrast, two electrophysiological abnormalities characterized the patient: (1) spontaneous elevation in the nociceptive reflex threshold of 350% as compared to control, and (2) a large (67%) and rapid (2--3 min) fall of this threshold for about 10 min following the administration of naloxone. These results raise the problem of the relationship between congenital insensitivity to pain and an hyperactivity of a naturally occurring "morphine-like" pain-inhibitory system.

Respective importance of different electrophysiological parameters in alcoholic neuropathy.

An electrophysiological study of alcoholic and normal subjects is presented. The aim was to evaluate the respective importance of the various parameters. The subjects were divided into 4 groups: (I) normal subjects; (II) chronic alcoholics without clinical evidence of neuropathy; (III) chronic alcoholics with sensory symptoms; (IV) chronic alcoholics with both motor and sensory symptoms. The electrophysiological parameters tested were: conduction velocity (CV) in Ia sensory fibres, motor fibres, and cutaneous sensory fibres of the popliteal nerve, CV in the sural nerve, amplitude of the cutaneous sensory action potentials (SAP) in the sural and popliteal nerves, H reflex and M response of the soleus muscle, and electromyograms from the extensor digitorum brevis muscle. In the 3 groups of alcoholics, the electrophysiological findings were more abnormal than the clinical symptoms could have predicted. The more sensitive parameters were: (1) CV in the Ia sensory fibres of the popliteal nerve, which is slowed very early (in Group II) and (2) measurement of the amplitude of sural and popliteal SAP's which are also reduced early (in Group II). The nature of the mechanisms involved are discussed.

Magnetic resonance imaging of subacute myelopathy due to cobalamin deficiency.

A 77-year-old woman presented with rapidly ascending sensory ataxia. Magnetic resonance imaging (MRI) showed extensive involvement of the dorsal columns of the spinal cord. Hematological data were normal despite severe cobalamin deficiency. The contribution of magnetic resonance imaging in subacute degeneration of the spinal cord is discussed.

Hot-water epilepsy in an adult: ictal EEG, MRI and SPECT features.

Reflex epilepsy constitutes a rare form of epileptic seizures. We observed a 20-year-old man who presented with seizures induced by immersion in hot water. The trigger stimulus was specific. Contrast CT scan and MRI were all normal, not revealing any structural lesion. Ictal EEG recorded during a hot bath showed focal epileptic discharges in the left temporo-occipital area. Interictal SPECT showed a hypometabolism in the same cerebral region. Neuroimaging studies were rarely performed in this uncommon type of epilepsy. Nevertheless, in our case the result of the SPECT suggests a localized functional disturbance in the emergence of the disorder.

[Failure of voluntary eyelid closure, motor impersistence and hemispheric functional specialization. A report on 3 cases (author's transl)]. / Non fermeture volontaire des paupières, impersistance motrice et spécialisation fonctionnelle hémisphérique.

The impossibility of voluntary closing of the eyelids is usually reported in the published literature as being associated with bilateral cerebral lesions. In the three cases reported by the authors, this rare symptom was caused by unilateral lesions of the right hemisphere. The inability to close the eyelids voluntarily is, with these types of lesion, a transient sign which is rapidly replaced by difficulty in maintaining the consign. The physiopathology of motor impersistence (neglect of instructions), and of absence of voluntarily closing of the eyelids may be connected. Two associated mechanisms are discussed : preferential activation of the left hemisphere during a verbal consign and a fault in interhemispheric inhibition.

[Neurologic manifestations of the acquired immunodeficiency syndrome]. / Les manifestations neurologiques du syndrome d'immuno-dépression acquise (SIDA).

Recognition of the neurological symptoms and signs of the acquired immunodeficiency syndrome (AIDS) since 1982 has demonstrated the involvement of the nervous system in approximately one third of the cases. Certain opportunistic infections or tumors had been previously described in the course of immunodeficiency states of other origins: cerebral toxoplasmosis, cryptococcosis, progressive multifocal leukoencephalopathy, atypical mycobacteriosis and cerebral lymphoma. Other disorders such as subacute encephalitis raise specific etiopathogenic questions. Several of these affections can be associated or succeed each other and this is the natural course in AIDS. The detection of those conditions that are curable, among which toxoplasmosis, is of primary importance.

[Hemichorea, hemiballism disclosing non-ketotic hyperglycemia]. / Hémichorée, hémiballisme révélateurs d'une hyperglycémie sans cétose.

