Selective Activation of peripheral nerve fibre groups of different diameter by triangular shaped stimulus pulses

1. The differential block of cutaneous nerve fibres has been achieved with a simple method of electrical stimulation, employing a single pair of active electrodes. 2. The method allows the selective activation of 95% of small myelinated (delta) axons, without activation of the larger (beta) ones; and activation of unmyelinated (C) fibres, without A fibre activation. Asynchronous firing of myelinated axons was absent in the majority of the experiments. 3. The method employs triangularly shaped electrical pulses, with a steep rise front and a slow exponential decay. The outward flow of current at the cathode fires conducted impulses in both larger and smaller axons, and the inward flow inactivates differentially the conduction in the smaller ones. 4. The differential effect of anodal currents rests upon the greater internal conductance and greater conduction velocity of larger fibres. 5. The method has the advantage over the conventional polarization block of simpler surgical preparation, longer nerve survival and minimal latency distortion. However, it cannot be applied in experiments requiring physiological stimulation of peripheral receptors.

[An uncommon pseudo tumoral skin disease; the so-called Papillomatosis cutis carcinoides. A review (author's transl)]

The review of the current literature on the subject is followed by the exposure of the clinical and histopathological data concerning a case of papillomatosis cutis carcinoides. The Authors conclude on the opportunity to maintain this nosographic pattern, to be enclosed among the cutaneous pseudo tumoral affections.

[Relationship between circadian rhythms and blood pressure and the pathogenesis of cerebrovascular insufficiency]

Cerebrovascular accidents occur more frequently during the morning, less frequently during the night, whether due to thrombosis or embolism. In cases with hypertension, however, there have been noted a more uniform distribution of these complications throughout the day. The preponderance in the morning of the number of accidents in non-embolic subjects, depends probably on the state of the autonomic nervous system during the night, which gives rise to a dilated and hypotonic microcirculation. Autoregulation is, in this way, reduced and the physiological increase in blood pressure during the morning may induce a break through of autoregulation. In embolic subjects, on the other hand, an important role may be played by heart arrhythmias which occur usually during the waking hours. In hypertensives, the microcirculatory bed is restricted and cerebro-vascular resistance relatively constant. The brain, paradoxically, is thus better defended against any moderate increase in blood pressure and fluctuations in blood pressure throughout 24 hours, which may leave cerebral autoregulation unchanged, which probably explains the more uniform distribution of cerebro-vascular accidents throughout the 24 hour period.

Treatment of epileptic seizures with clonazepam. A reappraisal

The therapeutic efficacy of orally administered clonazepam has been evaluated in 32 epileptic patients, with substantial improvement in 22. The drug is active in all types of seizures, particularly in myoclonus, petit mal absences, and partial complex epilepsy; it seems the drug of choice in generalized infantile organic epilepsy, although the treatment of these patients is still unsatisfactory. In some patients, the drug seemed less effective after months of therapy. Drowsiness is the main side effect.

The tonic ambulatory foot response. A clinical and electromyographic study

Three cases with "pyramidal" symptoms in which standing and/or walking evoked a tonic flexion of the toes and sole of the affected foot, have been studied from the clinical and electrophysiological standpoint. The phenomenon, for which the definition of tonic ambulatory foot respone (TAFR) is proposed, appeared to be triggered by cutaneous stimuli travelling along fibres lying in the range of nociceptive afferents, and to depend on a background of complex sensorimotor patterns of standing posture and/or stepping movements against resistance. The relationship of TAFR to other flexor foot responses described in the literature is discussed.

C-fiber responses in the ventrolateral column of the cat spinal cord

Saphenous nerve C-fiber volleys generate, in the ventrolateral column of the cat spinal cord, a conducted postsynaptic response revealed by averaging the integrated temporally dispersed axonal discharges. This finding is compatible with the hypothesis that the feline ventrolateral column includes a major pathway related to nociception.