Non ketotic hyperglycemia is a metabolic disorder which can induce various hyperkinetic disorders. We report the case of a 74-year old woman admitted to hospital because of choreo-ballic movements of her left hemibody. Laboratory tests revealed non-ketotic hyperglycemia. CT scan showed an increased density in the right putamen and head of caudate. Magnetic resonance imaging disclosed a hyperintense signal involving the right putamen on T1-weighted images. On T2-weighted images, there was a slight hyperintensity in the right putamen and head of caudate. Correction of the underlying hyperglycemia led to complete resolution of abnormal movements. Pathophysiology of this clinicoradiologic syndrome is briefly discussed.

[H-reflex in the extensor digitorum brevis muscle: study in the normal subject and in latent alcoholic neuropathies]. / Le réflexe H du muscle pédieux: étude chez le sujet normal et au cours des neuropathies alcooliques latentes

A comparative electromyographic study was carried out in normal subjects (group I) and in alcoholics without clinical evidence of polyneuropathy (group II). -The H reflex of the extensor digitorum brevis muscle (E.D.B.), the electromyogram of EDB, the conduction velocity of the fasted motor fibers of the peroneal nerve (PN), the sensory conduction velocity and amplitude of the evoked potential of the cutaneous fibers of PN, the H reflex of the soleus muscle. -Two kinds of changes were observed in group II: --a significant increase in the latent period of H respones in EDB, in particular the latent period of responses provoked by distal stimulation of PN (+25 PER CENT); --A SIGNIFICANT DECREASE IN THE AMPLITUDe of the sensory potential of the PN(--46 per cent). The other parameters studied in group II did not show any significant difference in comparison with the control group. These results indicate that PN is involved early in a complex fashion in latent alcoholic neuropathies. They confirm that the distinction between axonal neuropathy and segmental demyelination is rarely absolute.

[Cerebrospinal fluid beta-endorphin in chronic pain in man]. / Bêta-endorphine du liquide céphalo-rachidien et douleurs chroniques chez l'homme.

Concentrations of beta-endorphin in the cerebrospinal fluid were measured in 21 painless subjects and 37 patients with chronic pain. Statistical analysis of the results showed no significant difference between the two groups. This lack of correlation between beta-endorphin concentrations in the CSF and the presence of chronic pain highlights the difficulties and limitations encountered when trying to determine the role of endogenous opioid systems with this method.

[Study of pain thresholds by recording flexor reflexes in thalamic syndromes]. / Etude du seuil de la douleur par enregistrement des réflexes de flexion au cours des syndromes thalamiques.

Both thresholds of nociceptive flexion reflex and pain sensation were studied in 6 normal subjects and in 6 patients with typical thalamic pain. In these patients, on the painful side, these thresholds were found increased (98 p. 100; 89 p. 100 respectively) compared to the normal side. Values obtained in this latter did not significantly differ from those observed in normal subjects. After 8 days of indalpine treatment, the nociceptive reflex threshold was furthered increased in the painful side while the pain threshold was not modified by this drug. In the normal side, changes observed after indalpine were similar to that obtained in normal subjects. All the indalpine-induced modifications were reversed by naloxone in both patients and normals. These results are discussed in the context of the possible mechanisms of thalamic hyperpathia.

[Electrophysiological analysis of the blink reflex during hemiplegia due to hemispheric lesions]. / Analyse électrophysiologique du réflexe de clignement (blink reflex) au cours de l'hémiplégie par lésions hémisphériques

Electrical stimulation of the supra-orbital nerve induces at the same threshold an early reflex reaction in the ipsilateral orbicular muscle and a delayed bilateral reflex response. These reflex activities are modified bilaterally by unilateral hemispheric lesions. Reactions on the hemiplegic side are reduced in amplitude, unlike the responses on the "healthy side" which are facilitated. Adaptation of the reflexogenous threshold of the delayed responses to repeated stimulation is also irregular; cumulative depression occurs earlier on the hemiplegic side, the responses on the "healthy side", on the other hand, show less habituation or a total absence of it. These electrophysiological findings agree with experimental results concerning the influence of cortical structures on the activity of the nuclei of the brain stem. They also, by analogy with the results of research carried out on the limbs, support the tactile origin of the two constituents of the blink reflex.

[Improvement of Joseph's disease with sulfamethazole-trimethoprim]. / Amélioration d'une maladie de Joseph par le sulfaméthoxazole-triméthoprime.

A case of Joseph's disease characterized by spasticity in all 4 limbs, dystonia and disorders of ocular motility was considerably improved by cotrimoxazole, which confirms a recently published case. Further studies are required to establish this therapeutic effectiveness.

[Electrophysiological study of cutaneous reflexes during avoidance reaction of the arms (author's transl)]. / Etude électrophysiologiques des réflexes cutanés au cours d'un phénomène d'évitement du membre supérieur.

Electrophysiological studies of the cutaneous reflexes during avoidance reaction of the arms demonstrate more particularly the presence of facilitation of late reflex responses and stimultaneous activation of flexor and extensor muscles. The avoidance reaction is not the inverse electrophysiological image of pathological prehension, as it produces, at least in one of its aspects, a much more fundamental modification of the segmental reflex systems of muscle contraction regulation. This motor disorganization is rarely observed, and could result from a disequilibrium between proprioceptive sensitivity and skin sensitivity: the loss of proprioceptive control would facilitate contact reactions.

[Cerebrospinal fluid beta-endorphin in congenital insensitivity to pain]. / Béta-endorphine du liquide céphalo-rachidien au cours de l'insensibilité congénitale à la douleur.

Spontaneously elevated nociceptive threshold levels were markedly diminished after Naloxone injections in 4 patients with congenital insensitivity to pain. This finding suggested the hypothesis of a relation between congenital insensitivity to pain and permanent hyperfunction of an endomorphinic system. Radio-immunoassay of CSF beta-endorphin was performed in all 4 cases. The normal or only slightly elevated levels cannot explain electrophysiologic findings, but as a function of the multiplicity of endogenous opioid systems, hyperactivity of another endomorphinic system cannot be excluded. Other hypotheses may also be proposed.

[A case of cerebral giant-cell angiitis associated with cerebral amyloid angiopathy. Favorable evolution with corticosteroid therapy]. / Un cas d'angéite cérébrale à cellules géantes associée à une angiopathie amyloïde cérébrale. Evolution favorable sous traitement corticoïde.

We report a biopsy proven case of cerebral giant cell angiitis associated with cerebral amyloid angiopathy. Clinical history and radiological lesions were rapidly progressive. The patient recovered with corticosteroid treatment. The pathogenesis relationship between angiitis and amyloid angiopathy are discussed.

[Insensitivity to pain: electrophysiological study of the nociceptive reflex. Influence of naloxone (author's transl)]. / Insensibilité à la douleur: étude électrophysiologique du réflexe nociceptif. Influence de la naloxone.

Electrophysiological studies of the nociceptive reflex (R3) were carried out in eight normal subjects, and one patient with congenital insensitivity to pain, in order to compare the effects of naloxone and a placebo. No significant variation in the reflex threshold was seen in the normal subjects. Two electrophysiological abnormalities were observed in the patient: a 350 per cent spontaneous elevation in the R3 threshold compared to the control group; a rapid and large drop (67 per cent) in the threshold lasting for about ten minutes after the injection of Naloxone. These results suggest that in this particular case the insensitivity to pain could be related to the permanent hyperactivity of a morphine-like inhibitory system.

[Motor evoked potentials]. / Potentiels évoqués moteurs.

Due to the motor evoked potentials recorded in limb muscles after transcranial and spinal magnetic stimulation, conduction in the central motor pathways can now be evaluated safely and painlessly in man. The central motor conduction time obtained includes the time required for transmission, along the fast pyramidal fibres, from the cortex to the spinal motoneurons, the synaptic transmission to motoneurons and the conduction on a short segment of the motor nerve root. Lengthening of this time almost always reflects dysfunction of the central motor pathways. The abnormalities observed are not specific of any particular cause, and they must be interpreted in relation to the context. The usefulness of this new electrophysiological technique is being tested by radiological and anatomico-clinical correlations in various diseases of the central nervous system (e.g. disseminated sclerosis, cerebral infarction, spinal cord injury) and the locomotor apparatus (e.g. cervical myelopathy, radiculopathy).

[Methodology for a controlled trial in Alzheimer's disease]. / Méthodologie d'un essai contrôlé dans la maladie d'Alzheimer.

The various evaluation scales available to study the clinical courses of Alzheimer-like dementias are controverted, and the practical aspects of a controlled trial are being considered. A tentative protocol has been designed, in which multiple individual assessments are combined with several validated scales and tests. This protocol would lend itself to a multicentre study, as it only includes evaluation tools that are easy to handle and do not require too much time. It should make it possible to select a relatively homogeneous group of patients and provide an opportunity to quantify the course of Alzheimer's disease over one year. In the discussion, emphasis is laid upon the foreseeable difficulty to evaluate a therapeutic benefit in our present imperfect knowledge of the natural history and prognostic factors of the disease.